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    AuthorTitleYearJournal/ProceedingsReftypeDOI/URL
    D.A. deAlwis, Z.M. Easton, H.E. Dahlke, W.D. Philpot & T.S. Steenhuis  Unsupervised classification of saturated areas using a time series of remotely sensed images 2007 Hydrol. Earth Syst. Sci.
    Vol. 11 , pp. 1609-1620 
    article URL   
    Anteneh Zewdie Abiy  Geological controls in the formations and expansions of gullies over hillslope hydrological processes in the Highlands of Ethiopia, northern Blue Nile region 2009 School: Cornell University  mastersthesis URL   
    Abstract: The Northern Blue Nile River source region shallow depth highly weathered and fractured flood basalt with several local structures and intrusive dykes. Volcanic morphological features and erosion has formed smaller watersheds that exist within the Blue Nile basin. The control of the flow behavior of both surface and subsurface water form a central pool for the sediment transported to the Sudanese plain. The objective of this study is to define the geologic controls of hydrological processes aiding in the formation and expansion of gullies along hill slopes in a micro watershed in the Blue Nile River source region. Twenty-four piezometers were installed, and soil hydrological behavior was studied in 17 ha of land in the Debremawi watershed. Geologic features of the watershed include shallow depth, highly weathered and fractured basalt, an impermeable layer and a local dyke. Layers of clay soil deposits are defined in the middle down slope area of the watershed. The basalt is exposed in the upper slope area and underlies most of the watershed, forming a fractured media aquifer. The impermeable layer consists of weathered silt sand clay pyroclastic fall that has formed a compacted layer at the surface on the up hill. The local intrusive basaltic dyke, located at the middle of the watershed and perpendicular to the flow direction, has significant effect on the local ground water table distribution. Clay soil covering the middle area of the watershed and overlying on the basalt layer confines the water in the fractured media aquifer. Different sites with saturation excess runoff and infiltration excess runoff are identified to be controlled by the combined effect of the local geological material and land use type. Water head upstream of the dyke is near or above surface, but it is at a considerable depth below the surface when downstream of the dyke. Local saturation zones are subject to pore water pressure development and landslides. Saturated area soils have little strength and result in soil slumps. High piezometric head and small scale earth movement are identified in relation to the confining effect of the clay layer. Topographically controlled saturation zones are also vulnerable to landslides and extensional soil cracking failures. The ultimate impact of the local geology control is subsurface erosion features (soil pipes and tunnels) that develop into gullies. Hence, land management practices should consider detailed studies of the local geologic materials and structures. Incorporation of subsurface drainage mechanisms with the usual soil and water conservation practices are of paramount importance for a better achievement in resolving the existing erosion and sedimentation problems. [[Ethiopia]]
    Meseret Belachew Addisie  Assessment of Drinking Water Quality and Determinants of Household Potable Water Consumption in Simada District, Ethiopia 2012 School: Cornell University  mastersthesis URL   
    Abstract: The current aim of the Ethiopia's Millennium Development Goal declaration is to alleviate poverty through improving the strategy of effective utilization of water supply sources. In order to achieve the goal, a priority area is providing adequate and quality water. The study was conducted in Simada District, Amhara Regional State, Ethiopia, where after considerable expansion of the water supply systems, people still rely on unimproved water sources that may be contaminated with waterborne diseases. The objective of the research was to investigate the reasons behind the use of unprotected sources in both urban and rural settings. Sixteen water points were selected. Three water points (that were functional) were located in urban areas, and the remaining 13 in rural areas ranged from nonoperational to completely functional. Forty four households were interviewed in the urban area and 116 in the rural area, covering water consumption behavior, perception of water source quality, and factors determining use. Water quality was determined at 11 selected water points representing both improved and unimproved sources.

    In the urban areas people were generally satisfied with the water services provided by the municipality because the water quality was good and walking distances were short. The water cost was considered high especially for the poor who could not afford the cost and therefore used alternative unprotected services. In response, the municipality recently lowered the cost. . In other cases, because most of the systems were only a few years old, some people were not adjusted to taste and went back to the original, lower quality water sources. On some days, waiting times were too long, forcing some people to use a more distant, unimproved source.

    In contrast, more people in the rural areas did not use the constructed water points because of the quality of water, adequacy, distance and longer waiting times. Systems had broken down or failed for several reasons, the main one being that a functional organization did not exist within the community to manage the water supply. Other people who were dissatisfied did not like the taste of the water, could not pay for the water services and therefore sought out alternative unimproved sources.

    Sanitation coverage in urban areas was much less than that in rural areas where more extension and promotion has been conducted. Construction of latrines without waste decomposition or removal mechanisms service and the habit of open defecation were common problems especially in urban peripheries.

    L.J. Agnew, S. Lyon, P. Gérard-Marchant, V.B. Collins, A.J. Lembo, T.S. Steenhuis & M.T. Walter.  Identifying Hydrologically Sensitive Areas: Bridging the Gap Between Science and Application 2006 Journal of Environmental Management
    Vol. 78(1) , pp. 63-76 
    article URL   
    M.S. Akhtar, B.K. Richards, P.A. Medrano, M. DeGroot & T.S. Steenhuis  Dissolved phosphorus from undisturbed soil cores: Related to adsorption strength, flow rate, or soil structure? 2003 Soil Science Society of America Journal
    Vol. 67 , pp. 458-470 
    article URL   
    M.S. Akhtar, T.S. Steenhuis, B.K. Richards & M.B. McBride  Chloride and lithium transport in large arrays of undisturbed silt loam and sandy loam soil columns 2003 Vadose Zone J.
    Vol. 2 , pp. 715-727 
    article URL   
    Zemenu Awoke Alemeyehu  Assessment of Challenges of Sustainable Rural Water Supply: Quarit Woreda, Amhara Region 2012 School: Cornell University  mastersthesis URL   
    Abstract: Sustainability of water supplies is a key challenge, both in terms of water resources and service delivery. The United Nations International Children’s Fund (UNICEF) estimates that one third of rural water supplies in sub-Saharan Africa are non- operational at any given time. Consequently, the objective of this study is to identify the main challenges to sustainable rural water supply systems by evaluating and comparing functional and non-functional systems. The study was carried out in Quarit Woreda located in West Gojjam, Amhara Region, Ethiopia. A total of 217 water supply points (169 hand-dug wells and 50 natural protected springs) were constructed in the years 2005 to 2009. Of these water points, 184 were functional and 33 were non-functional. Twelve water supply systems (six functional and six non-functional) among these systems were selected. A household survey concerning the demand responsiveness of projects, water use practices, construction quality, financial management and their level of satisfaction was conducted at 180 households. All surveyed water projects were initiated by the community and the almost all of the potential users contributed money and labor towards the construction of the water supply point. One of the main differences between the functional and non-functional system was the involvement of the local leaders. In the functional systems nearly half of the local leaders were involved in the initiation of the project and selection of the location of the water point while this was less that 15% for the currently non- functioning systems. Since, there was an inverse relationship between the involvement of local leaders and the quality of workmanship of the water point, and since Woreda offices are greatly understaffed, local leaders form the focal point of the community to interact and supervise the work with the contractor and organize the community. Another interesting finding was that more than three quarters of the users in the non- functional systems did not have the means to pay for the water services while payments was a problem for less than one third for the users in the functional systems indicating that ability how to pay for the maintenance should be an important consideration for the donors. In addition participation of woman was less in the non-functional systems in the study area.
    Thus a general held belief that the community involvement during initiation and construction of the water supply system is most crucial factor in the success of a water supply system does not seem to be important factor in the Quarit Woreda, but instead the organization of the community by having an effective local leader to interact with the contractor and Quarit personnel is important factor as well having the means to afford the payments for maintenance for a water supply system.
    Tilashwork Chanie Alemie  The effect of Eucalyptus on crop productivity, and soil properties in the Koga watershed, western Amhara region, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: This study was conducted at the Koga Watershed in the Western Amhara region of Ethiopia. The main objective of the study was to observe if the Eucalyptus plantation is harmful for the ecosystem. The study through key informants? interview proved that almost all local farmers perceive that Eucalyptus trees are exhausting the once productive land because of its fast growth. Water points dried up, too. Despite this, the growers insist on planting Eucalyptus because of its fast biomass production to sell it after relative short time for cash income and use in construction. A triplicate experiment was established to understand the effect of Eucalyptus on soil properties, crop production and water bodies. Its effect was compared to other land uses such as Croton macrostachyus border plantation along maize farm (regarding soil bulk density, moisture content and maize plant count and height) and coffee garden (concerning undergrowth density). There were no pronounced changes in soil bulk density, organic matter, texture, pH, exchangeable potassium and available water capacity due to Eucalyptus hedgerows along maize farmland. Eucalyptus trees significantly affect available phosphorus (avail. P), exchangeable calcium (exch. Ca), total nitrogen (TN), moisture content (MC), soil hydrophobicity, light intensity and the density of the undergrowth. At 5 m distance from Eucalyptus stand, there were the greatest reductions of values of avail. P (3.5 mg kg-1), TN (0.1 %) and MC at maize maturity stage (8.7 %) compared to the not affected soil at 40 m away from the Eucalyptus trees. In addition, the exch. Ca value at 1 m distance was most reduced and was decreased by 4.1 (cmol (+) kg soil-1) compared to the control. The top dried field soils at 0 to 220 cm distances were water repellent since the water drop penetration time values were greater than 5 seconds. Moreover, Eucalyptus canopy intercepted 64.5 to 1579 lux of the light intensity resulting in poor performance of maize plants under its shade. Plant height, yield, biomass and count decreased with distance to Eucalyptus trees. This was not the case for Croton macrostachyus. The yield reduction was in the range of 4.9 to 13.5 ton ha-1. Furthermore, the undergrowth density of Eucalyptus was almost nil (24787 No.ha-1) as compared to that of coffee garden shade (171102 No.ha-1). Altogether, our findings lead to a conclusion that Eucalyptus plantation has a negative effect on sustainable cropping, soil, and water conservation systems by decreasing TN, avail. P and exch. Ca through plant uptake, lowering the soil moisture content both by its dense root system and by making the soil hydrophobic and taking light away from the crop due to its dense and long canopy. It has also been reported by local farmers that the dense Eucalyptus root network lowers water tables and dries up springs. [[Ethiopia]]
    Hussien Ali, Katrien Descheemaeker, Tammo S. Steenhuis & Suraj Pandey  Comparison of Landuse and Landcover Changes, Drivers and Impacts for a Moisture-Sufficient and Drought-Prone Region in the Ethiopian Highlands. 2011 Expl. Agric.
    Vol. 47(SI) , pp. 71-83 
    article DOI   
    Abstract: Land use and land cover changes are driven by human actions and, in turn, drive changes that alter the availability of products and services for people and livestock. For proper planning, these cause-and-effect interrelations need to be understood. This is especially important for Ethiopia where the resource base is declining and should be improved in order to feed the growing population. To better understand these interrelations, we studied trends in the natural resource base over a 35-year period for two contrasting sites in the Ethiopian Highlands: semi-arid and water-short Lenche Dima, and sub-humid and moisture-sufficient Kuhar Michael. Information was obtained using time-series satellite images, geographical positioning system, a socio-economic survey and a document review. Results showed that for sub-arid Lenche Dima there were minimal changes in land use and land cover patterns, while in water-sufficient Kuhar Michael cropland greatly increased at the expense of the grazing land and bare soil. At the same time land holding size and cattle numbers decreased in Lenche Dima while they remained the same in Kuhar Michael, although overall land holdings remained larger in Lenche Dima than in Kuhar Michael. This study thus found large differences in development of agriculture since the 1970s: intensification of agriculture is possible in the water-sufficient sub-humid climate by displacing animal husbandry with high value crops that need irrigation during the dry monsoon season. This is not possible for the semi-arid area where water is the limiting factor in production even if a market is close by. Agriculture in the semi-arid areas also requires larger land holdings because of the risk of droughts and low yields during some years. This comparative analysis suggests that without sufficient water, the shift from subsistent to commercial market-driven agriculture cannot be easily accomplished.
    M.S. Andreini & T.S. Steenhuis  Preferential Paths of Flow under Conventional and Conservation Tillage. 1990 Geoderma
    Vol. 46 , pp. 85-102 
    article   
    Biniam Biruk Ashagre  SWAT to identify watershed management options: (Anjeni watershed, Blue Nile basin, Ethiopia) 2009 School: Cornell University  mastersthesis URL   
    Abstract: Ethiopia is known for its wealth of natural resources. These result in part from extreme elevation variation. However, 5,000 years of land cultivation have degraded large areas of the natural environment. Soil erosion affects 82% of the country. The rich highland soil, which supports 80% of the total population, only covers 45% of the country. In these highlands the soil is becoming less fertile; droughts are more frequent and intense; and water resources are declining, due in part to the soil erosion. The Anjeni watershed is located in the highlands in the Blue Nile Basin with an annual soil loss of 18.33 tons/year/ha. The existence of soil erosion in a watershed is an indication of unsustainable land management practices. The objective of this study was to formulate sustainable land management options that alleviate soil erosion in the Anjeni watershed. The SWATWB model that simulates saturation excess flow was applied, and the result showed that the Anjeni watershed is dominated by saturated excess flow from the shallow soils rather than infiltration excess flow. The conventional SWAT model uses the SCScurve number method which considers only infiltration excess flow. In contrast, the SWAT-WB model simulates saturation excess flow in order to determine surface runoff. Hence, SWAT-WB was used to investigate the flow and sediment processes in the watershed and to compare different potential land management options to alleviate soil erosion. The model SWAT-WB was calibrated for flow and performed well with a coefficient of determination (R2) of 0.92 and Nash-Sutcliffe coefficient (ENS) of 0.91. The model also performed well in simulating soil erosion on a monthly basis with the coefficient of determination of 0.56 and the Nash-Sutcliffe coefficient of 0.55. The relatively poorer performance of the model in simulating soil erosion can be attributed to a gully in the watershed possibly contributing 30% of the annual soil loss from the watershed. Model simulation suggests that the existing terraces are saving 2,046 tons/year of soil loss. If further terraces are constructed, they could save an additional 932 tons/year. Forestation of degraded areas and bush lands was found to reduce soil erosion by 333 tons/year. Zero-tillage technique for all fields except those covered with teff in the watershed reduces erosion by only 45 tons/year. If gully rehabilitation work with a 90% erosion control practice is implemented in gullies, an additional 300 tons/year would be saved. Combining foresting degraded lands and bush lands with rehabilitation of gullies in Anjeni watershed is predicted to reduce soil loss from the watershed by 630 tons/year. The impact of further construction of terraces on productivity and its effect on the overall hydrological balance should be experimentally investigated before being implemented and if it shows a significant change, it can be practiced with some measures and innovations on the water availability during the dry season. [[Ethiopia]]
    Seleshi Bekele Awulachew, Matthew McCartney, Tammo S. Steenhuis & Abdalla A. Ahmed  A review of hydrology, sediment and water resource use in the Blue Nile Basin 2008 (Working Paper 131)   techreport URL   
    Abstract: This report presents a comprehensive literature review and broad-based analysis of the water
    resources of the Blue Nile (Abay) River. This work was undertaken as the initial phase in a study
    to evaluate approaches for improved land and water management in the Ethiopian highlands and
    assess the likely implications for downstream stakeholders in Sudan. Data and information have
    been compiled in relation to hydrology, sediment and water use in the basin. Section 1, Introduction,
    provides a context through the consideration of water resources both in Africa and the whole of the
    Nile Basin. Section 2, Blue Nile Physiography, presents an overview of the characteristics of the
    Blue Nile Basin, including a description of the meteorological monitoring network and the availability
    of historic data. It also reviews the geology, soil and land-use, and land-cover of the basin based
    on secondary sources. Section 3, Hydrology of the Blue Nile, describes the hydrology of the Blue
    Nile, including seasonal variation and trends over time. A summary of past hydrological modeling
    in the Nile and the Blue Nile is also presented. Section 4, Soil Erosion and Sedimentation, focuses
    on erosion and sediment transport and presents an overview of sediment in the major tributaries,
    including seasonal variations and trends over time. Section 5, Water Resource Development, reviews
    existing water resource development in both Ethiopia and Sudan and discusses the future potential
    with respect to major water uses (i.e., irrigation and hydropower). Section 6, Discussion/
    Recommendations, provides a summary of the research methods and models to be used in the study.
    The reference materials collated and listed at the end of this report provide an important resource
    for water management and future research to be undertaken in the basin.
    Seleshi B. Awulachew, M. Tenaw, T.S. Steenhuis, Z.M. Easton, Abdassalam Ahmed, K.E. Bashar & A. Hailesellassie Impact of watershed interventions on runoff and sedimentation in Gumera watershed, Ethiopia  2010 (in press)   inbook   
    Yidnekachew Ewnetu Ayalew  Irrigation, Food Production and Consumption Pattern in Smallholder Rural Households 2009 School: Cornell University  mastersthesis URL   
    Abstract: Conceptually, the benefits of irrigation are realized through improvements in agricultural productivity. At household level, the agricultural production increases could be followed by improvements in food consumption patterns. The goal of this thesis is to examine the relationship between irrigation, food production and household consumption patterns for the rural smallholders. A survey was undertaken and information was collected on demographics, landholdings and agriculture, irrigation, returns of crop cultivation, consumption behaviors, farmer perceptions and experiences, and other related variables. The results show that the addition of irrigation to the overall production system increases the agricultural income of households but the amounts spend on food for each household did not increase as consequence. However better dietary diversity was found on the consumption pattern of the irrigated households with higher income. Integrated approaches are needed to secure a healthy diet when the food supply of the family is increasing. [[Ethiopia]]
    Essayas Kaba Ayana  Remote Sensing Tools for Land and Water Management in Data Scarce Blue Nile Basin 2013 School: Cornell University  phdthesis URL   
    Abstract: Ground based water resources monitoring systems are often difficult to maintain consistently in developing countries. The decline in the number of stations, data quality and changes in the data holding policy has made water resources data less reliable for use in operational purposes. The objective of this dissertation is, therefore, to evaluate the utility of existing freely available remotely sensed images to monitor water resource systems. In this dissertation Moderate Resolution Imaging Spectroradiometer (MODIS) images were evaluated on the basis of their capability to (1) measure total suspended solid (TSS) and turbidity and generate historical TSS data, (2) estimate the water storage variation of Lake Tana and (3) monitor the state of biomass in the upper Blue Nile basin . The usability of historical TSS data in hydrologic modeling is also tested. Lake water samples were collected concurrent with the satellite overpass over the lake at the entry location of Gumera River, a major tributary to the lake. Reflectance in the red and near infrared (NIR) 250 m-pixel images taken on sampling days were correlated and validated using measured TSS and turbidity. The validated correlations were applied to the ten year image archive of MODIS to generate a 10-year TSS time series for the lake. In addition, MODIS images of the years 2002 – 2003, where the lake level variation was at its minimum, were used to generate the lake near-shore bathymetric model. The new near-shore bathymetric model reproduced water level measurements with a better accuracy than the existing bathymetric model of the lake.

    The usability of the TSS data was tested by initializing a hydrologic model for the Gumera watershed using the Soil and Water Assessment Tool (SWAT). The ten year TSS data generated were used to calibrate the model. The model was capable of predicting the monthly TSS variation. The potential of MODIS images in monitoring biomass recovery was also assessed at river basin scale. The enhanced vegetation index (EVI) – land surface temperature (LST) relation is used to map the trend in the disturbance of plantations put in place as conservation measures. In this dissertation the potential of satellite imagery as a data gap filling alternative to ground based monitoring systems in data scarce regions is tested.

    [Ethiopia]

    Getaneh Kebede Ayele  The Impact of Selected Small-Scale Irrigation Schemes on Household Income and the Likelihood of Poverty in the Lake Tana Basin of Ethiopia 2011 School: Cornell University  mastersthesis URL   
    Abstract: Poverty reduction has been largely a result of economic growth. The economic growth and extent of poverty in Ethiopia are determined primarily by the growth of agriculture because agriculture is the largest component of the economy. One of the major factors behind the weak performance of Ethiopian agriculture is lack of adequate rainfall, combined with variability in the onset and duration of rainfall. Irrigation development is one approach to address this problem, and it has been given significant attention in economic development programs in the country. This study examines the impact of selected small-scale irrigation schemes on crops grown, total income, and the likelihood of poverty at household level for a particular region.

    A survey of 180 randomly-selected household heads, semi-structured interviews and focus group discussions were undertaken in Fogera District, Tana basin, Ethiopia to assess irrigation impacts. Descriptive statistics and econometric modeling were used to assess the impacts of irrigation on household income and the likelihood of a household being classified as poor. The research reported herein had five major objectives. The first objective was to identify the major field crops and vegetables grown using small-scale irrigation in the study area. The main field crops grown using small-scale irrigation schemes in the study region are maize, oat, rice and vetch and the dominant vegetables are onion, tomato, potato and pepper. Onion production was the most important source of income from crops grown with irrigation.

    The second objective was to compare the relative advantages of four types of small-scale irrigation system, with emphasis on household gross income. Farmers using concrete canal river/spring diversion had higher mean cropping income per household on average than other irrigation types. Statistically significant differences were found between the household concrete canal river/spring diversion and
    traditional river diversion and pedal pump irrigation systems, but no significant difference exists between concrete river/spring diversion and motor pump, nor between traditional river diversion and pedal pump. Households using any of the four irrigation systems had statistically significantly higher mean gross household income than households not using irrigation.

    A third objective was to estimate the marginal impact of small-scale irrigation on gross household income controlling for other important factors that affect income. A censored regression model developed for this objective indicated that access to small–scale irrigation increased mean annual household income significantly (about ETB 3,353 per year, or a 27 % increase over non-irrigating households).

    The fourth objective of this research was to assess the impact of irrigation access on the likelihood of poverty. Descriptive analysis suggested that irrigating households had a lower probability of being poor than non-irrigating households: of households in the lowest quartile of income, only 12% were irrigating households and the remaining 88 % did not irrigate. A Logit regression model developed to assess the impact of irrigation on the likelihood of poverty controlling for other factors indicated that access to irrigation significantly reduced the odds that a household would be in the lowest quartile of household income, the key poverty threshold used in this study.

    A final objective was to examine the major problems encountered in the use of the small-scale irrigation systems. These were identified by farmers and development agents as: lack of access to surface water, loss of water through seepage, problem of irrigation water distribution, lack of spare parts for water pumps, high cost of fuel for water pumps, lack of market transparency and marketing facilities, crop disease, and the perceived high cost of inputs.

