The Nile Basin Development Challenge (NBDC) is one of six global focal basins of the Challenge Program on Water and Food (CPWF). The overall objective of the CPWF program is to increase water productivity and resilience of social and ecological systems, through broad partnerships and research that leads to local impact and wider change.
Within this framework, the NBDC has set out to improve and build on rainwater management strategies as a way to improve livelihoods and reduce poverty. The focus of the work has been on the Blue Nile where rainfed agriculture dominates and over 80% of the population relies on subsistence, rainfed agriculture. In contrast, the downstream countries, principally Egypt and Sudan, are dominated by large-scale irrigated agriculture. However they will also potentially benefit from improvements in rainwater management upstream through reductions in land degradation and associated soil erosion which when transported downstream reduces the efficacy of irrigation schemes.

To meet the Nile Basin Development Challenge, it was found necessary to adopt an outcome logic model in which a range of approaches have been used to generate outputs and outcomes to support policy development and enhance best practices in relation to selected land management. These are briefly presented in summary here with subsequent papers in the proceedings developing the issues in greater a depth.

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This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

In the Blue Nile basin, crop cultivation is predominantly rainfed and water availability is highly variable across both space and time. As a result, it often constitutes a limiting factor for reaching full agricultural potential in the region. While one third of the basin is estimated to have no soil moisture limitations, the remaining two thirds are crop water constrained in various ways.

Analysis shows that across approximately 40% of the basin available soil moisture is utilized sub-optimally with smart management and crop water limitations can be alleviated. In contrast, across a further 25% of the basin, water deficits strongly limit plant growth. While rainfed agriculture is still possible in some of these areas, appropriate management is even more important. A great deal of variation also exists in terms of market access for agricultural inputs and produce.

Travel time to markets in the basin can be up to 12 hours. One’s distance to market centres influences the accessibility of farm inputs such as fertilizers, improved seeds and veterinary services. Inaccessibility vs. accessibility to population dense areas also determines the potential for agricultural production and the marketing of crops and livestock products, in particular for perishable produce.

To capture the complexity and heterogeneity regarding both crop water limitations and agricultural market access, this study combines information on rainwater management potential and market proximity to map so-called water investment domains (WID). Context-specific recommendations for each of the domains are provided.

In the short term, the results point to a need for agricultural produce strategies that are spatially differentiated and in the longer term for investment in infrastructure in order to enable full utilization of the agricultural potential across the entire basin. The results are intended to guide policymakers and other rural development actors in the identification of appropriate investment decisions and for improved planning of rural development strategies. Thus, the study aligns to the ‘water-centred agricultural growth’ strategy adopted by the Ethiopian Government, developed in response to the poverty and food security challenges faced in the country.

The approach is widely applicable, easily replicable and can be used to inform decision-makers beyond the Blue Nile basin.

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See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

Restrictive soil layers commonly known as hardpans restrict water and airflow in the soil profile and impede plant root growth below the plough 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.

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See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

Poor rainwater management (RWM) practices and resultant problems of land degradation and low water productivity are severe problems in the rural highlands of Ethiopia.

The current study was undertaken at Meja watershed, which is located in the Jeldu district of Oromia region. The study investigated rainwater management practices and associated socio-economic and biophysical conditions in the watershed. The existing RWM interventions, their extent and the nature of changes in land use and land cover (LULC) conditions were mapped and evaluated.

Results indicated that over the two decades between 1990 and 2010 there was an increase in the extent of cultivated land and large expansion in eucalyptus plantation at the expense of natural forest and grazing lands. Results indicate that, with few exceptions of RWM interventions practised, there were mainly poor and inefficient rainwater management practices. The overall effect leads to inadequacy of water for household consumption, livestock and for intensifying agricultural production via small scale irrigation systems. Deforestation and poor resource management resulted in soil degradation, reduction of hydrological regimes and water productivities in the watershed.

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See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

Considering that agriculture remains a key sector in Ethiopia, commercialization of the sector necessitates improving participation of smallholder farmers in markets, hence improving their incomes and livelihoods.

Promoting smallholder commercialization through cash crop production is one avenue of such efforts. The main argument for smallholder commercialization through cash crop production is that it can allow households to increase their income directly. Sesame in Ethiopia can be taken as a good example in this regard. Although Diga has a potential land and the area is among the few areas which are agro-ecologically suitable for sesame production and productivity in the country, smallholder farmers are not participating actively in its production (constrained by a number of factors).

This study assesses factors determining smallholders’ participation in sesame production in Diga, West Ethiopia. Using structured questionnaires, the data was collected from a random sample of 120 smallholder farmers and analysed by using a double hurdle approach.

After all, this study highlighted that access to credit, farm landholding size, family labour, household assets (oxen, donkey), access to family food for the whole year and proximity to extension service centres significantly influence smallholders’ decision probability of participating in sesame production. On the other hand, access to credit, number of oxen owned and number of active family labour significantly determine the level of smallholders’ participation in sesame production.

The implication is that production potential due to favourable agro-ecological condition is necessary but not sufficient for smallholder farmers to participation in sesame production. Indicating household specific and institutional factors also influence their decision. Thus, if active participation of smallholder farmer is required in the field, institutional innovations should be developed and strengthened—in a way to involve all smallholder farmers.

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See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

The hydrology of Holetta River and its seasonal variability is not fully studied. In addition to this, due to scarcity of the available surface water and increase in water demand for irrigation, the major users of the river are facing a challenge to allocate the available water.

Therefore, the aim of this research was to investigate the water availability of Holetta River and to study the water management in the catchment. Soil and Water Assessment Tool (SWAT) modelled the rainfall runoff process of the catchment. Statistical (coefficient of determination [R2], Nash- Sutcliffe Efficiency Coefficient [NSE] and Index of Volumetric Fit [IVF]) and graphical methods used to evaluate the performance of SWAT model.

The result showed that R2, NSE and IVF were 0.85, 0.84 and 102.8, respectively for monthly calibration and 0.73, 0.67 and 108.9, respectively, for monthly validation. These indicated that SWAT model performed well for simulation of the hydrology of the watershed. After modelling the rainfall runoff relation and studying the availability of water at the Holetta River, the water demand of the area assessed. CropWat model and the survey analysis performed to calculate the water demand in the area. The total water demand of all three major users was 0.313, 0.583, 1.004, 0.873 and 0.341 MCM from January to May, respectively. The available river flow from January to May obtained from the result of SWAT simulation. The average flow was 0.749, 0.419, 0.829, 0.623 and 0.471 MCM from January to May respectively. From the five months, the demand and the supply showed a gap during February, March and April with 0.59 MCM.

Therefore, in order to solve this problem alternative source of water supply should be studied and integrated water management system should be implemented.

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Read the paper

See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.

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 costs.

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 1980s 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 require reshaping 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.

Read the paper

See the full proceedings of the NBDC Science meeting


This paper was first presented at the Nile Basin Development Challenge Science meeting. The NBDC Science meeting was held on 9 and 10 July 2013 at the ILRI-Ethiopia campus, with the objectives to exchange experiences and research results across NBDC scientists involved in the NBDC projects and to discuss challenges and possible solutions.