Ecohydrogeology provides detailed instructions among water (surface or groundwater), geology, environment, and biological processes to improve water security. Ecohydrogeological challenges are dominant in the territory of Ethiopia. According to the 1959 treaty with Sudan, the annual water share of Egypt is 55.5 km3.
The main controlling factor on water resources in East Africa is the East African Rift that is the largest continental rift on Earth, resulting in crustal mobility between the Arabian and African plates. Ethiopia is characterized by rugged topography, a unique regime of the short intense rainy season, high evaporation, flooding, drought, dominant basaltic rocks, an abundance of geologic faults and fractures, active volcanic eruptions and earthquakes, severe erosion and land degradation, siltation, and lack of major groundwater aquifers.
The Nile basin countries suffer from lack of electrical energy. By the end of the last twentieth century and the beginning of the new twenty-first century, the demand for hydropower energy has been increased for development in the Nile basin countries especially Ethiopia, resulting in political tension between the upstream and downstream countries.
Egypt has almost completely relied on the Nile River water for irrigation since the pharaohs. The Egyptian government signed about 15 agreements with some Nile basin countries for utilization of the Nile water. The construction of water projects in the Nile basin region in Ethiopia has produced political tensions between Egypt and Ethiopia over the construction of Tekeze in 2009, the Tana-Beles diversion in 2010, and the under-construction Grand Ethiopian Renaissance Dam (GERD) that has started in April 2011.
The present chapter deals with the geological characteristics of the Nile region in Ethiopia. It also discusses the environmental challenges in the region of Tekeze River (Atbara) in Ethiopia and its impacts on downstream countries Egypt and Sudan. Analysis of ASTER DEM of Tekeze River basin showed that it has a dendritic pattern. Tekeze reservoir area is 155 km2 at 1,140 m asl with a volume of 9.3 km3. Egypt and Sudan lost 4 km3 in 2008 and 2009 due to dead storage in addition to an annual loss estimated at 200–700 Mm3 from evaporation and irrigation.