Population growth in the Blue Nile Basin has led to fast land-use changes from forest to agricultural land, which resulted in speeding up the soil erosion processes producing highly negative impacts on the local soil fertility and agricultural productivity. The eroded sediment is transported downstream by water and sinks in the lower basin where it significantly reduces reservoir storage and irrigation canals capacity. The only effective solution to mitigate the sedimentation problem is to limit the sediment inputs from upstream by locally implementing erosion control practices. However, given the vastness and remoteness of the involved areas, this first requires the knowledge of the most critical zones. The book identifies the sources of the sediment depositing in the Lower Blue Nile Basin and quantifies the amounts involved providing essential information for the planning and implementation of any interventions aiming at reducing soil erosion. The methods used consist of extensive field work covering most of the basin, watershed, hydrodynamic and morphodynamic modelling and, for the first time, the mineralogical analysis of the sediment at the sources and sinks. The method is successful in indentifying the areas providing most of the transported sediment, where it is recommended to start with erosion control practices.

This study assessed the downstream river system adaptation in response to upstream damming on the Ribb River, Ethiopia, to irrigate 15,000 ha. It combined primary and secondary data, and the application of remote sensing and mathematical modeling. The pre-dam morphodynamic trends of the Ribb River were analyzed for 59 years based on aerial photographs, satellite images, and newly collected field data. Three dam operation scenarios were developed to analyze the long-term hydro-morphological effects of the dam on the downstream river reaches. It also assessed the applicability of physics-based analytical equations (Equilibrium Theory) compared to a 1D numerical model (SOBEK-RE) to determine the least-morphologically impactful dam operation scenario on the river reaches downstream of the dam. Moreover, a HEC-RAS 2D hydrodynamic model was developed to assess the effect of the dam on the flooding extent of the Fogera Plain. This was used to study the potential implications of hydrological alteration on the ecology of the floodplain wetlands, as they are the habitats of important fish and bird species. The results contribute to knowledge on the hydro-morphological and environmental impacts of dams on downstream river systems. The developed methodologies and findings may be used to study future hydro-morphological and ecological changes that may arise due to other dam operations or climate change.

The book provides a comprehensive overview of the hydrology of the Nile River, especially the ecohydrological degradation and challenges the basin is facing, the impact of climate change on water availability and the transboundary water management issues. The book includes analysis and approaches that will help provide different insights into the hydrology of this complex basin, which covers 11 countries and is home to over 300 million people. The need for water-sharing agreements that reflect the current situations of riparian countries and are based on equitable water- sharing principles is stressed in many chapters. This book explores water resource availability and quality and their trends in the basin, soil erosion and watershed degradation at different scales, water and health, land use and climate change impact, transboundary issues and water management, dams, reservoirs and lakes. The link between watershed and river water quantity and quality is discussed pointing out the importance of watershed protection for better water resource management, water accessibility, institutional set-up and policy, water demand and management. The book also presents the water sharing sticking points in relation to historical treaties and the emerging water demands of the upstream riparian countries. The need for collaboration and identification of common ground to resolve the transboundary water management issues and secure a win-win is also indicated. "

The Universal Soil Loss Equation (USLE) enables planners to predict the average rate of soil erosion for each feasible alternative combination of crop system and management practices in association with a specified soil type, rainfall pattern, and topography. When these predicted losses are compared with given soil loss tolerances, they provide specific guidelines for effecting erosion control within specified limits. The equation groups the numerous interrelated physical and management parameters that influence erosion rate under six major factors whose site-specific values can be expressed numerically. A half century of erosion research in many States has supplied information from which at least approximate values of the USLE factors can be obtained for specified farm fields or other small erosion prone areas throughout the United States. Tables and charts presented in this handbook make this information readily available for field use. Significant limitations in the available data are identified.

