Geomatics-Based Framework for Assessing Environmental Impacts of Grand Ethiopian Renaissance Dam (GERD) Reservoir

Despite the benefits of big project dams, their reservoirs may have significant environmental impacts. The main objective of this paper is to develop an integrated analysis framework of remotely-sensed data ad GIS techniques for delineating surface area of the dam reservoir, simulating their capacities and assessing associated environmental impacts with application to Grand Ethiopian Renaissance Dam (GERD). For this purpose, a methodology of four main steps was applied. The methodology involved delineating the up-to-date reservoir using remotely sensed data, simulating reservoir at full capacity, estimating current and potential reservoir capacity and finally assessing environmental impacts of the reservoir. The results revealed that the up-to-date reservoir covers a total area of 330.3 km2 with a gross storage capacity of 12 billion m3. Under full capacity scenario, the reservoir is estimated to cover a total area of 1650.9 km2, with a storage capacity of 63.4 billion m3. The GERD reservoir may lead to dramatic changes in the local environment with significant implications at both regional and global scales. In this respect, it was found that the reservoir will lead to destruction of ecosystems in a total area of 1300 km2 covered by grasslands and Savannah. Also, the GERD reservoir is expected to have significant impacts on GHGs emissions and global warming. Moreover, a massive quantity of water is expected to be lost by surface evaporation.