Water quality, storm flow, and wadi fan geology in the lower Semail drainage basin, Sultanate of Oman

Abstract

Wadi fan geology, water quality, and storm flow of the Semail Coastal Plain in Oman were examined. Pliocene—Quaternary-age fan deposits, dune sands, and sebkha deposits characterize the plain. The unconfined coastal aquifer consists of sand, gravel, clay, and cemented gravel. Resistivity, temperature, and caliper logs helped locate production zones. Native and coastal ground water differ in chloride and magnesium concentrations. Chemical analyses indicate four sources of water to the basin. Electrical conductivity and chloride values are lower near active wadi channels. Electrical conductivity profiles indicate that sea water underlies part of the fan deposits. No significant deterioration in water quality between 1978-1982 was noted. Wadi Semail acts as a line source with constricted lateral flow near the fan head and as a radiating line source below mid-fan. A pronounced recharge mound existed in 1982 as a result of storm flow. A diversion structure would increase recharge.