Groundwater Ocurrences in West Nile Delta, Egypt

The evaluation of the groundwater occurrences needs integration of more than one technique to give an accurate estimation of the groundwater potential. Since, the West Nile Delta suffered from the deterioration in groundwater due to intensive of exploitation which resulted in both groundwater depletion and salinity increase. So, the integrated geophysical, hydrological and isotopic investigations were carried out in Wadi El Farigh, western Nile delta to monitor and assessment of the changes in the groundwater level, quality, aquifer renewability and mixing between existing aquifers. Geophysical results reveal that there are two aquifer separated by basaltic sheet. The first one is represented by the Miocene aquifer (El-Moghra) and the second one is the Oligocene aquifer which has lower resistivities than the upper one and this is mainly due to increase of clay content and the water salinity. Hydrological results reveal that the saturated thickness of Miocene aquifer decreased during (2003–2015) period and this depletion was approximately ranged between 1.3 and 1.7 m/year. Total dissolved solids (TDS) content of groundwater samples varies from 234 to 2458 mg/L implying significant deterioration and salinization problems. Application of Drinking Water Quality Index (DWQI) reveals that water samples are ranked between excellent category (~33%) to poor category (~67%) which is almost always threatened or impaired. The δ18O–δ2H relationship is suggesting that two distinct sample groups were classified according to their isotopic compositions. These two groups are nonrenewable and have isotopic signals varied completely according to the time of recharge. The relation between δ18O‰ and Cl concentration in (epm) suggested that both of two groups are exposed to dissolution as a result of an over-pumping process or mixing with more depleted strata (Oligocene aquifer) through the faults as in group 2 that exhibits more saline water and more isotopic depletion. Results indicate that most of the wells are operated at relatively high pumping rates accompanied with low efficiency and specific capacities besides decline of well yields and water deterioration.