ASSESSMENT OF THE GROUNDWATER-BEARING FORMATIONS FOR SUSTAINABLE DEVELOPMENT IN WADI EL-ASYUTI, EASTERN DESERT, EGYPT

Demand of freshwater resources in arid regions is one of the significant problems that impede the sustainable development in Egypt due to increasing populations and limited water supplies. Wadi El-Asyuti drains westward along the eastern carbonate plateau in the Eastern Desert toward the Nile valley at Asyut city. This Wadi represents a promising area for development in Upper Egypt. In this region, the groundwater aquifers in Wadi El-Asyuti were evaluated in terms of hydrological setting and water quality. The studied water-bearing formations are classified into: Quaternary Aquifers; including the Middle-Upper Pleistocene Aquifer (60-160 m thickness) with high significant for exploitation and the Lower-Pleistocene Aquifer of secondly importance (100-260 m); the Eocene carbonate Aquifer (90 m); and pre-tertiary Nubian sandstone aquifer (475 m). The last two aquifers are unused in the region due to high salinity and great depth, respectively. The pumping tests were carried out on 51 water wells (27 step and 24 constant pumping) distributed along the downstream of the Wadi to estimate the hydraulic properties of the Quaternary Aquifers. The transmissivity, storativity, well losses, formation losses and well efficiency (%) at different pumping rates were calculated based on step drawdown tests. The analysis shows that approximately 720 m³/day pumping rate is suitable for sustainable use and good well efficiency ranges between 84 % - 93 %. The Isopiezometric contour map for the upper aquifer shows that the groundwater flow direction is to NW and W, with relatively uniform hydraulic gradient of 2 m /1 km. This indicates that the aquifer within this area discharges to the Nile. However, behind the Asyut Barrage the River Nile water flows laterally and recharges the aquifer. Hydrochemicaly, the salinity values increase toward NE and E directions near the carbonate plateau and decrease close to the River Nile. The quality of 34 groundwater samples was evaluated for its various potential usages according to national standards. The results demonstrate that the majority of water samples are less than the maximum permissible limits for human consumption, but are useable for irrigation, livestock and industrial uses that are essential for development projects in Wadi El-Asyuti.