摘要：AbstractSaudi Arabia is a desert country with no permanent rivers or lakes and very little rainfall. Ground water aquifers are the major source of water in Saudi Arabia. In the Riyadh region, several Wadies including Wadi Nisah store about 14×106m3of water, which is extracted for local irrigation purposes. In such areas, the water wells are as shallow as 200–300m in depth. The importance of Wadi Nisah is because the subsurface water aquifers that are present there could support the region for many years as a water resource. Accordingly, in this study, we performed a Magnetotelluric survey using a portable broadband sounding system (MT24/LF) to evaluate the ground water aquifer at great depths. We collected 10 broadband Magnetotelluric sounding stations (1station/day) with an interval of about 2–3km reaching a profile length of about 25–30km along Wadi Nisah. Additionally, we used available gravity data to image the subsurface structure containing the aquifer.MT results indicated a low resistivity layer, associated with alluvium deposits, which was defined at a depth of about 1–2km and extended horizontally about 15km. Gravity data analysis was used to model this resistivity layer indicating a basement surface at 3–4km depth.
