Evaluation of the potential impact of Grand Ethiopian Renaissance Dam and pumping scenarios on groundwater level in the Nile Delta aquifer Asaad M. Armanuos, Mona G. Ibrahim, Wael Elham Mahmod, Abdelazim Negm, C. Yoshimura, Jiro Takemura and Bakenaz A. Zidan 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 km 3 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 rst and second scenarios. Results reveal that the effect of increasing the pumping discharge on groundwater level in the Nile Delta is more signicant 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. Asaad M. Armanuos (corresponding author) Egypt-Japan University of Science and Technology, Alexandria, Egypt Tanta University and Tokyo Institute of Technology, Tokyo, Japan E-mail: asaad.matter@ejust.edu.eg; armanuos.a.aa@m.titech.ac.jp Mona G. Ibrahim Egypt-Japan University of Science and Technology, Alexandria, Egypt and Environmental Health Department, High Institute of Public Health, Alexandria University, Alexandria, Egypt Wael Elham Mahmod Egypt-Japan University of Science and Technology, Alexandria, Egypt and Civil Engineering Department, Faculty of Engineering, Assiut University Assiut, Egypt Abdelazim Negm Faculty of Engineering, Zagazig University, Zagazig, Egypt C. Yoshimura Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1Oookayama, Meguro, Tokyo 152-0033, Japan Jiro Takemura Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1 Oookayama, Meguro, Tokyo 152-8552, Japan Bakenaz A. Zidan Faculty of Engineering, Tanta University, Tanta, Egypt Key words | GERD, groundwater, irrigation canal networks, Nile Delta aquifer, recharge INTRODUCTION The Nile Delta receives almost 35.5 km 3 /year of the surface water from the Nile River. This also recharges the aquifer through the inltration of excess irrigation water and see- page from canals (Anon ; Shahein ; Kashef ), which is the main source of recharge for the Nile Delta aquifer (Wahaab & Badawy ; El Ramly ). Accord- ing to El Ramly (), the rate of groundwater recharge from the excess irrigation water ranges from 0.25 to 1.1 mm/day. The agricultural recharge to the Quaternary aquifer ranges from 0.8 to 1.1 mm/day for old lands and 1356 © IWA Publishing 2017 Water Science & Technology: Water Supply | 17.5 | 2017 doi: 10.2166/ws.2017.037 Downloaded from https://iwaponline.com/ws/article-pdf/17/5/1356/409364/ws017051356.pdf by guest on 14 June 2020