Vertical Electrical Soundings And Hydrochemical Studies For Groundwater Investigations, At Matrouh And Nigella Basins, Northwestern Coast, Egypt

The fast growing development in Egypt has required big movements of investments and people from the Nile Valley towards the North Western Coast of Mediterranean Sea. A hydrochemical and geoelectrical investigation was conducted in the matrouh-negilla area in the northwestern coast of Egypt to investigate and find out the groundwater aquifer, its extension, depth and thickness. Also, chemical analysis was used to evaluate the chemical characteristics of groundwater and assessment of water quality. Twelve profile of vertical electric sounding were conducted to examine the variations of subsurface geology and associated groundwater chemistry. Results of VES interpretation classified the subsurface sequence of oolitic limestone aquifer into four geoelectric zones, top surface, oolitic limestone, intercalation with clay, fracture limestone, and limestone with saline water. The fracture limestone constitutes the upper aquifer and Limestone with saline water is considered as the lower aquifer. The groundwater reserves in the study area are mainly contained in oolitic limestone and Miocene aquifers. About 42 water samples representing both the Pleistocene Oolitic limestone and Middle Miocene fissured limestone aquifers and quaternary were collected and analyzed. The results of the chemical analysis showed wide ranges of TDS (156-25290 mg/l), and chloride concentration of (12-13050 mg/l).The quaternary aquifer hashigh salinity (average TDS)=17140-19830 mg/l),and the Miocene aquifer are slightly brackish to saline water (average TDS=956-2250 mg/l). The hydrochemical data indicate that the majority of the groundwater samples of the localities are related to recent meteoric origin. The variation in the chemistry of water is thought to be related to the weathering of minerals of the water-bearing sediments, mixing with marine water, and leaching of rainfall in area.