Soil and Water Lab 
International Research 
   

 


Cornell's Master of Professional Study Program in Integrated Watershed Management and Hydrology at Bahir Dar University, Ethiopia

Master Theses


Aschalew Demeke:

Determination of household participation in water source management: Achefer, Amhara region, Ethiopia.

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. Full thesis.


Assefa Derebe Zegeye:

Assessment of upland erosion processes and farmer's perception of land conservation in Debre-Mewi watershed, near Lake Tana, Ethiopia.

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. Full thesis.


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.

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. Full thesis.


Zelalem Kassahun Tesemma:

Long term hydrologic trends in the Nile bsain.

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. Full thesis.


Tigist Yazie Tebebu:

Assessment of hydrological controls on gully formation near Lake Tana, northern Higlands of Ethiopia.

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) Full thesis.


Tilashwork Chanie Alemie:

The effect of Eucalyptus on crop productivity, and soil properties in the Koga watershed, western Amhara region, Ethiopia.

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. Full thesis.


Tegenu Ashagrie Engda:

Modeling rainfall, runoff and soil loss relationships in the northeastern Highlands of Ethiopia, Andit Tid watershed.

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. Full thesis.

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.

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. Full thesis.

Tegegne M. Tarekegne:

Sustainability of rural water supply and sanitation services in Ethiopia: A case study of twenty villages in Ethiopia.

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. Full thesis.

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 Ehtiopia.

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. Full thesis.

Elias Sime Legesse:

Modeling Rainfall-Runoff relationships for the Anjeni watershed in the Blue Nile Basin.

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. Full thesis.

Abrham Melesse Endalamaw:

Optimum utilization of ground water in Kobo valley, Eastern Amhara, Ethiopia.

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. Full thesis.

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.

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. Full thesis.

Biniam Biruk Ashagre:

SWAT to identify watershed management options: (Anjeni watershed, Blue Nile basin, Ethiopia).

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. Full thesis.

Fikru Assefa Mengstie:

Assessment of adoption behavior of soil ad water conservation practices in the Koga watershed, Highlands of Ethiopia.

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. Full thesis.

Yidnekachew Ewnetu Ayalew:

Irrigation, Food Production and Consumption Pattern in Smallholder Rural Households.

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. Full thesis.

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.

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. Full thesis.

 
 
 

© 2009. Soil and Water Laboratory. All rights reserved.
The URL of this website is: http://soilandwater.bee.cornell.edu/