Geoelectrical and hydrogeochemical studies for delineating ground-water contamination due to salt-water intrusion in the northern part of the Nile Delta, Egypt

A resistivity survey was conducted in the Nile Delta area to delineate ground-water contamination caused by an improper sewage and irrigation drainage system, leaching from old lagoonal deposits, and salt-water intrusion. Existing monitoring wells were used to measure the horizontal and vertical variations in water salinity. Vertical electrical sounding (VES) data for sounding points located near monitoring wells, together with the water salinity data of these wells, were used to obtain an empirical relationship between the inferred earth resistivity and the amount of total dissolved solids. This relationship was used together with the constructed apparent resistivity depth and geoelectric longitudinal sections to identify three zones of water-bearing formation (fresh-, brackish-, and salt-water zones). Along the studied profile, depth to the fresh-brackish interface exceeds 150 m at Tanta City and decreases northward to 40 m or less between Qutor and Kafr El-Sheikh. Depth to the brackish-saline interface exceeds 180 m south of Kafr-El-Sheikh and decreases northward to 70 m near Hadadi village