Potential ground-water resources and decrease in natural flow of wells in Dakhla Oases, Western Desert, Egypt

摘要

The Nubian Aquifer System is the primary aquifer in the Western Desert of Egypt. The Dakhla Oases are among five other oases relying on this aquifer as the only source of water. The water-bearing layers are mainly porous Cretaceous sandstones overlain by predominantly marine shales and clays of Late Cretaceous to Lower Paleocene age. Ground water occurs under artesian conditions causing the wells to flow freely for both human and agricultural needs. The present annual ground-water discharge in Dakhla is 2.09 x 10⁸ cubic meters. The natural movement of ground water into the Dakhla area is negligible in terms of recharge to the artesian zones. A review of previous investigations indicated a projected drawdown of up to 75 meters by the year 2025. Extensive extraction from the deep layers has led to a decrease in the piezometric pressure, causing vertical flow from the upper layers. The decrease in natural flow of the artesian wells is due to this decline in natural pressure. Egypt is in great need of its ground-water supply. In the context of population growth and greater demands for water, the value of water in Egypt will rise in the near future particularly in response to the imminent threat of African drought.