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.

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.

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.

This book is a social—ecological system description and feedback analysis of the Lake Tana Basin, the headwater catchment of the Upper Blue Nile River. This basin is an important local, national, and international resource, and concern about its sustainable development is growing at many levels. Lake Tana Basin outflows of water, sediments, nutrients, and contaminants affect water that flows downstream in the Blue Nile across international boundaries into the Nile River; the lake and surrounding land have recently been proposed as a UNESCO Biosphere Reserve; the basin has been designated as a key national economic growth corridor in the Ethiopian Growth and Transformation Plan. In spite of the Lake Tana Basin’s importance, there is no comprehensive, integrated, system-wide description of its characteristics and dynamics that can serve as a basis for its sustainable development. This book presents both the social and ecological characteristics of the region and an integrated, system-wide perspective of the feedback links that shape social and ecological change in the basin. Finally, it summarizes key research needs for sustainable development.

Lake Tana, located in the headwaters of the Blue Nile, is valuable for many people including the communities who live around the lakeshore and those who live immediately downstream. The area has been identified as a region for hydropower and irrigation development, vital for economic growth in Ethiopia. A multidisciplinary study was conducted to assess the possible impacts of this development. This study found that current development has benefited some local people but adversely affected others. Future development will exacerbate pressure on the lake. Hard choices must be made about how the water is best utilized. It is important that all stakeholders, including local people, are involved in the decision-making process.

The Nile River Basin supports the livelihoods of millions of people in Egypt, Ethiopia, Sudan and Uganda, principally as water for agriculture and hydropower. The resource is the focus of much contested development, not only between upstream and downstream neighbours, but also from countries outside the region. This book investigates the water, land and energy nexus in the Nile Basin. It explains how the current surge in land and energy investments, both by foreign actors as well as domestic investors, affects already strained transboundary relations in the region and how investments are intertwined within wider contexts of Nile Basin history, politics and economy. Overall, the book presents a range of perspectives, drawing on political science, international relations theory, sociology, history and political ecology.

Extreme Hydrology and Climate Variability: Monitoring, Modelling, Adaptation and Mitigation is a compilation of contributions by experts from around the world who discuss extreme hydrology topics, from monitoring, to modeling and management. With extreme climatic and hydrologic events becoming so frequent, this book is a critical source, adding knowledge to the science of extreme hydrology. Topics covered include hydrometeorology monitoring, climate variability and trends, hydrological variability and trends, landscape dynamics, droughts, flood processes, and extreme events management, adaptation and mitigation. Each of the book's chapters provide background and theoretical foundations followed by approaches used and results of the applied studies. This book will be highly used by water resource managers and extreme event researchers who are interested in understanding the processes and teleconnectivity of large-scale climate dynamics and extreme events, predictability, simulation and intervention measures. - Presents datasets used and methods followed to support the findings included, allowing readers to follow these steps in their own research - Provides variable methodological approaches, thus giving the reader multiple hydrological modeling information to use in their work - Includes a variety of case studies, thus making the context of the book relatable to everyday working situations for those studying extreme hydrology - Discusses extreme event management, including adaption and mitigation