    Getaneh K. Ayele, Charles F. Nicholson, Amy S.Collick, Seifu A.Tilahun & Tammo S. Steenhuis  The impact of small-scale irrigation schemes on household income and the likelihood of poverty in the Lake Tana basin of Ethiopia 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings   
    Abstract: This study uses Tobit and Logit models to examine the impacts of selected small-­scale irrigation schemes in the Lake Tana basin of Ethiopia on household income and the likelihood of poverty, respectively. Data for these analyses were collected from a sample of 180 households. Households using any of the four irrigation systems had statistically significantly higher mean total gross household income than households not using irrigation. The marginal impact of small-­scale irrigation on gross household income indicated that each small scale-­irrigation user increased mean annual household income by ETB 3,353 per year, a 27 % increase over income for non-­irrigating households. A Logit regression model indicated that access to irrigation significantly reduced the odds that a household would be in the lowest quartile of household income, the poverty threshold used in this study. Households using concrete canal river/spring diversion had higher mean cropping income per household than those using other irrigation types. Key challenges to further enhancing the benefits of irrigation in the region include water seepage, equity of water distribution, availability of irrigation equipment, marketing of irrigated crops and crop diseases facilitated by irrigation practices.
    D.A. Barry, J.Y. Parlange, L. Li, D.S. Jeng & M. Crapper  Green-Ampt Approximations 2005 Advances in Water Resources
    Vol. 28(10) , pp. 1003-1009 
    article   
    D.A. Barry, J.Y. Parlange, L. Li, D.S. Jeng & D.A. Lockington  Discussion of "Improved Decomposition Solution to Green and Ampt Equation" By Sergio E. Serrano - May/june 2003, Vol. 8, No. 3, Pp. 158-160. 2005 Journal of Hydrologic Engineering
    Vol. 10(5) , pp. 433-434 
    article   
    D.A. Barry, J.Y. Parlange, L. Li, D.S. Jeng, F. Stagnitti & D.A. Lockington  Discussion of "Modeling Groundwater Flow Under Transient Nonlinear Free Surface," By Sergio E. Serrano - May/june 2003, Vol. 8, No. 3, Pp. 123-132. 2005 Journal of Hydrologic Engineering
    Vol. 10(5) , pp. 428-429 
    article   
    T.W.J. Bauters, D.A. DiCarlo, T.S. Steenhuis & J. Y Parlange  Soil water content dependent wetting front charachteristics in sands. 2000 Journal of Hydrology
    Vol. 231-232 , pp. 244-254 
    article URL   
    T.W.J. Bauters, D.A. DiCarlo, T.S. Steenhuis & J.Y. Parlange  Preferential flow in Water Repellent Sands 1998 Soil Science Society of America J.
    Vol. 62 , pp. 1185-1190 
    article URL   
    T.W.J. Bauters, T.S. Steenhuis, D.A. DiCarlo, J.L. Nieber, L.W. Dekker, C.J. Ritsema, J. Y Parlange & R. Haverkamp  Physics of water repellent soils 2000 Journal of Hydrology
    Vol. 231-232 , pp. 233-243 
    article URL   
    Christine E. Baver  Dynamic Contact Angles and Wetting Front Instability in Soils 2013 School: Cornell University  mastersthesis URL   
    Abstract: Dynamic contact could provide a mechanism for initiating the instability of wetting fronts
    and the formation of gravity fingers/columns in porous media. To study those dynamic contact
    angles when gravity effects are present, rectangular capillary tubes are used to facilitate the
    observation of the complete interface without geometric distortion. Results show that if the
    dynamic contact angle minus the static contact angle is used, we obtain good agreement with
    previous observations. In addition, we show that in our experiments, unlike previous
    observations, contact angles are independent of capillary size. It also points out a way to
    calculate the capillary pressure at the wetting front as a function of the flux in the finger and
    grain size diameter.
    P. Baveye, C.W. Boast, S. Ogawa, J.Y. Parlange & T.S. Steenhuis  Influence of image resolution and thresholding on the apparent mass fractal characteristics of preferential flow patterns in field soils. 1998 Water Resources Research
    Vol. 34(11) , pp. 2783-2796 
    article URL   
    P. Baveye, J.Y. Parlange & B. Stewart Fractals in soil science  1998 In: Philippe Baveye, Jean-Yves Parlange & Bobby Stewart. Advances in Soil Science  inbook   
    Haimanote Kebede Bayabil  Modeling rainfall-runoff relationships and assessing impacts of soil conservation research program intervention on soil physical and chemical properties at Maybar research unit, Wollo, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: This study focuses on characterizing subsurface water flow and ground water table fluctuations in response to rainfall that leads to saturation excess runoff, the basic principle of variable source area hydrology. In particular, this study concentrates to develop a model that efficiently simulates the location of saturated runoff areas and predict river discharge, which finally could help in realistic planning of watershed interventions. Furthermore, the study assesses the impact of soil conservation research program intervention on selected physical and chemical soil properties of the study area. Long-term discharge and rainfall data was available at the watershed outlet and for four test plots. In addition, 29 piezometers were installed in 2008 and water table measurements were taken during the main rainy season. Based on major runoff mechanisms identified at the catchment-level, a conceptual rainfall-runoff model was developed to compute runoff. The model incorporates saturated excess overland flow from both bottomlands and subsoil exposed areas and baseflow and interflow from the hillsides. The model was tested on a daily, weekly, and monthly basis and fitted well the discharge data at the bottom of the watershed. In addition, the distributed model output agreed well with the ground water table measurements. The watershed was saturated (and produced runoff) in the flat areas near the river while the hillsides were unsaturated with a perched water table that responded rapidly to rainfall. Data from test plots showed that flatter areas produced more runoff than test plots at steeper slope areas. The model has potential to predict runoff in ungauged basins but should be further tested to do so. On the other hand, soil samples were tested for selected physical and chemical properties. The result indicated that AP and % OC contents of the soil were found in lower amount than before/early project intervention period, while the Db value has shown an increase. [[Ethiopia]]
    Haimanote K. Bayabil, Johannes C. Lehmann, Birru Yitaferu, Cathelijne Stoof & Tammo S. Steenhuis  Hydraulic properties of clay soils as affected by biochar and charcoal amendments. 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings   
    Abstract: Understanding soil hydraulic properties is crucial for planning effective soil and water management practices. A study was conducted to evaluate the effects of different biochar and charcoal treatments on soil-hydraulic properties of agricultural soils. Biochar and charcoal treatments were applied on 54, undisturbed soil-columns, extracted from three-elevation ranges, with replications along three transects. Daily weight losses of freely draining
    soil-columns and soil moisture contents, at five tensions, were measured. In addition, field infiltration tests and soil analyses for particle size distribution, bulk-density, and organic carbon content were conducted. Moreover, five-year event precipitation data, from the watershed, was analyzed and exceedance probability of rainfall intensity was computed. Results show treatments reduced soil moisture contents, for most of the cases. However, treatment effects were significant only at lower tensions (10 and 30 kPa) and within two days after saturation (p<0.05). On the other hand, relative hydraulic conductivity (Kr) coefficients, near saturation, of amended soils were higher than the control. Acidic to moderately acidic soils with high average clay (42%) and low organic carbon contents (1.1%) were dominant. Infiltration rate ranged between 1.9 and 36mm/h, with high variability (CV = 70%). At the same time, storms with short duration (< 15 min) and high average intensity (6.3 mm/h) contributed for 68% of annual precipitation (1616mm/yr). Dominant soil properties and rainfall characteristics suggest that infiltration could be a major problem on considerable number of fields, in the watershed. This implies, on such fields, constructing physical soil & water conservation structures alone will not reduce runoff and erosion effectively, unless soil infiltration and permeability rates are enhanced through integrated soil management approaches.
    Haimanote K. Bayabil, Johannes C. Lehmann, Birru Yitaferu, Cathelijne Stoof & Tammo S. Steenhuis  Spatial Variability of Soil Physical and Hydraulic Properties Affecting Runoff
    and Moisture Retention Characteristics of Tropical Soils: The Case of Anjeni
    Watershed
    2013 Proceedings of the International Conference on Science and Technology towards the Development of East Africa (ICST 2013), pp. 300-310  inproceedings   
    Abstract: Considering spatial variability of soil physical and hydraulic properties, which
    determine rainfall partitioning into infiltration and direct runoff, as well as moisture retention within
    the soil layer is crucial for effective soil and water management planning. Field and laboratory studies
    were conducted to assess spatial variability of selected soil physical and hydraulic properties:
    infiltration rate, soil-depth, particle distribution, bulk-density, organic-carbon, and organic matter
    contents. Spatial prediction maps, of selected soil parameters, were created using Ordinary-kriging
    interpolation technique. In addition, five-year (1989-1993) event rainfall and river flow data was
    analyzed and runoff threshold values were estimated. Moreover, effects of organic soil amendments
    (biochar and charcoal) on drainage and moisture retention characteristics of saturated soil-columns
    were studied. Results show that spatial variability of soil properties were high; particularly 70 and
    54% coefficients of variation were observed with infiltration and soil-depth data. Infiltration rate and
    soil depth were less than their respective median values (8.9mm/h and 90cm) on 52 and 68% of the
    total watershed area respectively. Clay soil textural class was dominant, with clay percentages greater
    than 35% for 78% of total soil samples. In addition, organic carbon and organic matter contents were
    low, with averages 1.08 and 1.86% respectively. On the other hand, rainfall events of short duration
    (<15min) with high average intensity (7.3mm/h) were predominant; on average contributed for 76%
    of annual precipitation. Moreover, mostly runoff threshold values were small (<20mm). Overlaying
    spatial prediction maps of infiltration rate, soil depth and clay percentage showed that soils with poor
    physical and hydraulic attributes cover 24.2% of the total watershed area. In agreement with this, the
    probability of rainfall intensity to exceed the median infiltration rate (8.9mm/h) was 21%. Combining
    these findings suggests infiltration rate could be a major constraint on 21-24% of the watershed area.
    This implies constructing physical soil and water conservation structures only will not reduce runoff
    from these fields; rather increasing soil infiltration rates, through integrated soil management
    approaches, will be effective. In light of this, amending soils with biochar and charcoal significantly
    increased moisture release rates and drainage of saturated soil-columns at lower tensions (10kPa and
    30kPa) and for the first three days after saturation (p<0.05). However, it should be also noted that
    increasing infiltration rates at a watershed scale does not mean total catchment runoff would be
    reduced.
    Haimanote K. Bayabil, Seifu A. Tilahun, A.S. Collick & T.S. Steenhuis  Are Runoff Processes Ecologically or Topographically Driven in the (Sub) Humid Ethiopian Highlands? The Case of the Mayabar Watershed 2010 Ecohydrology
    Vol. 3 , pp. 457-466 
    article DOI URL   
    Abstract: Understanding the basic runoff processes in the Ethiopian highlands is vital for effective management and utilization of water resources and soil conservation planning. An important question for judging the effectiveness of conservation practices is whether runoff is affected by ecology (mainly type of crop) or topography (landscape). A study was conducted in the 113 ha watershed of Maybar, located in the highlands. This watershed has long-term records of rainfall and discharge. To study runoff processes, piezometers were installed in eight transects up and down the slope. In addition, infiltration rates (measured earlier) were compared with rainfall intensities. The results show that the amount of runoff at the test plots was greater for cropland located on mild to intermediate slopes than for grasslands and woodlands on the steeper slopes. Water tables were closer to the surface on cropland for the mild to intermediate slopes than on grasslands and in woodlands for the steeper slopes. Thus, although water table depths and plot runoff were inconclusive on the type of runoff mechanisms, infiltration rates that were generally in excess of the rainfall rates imply that any ecological effect on the amount of surface runoff is small. This is because water infiltration is independent of crop type. Only in cases where the soil was saturated did runoff occur. Piezometer readings show that saturation occurs at the foot of the steep slopes and, therefore, it demonstrates that topographic processes are dominant. Ecology becomes important when infiltration rates are in the same order as the rainfall intensities.
    Melisew Misker Belay  Organization and Management of Irrigation Schemes in Eastern Amhara, Ethiopia: In Case of Sanka Traditional and Golina Modern Irrigation Schemes 2012 School: Cornell University  mastersthesis URL   
    Abstract: This study was initiated to evaluate the performance of Sanka traditional irrigation
    scheme and Golina small-scale modern irrigation scheme using performance indices.
    The technical evaluation was made by looking into selected performance indicators
    such as conveyance efficiency, application efficiency, dependability of irrigation
    interval and sustainability of irrigated command area. Moreover, availability of
    institutional and support services were also investigated through a questionnaire
    administered to beneficiary farmers and other stakeholders. Overall activities in
    primary data collected included: field observation, interviewing beneficiary farmers,
    discharge measurements in the canals, determination of moisture contents of the soil
    before and after irrigation and measurement of depth of water applied to the fields. In
    addition to primary data, secondary data were collected from the secondary sources.
    The results obtained showed that the main canal conveyance efficiency obtained on
    the two schemes, Sanka traditional irrigation and Golina modern irrigation, were 45.1
    and 98.2%, respectively. Application efficiency monitored on three farmers’ farm
    located on different ends of the command ranges from 36.2 to 59.1% and 51.9 to
    61.6% at Sanka and Golina irrigation schemes respectively. Dependability of the
    schemes evaluated in terms of irrigation interval shows that the schemes irrigate less
    frequently than was intended. The sustainability of the irrigated area is 240% at Sanka
    and 128% at Golina. Conflict among users is more severe at Sanka than at Golina.
    Support services rendered to the beneficiaries were minimal. There were very few
    indicators that production was market oriented at Golina; however, production at
    Sanka is mainly for household food consumption. In conclusion, the conveyance loss
    in Sanka is greater than Golina but in Sanka participation of farmers and sense of
    owner ship is rated to be 100%. Therefore, if proper canal and canal structures are in
    place and water users associations are empowered more in order for it to enforce its
    bylaws; it will augment the efficiency of the scheme exceedingly.
    Habtamu Addis Beyene  Factors Affecting the Sustainability of Rural Water Supply Systems: The Case of Mecha Woreda, Amhara Region, Ethiopia 2012 School: Cornell University  mastersthesis URL   
    Abstract: Many Ethiopian rural communities suffer from lack of safe drinking water. One of the reasons is that one third to one half of all drinking water systems fail shortly after construction. The goal of this study was find the reasons that these systems are not working. The MechaWoreda, in Amhara Region, Ethiopia was chosen. These types of wells are used: shallow dug wells, spring and deep wells. A survey was carried out with 160 household in 16 water supply systems constructed by different organizations. The results confirm literature findings about the importance of community involvement in the construction of well points. In Mecha Woreda only one of the 21 systems installed without community support was still functioning while only 12 of the 142 systems installed with community failed. One of the reasons of abandonment of dug wells despite full participation initially during planning and construction was the presence of (unprotected) springs in walking distance from water points because people generally preferred the taste of spring water above that of well water. Moreover, spring water was free, quantity unlimited and required usually less waiting time than for the constructed water point.
    The other important factor identified from analysis of the survey was the greater involvement of women in the decision making process of the functioning wells than initially for the abandoned wells. The institutional support of the water supply systems after construction was very weak mainly due to understaffing of the woreda office. Meaningful training of community members to make them responsible for operation, repair and maintenance of the water point will alleviate some of the understaffing problems in their system. Consideration of the above mentioned factors may help in decreasing the failure rate of newly installed water supply systems.
    P.L. Bishop, W.D. Hively, J.R. Stedinger, M.R. Rafferty & J.L. Lojpersberger  Surface Water Quality - Multivariate Analysis of Paired Watershed Data to Evaluate Agricultural Best Management Practice Effects on Stream Water Phosphorus 2005 Journal of Environmental Quality
    Vol. 34(3) , pp. 1087 
    article DOI   
    Abstract: Quantification of the effects of management programs on water quality is critical to agencies responsible for water resource protection. This research documents reductions in stream water phosphorus (P) loads resulting from agricultural best management practices (BMPs) implemented as part of an effort to control eutrophication of Cannonsville Reservoir, a drinking water supply for New York City. Dairy farms in the upstate New York reservoir basin were the target of BMPs designed to reduce P losses. A paired watershed study was established on one of these farms in 1993 to evaluate changes in P loading attributable to implementation of BMPs that included manure management, rotational grazing, and improved infrastructure. Intensive stream water monitoring provided data to calculate P loads from the 160-ha farm watershed for all runoff events during a two-year pre-treatment period and a four-year post-treatment period. Statistical control for inter-annual climatic variability was provided by matched P loads from a nearby 86-ha forested watershed, and by several event flow variables measured at the farm. A sophisticated multivariate analysis of covariance (ANCOVA) provided estimates of both seasonal and overall load reductions. Statistical power and the minimum detectable treatment effect (MDTE) were also calculated. The results demonstrated overall event load reductions of 43% for total dissolved phosphorus (TDP) and 29% for particulate phosphorus (PP). Changes in farm management practices and physical infrastructure clearly produced decreases in event P losses measurable at the small watershed scale.
    J. Boll, D. Van Buren, C.A. Campbell, E.S. Brooks, S. Chen, C.A. Stöckle, D.K. McCool & D. Feichtinger  Distributed modeling and economic analysis of erosion in GIS for watershed restoration. Manuscript for presentation at the Integrated Decision-Making for Watershed Management Symposium, Maryland, Jan 7-9, 2001 2001   other URL   
    J. Boll, R.P.G. van Rijn, K.W. Weiler, J.A. Ewen, J. Daliparthy, S.J. Herbert & T.S. Steenhuis  Using Ground-Penetrating Radar to Detect Layers in a Sandy Field Soil. In: Fingered Flow in Unsaturated Soil: From Nature to Model, T.S. Steenhuis, C.J. Ritsema, and L.W. Dekker, Eds. 1996 Geoderma
    Vol. 70(Special Issue) , pp. 117-132 
    article   
    J. Boll, J.S. Selker, G. Shalit & T.S. Steenhuis  Frequency distribution of water and solute transport properties derived from pan sampler data 1997 Water Resources Research
    Vol. 33(12) , pp. 2655-2664 
    article URL   
    J. Boll, T.S. Steenhuis & J.S. Selker  Fiberglass Wicks for Sampling Water and Solutes in the Vadose Zone. 1992 Soil Sci. Soc. Am. J.
    Vol. 56 , pp. 701-707 
    article   
    J. Boll, C.O. Stockle, S.K. Young, E.S. Brooks, J.E. Hammel, P.A. McDaniel & C.R. Campbell  Progress toward development of a GIS based water quality management tool for small rural watersheds: modification and application of a distributed model 1998 (982230) ASAE Annu. Int. Mtg.  inproceedings URL   
    A.S. Brooks, M.N. Rozenwald, L.D. Geohring, L.W. Lion & T.S. Steenhuis  Phosphorus removal by wollastonite: A constructed wetland substrate. 2000 Ecological Engineering
    Vol. 15 , pp. 121-132 
    article URL   
    E.S. Brooks, P.A. McDaniel & J. Boll  Hydrological modeling in watersheds of the eastern Palouse: Estimation of subsurface flow contributions. 2000 (Paper 2000-10) 2000 PNW-ASAE Regional Mtg.  inproceedings URL   
    C.F. Brush, M.F. Walter, L.J. Anguish & W.C. Ghiorse  Influence of pretreatment and experimental conditions on electrophoretic mobility and hydrophobicity of Cryptosporidium parvum Oocysts 1998 Applied and Environmental Microbiology
    Vol. 64(11) , pp. 4439-4445 
    article   
    B.P. Buchanan, R.L. Schneider & M.T. Walter  Incorporating VSA Hydrology into a spatially-distributed hydrologic model 2011 Journal of American Water Resources Association   article   
    B.P. Buchanan, M.T. Walter, G.N. Nagle & R.L. Schneider  Monitoring and assessment of a river restoration project in central NY 2010 River Research and Applications   article DOI   
    Luis A. Caballero  Hydrology, Hydrochemistry, and Implications for Water Supply of a Cloud Forest in Central America 2012 School: Cornell University  phdthesis URL   
    Abstract: Cloud-forest ecosystems are important sources of water supplies for the expanding cities of Central America. Surprisingly, few stream flow records are available for watersheds in Central America which has a climate with distinct wet and dry periods. Consequently, the tropical hydrology of cloud-forest watersheds is not well studied. To contribute to the understanding of the hydrology of this important
    ecosystem and to narrow the knowledge gap of tropical hydrology with that of temperate zones, we instrumented four neighboring catchments, located within La Tigra National Park in Central Honduras. This experimental watershed site is part of the headwater catchment of the Choluteca River Basin which drains into the Pacific Ocean. Although rainfall increased with the elevation gradient, it could not explain the greater water yield from the cloud forest watershed compared with the neighboring three watersheds at lower elevations. Additionally, analysis of the stream flow records suggests that subsurface flow paths are the primary mechanisms in all watersheds. Baseflow and interflow were greater and lasted longer for the cloud forest watershed. Any direct runoff was originated from saturated areas or from rock outcrops. Statistical analysis (MANOVA) of the of the stream flow chemistry confirms that the cloud forest watershed has a longer residence time because all the elements linked to parental material (Ca, Mg, SO4-S, Na, and SiO2-Si) had
    significantly lower concentrations in the cloud-forest watershed than in the non-cloud-forests watersheds. On the other hand, most elements associated with the immediate effect of rainfall events such as Dissolved Organic Carbon (DOC), nitrates, potassium, phosphorous, and iron were not significantly different between the four watersheds. Finally, using a simple water balance model we were able to simulate the observed daily discharges with the Nash Sutcliffe model efficiency index ranging from 0.67 to 0.91. The cloud-
    forest watershed had a distinctly smaller amount of available plant water and greater groundwater storage than the three non-cloud forest watersheds. This result is similar to the results obtained for an undisturbed paramo system in the Andes of South
    America. Consequently, protecting cloud-forests to maintain hydrologic processes overtime is critical for the sustained provision of clean water for the growing population of Central America.
    L.A. Caballero, Z.M. Easton, B.K. Richards & T.S. Steenhuis  Evaluating the bio-hydrological impact of a cloud forest in Central America using a semi-distributed water balance model 2013 J. Hydrol. Hydromech.
    Vol. 61(1) , pp. 9–20 
    article DOI URL   
    Abstract: Water scarcity poses a major threat to food security and human health in Central America and is increasingly recognized as a pressing regional issues caused primarily by deforestation and population pressure. Tools that can reliably simulate the major components of the water balance with the limited data available and needed to drive management decision and protect water supplies in this region. Four adjacent forested headwater catchments in La Tigra National Park, Honduras, ranging in size from 70 to 635 ha were instrumented and discharge measured over a one year period. A semi-distributed water balance model was developed to characterize the bio-hydrology of the four catchments, one of which is primarily cloud forest cover. The water balance model simulated daily stream discharges well, with Nash Sutcliffe model efficiency (E) values ranging from 0.67 to 0.90. Analysis of calibrated model parameters showed that despite all watersheds having similar geologic substrata, the bio-hydrological response the cloud forest indicated less plantavailable water in the root zone and greater groundwater recharge than the non cloud forest cover catchments. This resulted in watershed discharge on a per area basis four times greater from the cloud forest than the other watersheds despite only relatively minor differences in annual rainfall. These results highlight the importance of biological factors (cloud forests in this case) for sustained provision of clean, potable water, and the need to protect the cloud forest areas from destruction, particularly in the populated areas of Central America.
    Mehmet Ekrem Cakmak  Computational Fluid Flow and Transport of Colloidal Particles in Soil Pores 2011 School: Cornell University  phdthesis URL   
    Abstract: Transport of colloidal size particulate matter is of special interest of environmental studies because colloids and adsorbed chemicals can be transported over long distances. Colloid facilitated transport can pose potentially high risk for pollution of ground water. Visualizations of colloid transport using bright field and confocal microscopes have discovered interesting phenomena such colloids moving in circles that cannot be described by the traditional Darcy scale models. That is why computational pore scale models are needed to better understand colloid transport and fate in porous media. Transport and fate of colloids depend largely on flow field in the pores and it is, therefore, important to simulate the flow field while taking grain surface properties into account. The aim of this dissertation is hence to determine the flow fields in realistic pores by solving the incompressible Navier-Stokes equation with a powerful commercial available finite element program COMSOL Multiphysics. The dissertation has four chapters. In the first chapter a short introduction is given. In the second chapter the COMSOL Multiphysics program is tested by revisiting the classical colloid filtration theory on colloid retention on a spherical sand grain. Retention of colloids on grains simulated with COMSOL is found to be similar to semi-analytical solutions previously published. Subsequently colloid retention on an air bubble is simulated and greater colloid retention is calculated than on a soil grain due to the slip boundary condition at the Air-Water interface which creates higher velocities and more fluid flow around air bubble resulting in greater amounts of colloids that can diffuse to the interface. In the third chapter the effect of surface roughness on hydrodynamics of colloid transport in a saturated porous media is investigated by simulating the flow fields around perfectly smooth, smoothed, and naturally rough sand grains. The results show that micron scale surface asperities of rough grains create greater vorticity and more stagnant flow regions compared to smooth grains likely resulting in greater colloid retention for the rough grains. In the fourth chapter the dependence of dynamic contact angle between the interface of two immiscible fluids and solid surface on the interface velocity is simulated in an empty capillary channel to provide a new understanding on the formation of unstable wetting fronts in coarse or water repellent soils. The results show an increase in contact angle when the velocity of the front increases, which is consistent with experimental studies in the literature.
    M.E. Cakmak, B. Gao, J.L. Nieber & T.S. Steenhuis Pore Scale Simulation of Colloid Deposition  2008 In: G. Petrone & G. Cammarata. Modelling and Simulation  inbook URL   
    V.J. Camobreco, B.K. Richards, T.S. Steenhuis, J.H. Peverly & M.B. McBride  Movement of heavy metals through undisturbed and homogenized soil columns 1996 Soil Science
    Vol. 161(11) , pp. 740-750 
    article URL   
    D. Chandler & M.F. Walter  The Effects of Land Use on Runoff from Calcareous Tropical Uplands. 1998 Trans. of ASAE   article   
    D.G. Chandler & M.F. Walter  Runoff responses among common land uses in the uplands of Matalom, Leyte, Philippines 1998 ASAE Trans.
    Vol. 41(6) , pp. 1635-1641 
    article   
    W.L. Chao, J.Y. Parlange & T.S. Steenhuis  An analysis of the movement of wetting and non-wetting fluids in a homogeneous porous media. 2000 Transport in Porous Media
    Vol. 41 , pp. 121-135 
    article URL   
    W.A. Charlie, D. Durnford & T.S. Steenhuis  Rapid density profiling of consolidating clay using synchrotron radiation 1997 ASTM Geotechnical Testing Journal
    Vol. 20(3) , pp. 340-346 
    article URL   
    W. Cheng, N. Park, M.T. Walter, M.R. Hartman & D. Luo  Nanopatterning self-assembled nanoparticle superlattices by molding microdroplet 2008 Nature Nanotechnology
    Vol. 3(11) , pp. 682-690 
    article DOI   
    A.S. Collick, Z.M. Easton, Enyew Adgo, Seleshi B. Awulachew, Gete Zeleke & T.S. Steenhuis  Application of a physically-based water balance model on four watersheds throughout the upper Nile Basin in Ethiopia 2008 In: Abtew & Melesse. Proceedings of the Workshop on the Hydrology and Ecology of the Nile River Basin under Extreme Conditions  inproceedings URL   
    A.S. Collick, Z.M. Easton, Tegenu Ashagrie Engda, Biniam Biruk, Seifu A. Tilahun, Enyew Adgo, Seleshi B. Awalachew, Gete Zeleke & T.S. Steenhuis  A simple semi-distributed water balance model for the Ethiopian highlands 2009 Hydrological Processes
    Vol. 23 , pp. 3718-3727 
    article DOI   
    Abstract: The discharge of the Nile River is highly dependent on the flow generated in the highlands of Ethiopia. However, little is known about the local (i.e. small scale) watershed hydrological response, due in part to a lack of long duration, continuous hydrological data. The goal of this paper was to develop a realistic, simple model that is useful as a tool for planning watershed management and conservation activities so that the effects of local interventions on stream flow can be predicted at a larger scale. The developed model is semi-distributed in that it divides the watershed into different regions that become hydrologically active given different amounts of effective cumulative rainfall after the start of the rainy season. A separate water balance is run for each of the hydrologic regions using rainfall and potential evaporation as the major inputs. Watershed parameters that were calibrated included the amount of water required before each region becomes hydrologically active, the fraction of soil water that becomes runoff and subsurface flow, and aquifer characteristics, Model validation indicated that daily discharge values were predicted reasonably well with Nash Sutcliffe values ranging from 0·56 to 0·78. Despite the large distance between the test watersheds, the input parameter values for the watershed characteristic were remarkably similar for the humid highlands, indicating that the model could be used to predict discharge in un-gauged basins in the region. As expected, the watershed in the semi-arid region behaved somewhat differently than the other three watersheds. Good quality precipitation data, even for short durations, were key to the effective modelling of runoff in the highland watersheds. [[Ethiopia]]
    A.S. Collick, Z.M. Easton, F.A. Montalto, B. Gao, Y. Kim, L. Day & T.S. Steenhuis  Hydrological Evaluation of Septic Disposal Field Design in Sloping Terrains 2006 Journal of Environmental Engineering
    Vol. 132(10)  
    article URL  URL2 
    A.S. Collick, E.A. Fogarty, P.E. Ziegler, M.T. Walter, D.D. Bowman & T.S. Steenhuis  Survival of Cryptosporidium parvum oocysts in calf housing facilities in the New York City watersheds 2006 Journal of Environmental Quality
    Vol. 35(2) , pp. 680-687 
    article   
    Abstract: Pathogen contamination of the public drinking water supply in the New York City watersheds is a serious concern. New York City's Watershed Agriculture Program is working with dairy farms in the watersheds to implement management practices that will reduce the risk of pathogens contaminating the water supply. Solar calf housing (SCH) was suggested as a best management practice (BMP) to control Cryptosporidium parvum, a common protozoan parasite that causes disease in humans. This BMP targets young calves because they are the primary source of C. parvum in dairy herds. The objective of this project was to assess and compare the survivability of C. parvum in SCH and in conventional calf housing (CCH), usually located in the main barn. C. parvum oocysts were secured in sentinel chambers and placed in SCH and CCH bedding on four farms. The chambers were in thermal, chemical, and moisture equilibrium with their microenvironments. An oocyst-filled control chamber, sealed from its surroundings, was placed near each chamber. Chambers and controls were sampled after 4, 6, and 8 wk. Oocyst viability in the chambers decreased to less than 10% in warm months and between 15 and 30% in the winter months. The viability of the control oocysts was similar to the chambers during warm months and generally higher during winter months. There was no significant (P > 0.05) difference in the viability decrease between SCH and CCH. Although oocyst viability was similar in both types of calf housing, SCH allow contaminated calf manure to be isolated from the main barn manure and potentially managed differently and in a way to decrease the number of viable oocysts entering the environment during field spreading.
    A.S. Collick, S. Ingli, P. Wright, T.S. Steenhuis & D.D. Bowman  Inactivation of Ascaris suum in a biodrying compost system 2007 Journal of Environmental Quality
    Vol. 36(5) , pp. 1528-1533 
    article   
    J.T. Crist, J.F. McCarthy, Y. Zevi, P. Baveye, J.A. Throop & T.S. Steenhuis  Pore-scale visualization of colloid transport and retention in partly saturated porous media 2004 Vadose Zone J.
    Vol. 3 , pp. 444-450 
    article URL   
    J.T. Crist, Y. Zevi, J.F. McCarthy, J.A. Throop & T.S. Steenhuis  Transport and retention mechanisms of colloids in partially saturated porous media 2005 Vadose Zone J.
    Vol. 4 , pp. 184-195 
    article URL   
    Abstract: The transport, retention, and release of hydrophobic and hydrophilic polystyrene latex microsphere colloids were examined in 0.5-cm-thick, 26-cm-long slab chambers filled with either regular (hydrophilic) or weakly water-repellent sand. The water-repellent sand consisted of a mixture of 0.4% strongly water-repellent grains with unmodified regular sand for the remainder. The concentration of colloids in the outflow water was measured at the same time as the pore-scale distribution of colloids was recorded in still and video images. Although the type of sand affected the flow pattern in the top of the chamber, it did not affect the breakthrough for the same type of colloids. More hydrophilic colloids were eluted in the drainage water than hydrophobic colloids. Images showed that there was a greater retention of the hydrophobic colloids due to strongly attractive hydrophobic interaction forces between colloids and subsequent filtering of colloidal aggregates in the narrow passages between grains. Once filtered, these aggregates then served as preferred sites for attachment of other hydrophobic colloids. The hydrophilic colloids were retained primarily in a thin film of water at the edge of the menisci, the air-water-solid (AWS) interface. Centrifugal motion within the pendular rings observed in the videos contributed to movement of the colloids toward the AWS interface, where colloids were retained due to both low laminar flow velocities near the grain surface and straining in the thin water film at the edge of the meniscus. Except near the solid interface, sorption at the air-water (AW) interface was not observed and appeared unimportant to the retention of colloids. The findings form an essential link between colloid retention and transport processes at the interfacial, pore, and Darcy scales.
    P.J. Culligan, K. Banno, D.A. Barry, T.S. Steenhuis & J.Y. Parlange  Preferential flow of a nonaqueous phase liquid in dry sand 2002 J. Geotechnical and Geoenvironmental Engr.
    Vol. 128(4) , pp. 327-337 
    article URL   
    P.J. Culligan, D.A. Barry, J.Y. Parlange, T.S. Steenhuis & R. Haverkamp  Infiltration with controlled air escape. 2000 Water Resources Research
    Vol. 36(3) , pp. 781-785 
    article URL   
    Dessalegn Chanie Dagnew  Factors Determining Residential Water Demand in North Western Ethiopia, The Case of Merawi 2012 School: Cornell University  mastersthesis URL   
    Abstract: Growing populations and lack of available cost effective supply augmentation options make reliable estimates of residential water demand important for policy making. The interest of this thesis research was to assess factors affecting residential water demand among different households of the town of Merawi, North Western Ethiopia. Understanding variables that determine residential water demand and water source decisions helps the water supply utilities, local and regional governments and policy makers in their efforts of demand management and expanding service levels to the unserved sections of the society.
    The factors that were hypothesized to affect household water demand and source choice decisions in the town were: HH expenditure, income generating activities (employment) of household members, demographic factors such as family size and age sex composition, housing ownership and characteristics of the HH head.
    Data from 200 households were collected and analyzed using SPSS. Descriptive statistics was used for the descriptive results. Logistic regression and standard multiple regression analyses were also used to determine factors explaining households water source choice decisions and determinants of residential water demand (more specifically water used) of the surveyed HHs.
    The analyses indicate that monthly expenditure, housing ownership and educational status of the household head were statistically significant predictors of households’ decision to have private piped connection. Other factors were found not to have statistically significant contribution in predicting the water source decision of HHs.
    Monthly expenditure (as a surrogate for income and HH welfare), primary source of water and employment of the head had a statistically significant positive impact on daily per capita water consumption, whereas age and sex of the household head were found to have negative effect on the quantity of water demanded.

    The implications from the available data and estimated parameters shows that with the current population growth rate of 2.7% and a simple arithmetic growth rate of water demand, by 2020 the water demand of Merawi will grow by 45%. Similarly, it was also found that with the existing GDP growth rate, the current water demand for the town is expected to double by the year 2020.

    Dessalegn C Dagnew, Seifu A Tilahun, Amy S Collick, Tammo S Steenhuis & Charles F Nicholson  Determinants of Residential Water Consumption and Connection in
    Ethiopia; Evidence from Merawi
    2013 Proceedings of the International Conference on Science and Technology towards the Development of East Africa (ICST 2013), pp. 239-246  inproceedings   
    Abstract: In Ethiopia, rapid population growth and lack of cost-effective water supply options
    make reliable estimates of residential water demand important for policy making. The interest of
    this paper is to assess factors affecting residential water consumption and connection to piped
    water in Merawi, North Western Ethiopia. Understanding variables that determine consumption
    and connection to piped water services helps water supply utilities, local and regional governments
    and policy makers in their efforts of demand management. The factors that were hypothesized to
    affect household water consumption and source choice decisions were: household expenditure,
    income generating activities, demographic factors such as family size and age-sex composition,
    housing ownership and characteristics of the household head. Data from 200 households were
    collected and analyzed using SPSS. Descriptive statistics and regression analyses were used to
    analyze factors explaining household level determinants of residential water demand (more
    specifically water used) and access to piped water services of the surveyed households. The analyses
    indicate that monthly expenditure (as a surrogate for household income and welfare), primary
    source of water and employment of the head had a statistically significant positive impact on daily
    per capita water consumption, whereas age and sex of the household heads were found to have
    negative effect on the quantity of water consumed. Monthly expenditure of households, housing
    ownership, educational status and income generating activities at home were found to have a
    statistically significant impact on the likelihood of the household to have private piped connection.
    The implications from the available data and estimated parameters shows that with the current
    Ethiopia’s population growth rate of 2.7% and a simple arithmetic growth rate of water demand of
    the town, by 2020 the water demand of Merawi will grow by 45%. Similarly, it was also found that
    with the existing GDP growth rate, the current water demand for the town is expected to double by
    2020.
    H.E. Dahlke, Z.M. Easton, M.T. Walter & T.S. Steenhuis  Field Test of the Variable Source Area Interpretation of the Curve Number Rainfall-Runoff Equation 2012 Journal of Irrigation and Drainage Engineering
    Vol. 138(3)  
    article DOI   
    Abstract: The Soil Conservation Service Curve Number (SCS-CN) method is a widely used empirical rainfall-runoff equation. Although the physical basis of the method has been debated, several researchers have suggested that it can be used to predict the watershed fraction that is saturated and generating runoff by saturation excess from variable source areas (VSAs). In this paper, we compare saturated runoff-contributing areas predicted with the VSA interpretation of the SCS-CN method with field-measured VSAs in a 0.5 ha hillslope in central New York State. We installed a trench below a VSA and simultaneously recorded water flux from different soil layers at the trench face and water table dynamics upslope of the trench. This setup allowed us to monitor runoff initiation and saturation-excess overland flow in response to rainfall and different water table depths in the hillslope during 16 storm events. We found that the SCS-CN method accurately predicted the observed VSA and showed best agreement if the VSA was defined as the area where the water table was within 10 cm of the soil surface. These results not only demonstrate that the VSA interpretation of the SCS-CN method accurately predicts VSA extents in small watersheds but also that the transient water table does not necessarily need to intersect the land surface to cause a storm runoff response.
    Helen E. Dahlke  Improved Understanding of Subsurface Hydrology in Variable Source Areas and its Implications for Water Quality 2011 School: Cornell University  phdthesis URL   
    Abstract: Variable source areas (VSAs) are hot spots of hydrological (saturation-excess runoff)
    and biogeochemical processes (e.g. nitrogen, phosphorus, organic carbon cycling) in
    the landscapes of the northeastern U.S. Despite the substantial research conducted in
    the past 50 years, there is still process understanding to be gained on how VSA
    connect with the surrounding area, how this interaction influences surface and
    subsurface runoff generation and chemical transport and how these processes can be
    captured in ungaged basins using watershed models. To determine the controls on
    VSA formation and connectivity, a 0.5 ha hillslope was instrumented (trenched) in the
    southern tier of New York, U.S. Water flux from different soil layers in the trench and
    upslope water table dynamics were recorded for 16 events and isotopic and
    geochemical tracers were measured during five events. In conjunction with the surface
    and bedrock topography these measurements allowed detailed characterization of the
    subsurface storm flow response within the VSA. Analysis revealed that the most
    important control on storm flow response was antecedent moisture. During events
    with dry antecedent conditions subsurface flow was dominated by percolation through
    the fragipan (i.e. cracks and macropores). Flow from below the fragipan showed a
    constant flow rate (0.8 mm/h), which was independent of storm size and antecedent
    moisture. Under wet antecedent conditions hydrological connectivity increased and
    subsurface flow is dominated by lateral flow through the soil atop the fragipan. During
    these events flow contributing slope length to the trench was five to tenfold increased.
    Thus, pollutant and nutrient transport from a greater distance has to be considered in
    water management during events with wet antecedent conditions. Application of the
    empirical Soil Conservation Service Curve Number method showed that discharge
    volumes were generally well predicted but revealed that for continuous predictions of
    VSA dynamics more conceptually coherent solutions need to be developed that
    consider the effect of antecedent moisture on runoff generation. This research shows
    that indirect indicators such as the average water table depth, the base flow rate prior
    to events or water balance estimates of the soil water content can be incorporated into
    watershed models to improve predictions.
    H.E. Dahlke, T. Behrens, J. Seibert & L. Anderson  Test of statistical means for the extrapolation of soil depth point information using overlays of spatial environmental data and bootstrapping techniques 2009 Hydrological Processes
    Vol. 23 , pp. 3017-3029 
    article DOI   
    H.E. Dahlke, Z.M. Easton, D.R. Fuka, S.W. Lyon & T.S. Steenhuis  Modeling Variable Source Area Dynamics in a CEAP Watershed 2009 Ecohydrology
    Vol. 2 , pp. 337-349 
    article DOI   
    Helen E. Dahlke, Zachary M. Easton, Daniel R. Fuka, M. Todd Walter & Tammo S. Steenhuis  Real-Time Forecast of Hydrologically Sensitive Areas in the Salmon Creek Watershed, New York State, Using an Online Prediction Tool 2013 Water
    Vol. 5(3) , pp. 917-944 
    article DOI   
    Abstract: In the northeastern United States (U.S.), watersheds and ecosystems are impacted by nonpoint source pollution (NPS) from agricultural activity. Where agricultural fields coincide with runoff-producing areas - so called hydrologically sensitive areas (HSA) - there is a potential risk of NPS contaminant transport to streams during rainfall events. Although improvements have been made, water management practices implemented to reduce NPS pollution generally do not account for the highly variable, spatiotemporal dynamics of HSAs and the associated dynamics in NPS pollution risks. This paper presents a prototype for a web-based HSA prediction tool developed for the Salmon Creek watershed in upstate New York to assist producers and planners in quickly identifying areas at high risk of generating storm runoff. These predictions can be used to prioritize potentially polluting activities to parts of the landscape with low risks of generating storm runoff. The tool uses real-time measured data and 24–48 h weather forecasts so that locations and the timing of storm runoff generation are accurately predicted based on present-day and future moisture conditions. Analysis of HSA predictions in Salmon Creek show that 71% of the largest storm events between 2006 and 2009 were correctly predicted based on 48 h forecasted weather data. Real-time forecast of HSAs represents an important paradigm shift for the management of NPS in the northeastern U.S.
    C. Darnault, D.A. Dicarlo, T. Bauters, T.S. Steenhuis, J.Y. Parlange, C.D. Montemagno & P. Baveye  Visualization and measurement of multiphase flow in porous media using light transmission and synchrotron X-rays. Visualization and Imaging in Transport Phenomena Se Annals of the New York Academy of Sciences 972: 2002 , pp. 103-110  other   
    C.J.D. Darnault, T.S. Steenhuis, P. Garnier, Y.J. Kim, M.B. Jenkins, W.C. Chiorse, P.C. Baveye & J.Y. Parlange  Preferential flow and transport of Cryptosporidium parvum oocysts through the vadose zone: Experiments and modeling 2004 Vadose Zone Journal
    Vol. 3(3) , pp. 736 
    article URL  URL2 
    C.J.G. Darnault, D.A. DiCarlo, T.W.J. Bauters, A.R. Jacobson, J.A. Throop, C.D. Montemagno, J.Y. Parlange & T.S. Steenhuis  Measurement of fluid contents by light transmission in transient three-phase oil-water-air systems in sand 2001 Water Resources Research
    Vol. 37(7) , pp. 1859-1868 
    article   
    C.J.G. Darnault, P. Garnier, Y.J. Kim, K.L. Oveson, T.S. Steenhuis, J.Y. Parlange, M. Jenkins, W.C. Ghiorse & P. Baveye  Preferential transport of Cryptosporidium parvum oocysts in variably saturated subsurface environments 2003 Water Environment Research
    Vol. 75 , pp. 113-120 
    article   
    C.J.G. Darnault, J.A. Throop, A. Rimmer, D.A. DiCarlo, T.S. Steenhuis & J.Y. Parlange  Visualization by light transmission of oil and water contents in transient two-phase flow fields 1998 Journal of Contaminant Hydrology
    Vol. 31(3-4) , pp. 337-348 
    article URL   
    A. Dathe, M.A. Tarquis & E. Perrier  Multifractal analysis of the pore- and solid-phases in binary two-dimensional images of natural porous structures 2005 Geoderma
    Vol. (accepted)  
    article   
    A. Dathe & M. Thullner  The relationship between fractal properties of solid matrix and pore space in porous media 2005 Geoderma
    Vol. 129(3-4) , pp. 279-290 
    article URL   
    Annette Dathe, Yuniati Zevi, Brian K. Richards, Bin Gao, J.-Yves Parlange & Tammo S. Steenhuis  Functional models for colloid retention in porous media at the triple line in press Environmental Science and Pollution Research
    Vol. (New approaches for low-invasive contaminated site characterization, monitoring and modelling)  
    article URL   
    M. Deinert, J.Y. Parlange, K.B. Cady, T.S. Steenhuis & J.S. Selker  Comment on "On the Continuum-Scale Modeling of Gravity Driven Fingers in Unsaturated Porous Media: The Inadequacy of the Richards Equation with Standard Monotonic Constitutive Relations and Hysteretic Equations of State" by M. Eliassi and R.J. Glass 2003 Water Resources Research
    Vol. 39(9)  
    article URL   
    M.R. Deinert, C.W. Lowe, J.Y. Parlange, K. Unlu & K.B. Cady  Performance and Calibration of a Neutron Image Intensifier Tube Based Real-Time Radiography System 2005 IEEE Transactions on Nuclear Science
    Vol. 52(1 PN Part 2) , pp. 349-355 
    article   
    M.R. Deinert, J.Y. Parlange & K.B. Cady  Simplified Thermodynamic Model for Equilibrium Capillary Pressure in a Fractal Porous Medium 2005 Physical Review
    Vol. E 72(4 PN Part 1 AR 04120)  
    article URL   
    M.R. Deinert, J.Y. Parlange, T.S. Steenhuis, J. Throop, K. Unlu & B. Cady  Measurement of fluid contents and wetting front profiles by real-time neutron radiography 2004 J. Hydrology
    Vol. 290(3-4) , pp. 192-201 
    article   
    J. Deiss, M.T. Walter & D. D'Amore A. Love M. Menzies J. Powell) Southeast Alaska Wetland Research Team (inc.C.A. Byers, D. Clover  Transport of lead and diesel fuel through a peat soil near Juneau, AK: A pilot study 2004 Journal of Contaminant Hydrology
    Vol. 74 , pp. 1-18 
    article URL   
    Aschalew Demeke  Determination of household participation in water source management: Achefer, Amhara region, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Access to safe drinking water supplies and sanitation services in Ethiopia are among the lowest in Sub-Saharan Africa. While governmental and nongovernmental organizations have been implementing water supply and sanitation projects in recent years, many fail shortly after construction due improper management. In this study we examine socio-economic, institutional and exogenous factors which affect households' participation in the management of water sources. A survey was carried out involving 16 water supply systems and 160 households within Achefer area, in Amhara, Ethiopia. In addition, the water quality of eight water points was tested. The results show that households' demand for sustainable water services are positively affected by users' participation during the project design and implementation, advocacy provided by the project and greater household income. Thus, for drinking water systems to be sustainable these factors should be included in planning water supply projects. [[Ethiopia]]
    Tesfaye Habtamu Demeke  Assessment of Sustainable Watershed Management Approach: Case Study Lenche Dima, Tesgur Eyesus and Dijjil Watershed 2011 School: Cornell University  mastersthesis URL   
    Abstract: For several decades, integrated and sustainable watershed management has been suggested and tried in several countries in the world, as an effective way to address complex water and land resource challenges. However its implementation has not been successful in most cases, due to various barriers. In Ethiopia, this approach is new and requires appropriate strategies to overcome the barriers and practice effective integrated and sustainable watershed management. To design suitable and effective strategies, there is need to understand watershed management approaches implemented by different watershed projects at various spatial levels, which promote or hinder integration, sustainability and coordination. This paper therefore explores the prospects, approaches and barriers of integrated and sustainable watershed management of Dijjil, Tsegur Eyesus and Lenche Dima watersheds, by examining the existing complex set of biophysical and socio-economic conditions, stakeholders? attitudes and perceptions, arrangements for participation of communities, available institutional structures and recent policy of land certification. Information was gathered from official documents, direct observations, semi-structured interviews with experts, watershed committees and households of the three watersheds.

