Geophysical techniques and geomatics-based mapping for groundwater exploration and sustainable development at Sidi Barrani Area, Egypt

Abstract

The exploration of groundwater on the northwestern coast of Egypt holds significant importance for urbanization and sustainable development. This is due to a deficiency in water resources, particularly in the arid regions, and the increasing reliance on groundwater as an alternative water source in response to the declining rainfall in the region. Therefore, this study adopts a comprehensive approach that combines the Geographic Information System (GIS) and remote sensing techniques with a geophysical survey. The Time Domain Electromagnetic (TDEM) and Vertical Electrical Sounding (VES) methods are used in the survey to investigate and characterize the fractured limestone aquifer that dominates the study area. A pedological investigation, including both in-situ and laboratory testing, is conducted on the soil. The findings reveal multiple layers—such as the top fill layer, sandstone layer, upper limestone layer, clayey layer, middle gypsiferous limestone layer, and lower limestone layer—within the soil profile. The fill layer is typically composed of fine- to medium-grained sand. A total of 47.7 acres were lost and 28.6 acres were gained according to the results of the shoreline change over several spatial and temporal scales. Sea level rise-related shoreline changes result in saltwater intrusion, which has a substantial effect on the groundwater quality in coastal aquifers. The integration of geophysical tools indicates the presence of two geoelectrical layers in the subsurface succession. The second layer corresponds to the Marmarica limestone of the Middle Miocene, which represents a shallow water-bearing formation in the study area. This layer exhibits moderate and low resistivity, with depths ranging from 1.58 to 52.8 m and a thickness from 23.6 to 139.12 m.