The hydrogeology of the northwestern bajada region of the Sultanate of Oman

Abstract

The Northwestern Bajada of the Sultanate of Oman is an arid region which relies solely on ground water. Present abstraction, which accounts for about 70 percent of the fresh water entering the aquifer system, is almost entirely by aflaj (qanats) located near the mountain front. The results of 38 exploration boreholes drilled at 30 sites from 1982 to 1983 were analyzed along with field reconnaissance data. P110-Pleistocene sediments comprise the aquifer system which is highly heterogeneous with lithologies ranging from marine carbonates to well-sorted continental alluvium. Transmissivities range from 10 m²/d to over 2,000 m²/d. Ground-water quality is controlled by recharge, and conductivities range from less than 1,000 to over 100,000 micromhos. The predominant water type is sodium chloride, owing to the mainly marine deposition of the aquifer sediments. Fresh ground water occurs as shoe-string aquifers paralleling the active wadi channels which traverse the bajada. Intrusion of poor quality water will limit ground-water development.