    The result indicates that effective and sustainable watershed management can take place through participation of watershed community from the beginning, ownership of communal lands into private or association holdings, integration of multidisciplinary team, demand driven, changing the livelihood of the community within the short run by generating income from on farm and off farm activities, establishing community watershed management institution, and giving legislative support. [[Ethiopia]]

    Bezawit Adane Demisse  Discharge and Sediment Yield Modeling in Enkulal Watershed, Lake Tana Region, Ethiopia 2011 School: Cornell University  mastersthesis URL   
    Abstract: Land degradation is a major watershed problem causing significant loss of soil fertility and productivity in the Ethiopian highlands. Soil erosion is one form of land degradation. To develop effective erosion control plans and to achieve reductions in sedimentation, it is important to quantify the sediment yield and identify areas that are vulnerable to erosion. The objective of this study was to formulate sustainable land management options that alleviate soil erosion. The study was conducted in a small watershed located about 80 km North East of Bahir Dar.

    The runoff depth was measured and sediment sampling was performed during the main rainy season of 2010. Twenty-three piezometers were installed and water level measurements were taken for a 5 month period. In addition, infiltration rates were measured. A simple saturation excess water balance model was used to simulate the flow and sediment processes in the watershed and to identify runoff and sediment source areas. The watershed landscape was divided into saturated, degraded and hill slopes areas to understand the hydrologic behavior. Finally, the model output was compared to sediment and runoff data observed at the outlet of the watershed. The model predicted the daily stream flows and sediment concentration reasonably well. Twenty-two percent of the watershed consisted of degraded area as the only sources of surface runoff and sediment. Group discussion discovered that surface runoff from the lower degraded watershed was the major cause of soil erosion. This was in agreement with infiltration test measurements, which indicated that infiltration rates exceeded rainfall rates. Infiltration and recharge were greater on the steep slope compared with the lower slopes. Piezometer readings indicated that during the rainy season there was a perched water table, which disappeared after the rain stopped. In general perched water table depths were greater down slope than upslope but never reached the soil surface.

