Management of Egypt’s Surface and Groundwater Resources: Present and Future

Abstract:

The River Nile is the main source of fresh water in Egypt. Most of Egypt’s River Nile water (>85%) originates as precipitation over the Ethiopian highlands and is channeled by the Blue Nile. The construction (years: 2011 to 2017) of the Renaissance Dam (reservoir capacity: 70 x 10⁹m³) on the Blue Nile poses an extreme threat to Egypt’s population. If the reservoir was to be filled in 7 years, Egypt will lose (during each of 7 years following dam completion) a minimum of 15 x 10⁹m³ of its annual allocation (55 x 10⁹m³) to reservoir filling (10 x 10⁹m³), evaporation (3.5 x 10⁹m³), and infiltration (1.5 x 10⁹m³). Three solutions are proposed: Solution I takes advantage of the cyclicity of Nile floods and is based on findings from a calibrated (against temporal head data) unconfined 2-dimensional transient groundwater flow model for Lake Nasser and surroundings and a calibrated (against lake levels) surface water model. Models show with time: (1) losses to infiltration will decrease (1975-193: 58.4 10⁹m³; 1993-2001: 43.6 x 10⁹m³) due to silting of Lake bottom and encroachment of excess Lake Nasser water will increase (e.g., 1975-1993: none; 1993-2001: 17 x 10⁹m³). We propose to develop sustainable agricultural in the Western Desert: (1) In high flood years, excess Lake Nasser water (e.g., 1993-2001: 17 x 10⁹m³) is channeled across the plateau bounding (from west) the River Nile valley to artificially recharge the Nubian Sandstone Aquifer System (NSAS) that crops out west of the plateau and, (2) in low flood years, we extract the recharged groundwater. Solution II calls on mining the NSAS at reasonable rates. Using temporal (January 2003 – September 2012) Gravity Recovery and Climate Experiment (GRACE) data we estimate the annual depletion rates at 2 x 10⁹m³ due to artificial extraction (1.5 x 10⁹m³) and natural discharge (0.5 x 10⁹m³). Assuming current GRACE depletion rates, the recoverable groundwater (5,180 x 10⁹m³) will last for 2500 years; if we were to quadruple the artificial extraction rates (6 x 10⁹m³), the reservoir will last for some 800 years. Solution III calls on the sustainable utilization of the NSAS groundwater in Sinai that receives an estimated minimum annual modern recharge of 13 x 10⁶m³. Currently, these waters are lost as discharge in water bodies and/or diverted across political boundaries by major NE trending fault systems.