Environmental Impacts of the GERD Project on Egypt’s Aswan High Dam Lake and Mitigation and Adaptation Options

Abstract

Egypt, which suffers from water scarcity, has been listed among the ten top countries that are threatened due to the rapidly increasing population. With growing concerns about climate change and possible impacts on water shortage, human intrusion and development processes have had undeniable adverse impacts on maintaining healthy lakes. Aswan High Dam (AHD) Lake is considered a source of water to minimize the water scarcity problem. Lake Nasser is facing many challenges. One of these challenges is the Grand Ethiopian Renaissance Dam (GERD). GERD is now under construction on the Blue Nile River in Ethiopia. The question still to answer is “will the GERD affect Lake Nasser?” This chapter focuses on two objectives: first is to evaluate the land resources of Lake Nasser and second is to study the impact of GERD on AHD Lake. The challenges facing the sustainable development of AHD lake and their solutions are identified and discussed. First, soils surrounding Lake Nasser, i.e., Kalabsha, Toshka, El- Dakka, Abu Simbel at the western side of the lake, and Allaqui area on the eastern side, were deposited due to water action (wind action was not evaluated in this study). Wadi soils are heterogeneous and stratified and composed of subrounded grains; this may be linked to the distance of transportation. The parent materials of these soils are wadi sediments, shales, and Nubian sandstones. Sedimentation in Lake Nasser is estimated to be around 31 billion cubic meters, which is enough to be absorbed over 300–400 years. The silt is not regularly distributed on the lake floor but is mostly accumulating (more than 30 m in 1992) at the site of the second waterfall around the ancient city of Wadi Halfa. The amount of silt deposited is estimated as 109 million cubic meters per year. The sedimentation of silt can lead to the blockage of a large part of Nasser’s Lake around the second waterfall at Wadi Halfa. This may result in a significant loss of water due to evaporation and leakage. Because the Lake Nasser reservoir is approaching its maximum storage capacity, the depressions west of Lake Nasser in the southwestern desert of Egypt (Toshka Lakes) are a natural flood diversion basin to reduce possible downstream damage to the Nile Valley caused by exceptional flooding. Second, the impacts of GERD on AHD are a reduction in the water share to Egypt, reduction in power generated at AHD, increased salinity of Egypt’s agricultural lands, increase in seawater intrusion, and infilling Lake Nasser/Lake Nubia with sediment. Since this chapter aims to suggest some measures to help the decision/policy makers to solve the water shortage problem caused by GERD, a number of management actions and strategies are suggested to secure Egypt’s water demands and to minimize the water scarcity problems. Third, the actions identified to minimize the water scarcity in Egypt are reducing evaporation losses from Lake Nasser, maximizing the use of groundwater wells and rainwater in Egypt, seawater desalination, sewage treatment and reusing irrigation water, maximizing water use efficiency, and starting giant projects out of the narrow valley and delta. The yearly average of the daily evaporation rate from Lake Nasser is 6.3 mm day−1. The average volume of the annual water loss by evaporation is about 12.5 milliards cubic meter. To save more than 1 million cubic meters of water loss from Lake Nasser due to evaporation, 0.500 km2 must be covered with circular foam sheets with an efficiency of coverage equal to 90%. The circular foam system can be adjusted such that it has no impact on the passage of sunlight to aquatic life. The expected total amount of saved water using all the above strategies equals 40 BCM, which exceeds the expected losses caused by GERD. Adopting all or a combination of the suggested management actions and strategies could help reduce the impact of GERD on Egypt.