    D.A. DiCarlo, D.A. Barry & T.S. Steenhuis  Flow processes in hydrology: Contributions of J. -Y. Parlange 2005 Adv. in Water Res
    Vol. 28 , pp. 1001-1002 
    article   
    D.A. DiCarlo, T.W.J. Bauters, C.J.G. Darnault, T.S. Steenhuis & J.Y. Parlange  Rapid Determination of Constitutive Relations with Fingered Flow 1999 In: M.Th. Van Genuchten, F.J. Leij & L. Wu. Proc. Int. Workshop Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, pp. 433-440  inproceedings URL   
    D.A. DiCarlo, T.W.J. Bauters, C.J.G. Darnault, T.S. Steenhuis & J.Y. Parlange  Lateral expansion of preferential flow paths in sands 1999 Water Resources Research
    Vol. 35(2) , pp. : 427-434 
    article URL   
    D.A. DiCarlo, T.W.J. Bauters, C.J.G. Darnault, E. Wong, B.R. Bierck, T.S. Steenhuis & J.Y. Parlange  Surfactant-Induced Changes in Gravity Fingering of Water Through a Light Oil. 2000 J. Contam. Hydrol.
    Vol. 41 , pp. 317-334 
    article URL   
    D.A. DiCarlo, T.W.J. Bauters, T.S. Steenhuis, J.Y. Parlange & B.R. Bierck  High-Speed Measurements of Three-Phase Flow Using Synchrotron X-Rays 1997 Water Resources Research
    Vol. 33(4) , pp. 569-576 
    article URL   
    D.A. DiCarlo, Y. Zevi, A. Dathe, S. Giri, B. Gao & T.S. Steenhuis  In situ measurements of colloid transport and retention using synchrotron X-ray fluorescence 2006 Water Resour. Res.
    Vol. 42  
    article DOI URL   
    J. Diess, C.A. Byers, D. Clover, D. D'Amore, A. Love, M. Menzies, J. Powell & M.T. Walter  Transport of lead and diesel fuel through a peat soil near Juneau, AK: a pilot study 2004 Journal of Contaminant Hydrology
    Vol. 74 , pp. 1-18 
    article DOI   
    Rachel A. Dunn  Perspectives, Problems, and Pesticides: The Discrepancies between Institutional and Local Environmental Conservation Perspectives in Northern Thailand and the Implications for Natural Resource Management Model Development 2012 School: Cornell University  phdthesis URL   
    Abstract: Although the importance of integrating social and natural science understandings in natural resource management (NRM) models has been largely acknowledged, current evidence suggests that that there has been limited success in achieving such integration. Integrated NRM model development processes are complicated by the lack of consensus between disciplines as to how NRM problems should be defined and addressed. In the Northern Thailand region, attempts to define NRM problems, system boundaries, stakeholder groups or environmental processes are subject to complex and multi-facetted perspectives in a highly politicized context. The problems resulting from the complexity and political sensitivity of developing an NRM model for Doi Inthanon National Park in Chiang Mai, Thailand led to the formulation of three research questions addressed in this dissertation. 1. Perspectives: Whose perspectives have determined the NRM problem definitions of the NRM models developed for the Northern Thailand region and how has this influenced the integration of social and natural systems understandings? 2. Problems: Does the perspective used to develop an NRM model problem definition affect NRM model outcomes when modeling in a localized context? 3. Pesticides: Should the concerns of local stakeholder groups within Doi Inthanon National Park, such as pesticide use management, receive more attention as environmental conservation priorities in NRM model development processes? This dissertation demonstrates that the influence of a dominant national level environmental narrative decreases researcher and stakeholder satisfaction with an NRM model‟s representation of interactions between social and natural systems. Furthermore, within the localized context of Doi Inthanon National Park, perspectives on NRM problem definitions varied widely amongst stakeholder groups. Finally, the pesticide use management concerns identified by local stakeholder groups were shown to be legitimate NRM issues that need to be addressed. Accounting for the different perspectives about NRM issues in an area and the power differentials between those perspectives is necessary to better understand the interaction between stakeholder groups and their reactions to a NRM model development program. This increased understanding will reduce the perceptions of disciplinary incompatibility within a NRM model development program and ensure that the choice of NRM priorities is transparent as opposed to obscure.
    Travis Duran  How Capillary Barriers Stop Gas Leakage 2012 YouTube  electronic URL   
    J. Dziejowski, A. Rimmer & T.S. Steenhuis  Preferential movement of oxygen in soils? 1997 Soil Science Society of America J.
    Vol. 61 , pp. 1607-1610 
    article URL   
    Z.M. Easton  Landuse impact on urban runoff: Determining and modeling nutrient loading rates based on landuse 2006 School: Cornell University  phdthesis   
    Z.M. Easton  Data restructuring: I Changing raster values by selected area: II Changing raster values by geographic feature 2004 In A. J. Lembo, ed. How do I do that in ArcGIS/Manifold: Illustrating Classic GIS Tasks  electronic URL   
    Z.M. Easton  Vector overlay operations: Line in polygon 2004 In A. J. Lembo, ed. How do I do that in ArcGIS/Manifold: Illustrating Classic GIS Tasks  electronic URL   
    Z.M. Easton, Seleshi B. Awulachew, T.S. Steenhuis, A. Habte, B. Zemedam, Y. Seleshi, K. Bashar, V. Smakhtin & D. Pedon Hydrological processes in the Blue Nile River Basin [[Ethiopia]]  2010 (In Press) In: Seleshi B. Awulachew, D. Molden & D. Peden. The Nile River Basin: Water, Agriculture, Governance and Livelihoods  inbook   
    Zachary M. Easton, Daniel R. Fuka, Tammo S. Steenhuis, Byron Rupp & Paul Murawski  A Modified Soil and Water Assessment Tool (SWAT) Model for Flow and Sediment
    Transport in the Genesee River Basin
    2010?   techreport URL   
    Abstract: A modified version of the Soil and Water Assessment Tool (SWAT) model was
    employed to simulate the flow and sediments in the Genesee River Basin, New York.
    SWAT was modified to incorporate variable source area hydrology (SWAT-VSA) in the
    prediction of flow and sediment. Water quality concerns in the Genesee Basin primarily
    revolve around the amount of sediment discharged into Lake Ontario at Rochester, NY,
    as well as in stream sediment levels throughout the basin. A beneficial use impairment
    is in place because of degradation of the benthos, primarily the result of excessive
    sedimentation. Thus, the model is developed to assist the Genesee/Finger Lakes
    Regional Planning Council (GFLRPC) and state and local watershed managers in their
    evaluation, prioritization, and implementation of alternatives for soil conservation and
    non-point source pollution remediation in the watershed. The model was calibrated for
    flow and sediment during the 1975-1977 period at 12 gauges and run from 1970-2009
    for validation. Model results showed a good fit to measured data during both the
    calibration and validation periods. Daily Nash-Sutcliffe Efficiencies (NS) ranged from 0.5
    to 0.8. Modeled sediment predictions also showed good agreement with the short
    duration of measured data. Daily model predicted flows were within 15% of measured
    flows at all gauges, and considerably lower at most (<5%). While sediment export from
    the various gauged subbasins was highly variable, SWAT was able to capture the
    dynamics well. Daily model predicted sediment export from was generally within 25% of
    the measured export at the gauges. Interestingly, the model indicated that there was a
    significant amount of stream bank/channel erosion in the upland (first order subbasins)
    that was subsequently deposited in lowland subbasin under flow regimes less than the
    65th percentile. Under higher flows (> 65th percentile) these deposited sediments can be
    mobilized. The results of the model can be used to evaluate and direct implementation
    of alternatives for soil conservation and non-point source pollution remediation in the
    watershed.
    Z.M. Easton, D.R. Fuka, M.T. Walter, D.M. Cowan, E.M. Schneiderman & T.S. Steenhuis  Re-Conceptualizing the soil and water assessment (SWAT) model to predict runoff from variable source areas 2008 Journal of Hydrology
    Vol. 348 , pp. 279-291 
    article DOI URL   
    Z.M. Easton, D.R. Fuka, E.D. White, A.S. Collick, Biniam Biruk Ashagre, M. McCartney, Seleshi B. Awulachew, Abdassalam A. Ahmed & T.S. Steenhuis  A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia 2010 Hydrology and Earth Systems Science
    Vol. 14 , pp. 1827-1841 
    article DOI   
    Abstract: A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT) model was developed to predict runoff and sediment losses from the Ethiopian Blue Nile Basin. The model simulates saturation excess runoff from the landscape using a simple daily water balance coupled to a topographic wetness index in ways that are consistent with observed runoff processes in the basin. The spatial distribution of landscape erosion is thus simulated more correctly. The model was parameterized in a nested design for flow at eight and sediment at three locations in the basin. Subbasins ranged in size from 1.3 to 174 000 km2, and interestingly, the partitioning of runoff and infiltrating flow could be predicted by topographic information. Model predictions showed reasonable accuracy (Nash Sutcliffe Efficiencies ranged from 0.53-0.92) with measured data across all sites except Kessie, where the water budget could not be closed; however, the timing of flow was well captured. Runoff losses increased with rainfall during the monsoonal season and were greatest from areas with shallow soils and large contributing areas. Analysis of model results indicate that upland landscape erosion dominated sediment delivery to the main stem of the Blue Nile in the early part of the growing season when tillage occurs and before the soil was wetted up and plant cover was established. Once plant cover was established in mid August landscape erosion was negligible and sediment export was dominated by channel processes and re-suspension of landscape sediment deposited early in the growing season. These results imply that targeting small areas of the landscape where runoff is produced can be the most effective at controlling erosion and protecting water resources. However, it is not clear what can be done to manage channel erosion, particularly in first order streams in the basin.
    Z.M. Easton, P. Gérard-Marchant, A.M. Petrovic & T.S. Steenhuis  Identifying dissolved phosphorus source areas and predicting transport from an urban watershed using distributed hydrologic modeling 2007 Water Resources Research
    Vol. 43  
    article DOI   
    Z.M. Easton, P. Gérard-Marchant & T.S. Steenhuis  Hydrologic assessment of an urban variable source watershed in the northeast US 2007 Water Resources Research
    Vol. 43  
    article DOI   
    Z.M. Easton, P. Gérard-Marchant, M.T. Walter, A.M. Petrovic & T.S. Steenhuis  Identifying dissolved phosphorus source areas and predicting transport from an urban watershed using distributed hydrologic modeling 2007 Water Resources Research
    Vol. 43  
    article DOI URL   
    Z.M. Easton & A.M. Petrovic Determining nitrogen loading rates based on landuse in an urban watershed  2008 In: Petrovic In Nett, Carroll & eds. Horgan. The fate of nutrients and pesticides in the urban environment, pp. 19-42  inbook   
    Z.M. Easton & A.M. Petrovic Determining phosphorus loading rates based on landuse in an urban watershed  2008 In: Petrovic Nett, Carroll & Horgan. The fate of nutrients and pesticides in the urban environment, pp. 43-62  inbook   
    Z.M. Easton & A.M. Petrovic  Fertilizer source effect on ground and surface water quality in drainage from turfgrass 2004 Journal of Environmental Quality
    Vol. 33 , pp. 645-655 
    article DOI   
    Z.M. Easton, P.J. Sullivan, M.T. Walter, D.R. Fuka, A.M. Petrovic & T.S. Steenhuis  A simple metric to predict stream water quality from storm runoff in an urban watershed 2010 Journal of Environmental Quality
    Vol. 39 , pp. 1338-1348 
    article DOI   
    Z.M. Easton, M.T. Walter, E.M. Schneiderman & T.S. Steenhuis  Including source specific phosphorus mobility in a non-point source pollution model for agricultural watersheds 2009 ASCE Journal of Environmental Engineering
    Vol. 135(1) , pp. 25-35 
    article   
    Z.M. Easton, M.T. Walter & T.S. Steenhuis  Combined monitoring and modeling indicate the most effective agricultural best management practices 2008 Journal of Environmental Quality
    Vol. 37 , pp. 1798-1809 
    article DOI URL   
    Abstract: Although water quality problems associated with agricultural nonpoint source (NPS) pollution have prompted the rapid and widepread adoption of a variety of so called “best management practices” (BMPs), there have been few realistic efforts to assess their combined effectiveness in reducing NPS pollution. This study used the Variable Source Loading Function (VSLF) model, a distributed watershed model, to simulate phosphorus (P) loading from an upstate New York dairy farm before and after the implementation of a suite of BMPs. With minimal calibration, the model calculates the dissolved P (DP) losses from impervious surfaces (e.g., barnyards), the plant/soil complex, field-applied manure, and loads associated with baseflow conditions. The simulated DP loads agreed well with measured loads for both the pre-BMP and post-BMP periods. More importantly, results showed that BMPs reduced DP loads by 35%, which is over half of the expected reduction if all manure was removed from the watershed, i.e., ~50% reduction. The model results indicate that had no BMPs been installed DP loads would be ~37% greater than observed at the watershed outlet. The most effective BMPs were those that disassociated pollutant loading areas from areas prone to generating runoff, i.e., hydrologically sensitive areas. By contrast, attempts to
    reduce P content in manure were somewhat less effective. This study demonstrates that a combination of distributed, mechanistic modeling and long-term monitoring provides better insights into the effectiveness of water quality protection efforts than either individually.
    Z.M. Easton, M.T. Walter, M. Zion, E.M. Schneiderman & T.S. Steenhuis  Integrating source specific chemistry in basin scale models to predict phosphorus export from agricultural watersheds 2009 Journal of Environmental Engineering ASCE
    Vol. 135 , pp. 25-35 
    article   
    Abrham Melesse Endalamaw  Optimum utilization of ground water in Kobo valley, Eastern Amhara, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Shortage of precipitation in Kobo valley limits the production of vegetables during dry periods and the yield of cereals in the rainy periods. Irrigation from ground water could enable farmers to cultivate more than once a year. Since pumping has an effect on the ground water resources availability, effective management of water resources using reliable calculation of historical groundwater balances at local and subwatershed scales is required (Kendy et al 2004). We used CropWat 4 Window to determine PET of the area and the Crop Water Requirement (CWR) of onion, tomato and pepper, which are cultivated using irrigation during dry months; T-M and simple water balance equations were used to quantify annual recharge to the water table and water table status under different irrigation scenarios. Although irrigation from the groundwater could ensure the food security of the area, different water management scenarios showed that the ground water table will be declining as a result. Recharge and water table calculations show that irrigation increases the recharge to the water table but at the same time reduces the overall water table depth due to pumping. Water table depth will not be depleted if irrigation follows the CWR of vegetables. Calculations for future water table levels indicate that, if the current irrigation rate is extended across all of the irrigable land in the area, the water table level will fall by 2 m per year. To protect against further water table decline, flashfloods should be captured and used to recharge to the ground water. [[Ethiopia]]
    Tegenu Ashagrie Engda  Modeling rainfall, runoff and soil loss relationships in the northeastern Highlands of Ethiopia, Andit Tid watershed 2009 School: Cornell University  mastersthesis URL   
    Abstract: Understanding the basic relationships between rainfall, runoff and soil loss are vital for effective management and utilization of water resources and soil conservation planning. Most of these relationships used in Ethiopia today are developed for temperate climates and might not apply for a monsoonal climate. This study was conducted with the main objective of modeling the relationship between rainfall, runoff, and soil loss for climate conditions prevailing in Ethiopia. The study was conducted in a small watershed located about 180 km North East of Addis Ababa. Analysis of historical and field measured data sets, observation, previous studies and discussion with the community were used to understand the hydrological and erosion processes of the watershed. Soil infiltration rate and rainfall intensity analysis results indicated as infiltration excess runoff is not a dominant runoff mechanism in the upper un-degraded watershed. Effect of slope on runoff generation was also observed from piezometers readings and test plot data. The watershed landscape was divided into saturated, exposed rock and hillslopes areas after understanding of the hydrologic behavior, and each modeled separately using the simple water balance hydrology model. The model was tested for a total of ten years during both calibration and validation. The model predicted the daily, weekly and monthly time steps stream flows with reasonable accuracy. Although there is still substantial work to be done before the model can be routinely applied in all catchments of the Blue Nile Basin with different characteristics, it provides a good alternative to analyze different water and land resources management approaches. Moreover, the new insight of Ethiopian watersheds hydrology has a significant role on implying new land resources management approaches. Stream sediment load trend analysis, observation and on site discussion showed that surface runoff from the lower degraded watershed is the major cause for soil erosion. A simple sediment model which relates surface runoff outputs of the hydrology model with erosion was developed and used for four years daily data. Sediment load prediction provided good insight into the main factors of erosion found in the watershed. Surface runoff from the degraded lower part of the watershed cultivated during the main rainfall seasons was found the main cause of sediment transport to the stream. Further refining the sediment model by incorporating factors that affect erosion will improve the efficiency of the model. [[Ethiopia]]
    Tegenu A. Engda, Haimanote K. Bayabil, Elias S. Legesse, Essayas K. Ayana, Seifu A. Tilahun, Amy S. Collick, Zachary M. Easton, Alon Rimmer, Seleshi B. Awulachew & Tammo S. Steenhuis  Watershed Hydrology of the (Semi) Humid Ethiopian Highlands in a book, title and date unknown  misc URL   
    Abstract: Understanding the basic relationships between rainfall, runoff and soil loss is vital for effective
    management and utilization of water resources and soil conservation planning. A study was conducted
    in three small watersheds in or near the Blue Nile basin in Ethiopia, with long-term records of rainfall
    and discharge. To better understand the water movement within the watershed, piezometers were
    installed and infiltration rates were measured in the 2008 rainy season. We also reanalyzed the
    discharge from small plots within the watersheds. Infiltration rates were generally in excess of the
    rainfall rates. Based on this and plot discharge measurements, we concluded that most rainfall
    infiltrated into the soil, especially in the upper, steep and well-drained portions of the watershed. Direct
    runoff is generated either from saturated areas at the lower and less steep portions of the hill slopes or
    from areas of exposed bedrock. Using these principles, a simple distributed watershed hydrology model
    was developed. The models reproduce the daily discharge pattern reasonably well for the small
    watershed and the ten-day discharge values for the whole Blue Nile Basin in Ethiopia. The simplicity
    and scalability of the model hold promise for use in un-gauged catchments.
    Tegenu A. Engda, Habtamu T. Kassahun, A.S. Collick, T. Adissu, Biniam B. Ashagrie, Zelalem K. Tessema, Assefa Derebe, D. Solomon & T.S. Steenhuis  Soil Properties and Fertility Status Dynamics of North Western Ethiopia as Influenced by Land Use Changes: Case of Dibanke Watershed 2009 Journal of the Ethiopian Soil Science Society
    Vol. (submitted)  
    article URL   
    E.M. Evans, D.R. Lee, R.N. Boisvert, B. Arce, T.S. Steenhuis, M. Prano & S.V. Poats  Achieving efficiency and equity in irrication management: an optimization model of the El Angel watershed, Carchi, Ecuador. 2003 Agricultural Systems
    Vol. 77 , pp. 1-22 
    article URL   
    J. Faulkner, W.J. Zhang, L.D. Geohring & T.S. Steenhuis  Nutrient transport within three vegetative treatment areas receiving silage bunker runoff 2010 Journal of Environmental Management
    Vol. 93 , pp. 587-595 
    article DOI   
    J.W. Faulkner, Z.M. Easton, W. Zhang, L.D. Geohring & T.S. Steenhuis  Design and risk assessment tool for vegetative treatment areas receiving agricultural wastewater: preliminary results 2010 Journal of Environmental Management
    Vol. 91 , pp. 1794-1801 
    article DOI   
    J.W. Faulkner, T. Steenhuis, N. van de Giesen, M. Andreini & J.R. Liebe  Water use and productivity of two small reservoir irrigation schemes in Ghana's upper east region 2008 Irrigation and Drainage
    Vol. 57 , pp. 151-163 
    article DOI URL   
    J.W. Faulkner, W. Zhang, L.D. Geohring & T.S. Steenhuis  Tracer movement through paired vegetative treatment areas receiving silage bunkder runoff 2011 Journal of Soil and Water
    Conservation
    Vol. 66(1) , pp. 18-28 
    article DOI   
    J.W. Faulkner, W. Zhang, L.D. Geohring & T.S. Steenhuis  Nutrient transport within three vegetative treatment areas receiving silage bunker runoff 2010 Journal of Environmental Management
    Vol. 92 , pp. 587-595 
    article DOI   
    Carla S.S. Ferreira, Daniel Soares, Tammo S. Steenhuis, António J.D. Ferreira, Celeste O.A. Coelho & João L.M.P. de Lima  Avaliação da variabilidade espacial e temporal da infiltração de água no solo e suas implicações nos processos hidrológicos ao nível da Bacia 2011   other   
    James P. Fink, J.Y. Parlange & Aly I. El-Kadi  One last visit to the capillarity correction for free surface flow. 2001 Water Resour. Res.
    Vol. 37(3) , pp. 827 
    article   
    F. Flores-López, Z.M. Easton, L.D. Geohring & T.S. Steenhuis  Assessing phosphorus and nitrate transport on a valley farm in the New York City source watersheds, USA (in press) Water Environment Research   article   
    Francisco Flores-López, Zachary M. Easton, Larry D. Geohring, Peter J. Vermeulen, Van R. Haden & Tammo S. Steenhuis  Factors Affecting Phosphorous in Groundwater in an Alluvial
    Valley Aquifer: Implications for Best Management Practices
    2013 Water
    Vol. 5 , pp. 540-559 
    article DOI URL   
    Abstract: Many streams in the US are impaired because of high Soluble Reactive
    Phosphorous (SRP) contributions from agriculture. However, the drivers of ecological
    processes that lead to SRP loss in baseflow from groundwater are not sufficiently
    understood to design effective Best Management Practices (BMPs). In this paper, we
    examine how soil temperature and water table depth influence the SRP concentrations in
    groundwater for a dairy farm in a valley bottom in the Catskills (NY, USA). Measured
    SRP concentrations in groundwater and baseflow were greater during the fall, when soil
    temperatures are warmer, than during winter and spring. The observed concentrations were
    within the bounds predicted by groundwater temperatures using the Arrhenius equation,
    except during fall, when concentrations rose above these predictions. These elevated
    concentrations were likely caused by mineralization and consequent accumulation of
    phosphorous (P) in summer. In addition, SRP concentrations were greater in near-stream
    areas, where water tables where higher. In short, SRP concentrations are dependent on
    temperature, demonstrating the importance of understanding the underlying mechanism of
    ecological processes. In addition, results suggest BMPs that apply manure on land having a
    deep groundwater, instead of on land with a shallow water table will lower overall
    SRP contributions.
    F. Flores-López, Z.M. Easton & T.S. Steenhuis  Relative Effects of Ground Water and Near Stream Best Management Practices on Soluble Reactive Phosphorus and Nitrate Surface Water Concentrations on a Dairy Farm in a Catskill Mountain Valley (in press) Journal of Soil and Water Conservation   article   
    F. Flores-López, Z.M. Easton & T.S. Steenhuis  A multivariate analysis of covariance to determine the effects of near stream best management practices on nitrogen and phosphorus concentrations on a dairy farm in the New York City CEAP watershed 2010 Journal of Soil and Water Conservation
    Vol. 65(6) , pp. 438-449 
    article DOI   
    J.R. Frankenberger, E.S. Brooks, M.T. Walter, M.F. Walter & T.S. Steenhuis  A GIS-based variable source area model 1999 Hydrological Processes
    Vol. 13(6) , pp. 804-822 
    article URL   
    J.R. Frankenberger, M.F. Walter & J. Boll  Use of a GIS-Based Hydrologic Model to Schedule Farm Manure Application in the New York City Watershed 1996 Proc. Symposium: Watershed Restoration Management: Physical, Chemical, and Biological considerations. New York City Water Supplies Studies  inproceedings   
    Daniel R. Fuka  Simplifying Watershed Modeling 2013 School: Cornell University  phdthesis URL   
    Abstract: Obtaining representative meteorological data for an area, properly characterizing the physical characteristics of a watershed, and accurately representing the processes internal to watersheds can be complex. Several studies are presented that simplify the steps to obtain representative weather data, characterize the topography a watershed, and use this physical characterization to build a process based snowmelt model that requires no calibration to replace a calibration dependent temperature index based model. The objective of these studies is to present a suite of computational tools and proof of concept studies that simplify watershed modeling. First we present a method to quickly and easily obtain a 32-year record of meteorological forcing data for any location in the from the freely available Climate Forecast System Reanalysis dataset. Results from this analysis indicate that the CFSR data can reliably act as a first approximation of historical weather data over a watershed. The data consisting of precipitation, temperature, and other relevant weather information. Results show that using this dataset, can be as, or more, accurate than using weather records from the closest weather stations when using the Soil and Water Assessment Tool (SWAT) watershed model. The next two chapters describe two original software releases intended to provide watershed modeler with a suite of computational tools to better describe physical and chemical characteristics of a given watershed. The first, TopoSWAT, is a toolbox intended to characterize the topological properties of hydrological systems, and the second, SWATmodel, is an open-project porting of the legacy SWAT watershed model to be widely distributed and run as a linear-model-like function on multiple operating systems (OS) and processor platforms within the R language. These software packages have resulted in significant simplification of the integration of physical characteristics into the SWAT modeling system and have made the SWAT modeling framework available to more users in multiple environments including those scientists dependent on the Unix and Mac Osx based operating systems. The final chapter presents an integration example of the previous chapters, building a more process-based snow accumulation and snowmelt routine to replace the temperature index based routine in the aforementioned SWAT modeling system. The results of this integration show that spatial snow distributions predicted by a more process-based model better matched observations from LandSat imagery and a SNOTEL station, and requires limited extra effort when initialized using the previously described TopoSWAT toolbox.
    B. Gao, T.S. Steenhuis, Y. Zevi, V.L. Morales, J.L. Nieber, B.K. Richards, J.F. McCarthy & J.Y. Parlange  Capillary retention of colloids in unsaturated porous media 2008 Water Resources Research
    Vol. 44  
    article DOI   
    B. Gao, T.S. Steenhuis, Y. Zevi, J.Y. Parlange, R.N. Carter & T.A. Trabold  Visualization of unstable water flow in a fuel cell gas diffusion layer 2009 Journal of Power Sources
    Vol. 190 , pp. 493-498 
    article DOI URL   
    B. Gao, M.T. Walter, T.S. Steenhuis J.Y. Parlange, B.K. Richards, W.L. Hogarth & C.W. Rose  Investigating raindrop effects on transport of sediment and non-sorbed chemicals from soil to surface runoff 2005 J. Hydrology
    Vol. 308 , pp. 313-320 
    article URL   
    B. Gao, M.T. Walter, T.S. Steenhuis, W.L. Hogarth & J.Y. Parlange  Rainfall induced chemical transport from soil to runoff: Theory and experiments 2004 Journal of Hydrology
    Vol. 295 , pp. 291-304 
    article URL   
    B. Gao, M.T. Walter, T.S. Steenhuis, J.Y. Parlange, K. Nakano, C.W. Rose & W.L. Hogarth  Investigating ponding depth and soil detachability for a mechanistic erosion model using a simple experiment 2003 Journal of Hydrology
    Vol. 277(1-2) , pp. 116-124 
    article URL   
    Casey Ann Garland  A Study in Complexity of Distributed Hydrology Models: S.W.A.T. Versus a Parameter Efficient Model 2013 School: Cornell University  mastersthesis URL   
    Abstract: The 2007 National Water Inventory report to Congress estimated that 45% of all streams and
    rivers in the US donʼt support their designated use. Of the possible causes of impairment,
    sediment and siltation are listed as the most common followed by pathogens, habitat alterations,
    metals and nutrients where agriculture is the leading source of impairment. Growing numbers of
    hydrologists have found that the majority of runoff and non-point source pollution come from
    small, saturated areas in the landscape. Some work has been done to model these areas but
    they do not perform significantly differently than models that do not incorporate this type of
    hydrology. Spatial distribution is seen to be an important aspect to modeling these areas well
    but has not proven to yield significantly different results. This study compares two variable
    source areas based models, a complex, distributed saturated areas model with a simple non-
    distributed model. Two watersheds were used for the study: Little Tonawanda Creek and Black
    Creek. Black Creek is listed as impaired on New York's official Clean Water Act 303(d) list.
    Little Tonawanda is located just west of Black Creek and is not listed as impaired. The Soil and
    Water Assessment Tool with modification to include saturated areas (SWAT-VSA) was chosen
    as the complex model and the Parameter Efficient Distributed (PED) model with shallow
    aquifers was used as the simple model. SWAT-VSA divides the watershed into topographic
    index (TI) classes that indicate the degree of soil saturation for each unit and PED uses a similar
    approach. Modeling snowmelt is an important component to simulating stream flow in regions
    that receive significant amounts of snow. Three modified snowmelt datasets were created and
    used to determine how snowmelt affected flow predictions. Both models with each snowmelt
    dataset were applied to both watersheds. Black Creek models yielded daily Nash Sutcliffe
    Efficiency (NSE) as high as 0.71 using the PED model and percent bias of -10.7%; a NSE of
    0.62 and percent bias of -10.3% for Little Tonawanda Creek.. Validation periods using the PED
    model yielded higher NSE than calibrated years for Black and Little Tonawanda Creek. Based
    on flow analysis from each TI class, SWAT would need internal modifications to attribute
    saturation-based interflow to higher TI classes thereby simulating VSA hydrology better. More
    representative delineation of TI classes for SWAT and better simulated snowmelt would improve
    predicted flows as well as simplify model parameterization. The snowmelt+adjusted dataset
    improved predictions during the calibration and validation time periods for both watersheds and
    models with the exception of the SWAT model for Black Creek. Although both models achieved
    similar metrics, PED requires less time, input data and fewer parameters making it more
    desirable given the goals of a project. It also predicted flows outside of the calibration period
    well making it more useful to simulate future scenarios.
    P. Garnier, R. Angulo-Jaramillo, D.A. DiCarlo, T.W.J. Bauters, C.J.G. Darnault, T.S. Steenhuis, J.Y. Parlange & P. Baveye  Reply to "Comment on 'Dual-Energy Synchrotron X Ray Measurements of Rapid Soil Density and Water Content Changes in Swelling Soils During Infiltration' by J.M. Kirby and D.E. Smiles" 1999 Water Resour. Res.
    Vol. 35 , pp. 3589-3590 
    article URL   
    P. Garnier, R. Angulo-Jaramillo, D.A. DiCarlo, T.W.J. Bauters, C.J.G. Darnault, T.S. Steenhuis, J.Y. Parlange & P. Baveye  Dual-energy synchrotron X-ray measurements of rapid soil density and water content changes in swelling soils during infiltration. 1998 Water Resources Research
    Vol. 34(11) , pp. 2837-2842 
    article URL   
    N. van de Geisen, M. Kremer & T.S. Steenhuis  An evaluation of risks associated with underground storage tanks in Tompkins County. Ithaca, NY 1990   techreport   
    L.D. Geohring, O.V. McHugh, M.T. Walter, T.S. Steenhuis, M.S. Akthar & M.F. Walter  Phosphorus transport into subsurface drains by macropores after manure applications: Implications for best manure management Practices. 2001 Soil Science
    Vol. 166(12) , pp. 896-909 
    article URL   
    L.D. Geohring, P.E. Wright, T.S. Steenhuis & M.F. Walter  Fecal Coliforms in Subsurface Drains after Manure Application. 2000 J. of Env. Quality
    Vol. (submitted)  
    article   
    L.D. Geohring, P.E. Wright, T.S. Steenhuis & M.F. Walter  Fecal Coliforms in Tile Drainage Effluent. 1999   other   
    L.D. Geohring, P.E. Wright, T.S. Steenhuis & M.F. Walter  Subsurface Drain Water Quality Impacts from Manure Applications 1999 (9905) Presented at NE Agricultural/Biological Engineering Conference  inproceedings   
    N. van de Giesen, J. Liebe, M. Andreini & T.S. Steenhuis  Use of small reservoirs in West Africa as remotely-sensed cumulative runoff gauges. 2004 In: A.J. Teuling, H. Leijnse, P.A. Troch, J. Sheffield & E.F. Wood. Proceedings from 2nd international CAH-MDA workshop on: The Terrestial Water Cycle: Modelling and Data Assimilation Across Catchment Scales, pp. 32-35  inproceedings URL   
    Nick van de Giesen & Tammo S. Steenhuis  Steenhuis Receives 2011 International Award 2012 EOS
    Vol. 93(3) , pp. 35 
    article URL   
    Abstract: Tammo Steenhuis received the International Award at the 2011 Fall Meeting Honors Ceremony, held on 7 December 2011 in San Francisco, Calif. The award honors “an individual scientist or a small team for making an outstanding contribution to furthering the Earth and space sciences and using science for the benefit of society in less favored nations.”
    N. van de Giesen, T.S. Steenhuis & J.Y. Parlange  Short- and long-time behavior of aquifer drainage after slow and sudden recharge according to the linearized Laplace equation 2005 Adv. in Water Res.
    Vol. 28 , pp. 1122-1132 
    article URL   
    N.C. van de Giesen, J.Y. Parlange & T.S. Steenhuis  Transient Flow to Open Drains: Comparison of Linearized Solutions With and Without the Dupuit Assumption. 1994 Water Resour. Res.
    Vol. 30 , pp. 3033-3039 
    article   
    T.J. Gish, K.J.S. Kung, D.C. Perry, J. Posner, G. Bubenzer, C.S. Helling, E.J. Kladivko & T.S. Steenhuis  Impact of Preferential Flow at Varying Irrigation Rates by Quantifying Mass Fluxes 2004 J. Environ. Qual.
    Vol. 33 , pp. 1033-1040 
    article   
    R.J. Glass, S. Cann, J. King, N. Bailey, J.Y. Parlange & T.S. Steenhuis  Wetting Front Instability in Unsaturated Porous Media: A Three-Dimensional Study in Initially Dry Sand. 1990 TIPM
    Vol. 5 , pp. 247-268 
    article   
    R.J. Glass, G.H. Oosting & T.S. Steenhuis  Preferential Solute Transport in Layered Homogeneous Sands as a Consequence of Wetting Front Instability. 1989 J. Hydrol.
    Vol. 110 , pp. 87-105 
    article   
    R.J. Glass, J.Y. Parlange & T.S. Steenhuis  Immiscible Displacement in Porous Media: Stability Analysis of Three-Dimensional, Axisymmetric Disturbances with Application to Gravity-Driven Wetting Front Instability. 1991 Water Resour. Res.
    Vol. 27 , pp. 1947-1956 
    article   
    R.J. Glass, J.Y. Parlange & T.S. Steenhuis  Wetting Front Instability. 1. Theoretical Discussion and Dimensional Analysis. 1989 Water Resour. Res.
    Vol. 25 , pp. 1187-1194 
    article   
    R.J. Glass, T.S. Steenhuis & J.Y. Parlange  Wetting Front Instability. 2. Experimental Determination of Relationships Between System Parameters and Two-Dimensional Unstable Flow Field Behavior in Initially Dry Porous Media. 1989 Water Resour. Res.
    Vol. 25 , pp. 1195-1207 
    article   
    R.J. Glass, T.S. Steenhuis & J.Y. Parlange  Mechanism for Finger Persistence in Homogeneous, Unsaturated, Porous Media: Theory and Verification. 1989 Soil Sci.
    Vol. 148 , pp. 60-70 
    article   
    R.J. Glass, T.S. Steenhuis & J.Y. Parlange  Wetting Front Instability as a Rapid and Far-Reaching Hydrologic Process in the Vadose Zone. In: Rapid and Far-Reaching Hydrologic Processes in the Vadose Zone, P.F. Germann, Ed. 1988 J. Contam. Hydrol.
    Vol. 3 , pp. 207-226 
    article   
    B.A. Gleitsmann, M.M. Kroma & T.S. Steenhuis  Sustainable rural water supply management through partnerships and capacity building in Mali, West Africa. In: M. Kitissou, M. Ndulo, M. Nagel and M. Griego eds. Hydropolitics in Africa. A contemporary Challenge 133-156. 2007   other   
    B.A. Gleitsmann, M.M. Kroma & T.S. Steenhuis  Analysis of a rural water supply project in three communities in Mali: Participation and sustainability 2007 Natural Resources Forum
    Vol. 31 , pp. 142-150 
    article URL   
    C.L. Goodale, S.A. Thomas, G. Fredriksen, E.M. Elliott, K.M. Flinn, T.J. Butler & M.T. Walter  Unusual seasonal patterns and inferred processes of nitrogen retention in forested headwaters of the Upper Susquehanna River 2009 Biogeochemistry
    Vol. 93 , pp. 197?218 
    article DOI   
    C.D. Guzman, S.A. Tilahun, A.D. Zegeye & T.S. Steenhuis  Suspended Sediment Concentration-Discharge Relationships in the (Sub) Humid Ethiopian Highlands 2013 Hydrology and Earth System Sciences
    Vol. 17(3) , pp. 1067-1077 
    article DOI URL   
    Abstract: Loss of top soil and subsequent filling up of reservoirs in much of the lands with variable relief in developing countries degrades environmental resources necessary for subsistence. In the Ethiopia highlands, sediment mobilization from rain-fed agricultural fields is one of the leading factors causing land degradation. Sediment rating curves, produced from long-term sediment concentration and discharge data, attempt to predict suspended sediment concentration variations, which exhibit a distinct shift with the progression of the rainy season. In this paper, we calculate sediment rating curves and examine this shift in concentration for three watersheds in which rain-fed agriculture is practiced to differing extents. High sediment concentrations with low flows are found at the beginning of the rainy season of the semi-monsoonal climate, while high flows and low sediment concentrations occur at the end of the rainy season. Results show that a reasonably unique set of rating curves were obtained by separating biweekly data into early, mid, and late rainfall periods and by making adjustments for the ratio of plowed cropland. The shift from high to low concentrations suggests that diminishing sediment supply and dilution from greater base flow during the end of the rainfall period play important roles in characterizing changing sediment concentrations during the rainy season.
    C.D. Guzman, S.A. Tilahun, A.D. Zegeye, B. Yitaferu, R.W. Kay, G.N. Nagle & T.S. Steenhuis  Finding Eroding Areas and Patterns with GIS and Community Knowledge in the Ethiopian Highlands 2012 Proceedings for the ITU/MEDFRIEND International Conference on Sediment Transport Modeling in Hydrological Watersheds and Rivers, Istanbul, Turkey.  inproceedings   
    Abstract: In the Ethiopian highlands, soil erosion has greatly decreased agricultural productivity and continues unabatedly despite investing millions of dollars in soil and water conservation practices. The effectiveness of current soil conservation practices thus, must be re-examined from multiple perspectives to develop better comprehensive sustainable strategies for land management. GIS-based Universal Soil Loss Equation (USLE), community perceptions, and field observations are compared to examine spatio-temporal variations in erosion and subsequent soil nutrient changes at the Debre Mewi watershed. Sixteen sites were monitored during the 2012 rainy season for topsoil depth change, water table height, and soil nutrients. USLE treated only steeper slopes and cropped land as areas vulnerable to erosion, however discussions participants described spring paths, saturated areas, degraded areas and active gullies as primary zones of erosion. Observational evidence suggested that the highest midslope areas had greater soil depth decreases than the top of the slope, lower midslope, or downslope. Whereas the USLE overlaps parameters to find highly eroding areas, community members are mostly looking to concentrated overland flow paths. Hence, saturated pathways, inducing saturation-excess overland flow, subsurface flow, and gully formation, are identified more by the community than by USLE. Furthermore, higher saturation in the downslope area contributes to greater baseflow and reductions in sediment concentrations midway through the season for the watershed. Exchangeable cations also decreased here, while total nitrogen and available phosphorus increased.
    P. Gérard-Marchant, W.D. Hively & T.S. Steenhuis  Distributed hydrological modelling of total dissolved phosphorus transport in an agricultural landscape, part I: distributed runoff generation 2006 Hydrology and Earth System Sciences
    Vol. 10 , pp. 245-261 
    article URL   
    P. Gérard-Marchant, W.D. Hively & T.S. Steenhuis  Distributed hydrological modelling of total dissolved phosphorus transport in an agricultural landscape, part I: distributed runoff generation 2005 Hydrology and Earth System Sciences Discussions
    Vol. 2 , pp. 1537-1579 
    article URL   
    P. Gérard-Marchant, M.T. Walter & T.S. Steenhuis  Simple Models for Phosphorous Loss from Manure During Rainfall 2005 J. Environ. Quality
    Vol. 34(3) , pp. 872-876 
    article URL  URL2 
    D.L. Hanson, T.S. Steenhuis, M.F. Walter & J. Boll  Effects of Soil Degradation and Management Practices on the Surface Water Dynamics in the Talgua River Watershed in Honduras. 2004 Land Degradation & Development
    Vol. 15 , pp. 367-381 
    article URL   
    A.A. Harpold, D.A. Burns, S.B. Shaw, M.T. Walter & T.S. Steenhuis  Relating hydrogeomorphologic properties to stream buffering chemistry in the Neversink River watershed, New York, USA 2010 Hydrological Processes
    Vol. 24(26) , pp. 3759-3771 
    article DOI   
    A.A. Harpold, S.W. Lyon, P.A. Troch & T.S. Steenhuis  The hydrological effects of lateral preferential flow paths in a glaciated watershed in the Northeastern United States 2010 Vadose Zone Journal
    Vol. 9(2) , pp. 397-414 
    article DOI   
    E.Z. Harrison, U. Krogmann, A. Barker, A. Hay, M. McBride, W. McDowell, B.K. Richards, T.S. Steenhuis & R. Stehouwer  Guidelines for application of sewage biosolids to agricultural lands in the northeastern U.S. 2007 (Publication number E317)   techreport URL   
    E.Z. Harrison, M.B. McBride, B.K. Richards & T.S. Steenhuis  Sludge effects on land: a case for caution 1998 Resource
    Vol. 5(9) , pp. 11-12 
    article   
    Tara S. Hatami, L.D. Geohring & T.S. Steenhuis  Using a vegetative filter strip for dissolved phosphorus removal from milkhouse wastewater in Upstate NY. 2003 School: Cornell University  techreport   
    R.J. Haverkamp, J.Y. Parlange, R. Cuenca, P.J. Ross & T.S. Steenhuis 7. Scaling of the Richards Equation and its application to watershed modeling  1998 In: G. Sposito. Scale Dependence and Scale Invariance in Hydrology, pp. 190-223  inbook   
    A. Heilig, D. DeBruyn, M.T. Walter, C.W. Rose, J.Y. Parlange, T.S. Steenhuis, G.C. Sander, P.B. Hairsine, W.L. Hogarth & L.P. Walker  Corrigendum: Testing a mechanistic soil erosion model with a simple experiment 2006 Journal of Hydrology
    Vol. 317 , pp. 171-172 
    article   
    A. Heilig, D. DeBruyn, M.T. Walter, C.W. Rose, J.Y. Parlange, T.S. Steenhuis, G.C. Sander, P.B. Hairsine, W.L. Hogarth & L.P. Walker  Testing a mechanistic soil erosion model with a simple experiment. 2001 Journal of Hydrology
    Vol. 244 , pp. 9-16 
    article URL   
    A. Heilig, T.S. Steenhuis, M.T. Walter & S. Herbert  Funneled flow mechanisms in sloping layered soil: Field investigations 2003 J. Hydrology
    Vol. 279 , pp. 210-223 
    article URL   
    W.D. Hively, P. Gérard-Marchant & T.S. Steenhuis  Distributed hydrological modeling of total dissolved phosphorus transport in an agricultural landscape, part II: dissolved phosphorus transport 2006 Hydrology and Earth System Sciences
    Vol. 10 , pp. 263-276 
    article URL   
    W.D. Hively, P. Gérard-Marchant & T.S. Steenhuis  Distributed hydrological modeling of total dissolved phosphorous transport in an agricultural landscape, Part II: Dissolved Phosphorous transport. 2005 Hydrol. Earth System Sci. Discuss.
    Vol. 2 , pp. 1581-1612 
    article URL   
    W.L. Hogarth, J.Y. Parlange, C.W. Rose, C. Fuentes, R. Haverkamp & M.T. Walter  Interpolation Between Darcy-Weisbach and Darcy for Larninar and Turbulent Flows 2005 Advances in Water Resources
    Vol. 28(10) , pp. 1028-1031 
    article URL   
    W.L. Hogarth, J.Y. Parlange, C.W. Rose, G.C. Sander, T.S. Steenhuis & A. Barry  Soil erosion due to rainfall impact with inflow: An analytical solution with spatial and temporal effects 2004 J. Hydrology
    Vol. 295(1-4) , pp. 140-148 
    article   
    W.L. Hogarth, J.Y. Parlange, C.W. Rose, G.C. Sander, M.T. Walter & M.F. Walter  A note on Chows's description of the weak hydraulic jump 2008 Journal of Hydraulic Research
    Vol. 46(5) , pp. 703-706 
    article DOI   
    G. Holst-Warhaft & T.S. Steenhuis  Losing Paradise: The Water Crisis in the Mediterranean 2010   book URL   
    Abstract: (publisher promo) Taking a uniquely interdisciplinary view of the Eastern Mediterranean region's water problems, this book considers some of the technical and regulatory solutions being proposed or implemented to solve the difficulties of diminished or polluted water supplies. Stressing the importance of traditional and historical cultural understanding in addressing the water crisis, the authors demonstrate that what is required is an integrated legal, social and scientific management system appropriate to each country's stage of development and their cultural heritage. Using case studies from Lebanon, Italy, Spain, Egypt, Greece, Jordan and Cyprus, the authors focus on the urgency of the present crisis faced by each country and the need for cooperation. The suggested solutions also serve as a paradigm for the rest of the world as it faces similar issues of water shortage.
    R.E. Horton  Simplified methods of determining an infiltration-capacity curve from an infiltrometer experiment. 1942 Transactions American Geophysical Union
    Vol. 23 , pp. 570-575 
    article URL   
    R.E. Horton  A Simplified method of determining the constants in the infiltration-capacity equation. 1942 Transactions American Geophysical Union
    Vol. 23 , pp. 575-578 
    article URL   
    R.E. Horton  Analysis of runoff-flat experiments with varying infiltration-capacity. 1939 Transactions American Geophysical Union
    Vol. 20 , pp. 693-711 
    article URL   
    R.E. Horton  The role of infiltration in the hydrologic cycle. 1933 Transactions American Geophysical Union
    Vol. 14 , pp. 446-460 
    article URL   
    A.R. Jacobson, S. Klitzke, M.B. McBride, P. Baveye & T.S. Steenhuis  The desorption of silver and thallium from soils in the presence of a chelating resin with thiol functional groups 2005 Water, Air, and Soil Pollution
    Vol. 160 , pp. 41-54 
    article URL   
    A.R. Jacobson, M.B. McBride, P. Baveye & T.S. Steenhuis  Environmental factors determining the trace-level sorption of silver and thallium to soils 2005 Sci. of the Total Environ.
    Vol. 345 , pp. 191-205 
    article URL   
    D.S. Jeng, B.R. Seymour, D.A. Barry, L. Li & J.Y. Parlange  New Approximation for Free Surface Flow of Groundwater: Capillarity Correction. Advances in Water Resources
    Vol. 28(10) , pp. 1032-1039 
    article URL   
    D.S. Jeng, B.R. Seymour, D.A. Barry, J.Y. Parlange, D.A. Lockington & L. Li  Steepness Expansion for Free Surface Flows in Coastal Aquifers 2005 Journal of Hydrology
    Vol. 309(1-4) , pp. 85-92 
    article URL   
    A.G. Johnson, T. Morrow & M. Walter  Enhancing Learning through Cooperative Course Offerings 1998 ASEE Annual Conference Proceedings  inproceedings   
    M.S. Johnson, W.F. Coon, V.K. Mehta, T.S. Steenhuis, E.S. Brooks & J. Boll  Application of two hydrologic models with different runoff mechanisms to a hillslope dominated watershed in northeastern US: A comparison of HSPF and SMR 2003 J. Hydrology
    Vol. 284 , pp. 57-76 
    article URL   
    M.S. Johnson, J. Lehmann, T.S. Steenhuis, L.V. de Olveira & E.C.M. Fernades  Spatial and temporal variability of soil water repellency of Amazonian pastures 2005 Australian J. of Soil Res.
    Vol. 43 , pp. 319-326 
    article URL   
    Aemiro Gedefaw Kassa  Simulating the Hydrologic Response of Gilgel Abbay Watershed with a Simple Semi-Distributed Water Balance Model 2011 School: Cornell University  mastersthesis URL   
    Abstract: Almost all previous hydrological studies for Gilgel Abbay watershed use parameter
    intensive models usually for climates and landscapes unlike the Ethiopian Highlands.
    In this study a simple distributed water balance model was used that runs in excel
    spread sheet to simulate the runoff processes in the Gilgel Abbay watershed. The
    watershed was divided up into potentially saturated excess runoff areas at the bottom
    of the hillsides near rivers, and hill lands. The hill lands were either degraded
    producing surface runoff or not degraded. In the non-degraded area all rain water
    infiltrates and released with a time delay as interflow and baseflow. The model
    simulates well the river discharge except for some peak flows. The discharge variation
    of the Gilgel Abbay river was explained well with the determination coefficient, R2 =
    0.75 and Nash Sutcliffe efficiency, NSE= 0.74. The results indicate that the simple site
    specific water balance model can be an important tool in identifying and addressing
    runoff generation mechanisms with the scarce data availability and can be easily
    refined when new and comprehensive data are accessible.
    Habtamu Tilahun Kassahun  Payment for environmental service to enhance resource use efficiency and labor force participation in managing and maintaining irrigation infrastructure, the case of the upper Blue Nile basin 2009 School: Cornell University  mastersthesis URL   
    Abstract: Using the contingent valuation method, this research project explores how irrigation beneficiary households in the Upper Blue Nile Basin of Africa value irrigation water to enhance agricultural productivity. Research in this area is important because soil degradation and sedimentation threaten the livelihoods of many populations in the region. Furthermore, mitigation measures require continual large investment costs both in terms of human capital and financial resources. The research encompasses the analysis of data collected from 210 randomly selected household heads in the Koga Watershed of the Upper Blue Nile Basin in Ethiopia. The research reported herein has two major objectives. The first objective is to explore the value of irrigation provided to households as an initial step towards the development of a payment for environmental services (PES) program. Under this broad objective, there are two specific goals. The first is to estimate households? willingness to pay (WTP) to establish PES for upland soil and water conservation measures that ultimately reduce sedimentation loading in the newly constructed reservoir. The model results revealed that the aggregate expected WTP for the total of 7,000 hectares of irrigable land was 964,320 birr per year (9.65 birr equal $1 U.S.) with a household utility-maximizing price of 192 birr per hectare of irrigable land per year. The aggregate WTP was more than three times the annual budget allocated by the Koga Irrigation and Watershed Management project to reduce sedimentation loads (caused by upstream soil erosion) by 50 percent over the past 6 years. Thus, the aggregate expected WTP by downstream users has a potential to compensate upstream service providers and enhance resource use efficiency. The second major objective of this research is to examine the magnitude and determinants of labor supply behavior of farm households for the routine management and maintenance of irrigation infrastructure in the Upper Blue Nile basin of Ethiopia. For the total irrigable land area it is estimated that households could contribute an estimated 468,784 person labor days per year. This would meet more than 30% of the minimum annual labor requirement of the project for managing and maintaining of irrigation infrastructures. A logit model analysis indicated that households? willingness to contribute labor was influenced by education, age of the household head, expectations about yields in irrigated agriculture, wealth of the household, involvement in off-farm activities, time taken to walk to the nearest market, the household?s dependency ratio and randomly assigned bid working days. Of these determinant factors, an intervention measures for managing and maintaining irrigation infrastructure through labor force participation should emphasize education about the likely benefits of irrigated agriculture. To increase labor participation particularly for new development projects, description of resource valuation scenario and future benefits should be clearly explained to farmers. Furthermore, the number of persondays allotted for conservation activities per hectare of irrigable land should take into account the high elasticity of households? willingness to contribute for the randomly assigned bid working days. [[Ethiopia]]
    Habtamu T. Kassahun, Tegenu A. Engda, A.S. Collick, Husien A. Oumer, Haimanote K. Bayabil, Tigist Y. Tebebu, Anteneh A. Zewdie, D. Solomon, C.F. Nicholson & T.S. Steenhuis  The Effect of Land Use and Its Management Practices on Plant Nutrient Availability and Carbon Sequestration [[Ethiopia]] 2009   other URL   
    Habtamu T. Kassahun, C.F. Nicholson, D. Solomon, A.S. Collick & T.S. Steenhuis  Economics and policy context for the biological management of soil fertility (BMSF) in Ethiopia 2009   other URL   
    E. Kendy  The 2003 energy bill: Did politics trump science? 2004 Geotimes
    Vol. (article)  
    article   
    E. Kendy  Suppressing science in policy: Sharing responsibility. 2004 Geotimes
    Vol. (article)  
    article   
    E. Kendy, P. Gérard-Marchant, M.T. Walter, Y. Zhang, C. Liu & T.S. Steenhuis  A soil-water-balance approach to quantifying groundwater recharge from irrigated cropland in the North China Plain 2003 Hydrological Processes
    Vol. 17 , pp. 2011-2031 
    article URL  URL2 
    E. Kendy, J. Wang, D.J. Molden, C. Zheng, C. Liu & T.S. Steenhuis  Can urbanization solve inter-sector water conflicts? Insight from a case study in Hebei Province, North China Plain 2007 Water Policy
    Vol. 9(Supplement 1) , pp. 75-93 
    article URL   
    E. Kendy, Y. Zhang, C. Liu, J. Wang & T. Steenhuis  Groundwater recharge from irrigated cropland in the North China Plain: case study of Luancheng County, Hebei Province, 1949-2000 2004 Hydrological Processes
    Vol. 18 , pp. 2289-2302 
    article DOI URL   
    Abstract: Effective management of limited water resources in the North China Plain requires reliable calculation of historical
    groundwater balances at local, sub-watershed scales. These calculations typically are hindered by poorly constrained
    recharge estimates. Using a simple soil-water balance model, we independently calculated annual recharge from
    irrigated cropland to unconfined alluvial aquifers underlying Luancheng County, Hebei Province, in the western part
    of the North China Plain, for 1949–2000. Model inputs include basic soil characteristics and daily precipitation,
    potential evapotranspiration, irrigation, crop root depth, and leaf-area index; model outputs include daily actual
    evapotranspiration and areal groundwater recharge. Results indicate that areal recharge is not a constant fraction
    of precipitation plus irrigation, as previously assumed, but rather the fraction increases as the water inputs increase.
    Thus, model-calculated recharge rates range from 5 to 109 cm year 1 depending on the quantity of precipitation
    ,and irrigation applied. The important implication is that, because this drainage recharges the underlying aquifer,
    improving irrigation efficiency by reducing seepage does not save water. This explains why successful efforts to reduce
    groundwater pumping for irrigation have had no effect on water-table declines. So long as crop cover is extensive and
    all crop-water requirements are met—which has been the case in Luancheng County since the 1960s—groundwater
    levels will continue to decline at a steady rate. Potential solutions include reducing the irrigated area, reintroducing
    fallow periods, and shifting water from agriculture to other, less consumptive uses. Copyright  2004 John Wiley &
    Sons, Ltd.
    B.J. Kim, M.B. McBride, B.K. Richards & T.S. Steenhuis  The long-term effect of sludge application on Cu, Zn, and Mo behavior in soils and accumulation in soybean seeds 2007 Plant and Soil
    Vol. 299(1-2) , pp. 227-236 
    article DOI   
    S.J. Kim & T.S. Steenhuis Grid-Based Variable Source Area Storm Runoff Model (GRISTORM)  1998 In: V. Babovic & L. Larsen. Hydroinformatics 1998, pp. 1383-1390  inbook URL   
    S.J. Kim & T.S. Steenhuis  GRISTROM: Grid-based variable source area storm runoff model. 2001 Soil and Water Div. ASAE Trans.
    Vol. 44(4) , pp. 863-875 
    article URL   
    S.J. Kim & T.S. Steenhuis  GRIEROM: Grid-based variable source area soil-water erosion and deposition model 2001 Soil and Water Div. ASAE Trans.
    Vol. 44(4) , pp. 853-862 
    article URL   
    Y.J. Kim, C.J.G. Darnault, N.O. Bailey, J.Y. Parlange & T.S. Steenhuis  Equation for Describing Solute Transport in Field Soils With Preferential Flow Paths 2005 Soil Science Society of America Journal
    Vol. 69(2) , pp. 291-300 
    article URL   
    Y.J. Kim, L.D. Geohring, J.H. Jeon, A.S. Collick, S.K. Giri & T.S. Steenhuis  Evaluation of the effectiveness of vegetative filter strips for phosphorus removal with the use of a tracer 2006 Journal of Soil and Water Conservation
    Vol. 61(5) , pp. 293-302 
    article   
    Abstract: Vegetative filter strips are commonly used as a best management practice to control agricultural pollution. This study investigated the relationship between flow pattern and removal of dissolved phosphorus (P) within vegetative filter strips treating milk house wastewater on two dairy farms located in the Catskills/Delaware watersheds, which are the source of drinking water for New York. Numerous surface and subsurface wells were monitored in the two vegetative filter strips, and chloride tracer was applied to evaluate flow paths. Soluble reactive P concentrations were measured during regular milk house wastewater discharges prior to and during chloride application. Chloride breakthrough showed wastewater flowing preferentially through the vegetative filter strip. The soluble reactive P concentrations were significantly higher within the preferential flow paths compared to the other less saturated parts of the vegetative filter strip. Removal of soluble reactive P was minimal in a saturated flow path, which persisted for 15 m (50 ft) and only began to occur as the wastewater eventually dissipated into drier soil areas. Although soluble reactive P concentrations were eventually reduced to below 0.2 mg L-1 (0.2 ppm) at the bottom of both vegetative fitter strips, these results suggest the importance of proper design, site and location characteristics, and maintenance to assure uniform distribution and infiltration of wastewater within the vegetative fitter strip to maintain effectiveness and prolong the life of the vegetative fitter strip.
    Y.J. Kim, T.S. Steenhuis & K. Nam  Movement of Heavy Metals in Soil through Preferential Flow Paths under Different Rainfall Intensities 2008 CLEAN SOIL AIR WATER
    Vol. 36 , pp. 984-989 
    article   
    K.J.S. Kung, M. Hanke, C.S. Helling, E.J. Kladivko, T.J. Gish, T.S. Steenhuis & D.B. Jaynes  Quantifying pore-size spectrum of macropore-type preferential pathways 2005 Soil Science Society of Amer. J.
    Vol. 69 , pp. 1196-1208 
    article URL   
    K.J.S. Kung, E.J. Kladivko, C.S. Helling, T.J. Gish, T.S. Steenhuis & D.B. Jaynes  Quantifying the pore size spectrum of macropore-type preferential pathways under transient flow 2006 Vadose Zone Journal
    Vol. 5(3) , pp. 978-989 
    article   
    Abstract: It is well known that there is a spectrum of pores in a soil profile. The conventional use of a single lumped value of soil hydraulic conductivity to describe a spectrum of hydraulically active pores may have unintentionally impeded the development of field-scale chemical transport theory and perhaps indirectly hindered the development of management protocols for chemical application and waste disposal. In this study, three sets of four field-scale tracer mass flux breakthrough patterns measured under transient unsaturated flow conditions were used to evaluate the validity of an indirect method to quantify equivalent pore spectra of macropore-type preferential flow pathways. Results indicated that there were distinct trends in how pore spectra of macropore-type preferential flow pathways changed when a soil profile became wetter during a precipitation event. This suggests that the indirect method has predictive value and is perhaps a better alternative to the lumped soil hydraulic conductivity approach in accurately determining the impact of macropore-type preferential flow pathways on water movement and solute transport under transient unsaturated flow conditions.
    K.J.S. Kung, K.J. Kladivko, T.J. Gish, T.S. Steenhuis, G. Bubenzer & C.S. Helling  Quantifying preferential flow by breakthrough of sequentially applied tracers: Silt loam soil. 2000 Soil Science Society of America J.
    Vol. 64(4) , pp. 1296-1304 
    article URL   
    K.J.S. Kung & T.S. Steenhuis  Heat and Moisture Transfer in a Partly Frozen Nonheaving Soil. 1986 Soil Sci. Soc. Am. J.
    Vol. 50 , pp. 1114-1121 
    article   
    K.J.S. Kung, T.S. Steenhuis, K.J. Kladivko, T.J. Gish, G. Bubenzer & C.S. Helling  Impact of preferential flow on the transport of adsorbing and non-adsorbing tracers. 2000 Soil Science Society of America J.
    Vol. 64(4) , pp. 1290-1296 
    article URL   
    W.L. Kuo, T.S. Steenhuis, C.E. McCulloch, C.L. Mohler, D.A. Weinstein, S.D. DeGloria & D.P. Swaney  Effects of grid size on runoff of soil moisture for a variable-source-area (VSA) hydrology model 1999 Water Resources Research
    Vol. 35(11) , pp. 3419-3428 
    article URL   
    E.J. Langendoen, T.Y. Tebebu, T.S. Steenhuis & S.A. Tilahun  Assessing Gully Widening and Its Control in the Debra-Mawi Watershed, northern Ethiopia 2013 Proceedings of the International Conference on Science and Technology towards the Development of East Africa (ICST 2013), pp. 214-221  inproceedings   
    Abstract: The highlands of northern Ethiopia suffer from severe land degradation manifested by widespread gully and channel erosion and network development. Research on the geomorphic adjustment of similar landscapes in the midcontinental United States has resulted in the development of the computer models BSTEM and CONCEPTS, which have been used to assess the long-term evolution of incised channels and the stabilizing impact of conservation measures. These models express channel bank stability by a factor of safety (Fs). If Fs > 1 the bank slope is stable, otherwise it is unstable. The BSTEM model was used to: 1) evaluate the stability of the channel banks of a gully in the Debri-Mawi watershed near Lake Tana, Ethiopia during the 2008 rainy season; 2) test the hypothesis that groundwater dynamics are responsible for gully bank mass failure; and 3) evaluate measures to stabilize the gully banks. Model results show that the stability of the 2007 gully bank was controlled by the groundwater table. Factor of safety was typically greater than 1.3 for groundwater table elevations near the gully bottom, whereas factor of safety was smaller than 1 for saturated or near-saturated conditions even for high soil shear-strength values. The post-rainy season bank profile also has limited stability. Ongoing gully incision or steepening of the banks would destabilize the gully banks. Planting vegetation on the bank top has a limited effect; increases in factor of safety were only about 0.1-0.2. Stabilization needs to include a combination of grade control measures to stabilize the gully bottom, toe protection to prevent bank steepening, and planting vegetation on the bank top to reinforce the upper portion of the gully walls in order to limit the extent of tension cracks and lower pore-water pressure. Tension cracks could reduce factor of safety by a value of 0.2-0.3.
    P.C. Lee, T.S. Steenhuis, M.B. Timmons & D.A. Haith  Modeling pesticide volatilization from turf 2004 In: P.A. Nektarios. 1st International Conference on Turfgrass Management and Science for Sport Fields (Acta Horticulturae 661), pp. 433-440  inproceedings   
    Elias Sime Legesse  Modeling Rainfall-Runoff relationships for the Anjeni watershed in the Blue Nile Basin 2009 School: Cornell University  mastersthesis URL   
    Abstract: Models accurately representing the underlying hydrological processes in the Nile Basin are necessary for implementation of effective soil and water conservation practices. Despite this, most models currently being used in the Nile basin have been developed for temperate climates and might not apply fully to the monsoonal climates with distinct dry periods in the Nile basin. Recently a landscape based hydrology model was developed for the monsoonal climates in the Ethiopian highlands by dividing the watershed in areas that produce runoff and areas in which the all water infiltrates and eventually becomes interflow or base flow. The model was calibrated and validated to predict the discharge of the whole Blue Nile Basin. The objective of this study was to test the validity of the assumptions concerning the runoff processes on a small scale. The study was carried out in the Anjeni Watershed in the Blue Nile Basin for which discharge and rainfall measurements were available for an extended period. Thirty piezometers were installed in four transects and the water table was measured during the rainy season. The performance of the model was evaluated using three different techniques: coefficient of determination, Nash and Sutcliff, and root mean square error (RMSE). Model calibration and validation indicated a good fit between the observed and simulated discharge values. Values of coefficient of determination for calibration were obtained to be 0.84, 0.89 and 0.95 for the daily, weekly and monthly time steps, respectively. Similarly, Nash and Sutcliff values of 0.84, 0.83 and 0.96 were obtained respectively. The runoff production mechanism in the Northern part found to be saturation excess although in practice there is very little difference with infiltration excess runoff while in the southern, a combination of saturation excess from the top and flow of water through cracks and openings with more percentage of the flow is through the cracks and fissures. [[Ethiopia]]
    L. Li, D.A. Barry, F. Stagnitti & J.Y. Parlange  Submarine groundwater discharge and associated chemical input to a coastal sea 1999 Water Resour. Res.
    Vol. 35(11)  
    article   
    J. Liebe, M. Andreini, N. van de Giesen & T.S. Steenhuis  The small reservoirs project: research project to improve water availabily and economic development in rural semiarid areas. In: M. Kitissou, M. Ndulo, M. Nagel and M. Griego eds. Hydropolitics in Africa. A contemporary Challenge 2007? , pp. 133-156  other   
    J.R. Liebe, N. van de Giesen, M.S. Andreini, T.S. Steenhuis & M.T. Walter  Suitability and Limitations of ENVISAT ASAR for Monitoring Small Reservoirs in a Semiarid Area 2009 IEEE Transactions on Geoscience and Remote Sensing
    Vol. 47(5) , pp. 1536-1547 
    article URL   
    J.R. Liebe, N. van de Giessen, M.S. Andreini, M.T. Walter & T.S. Steenhuis  Determining watershed response in data poor environments with remotely sensed small reservoirs as runoff gauges 2009 Water Resources Research
    Vol. 45(W07410)  
    article DOI   
    B.M. Liu, Yitayew Abebe, O.V. McHugh, A.S. Collick, B. Gebrekidan & T.S. Steenhuis  Overcoming limited information through participatory watershed 2008 Physics and Chemistry of the Earth
    Vol. 33 , pp. 13-21 
    article URL   
    B.M. Liu, A.S. Collick, Gete Zeleke, Enyew Adgo, Z.M. Easton & T.S. Steenhuis  Rainfall-Discharge Relationships for a Monsoonal Climate in the Ethiopian Highlands 2008 HPtoday
    Vol. in press  
    article URL   
    Y. Liu, B.R. Bierck, J.S. Selker, T.S. Steenhuis & J.Y. Parlange  High-Intensity X-Ray and Tensiometer Measurements in Rapidly Changing Preferential Flow Fields 1993 Soil Sci. Soc. Am. J.
    Vol. 57 , pp. 1188-1192 
    article   
    Y. Liu, J.Y. Parlange & T.S. Steenhuis  A Soil Water Hysteresis Model for Fingered Flow Data. 1995 Water Resour. Res.
    Vol. 31 , pp. 2263-2266 
    article   
    Y. Liu, T.S. Steenhuis & J.Y. Parlange  Closed Form Solution for Finger Width in Sandy Soils at Different Water Contents 1994 Water Resour. Res.
    Vol. 30 , pp. 949-952 
    article   
    Y. Liu, T.S. Steenhuis & J.Y. Parlange  Formation and Persistence of Fingered Flow Fields in Coarse Grained Soils under Different Moisture Contents 1994 J. Hydrol.
    Vol. 159 , pp. 187-195 
    article   
    Eva Joelisa Romero Luna & Dina Poteau  Water Level Fluctuations of Lake Enriquillo and Lake Saumatre in Response to Environmental Changes 2011 School: Cornell University  mastersthesis URL   
    Abstract: The water level of Lake Saumatre in Haiti and Lake Enriquillo in the Dominican Republic has been
    increasing in a continuous manner for the past 10 years. This increase in volume has caused flooding of
    roads, cities and agricultural land causing the inhabitants of the area to complain about the current
    situation and seek help from their respective governments. Both national and international
    organizations have expressed interest in determining the causes of the continuous growth and from
    there, coming up with aid plans for the cities and inhabitants of the area.

