Evaluation of the potential impact of Grand Ethiopian Renaissance Dam and pumping scenarios on groundwater level in the Nile Delta aquifer

Abstract

The main objective of this study is to evaluate the potential impact of Grand Ethiopian Renaissance Dam (GERD) and pumping scenarios on groundwater level by a three-dimensional groundwater model of the Nile Delta using MODFLOW software. The Nile Delta has highly intensive irrigation canal networks that share yearly about 35.5 km3 of water. In this study, an integrated three-dimensional groundwater model is built considering the actual condition of the irrigation canals and their recharges of the Nile Delta aquifer. The model was calibrated for estimating the vertical and hydraulic conductivity. The model was run for three scenarios: (1) reduction of water depth in canals, (2) increasing pumping discharge from the aquifer and (3) combination between the first and second scenarios. Results reveal that the effect of increasing the pumping discharge on groundwater level in the Nile Delta is more significant than decreasing the water depth of the canals network due to the fact of the existence of the upper clay layer which reduces the amount of water penetrating and reaching the groundwater in the aquifer. The last scenario presents the worst case as the average drawdown reached 1.26 m, 1.7 m and 1.35 m in the western, central and eastern parts of the Nile Delta respectively. The study results should be taken in account for studying the saltwater intrusion and climate change impacts on the Nile Delta region.