Performance evaluation of DC resistivity and time-domain EM sounding as used in a complicated groundwater survey of the Batinah coastal plain, Oman

The Batinah coastal plain is located on the northem margin of the Northern Oman Mountains and stretches for a bout 300 km along the Gulf of Oman (Figure I). Scarce groundwater resources have been intensively exploited for agriculture, industrial and domestic use. The study area, Eastem Batinah, covers some 60x35 km and involves a coastal aquifer which is cornposed of alluvial fan and coastal deposits consisring rnostly of (partly) cemented gravels, sands and silts. Saline water intrusion poses a serious threat to a sustainable water supply. In the recent past, the district has been the subject of intensive geophysical exploration for various purposes. Among them are reflection seismics for hydrocarbon exploration, high resolution aeromagnetics and low density gravity for regiorial surveys. Since 1984 a number of dedicated groundwater surveys were executed, including Schlumberger De resistivity soundings (119), TDEM soundings (500) and wireline logging of a large number of monitoring and production boreholes (109).