    Various theories haven proposed by national and international organizations, and other technical
    groups, to explain the growth of the lakes. Among the hypotheses to explain the growth there is 1)
    Climate change in the area has affected the hydrological balance of the area by either increase in
    precipitation or decrease in evaporation rates and 2) Deforestation of the watershed which would also
    affect the hydrological balance by means of changing infiltration rates.

    This study looked into those two main theories to determine whether they are the cause of the growth.
    First, deforestation was studied by means of remote sensing the land cover on the years of 1986 and
    2010 and analyzing vegetation changes. A Normalized Differential Vegetation Index (NDVI) was also
    studied to validate the land cover change method. It was found, that although there has been some land
    cover change, the change has not been significant enough to influence major changes in the hydrological
    balance. A water balance was also done which resulted in a correlated lake level increases with
    precipitation patterns, indicating that the watersheds are highly responsive to precipitation trends.

    These are only preliminary results since there are many unknowns in the dynamics of the lakes’ systems.
    The objective of this study was to do a basic analysis of the dynamics of the two watersheds and provide
    a starting point for a more in depth research.

    S.W. Lyon, F. Dominguez, D.J. Gochis, N.A. Brunsell, C.L. Castro, F.K. Chow, Y. Fan, D. Fuka, Y. Hong, P.A. Kucera, S.W. Nesbitt, N. Salzmann, J. Schmidli, P.K. Snyder, A.J. Teuling, T.E. Twine, S. Levis, J.D. Lundquist, G.D. Salvucci, A.M. Sealy & M.T. Walter  Coupling terrestrial and atmospheric water dynamics to improve prediction in a changing environment 2008 Bulletin of the American Meteorological Society (BAMS)
    Vol. 89(9) , pp. 1275-1279 
    article DOI   
    S.W. Lyon, A.J. Lembo, M.T. Walter & T.S. Steenhuis  Defining Probability of Saturation With Indicator Kriging on Hard and Soft Data 2006 Advances in Water Resources
    Vol. 29(2) , pp. 181-93 
    article URL   
    S.W. Lyon, A.J. Lembo, M.T. Walter & T.S. Steenhuis  Internet mapping tools make scientific applications easy 2006 EOS
    Vol. 87(38) , pp. 386 
    article   
    S.W. Lyon, M. McHale, M.T. Walter & T.S. Steenhuis  Effect of runoff generation mechanism on estimating land use control of P concentrations 2006 J. Am. Water. Resour. Assoc.
    Vol. 42(3) , pp. 793-804 
    article   
    S.W. Lyon, J. Seibert, A.J. Lembo, M.T. Walter & T.S. Steenhuis  Incorporating landscape characteristics in a distance metric for interpolating between observations of stream water chemistry 2008 Hydrol. Earth Sys. Sci
    Vol. 12 , pp. 1229-1239 
    article URL   
    S.W. Lyon, J. Seibert, A.J. Lembo, M.T. Walter & T.S. Steenhuis  Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table 2006 Hydrol. Earth Sys. Sci.
    Vol. 10 , pp. 113-125 
    article URL   
    S.W. Lyon, M.T. Walter, P. Gérard-Marchant & T.S. Steenhuis  Using a topographic index to distribute variable source area runoff predicted with the SCS-curve number equation 2004 Hydrological Processes
    Vol. 18(15) , pp. 2757-2771 
    article URL   
    C.F. Malvicini, T.S. Steenhuis, M.T. Walter, J.Y. Parlange & M.F. Walter  Evaluation of spring flow in the uplands of Matalom, Leyte, Philippines 2005 Adv. in Water Res.
    Vol. 28(10) , pp. 1083-1090 
    article URL   
    Getachew Ewonetu Mamo  Identifying Major Constraints of Ground Water Use for Irrigated Crop Production: Fogera Plain, North Western Ethiopia 2013 School: Cornell University  mastersthesis URL   
    Abstract: Irrigated agriculture is becoming increasingly important in meeting the demands of food security, employment and poverty reduction. Fogera Woreda, located in the flood plain, 50 km north of Bahirdar on the road to Gonder in the northeastern portion of the Abbay basin, has a high groundwater potential. Currently, irrigated vegetables are grown in this woreda, but it is limited to those lands adjacent to the two perennial rivers --Rib and Gumara. Therefore, increasing the land available to irrigation through the increased use of groundwater sources for irrigation has a potential to increase productivity, overcome conflict between river water users, and involve those farmers who are not currently benefiting from irrigation. However, to ensure the feasibility of increased groundwater use, the major constraints were evaluated that may hinder the community from using groundwater for irrigation crop production. Qualitative data were gathered through focused group discussion, key informants’ interviews, informal discussions with farmers, and personal observations. Quantitative data were generated through standard survey questionnaires.

    Based on the survey of 210 households major constraints in using groundwater for irrigation were collapse of hand dug wells (61%), shortage of manpower (46%) siltation of the well, (45%) shortage of funds for constructing the well (43%). Groundwater irrigation can be improved by arranging proper credit system that can be used to purchase old tires concrete rings to prevent well collapsing or silting up and better pumps to reduce labor shortages ; In addition better training should be provided on proper irrigation techniques and optimum use of credit to assure increased groundwater use.

    R.D. Marjerison, Z.M. Easton, H.E. Dahlke & M.T. Walter  A P-Index transport factor based on variable source area hydrology for New York State 2010 J. Soil and Water Conserv.
    Vol. (in press)  
    article   
    M.C. Masiyandima, S. Diatta, N. van de Giesen, P.N. Windmeijer & T.S. Steenhuis  The Hydrology of Inland Valleys in the Sub-Humid Zone of West Africa: Runoff Processes in the M'bé Experimental Watershed 2003 Hydrological Processes
    Vol. 17 , pp. 1213-1225 
    article URL   
    M.B. McBride, E.A. Nibarger, B.K. Richards & T.S. Steenhuis  Trace Metal Accumulation by Red Clover Grown on Sewage Sludge-Amended Soils and Correlation to Mehlich 3 and Calcium Chloride-Extractable Metals 2003 Soil Sci.
    Vol. 168 , pp. 29-38 
    article   
    M.B. McBride, B.K. Richards & T.S. Steenhuis  Bioavailability and crop uptake of trace elements in soil columns amended with sewage sludge products 2004 Plant and Soil
    Vol. 262 , pp. 71-84 
    article DOI URL   
    M.B. McBride, B.K. Richards, T.S. Steenhuis, J.J. Russo & S. Suave  Mobility and solubility of toxic metals and nutrients in soil fifteen years after sludge application 1997 Soil Science
    Vol. 162 , pp. 487-500 
    article URL   
    M.B. McBride, B.K. Richards, T.S. Steenhuis & G. Spiers  Molybdenum uptake by forage crops grown on sewage sludge-amended soils in the field and greenhouse. 2000 Journal of Environmental Quality
    Vol. 29 , pp. 848-854 
    article URL   
    M.B. McBride, B.K. Richards, T.S. Steenhuis & G. Spiers  Long-term leaching of trace elements in a heavily sludge-amended silty clay loam soil 1999 Soil Science
    Vol. 164 , pp. 612-613 
    article URL   
    M. McCartney, T. Alemayehu, Y. Seleshi Shiferaw, Y.A. Ibrahim, Z.M. Easton & Seleshi B. Awulachew Simulating current and future water resource development in the Blue Nile River Basin [[Ethiopia]]  2010 (In Press) In: Seleshi B. Awulachew, D. Molden & D. Peden. The Nile River Basin: Water, Agriculture, Governance and Livelihoods  inbook   
    D.K. McCool, M.T. Walter & L.G. King  Runoff index values for frozen soil areas in the Pacific Northwest 1995 Journal of Soil and Water Conservation
    Vol. 50(5) , pp. 466-469 
    article   
    A.J. McDonald, S.J. Riha, J.M. Duxbury, T.S. Steenhuis & J.G. Lauren  Soil Physical responses to novel rice cultural practices in the rice-wheat system: Comparative evidence from a swelling soil in Nepal 2006 Soil and Tillage Research
    Vol. 86 , pp. 163-175 
    article URL   
    A.J. McDonald, S.J. Riha, J.M. Duxbury, T.S. Steenhuis & J.G. Lauren  Water balance and rice growth responses to direct seeding, deep tillage, and landscape placement: Findings from a valley terrace in Nepal 2006 Field Crops Research
    Vol. 95(2-3) , pp. 367-382 
    article URL   
    O.V. McHugh, A.S. Collick, B.M. Liu, Debele Bekele, J.E. Haldeman, T.S. Steenhuis, A. Yitayew & Gete Zeleke  Can integrated watershed management bring greater food security in Ethiopia? 2004 IFAC WORKSHOP "Modeling and Control for Participatory Planning and Managing Water Systems"  inproceedings URL   
    O.V. McHugh, A.N. McHugh, P.M. Eloundou-Enyegue & T.S. Steenhuis  Integrated Qualitative Assessment of Wetland Hydrological and Land Cover Changes in a Data Scarce Dry Ethiopian Highland Watershed 2007 Land Degrad. Develop
    Vol. 18 , pp. 1-16 
    article DOI URL   
    O.V. McHugh, T.S. Steenhuis, B. Abebe & E.C.M. Fernandes  Performance of in situ rainwater conservation tillage techniques on dry spell mitigation and erosion control in the drought-prone North Wello zone of the Ethiopian highlands 2007 Soil & Tillage Research
    Vol. 97 , pp. 19-36 
    article URL   
    H.J. Tromp van Meerveld, J.Y. Parlange, D.A. Barry, M.F. Tromp, G.C. Sander, M.T. Walter & M.B. Parlange  Influence of sediment settling velocity on mechanistic soil erosion modeling 2008 Water Resources Research
    Vol. 44 , pp. W06401 
    article DOI   
    V.K. Mehta, J. Krishnaswamy, M.T. Walter, S.D. DeGloria & P.J. Sullivan  Impacts of disturbance on soil properties in a dry tropical forest in southern India 2008 Ecohydrology
    Vol. 1 , pp. 161-175 
    article DOI   
    V.K. Mehta, J. Krishnaswamy, M.T. Walter, S.D. DeGloria & P.J. Sullivan  Ecosystem impacts of disturbance in a dry tropical forest in southern India 2008 Ecohydrology
    Vol. 1 , pp. 149-160 
    article DOI   
    V.K. Mehta, M.T. Walter, E.S. Brooks, T.S. Steenhuis, M.F. Walter, M. Johnson, J. Boll & D. Thongs  Evaluation and application of SMR for watershed modeling in the Catskill Mountains of New York State 2004 Environmental Modeling & Assessment
    Vol. 9(2) , pp. 77-89 
    article URL   
    M.S. Meixler, M.B. Bain & M.T. Walter  Predicting barrier passage and habitat suitability for migratory fish species 2009 Ecological Modeling
    Vol. 220 , pp. 2782?2791 
    article DOI   
    G.F. Mendoza & T.S. Steenhuis  Determination of hydraulic behavior of hillslopes with a hillslope infiltrometer 2002 Soil Science Society of America J.
    Vol. 66 , pp. 1501-1504 
    article URL   
    G.F. Mendoza, T.S. Steenhuis, M.T. Walter & J.Y. Parlange  Estimating basin-wide hydraulic parameters of a semi-arid mountainous watershed by recession-flow analysis 2003 Journal of Hydrology
    Vol. 270 , pp. 57-69 
    article URL   
    Fikru Assefa Mengstie  Assessment of adoption behavior of soil ad water conservation practices in the Koga watershed, Highlands of Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Land degradation is one of the major challenges in agricultural production in many parts of the world, especially in developing nations like Ethiopia. Even though a number of soil and water conservation methods were introduced to combat land degradation, adoption of these practices remains below expectations. This research was conducted in the Koga watershed, near Lake Tana, in the catchment of a recently constructed dam. It aimed to examine farmers? views on land degradation and to assess their adoption behavior of soil and water conservation knowledge. Structured questionnaire survey and focus group discussion methods were applied to collect the necessary information from farm households. A total of 100 households were interviewed and 282 plots and several fields were visited during transect walks. The Tobit regression model was used for analyzing correlations among area, household, plot characteristics and the adoption of three types of soil and water conservation practices. In addition, data were analyzed using descriptive statistics and cross-correlation methods. The results show that total area of plots, age of household head, education of household head, total number of livestock and distance to market from household home are among the major factors that positively and significantly influence adoption of soil and water conservation measures. Greater distance from home to farmland, smaller land to labor ratio and larger family size are factors that decreased adoption. The data showed in addition that more soil/stone bund terraces were implemented on steep land. Unlike in other studies in the region, sex of the household head did not seem to make a difference in adoption of three different SWC practices. [[Ethiopia]]
    I.A. Merwin, J.A. Ray, T.S. Steenhuis & J. Boll  Groundcover Management Systems Influence Fungicide and Nitrate-N Concentrations in Leachate and Runoff from a New York Apple Orchard 1996 J. Am. Soc. Hort. Sci.
    Vol. 121 , pp. 249-257 
    article   
    Mamaru A. Moges, Fasikaw A. Zemale, Muluken L. Alemu, Getaneh K. Ayele, Dessalegn C. Dagnew, Solomon S. Demissie, Seifu A. Tilahun & Tammo S. Steenhuis  Evaluation of Sediment Concentration Discharge Relationship for a
    Monsoonal Climate: Lake Tana Basin
    2013 Proceedings of the International Conference on Science and Technology towards the Development of East Africa (ICST 2013), pp. 255-261  inproceedings   
    Abstract: Increased concern for environmental sustainability has put more emphasis on predicting
    sediment concentrations rather than loads. Rating curves, relating sediment load to discharge, assume
    inherently a unique relationship of concentration and discharge and therefore although performing
    satisfactorily in predicting loads, it may be less applicable for predicting concentration. This is
    especially the case in the Blue Nile basin of Ethiopia where concentrations decrease for a given
    discharge during the course of the rainy monsoon phase. The objective of this paper is to improve the
    sediment concentration predictions throughout the monsoon period for the Ethiopian highlands. In
    this paper, we limit ourselves to the four main rivers in the Lake Tana basin where estimating
    sediment concentrations are important for the fish production and tourism industry. To improve the
    rating curve for sediment concentration, we assume that the sediment transport was at the transport
    limit early in the rainy season and then decrease linearly with effective rainfall towards source limited
    during the end of rainy period. The resulting concentration rating curve was more accurate in
    predicting sediment concentrations than deriving concentration from the existing calibrated load
    based rating curves. As expected, sediment load predictions were similar for both methods. The
    proposed rating curve after more extensive testing over a wider geographical area might offer more
    accurate predictions of sediment concentrations in monsoonal climates.
    M. Molodovskaya, O. Singurindy, B.K. Richards & T.S. Steenhuis  Nitrous oxide from aerated dairy manure slurries: Effects of aeration rates and oxic/anoxic phasing 2008 Bioresource Technology
    Vol. 99 , pp. 8643-8648 
    article   
    M. Molodovskaya, O. Singurindy, B.K. Richards & T.S. Steenhuis  Nitrous oxide emissions from dairy manure as affected by oxic and anoxic conditions 2008 Bioresource Technology
    Vol. 99 , pp. 8643?8648 
    article DOI   
    M. Molodovskaya, O. Singurindy, B.K. Richards, J.S. Warland, M. Johnson, G. Öberg & T.S. Steenhuis  Temporal variability of nitrous oxide from fertilized croplands: hot moment analysis. 2012 Soil Science Society of America Journal
    Vol. 76 , pp. 1728-1740 
    article DOI   
    Abstract: Nitrous oxide (N2O) emissions were monitored using the micrometeorological eddy covariance technique from manure-fertilized cropland on a large dairy farm in New York State in 2006 to 2009. Nitrous oxide emissions demonstrated episodic behavior with intermittent short-duration peak fluxes up to 39.7 mg N2O-N m−2 d−1, whereas most of background fluxes during the annual agricultural cycle were below 6.5 mg N2O-N m−2 d−1. This paper discusses temporal variability of measured N2O emissions using a “hot moment” approach. To identify and quantify peak events as potential hot moments and to determine whether or not they could be treated statistically as outliers, N2O daily fluxes were analyzed by the box plot method using multiple thresholds. Peak events exceeding outlier thresholds contributed up to 51% of cumulative annual N2O emissions, although they represented <7% of the total observation time. Individual N2O peaks were also categorized by their duration, as single day spikes and multiday events. The highest contributing instances were multiday N2O peaks during summer precipitation and early spring thaw, largely enhanced by manure fertilization. These high-intensity emission events demonstrated repetitive seasonal responses to a combination of environmental factors and were therefore identified as hot moments. Abrupt rises in both temperature and soil moisture appeared to trigger major hot moments, whereas the availability of manure N controlled their magnitude. In the absence of strong correlations between time-series of individual environmental factors and N2O emissions, the hot moment approach can be a promising tool for the integrated analysis of most significant N2O events in cultivated fields receiving manure applications.
    M. Molodovskaya, J.S. Warland, B.K. Richards, G. Öberg & T.S. Steenhuis  Nitrous oxide emission from heterogeneous agricultural landscape: source contribution analysis by eddy covariance and static chambers. 2011 Soil Science Society of America Journal
    Vol. 75 , pp. 1829-1838 
    article DOI   
    Abstract: Eddy covariance and static chambers are different-scale methods for monitoring agricultural N2O that, when used together on heterogeneous agricultural landscapes, can help identify flux sources and sinks and evaluate the effect of management interventions on landscape-scale N2O emissions. This study compared the N2O flux data obtained by eddy covariance and static chambers during a short-term N2O measurement campaign from two adjacent agricultural treatments: alfalfa (Medicago sativa L.) and corn (Zea mays L.) fields. Wind direction data from micrometeorological observations were used to downscale the integrated eddy covariance N2O flux and estimate the treatment contributions. The N2O data from static chambers installed on each treatment were used to verify the partitioned eddy covariance fluxes. Both methods consistently showed greater emissions for the alfalfa field, which received more N fertilizer earlier in the growing season. Two methods were also compared with respect to the landscape-integrated N2O flux measured at the eddy covariance mast location. Upscaling the chamber N2O fluxes was performed by totaling the contributions from individual chambers weighted toward the source area share associated with their field locations using a simple footprint model. The comparison of the chambers’ total to the measured eddy covariance emissions showed a difference of 7 to 33% between the methods. The best agreement was observed when the integrated eddy covariance flux was associated with uniform wind direction and a homogeneous source area. The results suggest that localization of the flux source using wind directions and footprint information can help in comparing different-scale N2O emissions.
    F.A. Montalto, J.Y. Parlange & T.S. Steenhuis  A simple model for predicting water table fluctuations in a tidal marsh 2007 Water Resources Research
    Vol. 43(3)  
    article URL   
    F.A. Montalto & T.S. Steenhuis  The link between hydrology and restoration of tidal marshes in the New York/New Jersey estuary 2004 Wetlands
    Vol. 24 , pp. 414-425 
    article   
    F.A. Montalto, T.S. Steenhuis & J.Y. Parlange  The hydrology of Piermont Marsh, a reference for tidal marsh restoration in the Hudson River estuary, New York 2006 Journal of Hydrology
    Vol. 316(1-4) , pp. 108-128 
    article DOI URL   
    F.A. Montalto, T.S. Steenhuis & J.Y. Parlange  The Restoration of Tidal Marsh Hydrology. In: Environmental Problems in Coastal Regions IV, C.A. Brebbia, Ed. Wessex Institute of Technology Press, Southampton, UK. pp. 2002 , pp. 35-47  other URL   
    Verónica Lorena Morales  Facilitated Transport of Groundwater Contaminants in the Vadose Zone: Colloids and Preferential Flow Paths 2011 School: Cornell University  phdthesis URL   
    Abstract: Although a wide variety of studies have been conducted to understand the
    numerous processes responsible for the transport of solutes and particulates through
    soils in order to prevent groundwater contamination, many gaps remain. This thesis
    presents the findings of two mechanisms (colloid facilitated transport and
    development of preferential flow infiltration) by which contaminants are able to
    expedite their transport through unsaturated soils (i.e., the vadose zone), easily reach
    deeper groundwater, and lower the filtering capacity of soils.

    The first study of this thesis bridges the gap between changes in polymeric
    characteristics of dissolved organic matter-colloid complexes induced by solution
    composition, and the effect these have on colloid transport through unsaturated soils.
    The second study presents a semi-empirical approach to improve existing models that
    predict attachment efficiency (α) of electrosterically stabilized suspensions moving
    through a porous medium using direct measurements of polymeric characteristics. The
    fourth study elucidates the capillary forces responsible for the transition between
    pinning or allowing particles to slip when they approach an air-water-solid interface.
    Lastly, bioclogging and soil-water repellency from dehydrated microbial exudates are
    studied in terms of biotic changes in structure and surface properties that generate
    points of wetting instability that can result in the formation of persistent preferential
    flow paths.

