SHAPING BURIED BEDROCK TOPOGRAPHY USING RESISTIVITY AND GRAVITY DATA IN WADI ALLAQI, EASTERN DESERT, EGYPT

Vertical electrical resistivity and Bouguer gravity data were assessed at Wadi Allaqi area, Eastern Desert, Egypt aiming at the configuration of the bedrock (basement) surface, potential of groundwater availability and assessment ofthe best locations for drilling groundwater boreholes. The results obtained from geoelectrical resistivity interpretation have shown that the interpreted depths of basement surface range from about five m to sixty m with three main deeper troughs considered as best locations for groundwater accumulation and suitable for drilling of groundwater boreholes. Since, the gravity anomaly magnitude is mainly controlled by the depth to the subsurface causative feature (basement) and its density contrast with overburden. Many trials for estimating the depth at varying density contrasts (0.1-1.0 gm/cm) were done. It is found that the closest depths from the gravity analysis to the obtained resistivity analysis are the ones that were computed using the density contrast of 0.2 gm/cm as an optimum value. Finally, re-mapping bedrock topography based on that optimum value was achieved.