New approach in sustainable development based on groundwater resources, Wadi Dara, Eastern Desert, Egypt

The Quaternary alluvial, Miocene sandstone and Lower Cretaceous sandstone aquifers represent the main source of water in Wadi Dara basin. The three aquifers are hydraulically connected through faults. The groundwater of the Quaternary aquifer is saline and exists at great depths from the ground surface, while the other two aquifers are between brackish to slightly saline and occur at relatively shallow depths. The groundwater salinity of the Quaternary aquifer varies from 4171 to 21,124 mg/l. The groundwater salinity of the Miocene aquifer varies from 6512 to 10,088 mg/l. The Lower Cretaceous aquifer represents the main source of water in the study area, its thickness ranges from 150 to about 450 m, and the groundwater salinity ranges from 2094 to 4380 mg/l. The hydrochemical results, application of inverse geochemical model in addition to the obtained water quality indices were used to recognize the source of groundwater salinization in the investigated area. The variation of groundwater salinities among the three investigated aquifers are mainly attributed to the nature of the aquifer matrix (lithofacies) as well as the recharging sources. The detected hypothetical salts reflect meteoric water origin (affected by leaching and dissolution of terrestrial salts) and paleo-water origin of the mature stage of chemical evolution. The chemical similarity between the three aquifers supports the presence of the hydraulic connection between them, and Quaternary alluvial aquifer at the downstream portion of Wadi Dara is influenced by seawater intrusion. The groundwater chemistry is mainly affected by the evaporation process during surface runoff and partially by the rock–water interaction. Carbonate, halite and sulfate minerals represent the main sources of salinity (mineralization) due to the leaching and dissolution processes. The quality of the investigated groundwater for the three aquifers is unsuitable for drinking purpose; only the groundwater of the Lower Cretaceous sandstone aquifer is suitable for irrigation with respect to salt-tolerant plants. Finally, some recommendations are given to develop the investigated area.