    V.L. Morales  Grain surface-roughness effects on colloidal retention in the vadose zone 2008 School: Cornell University  mastersthesis   
    V.L. Morales, M.E. Cakmak, A.E. Salvucci, W. Zhang & T.S. Steenhuis Biocolloids - Transport and retention in soils  2011 (in print) In: J. Glinski, J. Horabik & J. Lipiec. Encyclopedia of Agrophysics  inbook   
    V.L. Morales, B. Gao & T.S. Steenhuis  Grain Surface-Roughness Effects on Colloidal Retention in the Vadose Zone 2009 Vadose Zone Journal
    Vol. 8 , pp. 11-20 
    article DOI   
    V.L. Morales, J.Y. Parlange & T.S. Steenhuis  Are Preferential Flow Paths Perpetuated by Microbial Activity in the Soil Matrix? - A Review 2010 Journal of Hydrology
    Vol. 393 , pp. 29-36 
    article URL   
    V.L. Morales, W. Zhang, B. Gao, L.W. Lion, J.J. Bisogni, B.A. McDonough & T.S. Steenhuis  Impact of dissolved organic matter on colloid transport in the vadose zone: Deterministic approximation of transport deposition coefficients from polymer coating characteristics 2010 Water Research
    Vol. (in print)  
    article DOI   
    R.E. Muck & T.S. Steenhuis  Nitrogen Losses from Manure Storages. 1981 Agric. Wastes
    Vol. 4 , pp. 41-54 
    article   
    E.G. Neal, M.T. Walter & C. Coffeen  Linking the Pacific Decadal Oscillation to seasonal stream discharge patterns in Southeast Alaska 2002 Journal of Hydrology
    Vol. 263(1-4) , pp. 188-197 
    article URL   
    P.A. Nektarios, A.M. Petrovic & T.S. Steenhuis  Aeration type affects preferential flow in golf putting greens 2004 In: P.A. Nektarios. First International Conference on Turfgrass Management and Science for Sport Fields (Acta Horticulturae 661), pp. 421-425  inproceedings   
    P.A. Nektarios, A.M. Petrovic & T.S. Steenhuis  Preferential flow in simulated greenhouse golf putting green profiles as affected by aeration and two soil moisture regimes 2007 Soil Science
    Vol. 172(2) , pp. 108-123 
    article   
    P.A. Nektarios, A.M. Petrovic & T.S. Steenhuis  Effects of surfactant on fingered flow in laboratory golf greens 2002 Soil Science
    Vol. 167(9) , pp. 572-579 
    article URL   
    P.A. Nektarios, T.S. Steenhuis, A.M. Petrovic & J.Y. Parlange  Fingered flow in laboratory golf putting greens 1999 Journal of Turfgrass Management
    Vol. 3(1) , pp. 53-66 
    article URL   
    H.V. Nguyen, J.L. Nieber, P. Oduro, C.J. Ritsema, L.W. Dekker & T.S. Steenhuis  Modeling solute transport in a water repellent soil 1999 Journal of Hydrology
    Vol. 215 , pp. 188-201 
    article URL   
    H.V. Nguyen, J.L. Nieber, C.J. Ritsema, L.W. Dekker & T.S. Steenhuis  Modeling Gravity Driven Unstable Flow in a Water Repellent Soil 1999 J. Hydrol.
    Vol. 215 , pp. 202-212 
    article URL   
    J.L. Nieber, T.W.J. Bauters, T.S. Steenhuis & J. Y Parlange  Numerical simulation of experimental gravity-driven unstable flow in water repellent sand. 2000 Journal of Hydrology
    Vol. 231-232 , pp. 295-307 
    article URL   
    J.L. Nieber, T.S. Steenhuis, M.T. Walter & M. Bakker  Enhancement of seepage and lateral preferential flow by biopores on hillslopes 2006 Biologia, Bratislava
    Vol. 61(Suppl. 19) , pp. S225-S228 
    article URL   
    W.R. Norman & M.F. Walter  Small Scale Irrigation in Traditional and Private Systems in Niger. 1994 Applied Engineering in Agriculture
    Vol. 10(2) , pp. 225-231 
    article   
    W.R. Norman & M.F. Walter  Microsystems Irrigation in Niger, West Africa 1993 Journal of Irrigation and Drainage Engineering
    Vol. 119(5)  
    article   
    W.R. Norman, M.T. Walter, M.F. Walter & E.S. Brooks  Irrigation distribution and rotation methods among gravity flow systems of the West African Sahel. 2000 ASCE Division of Irrigation and Drainage
    Vol. 126(5) , pp. 304-313 
    article URL   
    S. Ogawa, P. Baveye, C.W. Boast, J.Y. Parlange & T.S. Steenhuis  Suface fractal characteristics of preferential flow patterns in field soils: evaluation and effect of image processing 1999 Geoderma
    Vol. 88 , pp. 109-136 
    article URL   
    C.B. Ogden, H.M. van Es, R.J. Wagenet & T.S. Steenhuis  Spatial-Temporal Variability of Preferential flow in a clay soil under no-till and plow-till 1999 Journal of Environmental Quality
    Vol. 28(4) , pp. 1264-1273 
    article URL   
    Hussien Ali Oumer  Land use and land cover change, drivers and its impact: A comparitive study from Kuhar Michael and Lenche Dima of Blue Nile and Awash basins of Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Land use and land cover change is driven by human actions and also drives changes that limit availability of products and services for human and livestock, and it can undermine environmental health as well. Therefore, this study was aimed at understanding land use and land cover change in Lenche Dima and Kuhar Michael of Amhara region, Ethiopia. Time-series satellite images that included Landsat MSS, TM, ETM+ and ASTER, which covered the time frame between 1972/3 to 2005, were used. Socio-economic Survey and review of documents was carried out to understand historical trends, collect ground truth and other secondary information required. Analysis of data and other data was accomplished through integrated use of ERDAS imagine (version 9.1), ENVI (version 4.3) and ArcGIS (version 9.2) software packages along with Microsoft office analytical tools. Remote sensing analysis revealed landscape level change of cultivated land to have a net increase in Kuhar Michael, while a decline is found for Lenche Dima. However, socio-economic surveys showed that household level cultivated land has decreased from 1.2ha to 1ha and from 2.2ha to 1.8ha in Kuhar Michael and Lenche Dima respectively, over the last 30years. Major contributing factors included population increase, occurrence of drought, land redistribution, and land degradation. Similarly, average land holding per household has decreased from 1.6ha to 1.5ha and from 2.9ha to 2.2ha in Kuhar Michael and Lenche Dima, respectively. This has jeopardized the capacity of individuals to provide land for their siblings further leading to landlessness, which is becoming a common phenomenon among rural youths. In Kuhar Michael, dense shrub/bush land decreased at an annual rate of -0.1%, while open shrub/bush land increased at a rate of 0.3%. As opposed to this, dense shrub/bush land increased at a rate of 0.2% and open shrub/bush land declined at annual rate of -0.2% in Lenche Dima. Grassland showed a net decrease at a rate of -0.3% in Kuhar Michael due to conversion into cultivated lands, while an increase with annual rate of 0.1% is found in Lenche Dima as a result of implementation of watershed management practices. Along with the observed decrease in vegetation cover, Limited availability and extinction of some tree/shrub species is also reported and research is required to quantify changes and understand the real impacts brought about. [[Ethiopia]]
    J.Y. Parlange, D.A. Barry, M.B. Parlange, W.L. Hogarth, R. Haverkamp, P.J. Ross, L. Ling & T.S. Steenhuis  New approximate analytical technique to solve richards equation for arbitrary surface boundary conditions 1997 Water Resources Research
    Vol. 33(4) , pp. 903-906 
    article URL   
    J.Y. Parlange, W.L. Hogarth, D.A. Barry, M.B. Parlange, R. Haverkamp, P.J. Ross, T.S. Steenhuis, D.A. DiCarlo & G. Katul  Analytical approximation to the solutions of Richards' equation with applications to infiltration, ponding and time compression approximation. In: Water Resources and Climate Change Processes, G. Kiely, Ed. 1999 Advances in Water Resources
    Vol. 23(Special Issue) , pp. 189-194 
    article URL   
    J.Y. Parlange, W.L. Hogarth, D.A. Barry, T.S. Steenhuis, M.B. Parlange, R. Haverkamp, P.J. Ross & L. Li  Comment on "Series solution for Richards Equation under concentration boundary conditions and uniform initial conditions" by G.D. Salvucci. 1998 Water Resources Research
    Vol. 34(11) , pp. 3211 
    article URL   
    J.Y. Parlange, W.L. Hogarth, M.B. Parlange, R. Haverkamp, D.A. Barry, P.J. Ross & T.S. Steenhuis  Approximate analytical solution of the nonlinear diffusion equation for arbitrary boundary conditions. 1998 Transport in Porous Media
    Vol. 30 , pp. 45-55 
    article URL   
    J.Y. Parlange, F. Stagnitti, A. Heilig, J. Szilagyi, M.B. Parlange, T.S. Steenhuis, W.L. Hogarth, D.A. Barry & L. Li  Sudden drawdown and drainage of a horizontal aquifer. 2001 Water Resources Research
    Vol. 37(8) , pp. 2097-2101 
    article URL   
    J.Y. Parlange, T.S. Steenhuis, R.J. Glass, J.S. Selker, Y. Liu, D. DiCarlo, T.W.J. Bauters, P. Culligan & P. Nektarios Groundwater recharge by preferential flow  1998 In: C. Poon, Y. Huang & C. Huang. Groundwater and Hydrogeology in Taiwan, pp. 1-14  inbook   
    J.Y. Parlange, T.S. Steenhuis, R. Haverkamp, D.A. Barry, P.J. Culligan, W.L. Hogarth, M.B. Parlange, P. Ross & F. Stagnitti 4. Soil Properties and Water Movement  1999 In: M. B. Parlange & J. W. Hopmans. Vadose Zone Hydrology - Cutting Across Disciplines, pp. 99-129  inbook URL   
    J.Y. Parlange, T.S. Steenhuis, L. Li, D.A. Barry & F. Stagnitti  Column Flow in Stratified Soils and Fingers in Hele-Shaw Cells: A Review. In: Environmental Mechanics: Water, Mass and Energy Transfer in the Biosphere, P.A.C. Raats, D. Smiles, and A.W. Warrick, Eds. AGU Geophysical Monograph 129: 2002 , pp. 79-85  other URL   
    M.B. Parlange, T.S. Steenhuis, D.J. Timlin, F. Stagnitti & R.B. Bryant  Subsurface Flow Above a Fragipan Horizon. 1989 Soil Sci.
    Vol. 148 , pp. 77-86 
    article   
    D. Pendleton, A. Dathe & P. Baveye  Influence of image resolution and evaluation algorithm on estimates of the lacunarity of porous media 2005 Physical Review
    Vol. E 72  
    article URL   
    N. Peranginangin, B.K. Richards & T.S. Steenhuis  Assessment of vadose zone sampling methods for detection of preferential pesticide transport 2009 Hydrol. Earth Syst. Sci. Discuss.
    Vol. 6 , pp. 7247-7285 
    article DOI URL   
    N. Peranginangin, R. Sakthivadivel, N.R. Scott, E. Kendy & T.S. Steenhuis  Water Accounting for conjunctive groundwater/surface water management: Case of the Singkarak-Ombilin River basin, Indonesia 2004 Journal of Hydrology
    Vol. 292 , pp. 1-22 
    article URL   
    E. Perrier, M.A. Tarquis & A. Dathe  A Java Applet for Fractal and Multifractal Analysis of Two-Dimensional Images 2005 Geoderma
    Vol. (accepted)  
    article   
    B .E. Pivetz & T.S. Steenhuis  Soil Matrix and Macropore Biodegradation of 2,4-D. 1995 J. Env. Qual.
    Vol. 24 , pp. 564-570 
    article   
    B.E. Pivetz, J.W. Kelsey, T.S. Steenhuis & M. Alexander  A Procedure to Calculate Biodegradation During Preferential Flow Through Heterogeneous Soil Columns 1996 Soil Sci. Soc. Am. J.
    Vol. 60 , pp. 381-388 
    article   
    Soni M. Pradhanang, Suresh D. Shrestha & Tammo S. Steenhuis 2. Comprehensive Review of Groundwater Research in the Kathmandu Valley, Nepal Kathmandu Valley Groundwater Outlook 2012 In: S. Shrestha, D. Pradhananga & V.P. Pandey. , pp. 6-18  inbook URL   
    Abstract: Drinking water quality and quantity has been one of the major concerns in water sector in the Kathmandu Valley, the biggest urban center in Nepal. Aquifer characteristics and groundwater flow properties are complex. They vary laterally, vertically and temporally creating dynamic, interdependent systems that can be affected in unpredictable and irreversible ways as a result of rapid development and mismanagement. Over-extraction of groundwater in the valley has resulted in groundwater depletion. The problems related to groundwater quality range from contamination from sewage line, septic failures, and open pit toilets, leaching from landfill sites, and direct disposal of domestic and industrial wastes to the surface water. Studies have shown that both the quantity and quality of groundwater in the valley are in immense threat that needs immediate attention. The research, development and management of groundwater resources are still emerging. Priorities need to be set up for effective mapping and monitoring of this resource by developing research, management plans and policies geared towards effective management of this valuable resource. This paper summarizes current status of groundwater research and suggests further research needs in the area based on available literature.
    Z. Qui, M.T. Walter & C. Hall  Managing variable source pollution in agricultural watersheds 2007 Journal of Soil and Water Conservation
    Vol. 63(3) , pp. 115-122 
    article   
    S. Qureshi, B.K. Richards, A.G. Hay, C.C. Tsai, M.B. McBride, P. Baveye & T.S. Steenhuis  Effect of microbial activity on trace element release from sewage sludge. 2003 Environmental Science& Technology
    Vol. 37 , pp. 3361-3366 
    article URL   
    S. Qureshi, B.K. Richards, M.B. McBride, P. Baveye & T.S. Steenhuis  Temperature and Microbial Activity Effects on Trace Element Leaching from Metalliferous Peats 2003 Journal of Environmental Quality
    Vol. 32 , pp. 2067-2075 
    article URL   
    S. Qureshi, B.K. Richards, T.S. Steenhuis, M.B. McBride, P. Baveye & S. Dousset  Microbial acidification and pH effects on trace element release from sewage sludge 2004 Environmental Pollution
    Vol. 132 , pp. 61-71 
    article DOI URL   
    K.P.C. Rao, T.S. Steenhuis, A.L. Cogle, S.T. Srinivasan, D.F. Yule & G.D. Smith  Rainfall infiltration and runoff from an alfisol in semi-arid tropical India. I. No-till systems 1998 Soil & Tillage Research
    Vol. 48 , pp. 51-59 
    article URL   
    Nalini S. Rao, Zachary M. Easton, David R. Lee & Tammo S. Steenhuis  Economic Analysis of Best Management Practices to Reduce Watershed Phosphorus Losses 2012 Journal of Environmental Quality
    Vol. 41(3)  
    article DOI   
    Abstract: In phosphorus-limited freshwater systems, small increases in phosphorus (P) concentrations can lead to eutrophication. To reduce P inputs to these systems, various environmental and agricultural agencies provide producers with incentives to implement best management practices (BMPs). In this study, we examine both the water quality and economic consequences of systematically protecting saturated, runoff-generating areas from active agriculture with selected BMPs. We also examine the joint water quality/economic impacts of these BMPs—specifically BMPs focusing on barnyards and buffer areas. Using the Variable Source Loading Function model (a modified Generalized Watershed Loading Function model) and net present value analysis (NPV), the results indicate that converting runoff-prone agricultural land to buffers and installing barnyard BMPs are both highly effective in decreasing dissolved P loss from a single-farm watershed, but are also costly for the producer. On average, including barnyard BMPs decreases the nutrient loading by about 5.5% compared with only implementing buffers. The annualized NPV for installing both buffers on only the wettest areas of the landscape and implementing barnyard BMPs becomes positive only if the BMPs lifetime exceeds 15 yr. The spatial location of the BMPs in relation to runoff producing areas, the time frame over which the BMPs are implemented, and the marginal costs of increasing buffer size were found to be the most critical considerations for water quality and profitability. The framework presented here incorporates estimations of nutrient loading reductions in the economic analysis, and is applicable to farms facing BMP adoption decisions.
    N.S. Rao, Z.M. Easton, E.M. Schneiderman, M.S. Zion, D.R. Lee & T.S. Steenhuis  Distributed modeling of agricultural best management practices to reduce phosphorus loading 2009 Journal of Environmental Management
    Vol. 90 , pp. 1385-1395 
    article   
    N.S. Rao, Z.M. Easton, E.M. Schneiderman, M.S. Zion, D.R. Lee & T.S. Steenhuis  Protecting critical areas in the New York City source watershed: Combining economic and water quality analysis to examine the effectiveness of best management practices 2009 Journal of Soil Water Conservation
    Vol. (in press)  
    article   
    T.L. Richard & T.S. Steenhuis  Tile Drain Sampling of Preferential Flow on a Field Scale. In: Rapid and Far-Reaching Hydrologic Processes in the Vadose Zone, P.F. Germann, Ed. 1988 J. Contam. Hydrol.
    Vol. 3 , pp. 307-325 
    article   
    B.K. Richards, J.F. McCarthy, T.S. Steenhuis, A.G. Hay, Y. Zevi & A. Dathe  Colloidal transport: The facilitated movement of contaminants into groundwater 2007 Journal of Soil and Water Conservation
    Vol. 62(3) , pp. 55A-56A 
    article   
    Brian K. Richards, Steven Pacenka, Anthony E. Salvucci, Sheila M. Saia, Luanne F. Whitbeck, Peter M. Furdyna & Tammo S. Steenhuis  Surveying Upstate NY Well Water for Pesticide Contamination: Cayuga and Orange Counties 2011 Ground Water Monitoring & Remediation
    Vol. 32(1) , pp. 73-82 
    article DOI URL   
    Abstract: Private wells in Cayuga and Orange counties in New York were sampled to determine the occurrence of pesticide contamination of groundwater in areas where significant pesticide use coincides with shallow or otherwise vulnerable groundwater. Well selection was based on local groundwater knowledge, risk modeling, aerial photo assessments and pesticide application database mapping. Single timepoint samples from 40 wells in each county were subjected to 93-compound chromatographic scans. All samples were nondetects (reporting limits <=1 μg/L), thus no wells from either county exceeded any of 15 state groundwater standards or guidance values. More sensitive ELISA immunoassays found two wells with quantifiable atrazine in each county (0.1-0.3 μg/L), one well with quantifiable diazinon (0.1 μg/L) in Orange County, and one well with quantifiable alachlor (0.2 μg/L) in Cayuga County. Trace detections (<0.1 μg/L) in Cayuga County included atrazine (5 wells), metolachlor (6 wells) and alachlor (1 well), including 3 wells with multiple detections. All 12 Cayuga County wells with ELISA detections had either corn/grain or corn/forage rotations as primary surrounding land uses (although 20 other wells with the same land uses had no detections) and all quantified detections and most trace detections occurred in wells up to 9 m deep. Orange County trace (<0.1 μg/L) ELISA detections (atrazine 3 wells, diazinon 1 well, and metolachlor 5 wells) and quantified detections were only generally associated with agricultural land uses. Finding acceptable drinking water quality in areas of vulnerable groundwater suggests that water quality in less vulnerable areas will also be good.
    B.K. Richards, N. Peranginangin, T.S. Steenhuis & L.D. Geohring  The unintentional secret 2003 Journal of Soil and Water Conservation
    Vol. 58 , pp. 104A-105A 
    article URL   
    B.K. Richards, J.H. Peverly, T.S. Steenhuis & B.N. Liebowitz  Effect of Processing Mode on Total and TCLP-Extractable Trace Elements in Dewatered Sludge Products 1997 Journal of Environmental Quality
    Vol. 26 , pp. 782-788 
    article URL   
    B.K. Richards, B.M. Schulte, A. Heilig, T.S. Steenhuis, M.B. McBride, E.Z. Harrison & P. Dickson  Environmental impacts of applying manure, fertilizer, and sewage biosolids on a dairy farm 2004 Journal of American Water Resources Association (JAWRA)
    Vol. 40(4) , pp. 1025-1042 
    article URL   
    B.K. Richards, T.S. Steenhuis, J.H. Peverly & M.B. McBride  Effect of sludge processing mode, soil texture and soil pH on metal mobility in undisturbed soil columns under accelerated loading. 2000 Environmental Pollution
    Vol. 109 , pp. 327-346 
    article URL   
    B.K. Richards, T.S. Steenhuis, J.H. Peverly & M.B. McBride  Metal mobility at an old, heavily-loaded sludge application site 1998 Environmental Pollution
    Vol. 99 , pp. 365-377 
    article URL   
    A. Rimmer, D.A. DiCarlo, T.S. Steenhuis, B. Bierck, D. Durnford & J.Y. Parlange  Rapid fluid content measurement method for fingered flow in an oil-water-sand system using synchrotron X-rays 1998 Journal of Contaminant Hydrology
    Vol. 31 , pp. 315-335 
    article URL   
    A. Rimmer, J.Y. Parlange, T.S. Steenhuis, C. Darnault & W. Condit  Wetting and Nonwetting Fluid Displacements in Porous Media 1996 TIPM
    Vol. 25 , pp. 205-215 
    article   
    A. Rimmer, T.S. Steenhuis & J.S. Selker  One-Dimensional Model to Evaluate the Performance of Wick Samplers in Soils 1995 Soil Sci. Soc. Am. J.
    Vol. 59 , pp. 88-92 
    article   
    C.J. Ritsema, L.W. Dekker, E.G.M. van den Elsen, K. Oostindie, T.S. Steenhuis & J.L. Nieber  Recurring fingered flow pathways in a water repellent sandy field soil. In: Preferential Water Flow and Solute Transport in Soils, A. Armstrong and N. Jarvis, Eds. 1997 Hydrology and Earth System Sciences
    Vol. 4(Special Issue) , pp. 777-786 
    article URL   
    C.J. Ritsema, L.W. Dekker, J.L. Nieber & T.S. Steenhuis  Modeling and field evidence of finger formation and finger recurrence in a water repellent sandy soil 1998 Water Resources Research
    Vol. 34(4) , pp. 555-567 
    article URL   
    C.J. Ritsema, J.L. Nieber, L.W. Dekker & T.S. Steenhuis  Stable or unstable wetting fronts in water repellent soils - effect of antecedent soil moisture content. 1998 Soil & Tillage Research
    Vol. 47 , pp. 111-123 
    article URL   
    C.J. Ritsema, T.S. Steenhuis, J.Y. Parlange & L.W. Dekker Predicted and Observed Finger Diameters in Field Soils  1996 Geoderma
    Vol. 70(Special Issue)In: T. S. Steenhuis, C. J. Ritsema & L. W. Dekker. Fingered Flow in Unsaturated Soil: From Nature to Model, pp. 185-196 
    inbook   
    C.W. Rose, B. Gao, M.T. Walter, T.S. Steenhuis, J.Y. Parlange, K. Nakano & W.L. Hogarth  Reply to P.I.A. Kinnell comment on 'Investigating ponding depth and soil detachability for a mechanistic erosion model using a simple experiment' by B. Gao, et al., 2003, Journal of Hydrology 277:116-124. 2004 Journal of Hydrology
    Vol. 289(1-4) , pp. 307-308 
    article URL   
    J.M. Rossing & M.F. Walter  Hydrologically-based Identification of Critical Areas for Water Quality Protection in the New York City Watershed 1995   other   
    E. Rothstein, T.S. Steenhuis, J.H. Peverly & L.D. Geohring  Atrazine Fate on a Tile Drained Field in Northern New York: A Case Study 1996 Agric. Water Mgmt.
    Vol. 31 , pp. 195-203 
    article   
    E. Rymshaw, M.F. Walter & A. van Wambeke  Processes of soil movement on steep cultivated hill slopes in the Venezuelan Andes 1997 Soil and Tillage Research
    Vol. 44 , pp. 265-272 
    article   
    Sheila Saia  Cretan Village Reconnects with its Water 2012 Revolve Magazine
    Vol. 3  
    article URL   
    Sheila M. Saia  Evaluating Best Management Practices for Minimized Pesticides Transport with the WEPP-UI Model 2012 School: Cornell University  mastersthesis URL   
    Abstract: Best management practice (BMP) tools that provide site-specific water quality suggestions with
    limited input data are needed to assist consultants and farm advisors as they work to target BMP
    placement and reduce dissolved and sediment bound pesticide loads from agricultural landscapes.
    BMP effectiveness largely depends on accurate characterization of dominant regional hydrologic
    processes. However, most BMP tools capture either infiltration excess runoff or saturation excess
    runoff but cannot predict a combination of the two. The objective is therefore to develop an easy-to-use BMP tool capable of (1) accurately characterizing the dominant hydrological processes in
    a region of interest and (2) evaluating the selection and placement of various BMPs for
    reductions in pesticide loss. In this study we show that the Watershed Erosion Prediction Project
    University of Idaho (WEPP-UI) model with coupled pesticide module can realistically simulate
    both types of runoff processes as well as dissolved pesticide loss. Simulated runoff and dissolved
    atrazine concentrations were compared to observed data from mulch till (MT) and no till (NT)
    plots in the Goodwater Creek Experimental Watershed (GCEW) of northeastern Missouri. The
    timing of runoff predictions by WEPP-UI coincided well with observed events and flow
    magnitudes were between minimum and maximum observations for the two replicate plots.
    Nash-Sutcliffe efficiencies (NSEs) were 0.84 and 0.79 for MT and NT runoff simulations,
    respectively. Both simulations and observations showed little difference in total growing season
    (planting to harvest) runoff between MT and NT. Dissolved atrazine loads were well predicted
    for MT and NT plots with NSEs of 0.59 and 0.71, respectively. Consistent with observations,
    seasonal NT atrazine losses were higher than losses from MT plots. Lastly, we also use the
    WEPP-UI pesticides module to simulate the impact of precision application on dissolved
    pesticide loss. While this study only focuses on dissolved pesticide transport at the bottom of a 4
    hillslope, the WEPP-UI pesticide transport module can predict loads for a variety of pesticide types from each section of the hillslope (i.e. top-slope, mid-slope, and toe-slope), including
    sediment bound pesticide loads. Vegetated buffer strip routines are also available but more
    extensive field monitoring is needed to validate these aspects of the model.
    S.M. Saia, E.S. Brooks, Z.M. Easton, C. Baffaut, J. Boll & T.S. Steenhuis  Incorporating pesticide transport into the WEPP model for mulch tillage and no tillage plots with an underlying claypan soil 2013 Applied Engineering in Agriculture
    Vol. 29(3) , pp. 363-372 
    article   
    Abstract: Best management practice (BMP) tools that provide site-specific water quality assessment with limited input
    data are needed to assist soil and water managers as they work to target BMP placement and reduce dissolved and
    sediment bound pesticide loss from agricultural landscapes. BMP effectiveness largely depends on accurate
    characterization of dominant regional hydrologic processes. However, most BMP tools are region specific in their
    characterization of hydrology (e.g., most models capture either infiltration excess runoff or saturation excess runoff but
    cannot predict a combination of the two). In this study, we develop and couple a pesticide transport module with the Water
    Erosion Prediction Project (WEPP) model (v2012.8). The WEPP model realistically simulates infiltration excess and
    saturation excess runoff as well as dissolved pesticide loss from hillslopes in the Goodwater Creek Experimental
    Watershed (GCEW) in northeastern Missouri. Simulated runoff and dissolved atrazine concentrations were compared to
    observed data from mulch till (MT) and no till (NT) plots in the GCEW. The timing of runoff predicted by WEPP coincided
    well with observed events and simulated flow magnitudes were between minimum and maximum observations for replicate
    plots. Event-based Nash-Sutcliffe Efficiencies (NSE) are 0.84 and 0.79 for MT and NT runoff simulations, respectively.
    Both simulations and observations showed little difference in total growing season (planting to harvest) runoff between
    MT and NT. Event-based dissolved atrazine loads are well predicted for MT and NT with NSEs of 0.59 and 0.71,
    respectively. Consistent with observations, seasonal NT atrazine losses were greater than losses from MT plots. While this
    study only focuses on dissolved pesticide transport from the base of hillslopes using MT and NT conservation practices,
    the WEPP pesticide transport module is capable of predicting both dissolved and sediment bound pesticide loss from each
    section of the hillslope (i.e., top-slope, mid-slope, and toe-slope) for a wide range of BMPs. However, further field data
    are needed to evaluate these aspects of the model.
    A.F.M. Saleh, T.S. Steenhuis & M.F. Walter  Groundwater Table Simulation under Different Rice Irrigation Practices. 1989 ASCE J. Irrig. Drain. Engr.
    Vol. 115 , pp. 530-544 
    article   
    C.D. Salmon, M.T. Walter, L.O. Hedin & M.G. Brown  Hydrological controls on chemical export from a remote old-growth forest in Chile 2001 Journal of Hydrology
    Vol. 253(1-4) , pp. 69-80 
    article URL  URL2 
    A.E. Salvucci & M.T. Walter  Using Geographic Information Systems to assess pesticide risks to groundwater. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 2(069), 8 pp. 2007   other   
    A.E. Salvucci, W. Zhang, V.L. Morales, M.E. Cakmak, A.G. Hay & T.S. Steenhuis  The impact of biofilm-forming potential and tafi on transport of environemntal Salmonella through unsaturated porous media 2009 Biologia
    Vol. 3  
    article DOI   
    A.E. Salvucci, W. Zhang, V.L. Morales, M.E. Cakmak, A.G. Hay & T.S. Steenhuis  The role of biofilms and curli in environmental Salmonella transport through unsaturated porous media 2009 Biologia
    Vol. 63(3) , pp. 460-464 
    article   
    G.C. Sander, J.Y. Parlange, I.G. Lisle & S.W. Weeks  Exact Solutions to Radially Symmetric Two-Phase Flow for an Arbitrary Diffusivity 2005 Advances in Water Resources
    Vol. 28(10) , pp. 1112-1121 
    article   
    W.E. Sanford, J.Y. Parlange & T.S. Steenhuis  Hillslope Drainage with Sudden Drawdown: Closed Form Solution and Laboratory Experiments 1993 Water Resour. Res.
    Vol. 29 , pp. 2313-2321 
    article   
    W.E. Sanford, T.S. Steenhuis, J.Y. Parlange, J.M. Surface & J.H. Peverly  Hydraulic Conductivity of Gravel and Sand as Substrates in Rock-Reed Filters 1995 Ecol. Engr.
    Vol. 4 , pp. 321-336 
    article   
    W.E. Sanford, T.S. Steenhuis, J.M. Surface & J.H. Peverly  Flow Characteristics of Rock-Reed Filters for Treatment of Landfill Leachate 1995 Ecol. Engr.
    Vol. 5 , pp. 37-50 
    article   
    G. Sayyad, M. Afyuni, S.F. Mousavi, K.C. Abbaspour, B.K. Richards & R. Schulin  Transport of Cd, Cu, Pb and Zn in a calcareous soil under wheat and safflower cultivation-a column study 2010 Geoderma
    Vol. 154(3-4) , pp. 311-320 
    article DOI   
    G. Sayyad, M. Afyuni, S.F. Mousavi, K.C. Abbaspour, B.K. Richards & R. Schulin  Effects of cadmium, copper, lead, and zinc contamination on metal accumulation by safflower and wheat 2009 Soil & Sediment Contamination
    Vol. 18 , pp. 216-228 
    article DOI   
    E.M. Schneiderman, T.S. Steenhuis, D.J. Thongs, Z.M. Easton, M.S. Zion, G.F. Mendoza, M.T. Walter & A.L. Neal  Incorporating variable source area hydrology into the curve number based Generalized Watershed Loading Function model 2007 Hydrol. Proc.
    Vol. 21 , pp. 3420-3430 
    article DOI   
    C.A. Scott, L.D. Geohring & M.F. Walter  Water quality impacts of tile drains in shallow, sloping structured soils as affected by manure applications. 1998 Applied Engineering in Agriculture
    Vol. 14(6) , pp. 599-603. 
    article   
    C.A. Scott & M.F. Walter  Residual phosphorus in runoff from successional forest on abandoned agricultural land: 2. Hydrological and soluble reactive P Budgets. 2001 Biogeochemistry
    Vol. 55(3) , pp. 311-325 
    article   
    C.A. Scott & M.F. Walter  Local Knowledge and Conventional Soil Science Approaches to Erosional Processes in the Shinalik-Himalaya 1993 Mountain Research and Development
    Vol. 13(1) , pp. 61-72 
    article   
    C.A. Scott, M.F. Walter, E.S. Brooks & J. Boll  Water Quality Imports of Historical Changes in Land Use and Dairy Herds 1998 J. Environmental Quality
    Vol. (accepted)  
    article   
    C.A. Scott, M.F. Walter, E.S. Brooks, J. Boll, M.B. Hes & M.D. Merrill  Historical Changes in Land Use and Dairy Herds on Water Quality in the Catskills Mountains 1998 J. Environmental Quality
    Vol. 27 , pp. 1410-1417 
    article   
    C.A. Scott, M.F. Walter, G.N. Nagle, M.T. Walter, N.V. Sierra & E.S. Brooks  Residual phosphrus in runoff from a successional forest on abandoned agricultural land 1: Biogeochemical and hydrological processes. 2001 Biogeochemistry
    Vol. 55(3) , pp. 293-309 
    article URL   
    C.A. Scott, M.F. Walter, N.V. Sierra, E.S. Brooks & M.T. Walter  Residual Phosphorus in Runoff from Successional Forest and Abandoned Agricultural Land 1997 Water Resources Research
    Vol. In Press  
    article   
    J.S. Selker, L. Graff & T.S. Steenhuis  Non-Invasive Time Domain Reflectometry Moisture Measurement Probe. 1993 Soil Sci. Soc. Am. J.
    Vol. 57 , pp. 934-936 
    article   
    J.S. Selker, P. Leclerq, J.Y. Parlange & T.S. Steenhuis  Fingered Flow in Two Dimensions. Part 1. Measurement of Matric Potential. 1992 Water Resour. Res.
    Vol. 28 , pp. 2513-2521 
    article   
    J.S. Selker, J.Y. Parlange & T.S. Steenhuis  Fingered Flow in Two Dimensions. Part 2. Predicting Finger Moisture Profile. 1992 Water Resour. Res.
    Vol. 28 , pp. 2523-2528 
    article   
    J.S. Selker, J.Y. Parlange & T.S. Steenhuis  Comments on: "Laboratory Tests of a Theory of Fingering During Infiltration into Layered Soils" by R.S. Baker and D. Hillel. 1991 Soil Sci. Soc. Am. J.
    Vol. 55 , pp. 896 
    article   
    J.S. Selker, T.S. Steenhuis & J.Y. Parlange  An Engineering Approach to Fingered Vadose Pollutant Transport. In: Fingered Flow in Unsaturated Soil: From Nature to Model, T.S. Steenhuis, C.J. Ritsema, and L.W. Dekker, Eds. 1996 Geoderma
    Vol. 70(Special Issue) , pp. 197-206 
    article   
    J.S. Selker, T.S. Steenhuis & J.Y. Parlange  Wetting Front Instability in Homogeneous Sandy Soils Under Continuous Infiltration. 1992 Soil Sci. Soc. Am. J.
    Vol. 56 , pp. 1346-1350 
    article   
    G. Shalit & T.S. Steenhuis  A Simple Mixing Layer Model Predicting Solute Flow to Drainage Lines under Preferential Flow 1996 J. Hydrol.
    Vol. 183 , pp. 139-149 
    article   
    G. Shalit, T.S. Steenhuis, H.M. Hakvoort, J. Boll, L.D. Geohring & H.M. van Es  Subsurface Drainage Water Quality from a Structured Soil 1995 ASCE J. Irrig. Drain.
    Vol. 121 , pp. 239-247 
    article   
    S.B. Shaw, A.A. Harpold, J.C. Taylor & M.T. Walter  Investigating a high-resolution stream chloride time series from the Biscuit Brook catchment, Catskills, NY 2008 Journal of Hydrology
    Vol. 348(3-4) , pp. 245-256 
    article   
    S.B. Shaw, R. Mahklouf, M.T. Walter, J.Y. Parlange & I. Lisle  Experimental testing of a stochastic sediment transport model 2008 Journal of Hydrology
    Vol. 348(3-4) , pp. 425-430 
    article   
    Stephen B. Shaw, Rebecca D. Marjerison, David R. Bouldin, Jean-Yves Parlange & M. Todd Walter  Simple Model of Changes in Stream Chloride Levels Attributable to Road Salt Applications 2012 Journal of Environmental Engineering
    Vol. 138(1) , pp. ??? 
    article DOI   
    Abstract: Increasing stream chloride (Cl-) concentrations have been observed over the last several decades in regions that receive regular road salt. In many cases, these increases occur even when road salt application has remained nearly constant, indicating the presence of multiyear attenuation within watersheds. This paper presents a simple mixing model to interpret the relationship between Cl- inputs and Cl- in stream discharge. The model was applied to data collected between 1972 and 2003 from Fall Creek in central New York, and the results indicate that stream salt concentrations may continue to increase for several decades. The estimated average residence time of road salt in the watershed was approximately 50 years, although the uncertainty in road salt application history suggests residence times of 40–70 years are reasonable. Hydrologists may be able interpret historical road salt applications and stream salt responses as essentially a regional tracer experiment to gain insights into macroscale watershed characteristics that could dominate average water residence time.
    S.B. Shaw, J.R. Stedinger & M.T. Walter  Evaluating urban pollutant build-up/wash-off models using a Madison, Wisconsin catchment 2010 Journal of Environmental Engineering, ASCE
    Vol. 136 , pp. 194-203 
    article   
    S.B. Shaw & M.T. Walter  Estimating storm runoff risk using bivariate frequency analyses of rainfall and antecedent watershed wetness 2009 Water Resources Research
    Vol. 45 , pp. W03404 
    article DOI   
    S.B. Shaw, M.T. Walter & J.Y. Parlange  Accounting for surface roughness in a physically-based urban wash-off model 2009 Journal of Hydrology
    Vol. 367(1-2) , pp. 79-85 
    article   
    S.B. Shaw, M.T. Walter & T.S. Steenhuis  Comment on 'A physical model of particulate wash-off from rough impervious surfaces' by Shaw et al. [Journal of Hydrology 327 (2006) 618-626] - Reply 2008 Journal of Hydrology
    Vol. 351(1-2) , pp. 258-260 
    article   
    S.B. Shaw, M.T. Walter & T.S. Steenhuis  A physical model of particulate wash-off from rough impervious surfaces 2006 Journal of Hydrology
    Vol. 327 , pp. 618-626 
    article URL   
    A.C. Siepel, T.S. Steenhuis, C.W. Rose, J.Y. Parlange & G.F. McIsaac  A simplified hillslope erosion model with vegetation elements for practical applications 2002 J. Hydrology
    Vol. 258 , pp. 111-121 
    article URL   
    O. Singurindy, M. Molodovskaya, B.K. Richards & T.S. Steenhuis  Nitrous oxide emission at low temperatures from manure-amended soils under corn (Zea mays L.) 2009 Agriculture, Ecosystems and Environment
    Vol. 132 , pp. 74-81 
    article DOI URL   
    O. Singurindy, M. Molodovskaya, B.K. Richards & T.S. Steenhuis  Gaseous nitrogen emission from soil aggregates as affected by clay mineralogy and repeated urine applications 2008 Water, Air, and Soil Pollution
    Vol. 195 , pp. 285-299 
    article DOI   
    O. Singurindy, B.K. Richards, M. Molodovskaya & T.S. Steenhuis  Nitrous oxide and ammonia emissions from urine-applied soils: texture effect 2006 Vadose Zone Journal
    Vol. 5 , pp. 1236?1245 
    article DOI   
    M.G. Sinkevich, M.T. Walter, A.J. Lembo Jr., B.K. Richards, N. Peraginangin, S.A. Aburime & T.S. Steenhuis  A GIS-Based Ground Water Contamination Risk Assessment Tool for Pesticides 2005 Ground Water Monitoring & Remediation
    Vol. 25(4) , pp. 82-91 
    article URL   
    Indu Thekkemeppilly Sivakumar  Future Water Table Levels under Intensification of Rice Cultivation in a Monsoon Climate 2014 School: Cornell University  mastersthesis URL   
    Abstract: The long-term response of the groundwater table level to irrigation and climate change
    is studied using a one-dimensional numerical model employing the Thornthwaite-
    Mather procedure to calculate the root-zone water balance. The study focuses on rice
    cultivation at Avanigadda in the Krishna district of the state of Andhra Pradesh, India
    which experiences a monsoon climate. The effect of intensifying the cultivation is
    addressed by considering the cases of having one, two, and three crops per year with a
    single rainfed crop and the rest supported by groundwater irrigation. To address the
    effect of climate change, three well-known IPCC scenarios SRESA1B, SRESA2, and
    SRESB1 are simulated. Single crop agriculture is found to be sustainable irrespective
    of the climate scenario while two and three crop cultivations are found to be
    unsustainable with the water table level dropping to 200 – 1000 meters at the end of
    21st century.
    J. Smith, B. Gao, H. Funabashi, T.N. Tran, D. Luo, B.A. Ahner, T.S. Steenhuis, A.G. Hay & M.T. Walter  Pore-scale quantification of colloid transport in saturated porous media 2008 Environmental Science & Technology
    Vol. 42 , pp. 517-523 
    article DOI   
    M .S. Srinivasan, P. Gérard-Marchant, T.L. Veith, W.J. Gburek & T.S. Steenhuis  Watershed scale modeling of critical source areas of runoff generation and phosphorus transport 2005 J. Amer. Water Resources Assoc.
    Vol. 41 , pp. 361-375 
    article   
    F. Stagnitti, L. Li, A. Barry, G. Allinson, J.Y. Parlange, T.S. Steenhuis & E. Lakshmanan  Modelling Solute Transport in Structured Soils: Performance Evaluation of the ADR and TRM Models. 2001 Mathematical &. Computer Modeling
    Vol. 34 , pp. 433-440 
    article URL   
    F. Stagnitti, L. Li, J.Y. Parlange, W. Brutsaert, D.A. Lockington, T.S. Steenhuis, M.B. Parlange, D.A. Barry & W.L. Hogarth  Drying front in a sloping aquifer: Nonlinear effects 2004 Water Resources Research
    Vol. 40 , pp. W04601 
    article   
    F. Stagnitti, J.Y. Parlange & T.S. Steenhuis Percolation  2008 In: W. Chesworth. Encyclopedia of Soil Science  inbook URL   
    F. Stagnitti, J.Y. Parlange, T.S. Steenhuis, M.B. Parlange & C.W. Rose  A Mathematical Model of Hillslope and Watershed Drainage. 1992 Water Resour. Res.
    Vol. 28 , pp. 2111-2122 
    article   
    F. Stagnitti, M.B. Parlange, T.S. Steenhuis & J.Y. Parlange  Reply to Comments on "Drainage From a Uniform Soil Layer on a Hillslope"" by D.G. Hurley and G. Pantelis. 1987 Water Resour. Res.
    Vol. 23 , pp. 1703-1704 
    article   
    F. Stagnitti, M.B. Parlange, T.S. Steenhuis & J.Y. Parlange  Drainage from a Uniform Soil Layer on a Hillslope. 1986 Water Resour. Res.
    Vol. 22 , pp. 631-634 
    article   
    F. Stagnitti, N. Villiers, J. Y Parlange, T.S. Steenhuis, G.H. de Rooij, L. Li, D.A. Barry, X. Xiong & P. Li  Solute and contaminant transport in heterogeneous soils 2003 Bull. Environmental Contamination & Toxicology
    Vol. 71 , pp. 737-745 
    article URL   
    T.S. Steenhuis  Discussion of "Streamflow Generation from Variable Width, Inclined, Shallow Hillslopes". 1988 Mech. Engr. Trans.
    Vol. ME13 , pp. 40-41 
    article   
    T.S. Steenhuis, L. Agnew, P. Gérard-Marchant & M.T. Walter Overland flow.  2005 In: D. Hillel. Encyclopedia of Soils in the Environment. Vol. 3, pp. 130-134  inbook URL   
    T.S. Steenhuis, J. Boll, G. Shalit, J.S. Selker & I.A. Merwin  A Simple Equation for Predicting Preferential Flow Solute Concentrations. 1994 J. Env. Qual.
    Vol. 23 , pp. 1058-1064 
    article   
    T.S. Steenhuis, R. Bottcher & M.F. Walter  Drainage Design by Microcomputer. 1987 Appl. Agric. Res.
    Vol. 2 , pp. 272-276 
    article   
    T.S. Steenhuis, G.D. Bubenzer, J.C. Converse & M.F. Walter  Winter Spread Manure Nitrogen Loss. 1981 ASAE Trans.
    Vol. 24 , pp. 436-441, 449 
    article   
    T.S. Steenhuis, G.D. Bubenzer & J.C. Converse  Ammonia Volatilization of Winter Spread Manure 1979 ASAE Trans.
    Vol. 22 , pp. 152-157 
    article   
    T.S. Steenhuis, A.S. Collick, Seleshi B. Awulachew, Enyew Adgo, Abdassalam Ahmed & Z.M. Easton  Modelling erosion and sedimentation in the upper Blue Nile [[Ethiopia]] 2008 Proceedings of the Workshop on the Hydrology and Ecology of the Nile River Basin under Extreme Conditions  inproceedings URL   
    T.S. Steenhuis, A.S. Collick, Z.M. Easton, Elias S. Leggesse, Haimanote K. Bayabil, E.D. White, Seleshi B. Awulachew, Enyew Adgo & Abdassalam A. Ahmed Predicting discharge and erosion for the Abay (Blue Nile) with a simple model [[Ethiopia]]  2009 In: Abtew & Melesse. Hydrology and Ecology of the Nile River Basin Under Extreme Conditions, pp. 200-212  inbook DOI URL   
    T.S. Steenhuis, A. Dathe, Y. Zevi, J.L. Smith, B. Gao, S.B. Shaw, D. deAlwis, S. Amaro-Garcia, R. Fehrman, M.E. Cakmak, I. Toevs, B.M. Liu, S.M. Beyer, J.T. Crist, A.G. Hay, B.K. Richards & J.F. McCarthy  Characterization of transport and retention of biocolloids in unsaturated soils. 2006 BIOHYDROLOGY 2006 International Conference  inproceedings URL   
    T.S. Steenhuis, A. Dathe, Y. Zevi, J.L. Smith, B. Gao, S.B. Shaw, D. deAlwis, S. Amaro-Garcia, R. Fehrman, M.E. Cakmak, I. Toevs, B.M. Liu, S.M. Beyer, J.T. Crist, A.G. Hay, B.K. Richards & J.F. McCarthy  Biocolloid retention in partially saturated soils 2006 Biologia, Bratislava
    Vol. 61(Suppl. 19) , pp. S229-S233 
    article URL   
    T.S. Steenhuis, L.W. Dekker, J.Y. Parlange & C.J. Ritsema  How Rapid Flow Through Preferential Paths May Pollute the Groundwater 1995 H2O Tijdschrift voor Watervoorziening en Afvalwaterbehandeling
    Vol. 28 , pp. 118-121 
    article   
    T.S. Steenhuis, Z.M. Easton, Seleshi B. Awulachew, Abdassalam Ahmed, K. Bashar, Y. Selassie, Enyew Adgo & Seifu Tiluhan Erosion, sediment loss and land degradation with emphasis on the Blue Nile River Basin [[Ethiopia]]  2010 (in press) In: Seleshi B. Awulachew, D. Molden & D. Peden. The Nile River Basin: Water, Agriculture, Governance and Livelihoods  inbook   
    Tammo S. Steenhuis, Mohammad Enkamil, Dawit Asmare, Seifu Tilahun, Birru Yitaferu, Abeyou Worqlul, Birhanu Zemadin, Charlotte MacAlister, Tracy Baker & Simon Langan  Evaluation of Rain Water Management Practices for Sediment Load Reduction
    in the (Semi) Humid Blue Nile basin
      article   
    T.S. Steenhuis, A.G. Hunt, J.Y. Parlange & R.P. Ewing  Assessment of the Application of Percolation Theory to a Water Repellent Soil 2005 Australian Journal of Soil Research
    Vol. 43(3) , pp. 357-60 
    article URL   
    T.S. Steenhuis, C. Jackson, K.J.S. Kung & W.H. Brutsaert  Measurement of Groundwater Recharge on Eastern Long Island. 1985 J. Hydrol.
    Vol. 79 , pp. 145-169 
    article   
    T.S. Steenhuis, Y. Kim, J.Y. Parlange, M.S. Akhtar, B.K. Richards, K.J.S. Kung, T.J. Gish, L.W. Dekker, C.J. Ritsema & S.O. Aburime  An equation for describing solute transport in field soils with preferential flow paths 2001 In: D.D. Bosch & K.W. King. Preferential Flow, Water Movements and Chemical Transport in the Environment, pp. 137-140  inproceedings URL   
    T.S. Steenhuis, M.B. McBride, B.K. Richards & E.Z. Harrison  Trace metal retention in the incorporation zone of land-applied sludge 1999 Environmental Science & Technology
    Vol. 33 , pp. 1171-1174 
    article URL   
    T.S. Steenhuis, J.F. McCarthy, J.T. Crist, Y. Zevi, P.C. Baveye, J.A. Throop, R.L. Fehrman, A. Dathe & B.K. Richards  Reply to "Comments on 'Pore-Scale Visualization of Colloid Transport and Retention in Partly Saturated Porous Media'" by Wan, J., Tokunaga, T.K. 2005 Vadose Zone Journal
    Vol. 4 , pp. 957-958 
    article DOI URL   
    T.S. Steenhuis & W.H. van der Molen  The Thornthwaite-Mather Procedure as a Simple Engineering Method to Predict Recharge. 1986 J. Hydrol.
    Vol. 84 , pp. 221-229 
    article   
    T.S. Steenhuis & R.E. Muck  Preferred Movement of Nonadsorbed Chemicals on Wet, Shallow, Sloping Soils. 1988 J. Environ. Qual.
    Vol. 17 , pp. 376-384 
    article   
    T.S. Steenhuis & L.M. Naylor  A Screening Method for Preliminary Assessment of Risk to Groundwater from Land-Applied Chemicals. 1987 J. Contam. Hydrol.
    Vol. 1 , pp. 395-406 
    article   
    T.S. Steenhuis, R.L. Oaks, R. Johnson, R. Sikkens & E.J. Vander Velde  Irrigation Rehab: A Computer Aided Learning Tool for System Rehabilitation. 1989 Irrig. Drain. Sys.
    Vol. 3 , pp. 241-253 
    article   
    T.S. Steenhuis & others  A Historical and Technical Review and Analysis of TCE Contamination in the South Hill Area of Ithaca, NY 2006   electronic URL   
    T.S. Steenhuis, S. Pacenka & K.S. Porter  MOUSE: A Management Model for Evaluating Groundwater Contamination from Diffuse Surface Sources Aided by Computer Graphics. 1987 Appl. Agric. Res.
    Vol. 2 , pp. 277-289 
    article   
    T.S. Steenhuis & J.Y. Parlange  Preferential Flow in Structured and Sandy Soils. 1990 Engineering Quarterly
    Vol. 25 , pp. 7-14 
    article URL   
    T.S. Steenhuis, J.Y. Parlange & M.S. Andreini  A Numerical Model for Preferential Solute Movement in Structured Soils 1990 Geoderma
    Vol. 46 , pp. 193-208 
    article   
    T.S. Steenhuis, J.Y. Parlange, D.A. DiCarlo, J.S. Selker, P.A. Nektarios, Y.Y. Kim, D.A. Barry & F. Stagnitti  Unstable Fingered Flow   other URL   
    T.S. Steenhuis, J.Y. Parlange, J.Y. Kim, D.A. DiCarlo, J.S. Selker, P.A. Nektarios, D.A. Barry & F. Stagnitti Unstable flow  2004 In: D. Hillel. Encyclopedia of Soils in the Environment. Vol. 4, pp. 197-202  inbook URL   
    T.S. Steenhuis, J.Y. Parlange & K.J.S. Kung  Comment on "The Diversion Capacity of Capillary Barriers" by B. Ross. 1991 Water Resour. Res.
    Vol. 27 , pp. 2155-2156 
    article   
    T.S. Steenhuis, J.Y. Parlange, M.B. Parlange & F. Stagnitti  A Simple Model for Flow on Hillslopes. 1988 Agric. Water Mgmt.
    Vol. 14 , pp. 153-168 
    article   
    T.S. Steenhuis, J.Y. Parlange, W.E. Sanford, A. Heilig, F. Stagnitti & M.F. Walter  Reply to "Comment on Can We Distinguish Richards' and Boussinesq's Equations for Hillslopes? The Coweeta Experiment Revisited" by C. Michel 1999 Water Resour. Res.
    Vol. 35 , pp. 3575-3576 
    article URL   
    T.S. Steenhuis, J.Y. Parlange, W.E. Sanford, A. Heilig, F. Stagnitti & M.F. Walter  Can we distinguish Richards' and Boussinesq's equations for hillslopes?: The Coweeta experiment revisited. 1999 Water Resources Research
    Vol. 35(2) , pp. 589-593 
    article URL   
    T.S. Steenhuis, T.L. Richard, M.B. Parlange, S.A. Aburime, L.D. Geohring & J.Y. Parlange  Preferential Flow Influences on Drainage of Shallow Sloping Soils. 1988 Agric. Water Mgmt.
    Vol. 14 , pp. 137-151 
    article   
    T.S. Steenhuis, J. Caldero Rivera, C.J. Martinez Hernadez, M.T. Walter, R.B. Bryant & P.A. Nectarios  Water repellency in New York State soils. 2001 Int. Turfgrass Soc. Res. J.
    Vol. 9 , pp. 624-628 
    article URL   
    T.S. Steenhuis, W. Staubitz, M. Andreini, J. Surface, T.L. Richard, R. Paulsen, N.B. Pickering, J.R. Hagerman & L.D. Geohring  Preferential Movement of Pesticides and Tracers in Agricultural Soils. 1990 ASCE J. Irrig. Drain. Engr.
    Vol. 116 , pp. 50-66 
    article   
    T.S. Steenhuis, J. Taylor, Z. Easton, A. Collick, N. van de Giesen, J. Liebe, Abdassalam A. Ahmed & M. Andreini  Rainfall-discharge relationships for monsoonal climates 2009 In: Seleshi B. Awulachew, T. Erkossa, V. Smakhtin & A. Fernando. Improved water and land management in the Ethiopian highlands: Its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia  inproceedings DOI URL   
    Abstract: Methods for estimating runoff that have been developed for temperate climates may not be suitable for use in the monsoonal climates of Africa, where there is a distinct dry season during which soils dry out to a considerable depth. This has a distinct effect on runoff generation that is not captured by "the temperate climate" models. The scope of this tool is to develop a simple water balance method for predicting river discharge. Water balance models have been shown to better predict river discharge in regions with monsoonal climates than alternative methods based on the United States Department of Agriculture-Soil Conservation Service (USDA-SCS) curve number. The latter is an empirical-based model developed in the USA that does not apply to monsoonal climates with distinct dry and wet periods.
    Tammo S. Steenhuis, Tigist Y. Tebebu, Birara C. Tarekegn, Anteneh Z. Abiy, Assefa D. Zegeye, Getaneh K. Ayele, Christian D. Guzman & Seifu A. Tilahun  Hydrological Controls on Gully Formation in the Ethiopian Highlands (Extended Abstract) 2013 New Nile Perspectives: Scientific Advances in the Eastern Nile Basin, Khartoum, Sudan, May 6-7, 2013.  inproceedings URL   
    Tammo S. Steenhuis, Seifu A. Tilahun, Muhammad Elkamil, Fasikaw Atanaw, Abeyou W. Worqlul, Essayas K Ayana, Anteneh Z. Abiy, Muluken L. Alemu, Zelalem K. Tesemma & Yasir A. Mohamad  Simulating discharge and sediment concentrations in the increasingly degrading Blue Nile basin 2013 Proceedings of the International Conference on Science and Technology towards the Development of East Africa (ICST 2013), pp. 291-299  inproceedings URL   
    Abstract: Future discharge predictions seldom take into account the degrading landscape. The objective of this paper is to investigate based on past records of precipitation, discharge and sediment concentrations, the effect of a changing landscape on the hydrology and sediment transport in the Ethiopian Blue Nile Basin. We used the Parameter Efficient Distributed (PED) model to examine how the relationship between precipitation, discharge and sediment concentration changed in time. All input data to the PED model were kept constant except for a conversion of permeable hillside to degraded soil in time. Our results show that with a gradual increase of the degraded areas from 10 % in the 1960’s to 22% in 2000’s, the observed discharge pattern and sediment concentration could be simulated well. Simulated annual runoff increases by 10% over the 40 year periods as a result of the increase in degraded soils. Sediment loads appeared to be increased many times more, but this needs to be further validated due to limited data available. In general, the model results would indicate that rehabilitating the degraded and bare areas by planting permanent vegetation would be extremely effective in decreasing the sediment concentration in the rivers. Research should be undertaken to investigate the effectiveness of these plantings.
    Tammo S. Steenhuis, Seifu A. Tilahun, Zelalem K. Tesemma, Tigist Y. Tebebu, Mamaru Moges, Fasikaw A. Zimale, Abeyou W. Worqlul, Muluken L. Alemu, Essayas K. Ayana & Yasir A. Mohamed Soil Erosion and Discharge in the Blue Nile Basin: Trends and Challenges Nile River Basin: Ecohydrological Challenges, Climate Change and Hydropolitics 2014 (in press) In: Assefa Melesse, Wossenu Abtew & Gebriye Shimelis.   inbook URL   
    Abstract: [Ethiopia]
    T.S. Steenhuis, K. Vandenheuvel, K.W. Weiler, J. Boll, J. Daliparthy, S. Herbert & K.J.S. Kung  Mapping and interpreting soil textural layers to assess agri-chemical movement at several scales along the eastern seaboard (USA) 1998 Nutrient Cycling in Agroecosystems
    Vol. 50 , pp. 91-97 
    article URL   
    T.S. Steenhuis & M.F. Walter  Will Drainage Increase Spring Soil Temperatures in Cool and Humid Climates? 1986 ASAE Trans.
    Vol. 29 , pp. 1641-1645, 1649 
    article   
    T.S. Steenhuis & M.F. Walter  Closed Form Solution for Pesticide Loss in Runoff Water 1980 ASAE Trans.
    Vol. 23 , pp. 615-620, 628 
    article   
    T.S. Steenhuis, M. Winchell, J. Rossing, J.A. Zollweg & M.F. Walter  SCS Runoff Equation Revisited for Variable-Source Runoff Areas 1995 ASCE J. Irrig. Drain.
    Vol. 121 , pp. 234-238 
    article   
    T.J. Stomph, N. De Ridder, T.S. Steenhuis & N.C. Van De Giesen  Scale effects of Hortonian Overland Flow and rainfall-runoff dynamics: Laboratory validation of a process based model. 2002 Earth Surface Processes & Landforms
    Vol. 27 , pp. 847-855 
    article URL   
    Cathelijne R. Stoof, Demie Moore, Paulo M. Fernandes, Jetse J. Stoorvogel, Ricardo E.S. Fernandes, António J.D. Ferreira & Coen J. Ritsema  Hot fire, cool soil 2013 Geophysical Research Letters
    Vol. Early View  
    article DOI   
    Abstract: Wildfires greatly increase a landscape's vulnerability to flooding and erosion events by removing vegetation and changing soils. Fire damage to soil increases with increasing soil temperature, and, for fires where smoldering combustion is absent, the current understanding is that soil temperatures increase as fuel load and fire intensity increase. Here, however, we show that this understanding that is based on experiments under homogeneous conditions does not necessarily apply at the more relevant larger scale where soils, vegetation, and fire characteristics are heterogeneous. In a catchment-scale fire experiment, soils were surprisingly cool where fuel load was high and fire was hot and, conversely, soils were hot where expected to be cooler. This indicates that the greatest fire damage to soil can occur where fuel load and fire intensity are low rather than high, and has important implications for management of fire-prone areas prior to, during, and after fire events.
    Birara Chekol Tarekegn  A Case Study of Gully Erosion in the Ethiopian Highlands: The Warke Watershed 2012 School: Cornell University  mastersthesis URL   
    Abstract: Gully erosion affects large areas in Ethiopia. It is the source of sediment in the rivers
    and takes agricultural land of production. Understanding factors for gully expansion is
    essential for application of effective preventive and remedial measures towards
    sustainable land resources management. Therefore, the objective of this study is to
    study the underlying causes of the rapid gully expansion, to recommend strategies to
    prevent further gully formation and to reclaim existing gullies.

