STUDYING THE QUATERNARY AQUIFER AT AL JAWW PLAIN BY ERT METHOD, AL-AIN, UNITED ARAB EMIRATES (UAE)

Al Jaww plain, situated to the east of Jabal Hafit in Al-Ain, UAE, is considered as an important area from the hydrogeological point of view due to the main wadies which are crossing east of Al Jaww plain. These Wadies like Wadi Muthayimmah, Wadi Sa'a and Wadi Muraykhat, originated from the Oman Mountains and form the catchment and feeding area of the water resources. For a better understanding of the aquifer system, water flow and water quality, electrical resistivity tomography (ERT) survey has been carried out along selected profiles in Wadi Muraykhat and Wadi Sa'a. The data was integrated with the available borehole data to image the Quaternary aquifer in the study area. The results of the survey are 2-D resistivity tomograms, which indicate remarkably the different hydro-stratigraphic units of the Quaternary aquifer along the study area. Three identified geoelectric-lithologic zones have been interpreted. A surficial zone consists of loose to weakly consolidated sand and gravel. This zone corresponds to the upper part of the very resistive layer (> 100 ohm-m). The resistive nature of this layer is indicative of dry conditions in the upper part of the alluvium. Thick zone of gravel and sand comprises the bulk of the alluvium. The moderate to relatively small resistivity in this middle interval suggests partial saturation and/or the presence of a clay-rich matrix. However, at certain locations along these tomograms, there is a zone of coarse gravel of a varying thickness at the bottom of the alluvial section. This zone appears to represent a basal deposit of the saturated channel gravels. Erosional unconformities at the base of the Quaternary alluvium are traced along some of the profiles. These unconformities represent the paleochannels in the bed rock that were formed in the geological past by the ancient wadies and may be considered as promising targets for fresh groundwater exploration, as they contain appreciable thickness of water bearing formations that are charged from surrounding mountain region.