This proceeding provides the papers and discussion results of a two-day workshop that was organized at International Water Management Institute (IWMI) office in Addis Ababa during the period of February 6-8, 2009 in relation to CPWF Project 19 – Improved water and land management in the Ethiopian Highlands and its impact on downstream stakeholders dependent on the Blue Nile. Short title: Upstream Downstream (USDS) in the Nile. The project is being under implementation during the last one and half years in partnership with various institutions that include International Livestock Research Institute, Cornell University, Omdurman Islamic University-UNESCO Chair in Water Resources, Addis Ababa University, Bahir Dar University, Amhara Regional Agricultural Research Institute and Forum for Social Studies. The main aims of the workshop had been: Bring together key stakeholders relevant to the project; Present, debate and validate the intermediate results of the project; Disseminate key results to wider audiences through workshop participating stakeholders; Follow up on the progress of the project and plan remaining tasks of the project. The workshop focus themes were: General characterization of the Blue Nile Basin; Watershed modeling and analysis; Water demand and allocation modeling and simulation; Policy and institutions of the water management in the Blue Nile basin.

The Eastern Nile riparian countries Egypt, Ethiopia and Sudan are currently developing several reservoir projects to contribute to the needs for energy and food production in the region. The Nile Basin, particularly the Eastern Nile Sub-basin, is considered one of a few international river systems with potential conflicts between riparian countries. In the absence of formal mechanisms for collaboration, the transboundary nature of this basin makes sound water resources development challenging. The large seasonal and inter-annual variability of the river flow exacerbates those challenges. A further complication is the high sediment load in the Eastern Nile rivers during the high flow season. This study contributes to fill relevant knowledge gaps through a better understanding of the methods needed for a complex system of multipurpose reservoirs, considering both water quantity and sediment load. The study quantifies the impacts of water resources development in the Eastern Nile basin and identifies system management options at both regional and country level. Developing a collaborative and unified perspective of the countries towards new projects can be beneficial for all. New operation rules are proposed for improving operation of the current system when new infrastructures are developed and operated either unilaterally or, ideally, cooperatively.

Climate and anthropogenic changes impact the conditions of erosion and sediment transport in rivers. Rainfall variability and, in many places, the increase of rainfall intensity have a direct impact on rainfall erosivity. Increasing changes in demography have led to the acceleration of land cover changes in natural areas, as well as in cultivated areas, and, sometimes, in degraded areas and desertified landscapes. These anthropogenized landscapes are more sensitive to erosion. On the other hand, the increase in the number of dams in watersheds traps a great portion of sediment fluxes, which do not reach the sea in the same amount, nor at the same quality, with consequences on coastal geomorphodynamics. This book is dedicated to studies on sediment fluxes from continental areas to coastal areas, as well as observation, modeling, and impact analysis at different scales from watershed slopes to the outputs of large river basins. This book is concentrated on a number of keywords: “erosion” and “sediment transport”, “model” and “practice”, and “change”. The keywords are briefly discussed with respect to the relevant literature. The contributions in this book address observations and models based on laboratory and field data, allowing researchers to make use of such resources in practice under changing conditions.

Despite the mechanisms of reservoir sedimentation being well known for a long time, sustainable and preventive measures are rarely taken into consideration in the design of new reservoirs. To avoid operational problems of powerhouses, sedimentation is often treated for existing reservoirs with measures which are efficient only for a limited time.Th

This unique volume discusses various aspects of the Grand Ethiopian Renaissance Dam (GERD) and the Aswan High Dam (AHD) including their positive and negative impacts. It presents up-to-date research findings by Egyptian scientists and researchers covering several interesting hot topics under the following main themes: · Major impacts of GERD compared with the AHD · Environmental impacts of the AHD · Modeling scenarios investigating the impacts of GERD on the AHD and downstream · Environmental and social impacts of GERD on Egypt · Status and assessment of the sediment of the AHD reservoir and modeling the impacts of GERD on Lake Nubia sediment accumulation · Proposed scenarios for maximizing the benefits of the AHD reservoir · International aspects of GERD and the AHD The volume also offers a set of conclusions and recommendations to optimize the cooperation between Egypt, Sudan, and Ethiopia. It appeals to postgraduate students, researchers, scientists, professionals and policy planners.

The Nile is the world's longest river and sustains the livelihoods of millions of people across ten countries in Africa. This book provides unique and up-to-date insights on agriculture, water resources, governance, poverty, productivity, upstream-downstream linkages, innovations, future plans and their implications.