    The research was conducted in Warke watershed at an altitude between 2632- 2500 m
    in the upper Blue Nile Basin, Ethiopia. The area has a humid monsoon climate with an
    average annual rainfall of 1300 mm. Thirty years ago, gully formation started after the
    area became intensively cultivated. Gullies have expanded continuously since that
    time. Structural and biological conservation measures to try to stop the gully
    expansion have been installed in the whole watershed and maintained in one part of
    the watershed.

    Piezometers were installed at the top hill, middle, and bottom outlet of both
    watersheds. Average gully width, depth and lengths were measured using measuring
    tape at the beginning and end of the rainy season. Soil Infiltration rates were also
    measured using single ring infiltrometer. Long and short term erosion rates were
    estimated using AGERTIM (Assessment of Gully Erosion Rates through Interviews
    and Measurements).

    Fifty years old land users in a group discussion recalled that gully formation started in
    the1980’s when farm plots were demarcate/separate using traditional small waterways
    (locally called Fesses) along the slope. Erosion rates since the initiation of the gullies
    were 22 t/ha/yr and 58 t/ha/yr for the two gullies in the watershed with the
    conservation practices and 48 t/ha/yr for the gully in the area without conservation
    practices. Short term soil loss rates were many times greater indicating that these
    gullies were in their acceleration phase. Since rainfall exceeds the evaporative demand
    of the crop a perched water table formed over the restrictive layer during the rainy
    monsoon phase. The water table was generally deeper in the upper watershed than at
    lower elevations where the slope decreased. Active gully formation occurred in areas
    where the groundwater was above the gully bottom. Since infiltration was in general
    greater than the prevailing rainfall intensities and most of the rainfall infiltrated in the
    soil, gully function was caused by subsurface flow and not by surface flow.

    Tegegne M. Tarekegne  Sustainability of rural water supply and sanitation services in Ethiopia: A case study of twenty villages in Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Providing access to safe water and sanitation to combat poor health is an integral part of the strategy to alleviate poverty in many countries according to the United Nations Development Assistance Framework (UNDAF, 2006). Although sustainable water supply and sanitation services is a basic requirement for development, there are only very few systems implemented over last 25 years in rural areas of Ethiopia that are still functioning The objective of the research was to investigate the reasons behind the low sustainability of rural water supply and sanitation services among different organizations each with their unique approach. The research was conducted in the Libo Kemkem Woreda near Lake Tana Ethiopia where a recent survey showed that two-thirds of constructed water points were not functioning, and there was a low coverage of sanitation services. In this study a survey was undertaken covering 20 villages in which more than 400 respondents were interviewed examining a range of aspects such as community participation, operation and maintenance practice, institutionalization of schemes, community preferences and thoughts and major problems in water supply and sanitation services. Results showed the sustainability of rural water supply and sanitation service depended on the approach followed by the providers. Water supply systems were sustainable in which the community participated in all stages of the project, selected members of the community were educated in operating the system and spare parts and man power were available and manpower from the agency are special factors to sustain the system; Latrine construction coverage and hygienic behavior was improved in villages where volunteers and community facilitator teams were working. The survey indicated that the best place to meet was on holidays in formal locations and not in church after church program. Finally, organizations should focus on latrine construction, both household and communal latrines around farming and grazing places. [[Ethiopia]]
    J.C. Taylor, N. van de Giesen & T.S. Steenhuis  West Africa: Volta discharge data quality assessment and use 2006 Journal of the American Water Resources Association
    Vol. 42(4) , pp. 1113-1126 
    article URL   
    Abstract: Water resource management in West Africa is often a complicated process due to inadequate resources, climatic extremes, and insufficient hydrological information. Insufficient data hinder sustainable watershed management practices, one of the top priorities in the Volta River Basin. This research properly fills in missing data by modeling the hydrological dis- tribution in the Volta River Basin. On average, discharge gages across the basin are missing 20 percent of their monthly data over 20 years. Two methods were used to supplement missing data: a statistically linear model and a conceptual hydrological model. A linear equation, developed from the regression of pre- cipitation and runoff, was used to evaluate the quality of exist- ing data. The hydrological model separates the system into root and groundwater zones. Measured values were used to cali- brate the hydrological model and to validate the statistical model. The quality of existing data was analyzed and organized for usability. Accuracy of the hydrological model was also eval- uated for its effectiveness using R2 and standard error. It was found that the hydrological model was an improvement from the linear model on a monthly basis; R2 values improved by as much as 0.5 and monthly error decreased. Monthly predictions of the hydrological model were used to fill gaps of measured data sets.
    Tigist Tebebu, Christine Baver, Cathelijne Stoof & Tammo Steenhuis  Visualizing clogging up of soil pores in the tropical degraded soils and their impact on green water productivity 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings URL   
    Abstract: Restrictive soil layers commonly known as hardpans restrict water and airflow in the soil profile andimpede plant root growth below the plow depth. Preventing hardpans to form or ameliorate existing hardpans will allow plants root more deeply, increase water infiltration and reduce runoff, all resulting in greater amounts of water available for the crop (i.e. green water). However, there has been a lack of research on understanding the influence of transported disturbed soil particles (colloids) from the surface to the subsurface to form restrictive soil layers, which is a common occurrence in degraded soils. In this study we investigated the effect of disturbed soil particles on clogging up of soil pores to form hardpans. Unsaturated sand column experiments were performed by applying 0.04 g/ml soil water solution in two sand textures. For each experiment, soil water solution infiltration process was visualized using a bright field microscope and soil particles remained in the sand column was quantified collecting and measuring leachate at the end of the experiment in the soil and water lab of Cornell University. Preliminary results show that accumulation of significant amount of soil particles occur in between sand particles and at air water interfaces, indicating the clogging of soil pores occurs as a result of disturbed fine soil particles transported from the soil surface to the subsurface.
    Tigist Yazie Tebebu  Assessment of hydrological controls on gully formation near Lake Tana, northern Higlands of Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Over the past five decades, gullying has been widespread and has become more severe in the Ethiopian highlands. Besides negatively affecting soil resources, lowering crop yields in areas between the gullies and reducing grazing land available for livestock, gully erosion is one of the major causes of silting of reservoirs. Assessing the rate of gully development and the controlling factors of gullying will help to explain the causes for current land degradation and to design reliable conservation measures for already existed gullies and preventing strategies for those areas susceptible to further gullying. The study was conducted in the 523 ha of Debre-Mewi watershed south of Bahir Dar, Amhara region, Ethiopia. A comparison of the gully area estimated from 0.58 m resolution quick bird image with current gully area walked with a garmin GPS, indicated that the total eroded area of gully was increased by 43% and 60% from 0.65 ha in 2005 to 1.0 ha on 2007 and 1.43 ha on 2008. Semi structured group interview and monitoring of gully development through time was made with profile measurements of contemporary gully volumes. Gullying started in the beginning of the 1980`s followed the clearance of indigenous vegetation, leading to an increase of surface and subsurface runoff from the hillside to the valley bottoms. Gully heads retreat into the hillslope during the rainy season. The water levels of gully contributing area showed that actively eroding sections the water table was in general closer to the ground surface on the gully shoulder than in stabilized sections. Piping and tunneling together with a high water table facilitate the slumping of the gully wall and their retreat. Estimated long-term average soil loss rate by gully erosion in the mid slope gully was 21 t ha-1 yr-1 and 27 t ha-1 yr-1 in the valley bottom saturated gullies. The area specific short-term gully erosion rates vi between 2007 and 2008 were approximately 128 t ha-1 yr-1 for the midslope gully and contributes to 1.7 cm soil loss for the 16.5 ha watershed and 402 t ha-1 yr-1 for the valley bottom gully (equivalent to 3 cm soil loss of the 17.4 ha watershed). [[Ethiopia]]
    Tigist Y. Tebebu, Anteneh Z. Abiy, Assafa Adzo, Helen E. Dahlke, Eric D. White, Amy S. Collick, Selemyihun Kidnau, Farzad Dadgari & Tammo S. Steenhuis  Assessment of hydrological controls on gully formation and upland erosion near Lake Tana, Northern Highlands of Ethiopia 2009 In: Seleshi B. Awulachew, T. Erkossa, V. Smakhtin & A. Fernando. Improved water and land management in the Ethiopian highlands: Its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia  inproceedings DOI   
    Abstract: For the past five decades, gully erosion has been the dominant degradation process in the Ethiopian Highlands. Gully erosion negatively affects soil resources, lowers soil fertility in inter-gully areas, reduces the pastureland available for livestock, and aggravates siltation of reservoirs. Assessing the location and rate of gully development and changes in the controlling factors (climate, soil, hydrology and land cover) of gully erosion will help explain the acceleration in land degradation that is faced. The study was performed in a gully system in the 800 ha Debre-Mewi Watershed south of Bahir Dar, Amhara region, Ethiopia. Analyses comprised monitoring gully development through profile measurements, air photograph interpretations, and semi-structured interview techniques. Gully hydrological processes were investigated based on measurements of gully runoff and water levels in 24 piezometers in the gully contributing area. Upland erosion was also assessed. The Debre-Mewi gully is still an actively eroding gully system. A comparison of the gully area estimated from a 0.5 m resolution QuickBird image with the current gully area, walked with a Garmin GPS, showed that the eroded gully area increased by 30% from 0.51 ha in 2005 to 0.735 ha in 2008. Based on measurements of several gully cross-sections, an approximate gully volume of 7,985 cubic meters (m3) and an average gully erosion rate of 24.8 t ha-1 a-1 could be estimated. Gully erosion rates accelerated since 1991 through the increased degradation of the vegetation cover and clearance of indigenous vegetation on the hillsides, leading to an increase of surface and subsurface runoff from the hillsides to the valley bottoms. Gully heads retreat into the hillslope through concentrated runoff during the rainy season, erodes existing soil pipes and cracks in the vicinity of the gully head and banks. Piping and tunneling facilitate the slumping of the gully wall and their retreat. The sediment produced from the collapsing walls is exported during heavy storm events. The loss of erosion due to gulley formation is many times that of upland erosion. We find that alteration of the runoff response due to reestablishing the natural vegetation on the hillside and improvement of existing farming practices will be most important to decelerate current erosion rates.
    Tigist Y. Tebebu, Anteneh Z. Abiy, Assafa Adzo, H.E. Dahlke, E.D. White, A.S. Collick, Selemyihun Kidnau, Farzad Dadgari & T.S. Steenhuis  Assessment of hydrological controls on gully formation and upland erosion near Lake Tana, Northern Highlands of Ethiopia 2010 Proceedings of the 4th Joint Federal Interagency Hydrologic Modeling Conference and the 9th Federal Interagency Sedimentation Conference, Las Vegas NV, June 27-July 1st, 2010.  inproceedings URL   
    Abstract: Over the past five decades, gullying has been widespread and has become more severe in the Ethiopian highlands. Besides negatively affecting soil resources, lowering crop yields in areas between the gullies and reducing grazing land available for livestock, gully erosion is one of the major causes of silting of reservoirs. Assessing the rate of gully development and the controlling factors of gullying will help to explain the causes for current land degradation and to design reliable conservation measures for already existed gullies and preventing strategies for those areas susceptible to further gullying. The study was conducted in the 523 ha of Debre-Mewi watershed south of Bahir Dar, Amhar region, Ethiopia, where active gullies were retreating upslope. Semi structured group interview and monitoring of gully development through time was made with profile measurements of contemporary gully volumes. Gullying started in the beginning of the 1980`s following the clearance of indigenous vegetation, leading to an increase of surface and subsurface runoff from the hillside to the valley bottoms. A comparison of the gully area estimated from 0.58 m resolution quick bird image with current gully area walked with a Garmin GPS, indicated that the total eroded area of gully was increased from 0.65 ha in 2005 to 1.0 ha in 2007 and 1.43 ha in 2008. The water levels measured with piezometers showed that in the actively eroding sections the water table was in general above the gully bottom and below it in stabilized sections. Piping and tunneling together with a high water table facilitate the slumping of the gully wall and their retreat. Water table height is decreasing after the gully has been formed. The gully erosion rate between 2007 and 2008 was 530 t ha-1 yr-1 in the 17.4 ha watershed, equivalent to almost 5 cm soil loss in the contributing area. Gully erosion rate was approximately 20 times the measured upland soil losses.
    Tigist Y. Tebebu, Anteneh Z. Abiy, Assefa D. Zegeye, H.E. Dahlke, Z.M. Easton, Seifu A. Tilahun, A.S. Collick, Selemyihun Kidnau, S. Moges, Farzad Dadgari & T.S. Steenhuis  Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the northern highlands of Ethiopia 2010 Hydrology and Earth Systems Science
    Vol. 14 , pp. 2207-2217 
    article DOI   
    Tigist Y. Tebebu, Assefa D. Zegeye, Eddy J. Langendoen, Getaneh K. Ayele, Seifu A. Tilahun, Essayas K. Ayana & Tammo S. Steenhuis  Arresting gully formation in the Ethiopian highlands 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings   
    Abstract: Over the past five decades, gullying has been widespread and has become more severe in the Ethiopian highlands. Only in very few cases rehabilitation of gullies has been successful in Ethiopia due to the high cost. The objective of this paper is to introduce cost effective measures to arrest gully formation. The research was conducted in the Debre-Mewi watershed located at 30 km south of Bahir Dar, Ethiopia. Gullying started in the 1980's following the clearance of indigenous vegetation and intensive agricultural cultivation, leading to an increase of surface and subsurface runoff from the hillside to the valley bottoms. Gully erosion rates were 10-­20 times the measured upland soil losses. Water levels, measured with piezometers, showed that in the actively eroding sections the water table was in general above the gully bottom and below it in the stabilized sections. In order to develop effective gully stabilizing measures, we tested and then applied the BSTEM and CONCEPT models for their applicability for Ethiopian conditions where active gully formation has been occurring. We found that the model predicted the location of slips and slumps well with the observed groundwater depth and vegetation characteristics. The validated models indicated that any gully rehabilitation project should first stabilize the head cuts. This can be achieved by regrading these head cuts to slope of 40 degrees and armoring it with rock. Head cuts will otherwise move uphill in time and destroy any improvements. To stabilize side walls in areas with seeps, grass will be effective in shallow gullies, while deeper gullies requirere shaping of the gullies walls then planting the gully with grasses, eucalyptus or fruit trees that can be used for income generation. Only then there is an incentive for local farmers to maintain the structures.
    Zelalem Kassahun Tesemma  Long term hydrologic trends in the Nile basin 2009 School: Cornell University  mastersthesis URL   
    Abstract: A study has been conducted to examine if and how streamflow in the Nile Basin has varied over the period of available records. Streamflow records from 13 flow gauging stations in four major river basins of the Nile and 38 precipitation stations all over the Nile basin were studied. Monthly measured discharge (1912-1982) and rainfall data for those selected stations were collected from four different data sources and Global Hydro Climate Data Network available at http://dss.ucar.edu/datasets/ds553.2/data/ and Global Historical Climatology Network available at http://gpcc.dwd.de were selected as the main data sources except those Ethiopian stations. The remaining recent 20 years data were collected from countries. Monthly and annual streamflows (up to the year 2000, some up to 2007) were extracted and analyzed for each of the 13 station. The raw data were validated thoroughly by comparing different sources, corrected and augmented if needed. The Mann-Kendal and Sen?s T non-parametric test was used to detect significant trends in the selected years in combination with the Trend Free Pre-Whitening (TFPW) method for correcting time series data from serial correlation. The slope of the data set was computed using the Thiel-Sen Approach (TSA). For this study a 5- percent level of significance was selected to indicate the presence of statistical significant trends. Rainfall-Runoff Modeling was done on the upper Blue Nile using the Thronthwait-Mather model to understand the land cover changes on runoff over the past 30 years. The mean annual natural streamflow on the Blue Nile Stations (Bahir Dar, Kessie and El Diem) show no trend. The rainfall over the basin also shows no significant trend. The Monthly runoff showed moderate variability at El Diem with 19% and 34% at Bahir Dar and Kessie. This might be a result that more land was cultivated growing of different crops as shown by rainfall-runoff modeling over the last 30 years. White Nile Stations (Jinja, Mongalla and Malakal) show a significant increasing trend on both rainfall and streamflow. The runoff increased 72%, 67% and 20% of the mean annual flow at Jinja Mongalla and Malakal respectively. Stations of the Main Nile (Tamaniate, Hassanab and Dongolla) show significant decreasing trend in streamflow due to abstraction of flow before reach gauging stations. For water resources management the key conclusion, that Nile natural streamflows have not changed significantly during the last 100 years. [[Ethiopia]]
    Zelalem K. Tessema, Yasir A. Mohamed & Tammo S. Steenhuis  Trends in Rainfall and Runoff in the Blue Nile Basin: 1964-2003 2010 Hydrological Processes
    Vol. 25 , pp. 3747-3758 
    article URL   
    Abstract: Most Nile water originates in Ethiopia but there is no agreement on how land degradation or climate change affects the future flow in downstream countries. The objective of this paper is to improve understanding of future conditions by analyzing historical trends. During the period 1963 to 2003, average monthly basin wide precipitation and monthly discharge data were collected and analyzed statistically for two stations in the upper 30% of Blue Nile Basin and one station at the Sudan-Ethiopia border. A rainfall runoff model examined the causes for observed trends. The results show that while there was no significant trend in the seasonal and annual basin-wide average rainfall, significant increases in discharge during the long rainy season (June to September) at all three stations were observed. In the upper Blue Nile the short rainy season flow (March to May), increased while the dry season flow (October to February) stayed the same. At the Sudan border the dry season flow decreased significantly with no change in the short rainy season flow. The difference in response was likely due to weir construction in the nineties at the Lake Tana outlet that affected significantly the upper Blue Nile discharge but only affected less than 10% of the discharge at the Sudan border. The rainfall runoff model reproduced the observed trends, assuming that an additional ten percent of the hillsides were eroded in the 40 year time span and generated overland flow instead of interflow and base flow. Models concerning future trends in the Nile cannot assume that the landscape runoff processes will remain static.
    Aschalew D. Tigabu, Charles F. Nicholson, Amy S. Collick & Tammo S. Steenhuis  Determinants of household participation in the management of rural water supply systems: A case from Ethiopia 2013 Water Policy   article DOI URL   
    Abstract: Access to safe drinking water supply in Ethiopia is among the lowest in sub-Saharan Africa.
    While both governmental and non-governmental organizations have implemented water supply
    projects in recent years, many fail shortly after construction due to improper management. In this
    paper, we examine socio-economic, institutional and exogenous factors affecting household
    participation in the management of water supply systems for drinking purposes. A survey was
    carried out involving 16 water supply systems and 160 households within the Achefer area, in
    the Amhara region, Ethiopia. The results show that household contributions to water supply
    system management are positively and significantly affected by user participation during the
    project design and implementation, by advocacy provided by the project and by greater
    household income. Thus, for drinking water systems in rural areas to be sustainable, these factors
    should be included when planning water supply projects.
    Seifu Admassu Tilahun  Observations and Modeling of Erosion from Spatially and Temporally Distributed Sources in the (Semi) Humid Ethiopian Highlands 2012 School: Cornell University  phdthesis URL   
    Abstract: Despite long term efforts to reduce erosion in the Blue Nile Basin, river sediment concentrations
    have not declined. Lack of progress on sediment reduction indicates that runoff and erosion
    processes are not fully understood. The objective of this dissertation was, therefore, to
    understand runoff and erosion processes by investigating where runoff and erosion takes place in
    the landscape and to use this information to model erosion. Runoff processes were investigated
    in Debre Mawi, a 95-ha watershed south of Lake Tana. During the rainy period of the 2010 and
    2011 monsoons, storm runoff and sediment concentrations were measured from four sub-
    watersheds and at the main watershed outlet. In addition, perched groundwater tables, infiltration
    rates, rill erosion from agricultural fields and gully expansion were measured. The results show
    that saturation excess runoff was the main runoff mechanism because median infiltration rate
    was only exceeded 3% of the time. Early during rainy period, runoff produced from shallow soils
    upslope infiltrated before it reached the outlet, and sediment concentrations were very high as rill
    networks developed on the ploughed land. At the end of July, the bottom lands became saturated,
    the runoff coefficient at the outlet became greater than upslope areas and rill networks were fully
    developed reducing the velocities and thereby the sediment concentrations.

    A semi-distributed hillslope erosion model relating sediment concentration with overland flow
    using only four calibrated sediment parameters was developed based on input data from various
    watersheds in Blue Nile Basin. The erosion model assumed that sediment concentration is
    transport limiting at the beginning of the rainy phase when lands are plowed and source limited
    at the end. Overland flow was simulated with the semi-distributed water balance hydrology
    model. The model predicted daily sediment concentrations well in three small watersheds
    including the Debre Mawi as well as in the Blue Nile Basin at the Sudanese border. The
    implication of this research is that shallow degraded soils and bottom lands with gullies are the
    greatest sediment sources and should be targeted for erosion control.

    Seifu A. Tilahun & Amy S. Collick  Can Communities Manage Complex Technologies? 2012 (Briefing note 5)   techreport URL   
    Seifu Admassu Tilahun & Amy S. Collick  Wisdom at the source of the Blue Nile - MUS 2011 (Briefing note 2)   techreport URL   
    Seifu Admassu Tilahun & Amy S. Collick  Bottlenecks of operation and maintenance 2011 (Briefing note 1)   techreport URL   
    Seifu A. Tilahun & Amy S. Collick  Sanitation promotion and household latrine 2011 (Briefing note 3)   techreport URL   
    Seifu A. Tilahun & Amy S. Collick  Solar Power: An Alternative Technology for Pumping Water 2011 (Briefing note 4)   techreport URL   
    Seifu A. Tilahun & Amy S. Collick  The Role of Users at the Different Levels of WaSH Projects 2011 (Briefing note 6)   techreport URL   
    Seifu A. Tilahun, Amy S. Collick & Manyahlshal Ayele  Assessment of Water Supply and Sanitation in Amhara Region 2012   techreport URL   
    Abstract: Great effort has been put forth to increase the number of people with access to safe water supply, adequate sanitation and effective hygiene in the developing world. However, the issues and factors of sustainability of these services are just as important and not documented very well. WaterAid has made an effort to address the challenges of sustainability by funding a project to improve the documentation of the conditions and status of 32 localities in which Water, Sanitation and Hygiene (WaSH) schemes have been implemented throughout the Amhara Region. These 32 WaSH schemes have been investigated by using physical observation and checklist interviews conducted with communities, water user committees and woreda experts. Additional information was gathered through the review of five Cornell-BDU master theses concerning rural water supply and sanitation and their factors of sustainability. The findings showed that the idea of simple technology is not always a solution as two different communities (Kule and Awera Amba localities) have been able to manage for long period of time a borehole equipped with a diesel pump. However, they have encountered the major challenge of the high cost of fuel to run the diesel. In this study, it is shown that pumps powered by solar panesl can be an alternative technology in such cases where the sites are far from the electric grid system. The simple technologies such as hand pump fitted on hand dug well works well in areas where there is no alternative water supply sources as shown in Enbes Sar Mider locality and in areas where springs can be developed for multiple use of water (cattle trough and irrigation).

    The sustainability of developed water supply sources is often dependent on the existence of alternative water supply sources. In areas where there are a sufficient number of alternative sources, the strategy should be to develop the water point most preferred by the community, or to direct efforts towards household provision of water rather than a communal water point. Otherwise, the communities would not buy into the operation and maintenance since their preferred water source remains undeveloped but free of charge to use. The most common challenges observed at the study sites were (1) collected fees paid for maintenance only, (2) confusion about the management prevailed where there were different types of users and (3) conflict often raged between users and farmer who owned the land on which the scheme was constructed. In such cases, more complete community participation and awareness and implementation of multiple uses at a water scheme are better approaches and lead to potential solutions of these challenges.

    Finally, sanitation and hygiene practices are observed to be low. In most cases, the latrines have little or no walls or roofs and are not suitable for people who are disabled. Those households reported to have latrines are in most cases not the actual users of the latrine or the hand washing facilities. Reasons for not using latrines were found to be the additional work to dig a hole was excessive, the latrine was not able to be used during the summer due to runoff, the location at the homestead was far from the users’ agricultural land where they worked for most of the day and many more. Furthermore, it is important to evaluate the impact of current sanitation and hygiene practices on the water quality of the water sources and domestic water at individual households and on the overall health of the community.
    [[Ethiopia]]

    Seifu Admassu Tilahun, Tegenu Ashagrie Engda, Elias Sime Legesse, C.D. Guzman, Assefa Derebe Zegeye, A.S. Collick, A. Rimmer & T.S. Steenhuis  An efficient semi-distributed hillslope sediment model: the Anjeni in the sub humid Ethiopian Highlands 2011 Hydrol. Earth Syst. Sci. Discuss.
    Vol. 8 , pp. 2207-2233 
    article DOI   
    Abstract: Prediction of sediment loss in Africa is not well developed. In most case models developed in western countries with a temperate climate do not perform well in the monsoon climate prevailing in Africa. In this paper we base our sediment prediction on a simple distributed saturated excess hydrology model that predicts surface runoff from bottom lands that become saturated during the rainy season and from severely degrade lands and interflow and base flow from the remaining portions of the landscape. By developing an equation that relate surface runoff and sediment concentration from runoff source areas assuming that base flow and interflow are sediment free, we were able to predict the daily sediment concentrations in a 113 ha Anjeni watershed in the Ethiopian Highlands with a Nash Sutcliffe efficiency ranging from 0.64?0.77 using only two calibrated sediment parameters. The daily flows were predicted with a Nash Sutcliffe efficiency values ranging from 0.80 to 0.84 based on 14% of the watershed consisted of degraded area as the only surface runoff source. The analysis seems to suggest that identifying the runoff source areas and predicting the surface runoff correctly is an important step in predicting the sediment concentration at least for the Anjeni watershed.
    Seifu.A. Tilahun, Christian.D. Guzman, Assefa.D. Zegeye, Essayas K. Ayana, A.S. Collick, Birru Yitaferu & T.S. Steenhuis Spatial and Temporal Patterns of Soil Erosion and in the semi-humid Ethiopian Highlands: A Case Study of the debre Mawi Watershed Nile River Basin: Ecohydrological Challenges, Climate Change and Hydropolitics 2014 (in press) In: Assefa Melesse, Wossenu Abtew & Gebriye Shimelis Setegn.   inbook URL   
    Abstract: [Ethiopia]
    S.A. Tilahun, C.D. Guzman, A.D. Zegeye, T.A. Engda, A.S. Collick, A. Rimmer & T.S. Steenhuis  An efficient semi-distributed hillslope erosion model for the subhumid Ethiopian Highlands 2013 Hydrol. Earth Syst. Sci.
    Vol. 17 , pp. 1051-1063 
    article DOI URL   
    Abstract: Erosion modeling has been generally scaling up from plot scale but not based on landscape topographic position, which is a main variable in saturation excess runoff. In addition, predicting sediment loss in Africa has been hampered by using models developed in western countries and do not perform as well in the monsoon climate prevailing in most of the continent. The objective of this paper is to develop a simple erosion model that can be used in the Ethiopian Highlands in Africa. We base our sediment prediction on a simple distributed saturated excess hydrology model that predicts surface runoff from severely degraded lands and from bottom lands that become saturated during the rainy season and estimates interflow and baseflow from the remaining portions of the landscape. By developing an equation that relates surface runoff to sediment concentration generated from runoff source areas, assuming that baseflow and interflow are sediment-free, we were able to predict daily sediment concentrations from the Anjeni watershed with a Nash–Sutcliffe efficiency ranging from 0.64 to 0.78 using only two calibrated sediment parameters. Anjeni is a 113 ha watershed in the 17.4 million ha Blue Nile Basin in the Ethiopian Highlands. The discharge of the two watersheds was predicted with Nash–Sutcliffe efficiency values ranging from 0.80 to 0.93. The calibrated values in Anjeni for degraded (14%) and saturated (2%) runoff source area were in agreement with field evidence. The analysis suggests that identifying the runoff source areas and predicting the surface runoff correctly is an important step in predicting the sediment concentration.
    Seifu Admassu Tilahun, Rajith Mukundan, Bezawit A. Demisse, Tegenu Ashgary, Christian Guzman, Birara C. Tarakegn, Zachary M. Easton, Amy S Collick, Assefa D. Zegeye, Elliot M. Schneiderman, J.-Yves Parlange & Tammo S. Steenhuis  A Saturation Excess Erosion Model 2011 International Symposium on Erosion and Landscape Evolution CD-Rom Proceedings (18-21 September 2011)  inproceedings URL   
    Abstract: Scaling up sediment transport has been problematic because most sediment loss models (e.g., the Universal Soil Loss Equation) are developed using data from small plots where runoff is generated by infiltration excess. However, in most watersheds, runoff is produced by saturation excess processes. Therefore, scaling up requires a hydrology model that accurately predicts the location and extent of runoff source areas. These runoff predictions can then be used for simulating sediment concentrations. We base sediment predictions on a simple, well-tested distributed saturation excess hydrology model, which calculates surface runoff, interflow, and baseflow. Surface runoff originates from bottom lands that become saturated during the rainy season or from severely degradedlands with little or no storage capacity. Baseflow and interflow are generated from the remaining parts of the landscape. Interflow comes from the shallow soils over an impermeable surface and base flow results from percolation below the impervious layer. To obtain the sediment concentrations, we assume that during surface runoff, there is a linear relationship between runoff velocity and sediment concentration, but baseflow and interflow are sediment free. Thus only the runoff component of stream discharge is involved in active erosive work (sediment transport, sediment entrainment, re-entrainment of deposited sediment) compared to baseflow and interflow that contribute minimally to watershed sediment yield. To show the general applicability of the Saturation Excess Erosion Model (SEEModel), the model was tested for watersheds located 10,000 km apart, in the United States and in Ethiopia. In the Ethiopia highlands, we simulated the 113 ha Anjeni watershed, the 400 ha Enkulal watershed and the 180,000 km2 the Blue Nile basin. In the Catskill Mountains in New York State, the sediment concentrations were simulated in the upper 493 km2 Esopus Creek watershed. Daily discharge and sediment concentration were well simulated over the range of scales with comparable parameter sets. The Nash Sutcliffe values for the daily stream discharge were greater than 0.80 and the daily sediment concentrations had Nash Sutcliffe values of 0.65 using only two calibrated sediment parameters and the subsurface and surface runoff discharges calculated by the hydrology model. The model results suggest that correctly predicting both amount of surface runoff and subsurface flow is an important step in simulating the sediment concentrations.
    S.A. Tilahun, R. Mukundan, B.A. Demisse, T.A. Engda, C.D. Guzman, B.C. Tarakegn, Z.M. Easton, A.S. Collick, A.D. Zegeye, E.M. Schneiderman, J.-Y. Parlange & T.S. Steenhuis  A Saturation Excess Erosion Model 2013 Transactions of the ASABE
    Vol. 56(2) , pp. 681-695 
    article   
    Abstract: ABSTRACT . Scaling-up sediment transport has been problematic because most sediment loss models (e.g., the Universal
    Soil Loss Equation) are developed using data from small plots where runoff is generated by infiltration excess. However,
    in most watersheds, runoff is produced by saturation excess processes. In this article, we improve an earlier saturation ex-
    cess erosion model that was only tested on a limited basis, in which runoff and erosion originated from periodically satu-
    rated and severely degraded areas, and apply it to five watersheds over a wider geographical area. The erosion model is
    based on a semi-distributed hydrology model that calculates saturation excess runoff, interflow, and baseflow. In the de-
    velopment of the erosion model, a linear relationship between sediment concentration and velocity in surface runoff is as-
    sumed. Baseflow and interflow are sediment free. Initially during the rainy season in Ethiopia, when the fields are being
    plowed, the sediment concentration in the river is limited by the ability of the surface runoff to move sediment. Later in the
    season, the sediment concentration becomes limited by the availability of sediment. To show the general applicability of
    the Saturation Excess Erosion Model (SEEModel), the model was tested for watersheds located 10,000 km apart, in the
    U.S. and in Ethiopia. In the Ethiopian highlands, we simulated the 1.1 km2 Anjeni watershed, the 4.8 km2 Andit Tid water-
    shed, the 4.0 km2 Enkulal watershed, and the 174,000 km2 Blue Nile basin. In the Catskill Mountains in New York State,
    the sediment concentrations were simulated in the 493 km2 upper Esopus Creek watershed. Discharge and sediment con-
    centration averaged over 1 to 10 days were well simulated over the range of scales with comparable parameter sets. The
    Nash-Sutcliffe efficiency (NSE) values for the validation runs for the stream discharge were between 0.77 and 0.92. Sedi-
    ment concentrations had NSE values ranging from 0.56 to 0.86 using only four calibrated sediment parameters together
    with the subsurface and surface runoff discharges calculated by the hydrology model. The model results suggest that cor-
    rectly predicting both surface runoff and subsurface flow is an important step in simulating sediment concentrations.
    Seifu A. Tilahun, Aschalew D. Tigabu, Tegegne M. Tarekegne, Meseret B. Addisie, Habtamu A. Beyene, Zemenu A. Alemeyehu, Manyahlshal Ayele, Amy S. Collick & Tammo S. Steenhuis  Factors in sub-optimum performance of rural water supply systems (as lessons learned for rain water management systems) in the Ethiopian highlands 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings   
    Abstract: Access to safe drinking water services in the Ethiopian Highlands is one of lowest worldwide due to failure
    of water supply services shortly after construction. Over hundred water supply systems were surveyed to find the
    underlying causes of failure and poor performance throughout the Amhara Regional State. The results show generally
    systems with decision making power at the community level during design and construction remained working longer
    than when the decisions were made by a central authority. In addition, the sustainability was better for water
    systems that were farther away from alternative water resources and contributed more cash and labor. The results of
    this study of the importance of decision making at the local level in contrast to the central authority is directly
    applicable to the introduction of rain water management systems as shown by earlier efforts of installing rain water
    harvesting systems in the Ethiopian highlands.
    M.D. Tomer, J. Boll, K.J.S. Kung, T.S. Steenhuis & J.L. Anderson  Detecting Illuvial Lamellae in Fine Sand Using Ground-Penetrating Radar 1996 Soil Sci.
    Vol. 161 , pp. 121-129 
    article   
    C. Tripler, S.S. Kaushal1, G.E. Likens & M.T. Walter  Environmental change and the role of potassium in forested ecosystems 2006 Ecology Letters
    Vol. 9 , pp. 451-466 
    article   
    V.L. Versace, D. Ierodiaconou, F. Stagneitti, A.J. Hamilton, M.T. Walter & M. LeBlanc  The relationship between native vegetation and in-stream salinity: an Australian case study 2007 Hydrological Sciences Journal/Journal des Sciences Hydrologiques, (IAHS)
    Vol. 317 , pp. 72?76 
    article   
    Abeyou Wale, Amy S Collick, David G Rossiter, Simon Langan & Tammo S. Steenhuis  Realistic assessment of irrigation potential in the Lake Tana basin, Ethiopia. 2013 Proceedings of the Nile Basin Development Challenge Science Meeting on Rainwater Management for Resilient Livelihoods  inproceedings   
    Abstract: Although Ethiopia has a large potential to develop irrigation, only 5% of the 3.5 million hectare potentially available has been developed. To examine the underlying causes, this study evaluates the suitability of surface water irrigation for the Lake Tana Basin development corridor. Surface water availability and land potentially suitable for medium and large-scale irrigation development (200 ha and larger) was considered. Surface water potential was examined by considering river discharges. Land suitable for irrigation was determined with a GIS-based multi-criteria evaluation (MCE), which considers the interaction of various factors, such as climate, river proximity, soil type, land cover, topography/slope, and market outlets. Nearly 11% of the Lake Tana Basin is suitable for irrigation. However, by analyzing 27 years of river discharge, less than 3% of the potential irrigable area (or less than 0.25% of the basin area) could be irrigated consistently by run-of-the-river-systems. Thus, the irrigation potential in the Lake Tana Basin can only be met by increasing dry season flows (if proven feasible) and by supplying water from existing or future reservoirs or by using water directly from Lake Tana.
    J. Walker, M.T. Walter, J.Y. Parlange, C.W. Rose, H.J. Tromp vanMeerveld, B. Gao & A.M. Cohen  Infiltration reduces raindrop-impact driven soil erosion 2007 Journal of Hydrology
    Vol. 342(3-4) , pp. 331-335 
    article   
    M.J. Walker, M.F. Walter & K. McDonough  Large volume samples for Cryptosporidium and Giardia from small streams. 1997 J. of Environmental Quality,
    Vol. 123(1)  
    article   
    R. Wallach, J.Y. Parlange & T.S. Steenhuis  Modeling the Movement of Water and Solute through Preferential Paths. In: J. Delleur (Ed.) Groundwater Engineering Handbook 2/e, CRC Press 2005   other URL   
    R. Wallach & T.S. Steenhuis  Model for nonreactive solute transport in structured soils with continuous preferential flow paths. 1998 Soil Science Socienty of America J.
    Vol. 62 , pp. 881-886 
    article   
    R. Wallach, T.S. Steenhuis & J.Y. Parlange 7. Modeling the movement of water and solute through preferential flow paths  1998 In: J. Delleur. The Handbook of Groundwater Engineering, pp. 7-1 - 7-21  inbook   
    M.F. Walter  Book Review. Land and Water Development in the Asia-Pacific Region, V.V.N. Murth and K. Takeuchi, Science Publishers, Inc., Lebanon, NH. 1998 Agricultural Water Management
    Vol. 33 , pp. 211-212 
    article   
    M.F. Walter, T.S. Steenhuis & D.A. Haith  Nonpoint Source Pollution Control by Soil and Water Conservation Practices. 1979 ASAE Trans.
    Vol. 22 , pp. 834-840 
    article   
    M.T. Walter  A groundwater recovery system for the extraction of a contaminant plume. ME(C) design project 1991 School: School of Civil and Environmental Engineering, Cornell University  mastersthesis   
    M.T. Walter, J.A. Archibald, B. Buchanan, H. Dahlke, Z.M. Easton, R.D. Marjerison, A.N. Sharma & S.B. Shaw  A new paradigm for sizing riparian buffers to reduce risks of polluted storm water: A practical synthesis 2009 ASCE Journal of Irrigation and Drainage Engineering
    Vol. 135(2) , pp. 200-209 
    article   
    M.T. Walter, E.S. Brooks, D.K. McCool, L.G. King, M. Molnau & J. Boll  Process-based snowmelt modeling: Does it require more input data than temperature-index modeling? 2005 Journal of Hydrology
    Vol. 300(1-4) , pp. 65-75 
    article URL   
    M.T. Walter, E.S. Brooks, M.F. Walter, T.S. Steenhuis, C.A. Scott & J. Boll  Evaluation of soluble phosphorus transport from manure-applied fields under various spreading strategies. 2001 J. Soil and Water Conservation
    Vol. 56(4) , pp. 329-336 
    article URL   
    M.T. Walter, B. Gao & J.Y. Parlange  Modeling soil solute release into runoff with infiltration 2007 Journal of Hydrology
    Vol. 347 , pp. 430?437 
    article   
    M.T. Walter, P. Gérard-Marchant, T.S. Steenhuis & M.F. Walter  Closure to "Simple estimation of Prevalence of Hortonian Flow in New York City Watersheds" by M. Todd Walter, Vishal K. Mehta, Alexis M. Marrone, Jan Boll, Pierre Gérard-Marchant, Tammo S. Steenhuis and Michael F. Walter. 2005 J. of Hydrologic Engr., ASCE
    Vol. 10(2) , pp. 169-170 
    article   
    M.T. Walter, J.S. Kim, T.S. Steenhuis, J.Y. Parlange, A. Heilig, R.D. Braddock, J. Selker & J. Boll  Funneled flow mechanisms in sloping layered soil: Laboratory investigation 2000 Water Resources Research
    Vol. 34(4) , pp. 841-849 
    article URL   
    M.T. Walter & D.K. McCool  Closure: 'A simple snowdrift model for distributed hydrological modeling' 2005 ASCE Journal of Hydrologic Engineering
    Vol. 10(6) , pp. 524-525 
    article   
    M.T. Walter, D.K. McCool, L.G. King, M. Molnau & G.S. Campbell  A simple snowdrift model for distributed hydrological modeling 2004 ASCE Journal of Hydrologic Engineering
    Vol. 9(4) , pp. 280-287 
    article URL  URL2 
    M.T. Walter, V.K. Mehta, A.M. Marrone, J. Boll, P. Gérard-Marchant, T.S. Steenhuis & M.F. Walter  Simple Estimation of Prevalence of Hortonian Flow in New York City Watersheds 2004 J. Hydrol. Engr.
    Vol. 9 , pp. 70 
    article   
    M.T. Walter, V.K. Mehta, A.M. Marrone, J. Boll, T.S. Steenhuis & M.F. Walter  Simple Estimation of Prevalence of Hortonian Flow in New York City Watersheds 2003 ASCE J. Hydrol. Engr.
    Vol. 8(4) , pp. 214-218 
    article URL   
    M.T. Walter, P. Mutch, C.D. Salmon, D.K. McCool & L.O. Hedin  Digitizing chart recorder data: Coordinate system conversion for rain gages and similar recording instruments 1999 Journal of Atmospheric and Oceanic Technology
    Vol. 16(8) , pp. 1138-1142 
    article URL   
    M.T. Walter, J.Y. Parlange & P.C.A. Raats  Vadose zone dynamics and the legacy of Wilford R. Gardner 2007 Transport in Porous Media
    Vol. 68(1) , pp. 1-4 
    article   
    M.T. Walter, J.Y. Parlange, M.F. Walter, X. Xin & C.A. Scott  Modeling pollutant release from a surface source during rainfall-runoff 2001 Journal of Environmental Quality
    Vol. 30(1) , pp. 151-159 
    article URL   
    M.T. Walter & S.B. Shaw  Discussion: "Curve Number Hydrology in Water Quality Modeling: Uses, Abuses, and Future Directions," By David C. Garen and Daniel S. Moore. 2005 Journal of the American Water Resources Association
    Vol. 41(6) , pp. 1491-1492 
    article   
    M.T. Walter, T.S. Steenhuis, V.K. Mehta, D. Thongs, M. Zion & E. Schneiderman  Refined conceptualization of TOPMODEL for shallow subsurface flows 2002 Hydrological Processes
    Vol. 16(10) , pp. 2041-2046 
    article URL   
    M.T. Walter & M.F. Walter  The New York City Watershed Agricultural Program (WAP): A model for comprehensive planning for water quality and agricultural economic viability 1999 Water Resources Impact
    Vol. 1(5) , pp. 5-8 
    article   
    M.T. Walter, M.F. Walter, E.S. Brooks, T.S. Steenhuis, J. Boll & K.R. Weiler  Hydrologically sensitive areas: Variable Source Area hydrology implications for water quality risk assessment 2000 J. Soil and Water Conservation
    Vol. 55(3) , pp. 277-284 
    article URL   
    M.T. Walter, D. Wilks, J.Y. Parlange & R.L. Schnieder  Increasing evapotraspiration from the conterminous U.S. 2004 Journal of Hydrometeorology
    Vol. 5(3) , pp. 405-408 
    article URL   
    K.R. Weiler, M.T. Walter, E.S. Brooks & C.A. Scott  Temporally dependent risk analysis for flood plains in the Delaware River Basin 1998 J. Water Resource Planning and Management, ASCE
    Vol. 126(5) , pp. 320-329 
    article   
    K.R. Weiler, M.T. Walter, M.F. Walter, E.S. Brooks & C.A. Scott  Seasonal risk analysis for flood plains in the Delaware River Basin. 2000 ASCE Journal of Water Resources Planning and Management
    Vol. 126(5) , pp. 320-329 
    article URL   
    K.W. Weiler, T.S. Steenhuis, J. Boll & K.J.S. Kung  Comparison of ground-penetrating radar and time-domain reflectometry as soil water sensors 1998 Soil Science Society of America J.
    Vol. 62 , pp. 1237-1239 
    article URL   
    J.C. Wells & M.F. Walter  Experiments on entry of a rough circular cylinder into water. Applications to rainsplash eroision of soil 1999 Annual Journal of Hydraulic Engineering
    Vol. 43 , pp. 785-790 
    article   
    R.R. Wells, D.A. DiCarlo, T.S. Steenhuis, J.Y. Parlange, M.J.M. Romkins & S.N. Prasad  Infiltration and surface geometry features of a swelling soil following successive simulated rainstorms 2003 Soil Science Society of America J.
    Vol. 67 , pp. 1344-1351 
    article URL   
    R.R. Wells, M.J.M. Romkens, J.Y. Parlange, D.A. DiCarlo, T.S. Steenhuis & S.N. Prasad  A Simple Technique for Measuring Wetting Front Depths for Selected Soils 2007 Soil Sci. Soc. Am. J.
    Vol. 71(3) , pp. 669-673 
    article DOI   
    E.D. White, Z.M. Easton, D.R. Fuka, A.S. Collick, M. McCartney, Seleshi B. Awulachew & T.S. Steenhuis  A Water Balance-Based Soil and Water Assessment Tool (SWAT) for Improved Performance in the Ethiopian Highlands 2009 In: Seleshi B. Awulachew, T. Erkossa, V. Smakhtin & A. Fernando. Improved water and land management in the Ethiopian highlands: Its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia  inproceedings DOI URL   
    Abstract: The Soil Water Assessment Tool (SWAT) is a watershed model widely used to predict water quantity and quality under varying land use and water use regimes. To determine the respective amounts of infiltration and surface runoff, SWAT uses the popular Curve Number (CN). While being appropriate for engineering design in temperate climates, the CN is less than ideal when used in monsoonal regions where rainfall is concentrated into distinct time periods. The CN methodology is based on the assumption that Hortonian flow is the driving force behind surface runoff production, a questionable assumption in many regions. In monsoonal climates water balance models generally capture the runoff generation processes and thus the flux water or transport of chemicals and sediments better than CN-based models. In order to use SWAT in monsoonal climates, the CN routine to predict runoff was replaced with a simple water balance routine in the code base. To compare this new water balance-based SWAT (SWAT-WB) to the original CN- based SWAT (SWAT-CN), several watersheds in the headwaters of the Abay Blue Nile in Ethiopia were modeled at a daily time step. While long term, daily data is largely nonexistent for portions of the Abay Blue Nile, data was available for one 1,270 km2 subbasin of the Lake Tana watershed, northeast of Bahir Dar, Ethiopia, which was used to initialize both versions of SWAT. Prior to any calibration of the model, daily Nash- Sutcliffe model efficiencies improved from -0.05 to 0.39 for SWAT-CN and SWAT-WB, respectively. Following calibration of SWAT-WB, daily model efficiency improved to 0.73, indicating that SWAT can accurately model saturation-excess processes without using the Curve Number technique.
    E.D. White, Z.M. Easton, D.R. Fuka, A.S. Collick & T.S. Steenhuis  Development and application of a physically based landscape water balance in the SWAT model 2011 Hydrol. Proc.
    Vol. 25(6) , pp. 915-925 
    article DOI   
    Abstract: (before editing) Watershed scale hydrological and biogeochemical models rely on the correct spatial-temporal prediction of processes governing water and contaminant movement. The Soil and Water Assessment Tool (SWAT) model, one of the most commonly used watershed scale models, uses the popular Curve Number (CN) method to determine the respective amounts of infiltration and surface runoff. While appropriate for flood forecasting in temperate climates, the CN method has been shown to be less than ideal in many situations (e.g., monsoonal climates and areas dominated by variable source area hydrology). The CN model is based on the assumption that there is a unique relationship between the average moisture content and the CN for all hydrologic response units, and that the moisture content distribution is similar for each runoff event, which in many regions is not the case. A physically based water balance was developed and coded in the SWAT model to replace the CN method of runoff generation. To compare this new water balance SWAT (SWAT-WB) to the original CN based SWAT (SWAT-CN), two watersheds were initialized: one in the headwaters of the Blue Nile in Ethiopia and one in the Catskill Mountains of New York State. In the Ethiopian watershed streamflow predictions were significantly better using SWAT-WB than SWAT-CN (Nash-Sutcliffe efficiencies (NSE) of 0.76 and 0.67, respectively). In the temperate Catskills, SWAT- WB and SWAT-CN predictions were approximately equivalent (NSE>0.5). Interestingly, and perhaps more importantly, the spatial distribution of runoff generating areas differed greatly between the two models, with SWAT-WB providing a more realistic distribution of saturated and thus runoff source areas. These results suggest that the addition of a water balance in SWAT significantly improves model predictions in monsoonal climates, and provides equally acceptable levels of accuracy in stream flow prediction under temperate northeastern USA conditions. Spatially distributed watershed areas are predicted realisticly with SWAT-WB.
    Tenagne Addisu Wondie  The impact of urban storm water runoff and domestic waste effluent on water quality of Lake Tana and local groundwater near the city of Bahir Dar, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: In urban areas, the main task of town planners and engineers is providing drainage structures to prevent flooding. Recently the effect of these drainage structures on water quality has become a concern. However, little is known about the magnitude of the pollution. There fore the objective of this study is to characterize pollution loads from one Ethiopian urban area, Bahir Dar, on the southern end of Lake Tana which is experiencing dramatic expansion. In particular this research measured the quantity and quality of storm runoff and ground water. To determine the pollutant concentration and its effect on the quality of ground water, three shallow wells were installed. Urban storm water runoffs at six storm drains, which empty to Lake Tana, were instrumented for discharge and water quality measurements. The quality parameters considered were the total coliform, dissolved oxygen, total solids (TS), total suspended solids (TSS), biological and chemical oxygen demand (BOD/COD), total nitrogen (TN), total phosphorus (TP), pH, and conductivity. Three-rainfall event samples were taken in each month during rainy season (July, August, September and October) for a total of 9 rainfall events. Magnitude of pollutant load concentration flowing in to Lake Tana during low and high storm flow and contributions to groundwater were determined. In addition low flow characteristics (base flow) was determined once in a month. The results indicate that the water quality parameters like total nitrogen; total phosphorus and total suspended solids are found to be high with an average concentration load of 22.8mg/l, 0.46mg/l and 365mg/l respectively. The average concentration for dissolved solid, electric conductivity, dissolved oxygen COD, and total coliform are178mg/l, 338ì/cm, 2.8mg/l, and 3.28mg/l and169coli/100ml respectively. From the six sub watersheds assessed in this study, the sub watershed that drains the hotel discharge (station-5) had the elevated concentration for all pollutant except dissolved oxygen. All runoff concentration means found in this study area except the mean recorded for chemical oxygen demand, are higher than the means found in the data base for North American cities (CDM and NURP) and it shows that the Bahir Dar storm water runoff pollutant load is in excess of the North American cities. [[Ethiopia]]
    X. Xiong, F. Stagnitti, G. Allinson, N. Turoczy, P. Li, M. LeBlanc, M.A. Cann, S.H. Doerr, T.S. Steenhuis, J.Y. Parlange, G. de Rooij, C.J. Ritsema & L.W. Dekker  Effects of clay amendment on adsorption and desorption of copper in water repellent soils 2005 Australian J. of Soil Res.
    Vol. 43 , pp. 397-402 
    article URL   
    X. Xiong, F. Stagnitti, N. Turoczy, G. Allinson, P. Li, J. Nieber, T.S. Steenhuis, J.Y. Parlange, M. LeBlanc, A.K. Ziogas, A.J.D. Ferreira & J.J. Keizer  Competitive Sorption of Metals in Water Repellent Soils: Implications for Irrigation Recycled Water. 2005 Australian Journal of Soil Research
    Vol. 43(3) , pp. 351-356 
    article URL   
    T. Yao, J.Y. Parlange, T.S. Steenhuis & J.M.H. Hendrickx  Practical estimation of finger sizes for field application 1998 Water Resources Research   article   
    Assefa Derebe Zegeye  Assessment of upland erosion processes and farmer's perception of land conservation in Debre-Mewi watershed, near Lake Tana, Ethiopia 2009 School: Cornell University  mastersthesis URL   
    Abstract: Soil erosion is affecting global food security. Though it is a natural process, its rate has increased significantly during the last century mainly by human activity. Indeveloping countries in order to combat erosion, many soil and water conservation practices have been proposed but only a few, if any, are implemented by farmers on a long-term basis. Therefore, this study sets out to evaluate upland erosion and evaluate the effectiveness of practices used by farmers and the farmers’ perception about erosion and control practices and to identify factors affecting farmers’ land conservation decision-making processes. The watershed chosen was Debre-Mewi located south of Bahir Dar, 30 km from Lake Tana. In this study, the paper presents and discusses the results of the 15 surveyed agricultural fields and personal interview of 80 households conducted in the Debre Mewi watershed. To quantify the amount of soil loss due to rill erosion in the watershed, each rill’s dimensions were carefully measured to determine its volume and hence to obtain average magnitudes and rates of soil erosion for the fields. The result showed that the average soil loss in the surveyed fields was 36t/ha provided that the contribution of inter-rill erosion assumed to be 25% of the actual soil loss (taken from different literatures). Sediment measured from the control plot of AARC experimental station located within surveyed fields was estimated as 38.3 t/ha whereas using USLE model predicted 39 t/ha. Thus, all three methods gave similar results. The knowledge and perceptions of the farmers about erosion problems and mitigation measures, their reasons for not carrying out periodic maintenance and construction of new conservation measures and conservations practices that are widely used by the farmers are also discussed in this paper. [[Ethiopia]]
    Assefa Derebe Zegeye, T.S. Steenhuis, R.W. Blake, Selemyihun Kidnau, A.S. Collick & Farzad Dadgari  Assessment of Upland Erosion Processes and Farmer Perception of Land Conservation in Debre Mewi Watershed, near Lake Tana, Ethiopia 2011 Ecohydrology and Hydrobiology
    Vol. 10(2-4) , pp. 297-306 
    article DOI URL   
    Abstract: Erosion is of great concern in the Ethiopian highlands. The objective of this study was to determine the soil erosion rates under actual farming conditions by measuring the dimensions and number of rills in 15 agricultural fields in the Debre Mewi watershed near Lake Tana, and to understand farmers' attitudes towards land conservation through personal interviews with one-third of the watershed households. The annual rill erosion rate was 8 to 32 t ha-1. Greatest rates of erosion occurred at planting early in the season but became negligible in August. Major factors influencing land conservation decisions were the demand of labor and lack of technical support for implementing new conservation measures from experts.
    Assefa Derebe Zegeye, Tigist Yazie Tebebu, Anteneh Z. Abiy, H.E. Dahlke, E.D. White, A.S. Collick, Selemyihun Kidnau, Farzad Dadgari, M. McCartney & T.S. Steenhuis  Assessment of hydrological and landscape controls on gully formation and upland erosion near Lake Tana 2009 In: Seleshi B. Awulachew, T. Erkossa, V. Smakhtin & A. Fernando. Improved water and land management in the Ethiopian highlands: Its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia  inproceedings DOI URL   
    Abstract: Gully formation and upland erosion were studied in the Debre-Mewi Watershed in the
    Gilgil Abay Basin south of Lake Tana. Gully erosion rates were found to be equivalent to
    over 500 tonnes/ha/year for the 2008 rainy season when averaged over the contributing
    watershed. Upland erosion rates were twentyfold less. Gully formation is accelerated
    when the soils are saturated with water as indicated by water table readings above
    bottom of the gully. Similarly, upland erosion was accelerated when the fields were
    close to saturation during the occurrence of a rainfall event. Height of the water table
    is an important parameter determining the amount of erosion and should, therefore, be
    included in simulation models.
    Y. Zevi, A. Dathe, B. Gao, B.K. Richards & T.S. Steenhuis  Quantifying colloid retention in partially saturated porous media 2006 Water Resources Research
    Vol. 42 , pp. W12S03 
    article DOI URL   
    Y. Zevi, A. Dathe, B. Gao, W. Zhang, B.K. Richards & T.S. Steenhuis  Transport and retention of colloidal particles in partially saturated porous media: effect of ionic strength 2009 Water Resources Research
    Vol. 45 , pp. W12403 
    article DOI   
    Y. Zevi, A. Dathe, J.F. McCarthy, B.K. Richards & T.S. Steenhuis  Distribution of Colloid Particles onto Interfaces in Partially Saturated Sand 2005 Environ. Sci. Technol.
    Vol. 39 , pp. 7055-7064 
    article URL   
    Y. Zevi, B. Gao, W. Zhang, V.L. Morales, M.E. Cakmak, E.A. Medrano, W.J. Sang & T.S. Steenhuis  Colloid retention at the meniscus-wall contact line in an open microchannel 2012 Water Research
    Vol. 46 , pp. 295-306 
    article DOI   
    Abstract: Colloid retention mechanisms in partially saturated porous media are currently researched with an array of visualization techniques. These visualization techniques have refined our understanding of colloid movement and retention at the pore scale beyond what can be obtained from breakthrough experiments. One of the questions remaining is the mechanisms for colloid immobilization at the triple point where air, water, and grain meet. The objective of this study was to investigate how colloids are transported to the air-water-solid (AWS) contact line in an open triangular microchannel, and then retained as a function of meniscus contact angle with the wall and solution ionic strength. Colloid flow path, meniscus shape and contact angle, and colloid retention at the AWS contact line were visualized and quantified with a confocal microscope. Experimental results demonstrated that when the contact angle was less than 16 degrees, colloid retention at the contact line was significant; while for contact angles exceeding 20 degrees, retention of colloids was small. Tracing of individual colloids and computational hydrodynamic simulation both revealed that for small contact angles, counter flow and flow vortices formed near the AWS contact line, but not for large contact angles. This counter flow helped deliver the colloids to the wall just below the contact line. In accordance with DLVO and hydrodynamic torque calculations, colloid movement may be stopped when the colloid reached
    the secondary minimum at the wall near the contact line. However, contradictory to the prediction of the torque analysis, colloid retention at the contact line decreased with increasing ionic strength, indicating that the air-water interface was involved through both counter flow and capillary force. We hypothesize that capillary forces pushed the colloid through the energy barrier to the primary minimum when small fluctuations in water level stretched the meniscus over the colloid. For large contact angles counter flow was not observed resulting in lower colloid retention, because less colloid were transported to the contact line.
    W. Zhang, J.W. Faulkner, S.K. Giri, L.D. Geohring & T.S. Steenhuis  Evaluation of two Langmuir models for phosphorus sorption of phosphorus-enriched soils in New York for environmental applications 2009 Soil Sci.
    Vol. 174(10) , pp. 523-530 
    article URL   
    W. Zhang, S.K. Giri, L.D. Geohring & T.S. Steenhuis  Effect of soil reduction on phosphorous sorption of an organic-rich silt loam 2010 Soil Science Society of America Journal
    Vol. 74(1) , pp. 240-249 
    article DOI   
    W. Zhang, V.M. Morales, M.E. Cakmak, A.E. Salvucci, L.D. Geohring, A.G. Hay, J.Y. Parlange & T.S. Steenhuis  Colloid transport and retention in unsaturated porous media: Effect of colloid input concentration 2010 Environmental Sciencs and Technology
    Vol. 44 , pp. 4965-4972 
    article DOI   
    W. Zhang, J. Niu, V.L. Morales, X. Chen, A.G. Hay, J. Lehmann & T.S. Steenhuis  Transport and retention of biochar particles in porous media: Effect of pH, ionic strength, and particle size 2010 Ecohydrology
    Vol. 3 , pp. 497-508 
    article DOI   
    J.A. Zollweg, W.J. Gburek & T.S. Steenhuis  SMoRMod - A GIS-Integrated Rainfall-Runoff Model Applied to a Small Northeast U.S. Watershed. 1996 Trans. ASAE
    Vol. 39 , pp. 1299-1307 
    article   
    K.A.V. Zubris & B.K. Richards  Synthetic fibers as an indicator of land application of sludge 2005 Environmental Pollution
    Vol. 138 , pp. 201-211 
    article DOI   

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