INTEGRATED GRAVITY AND RESISTIVITY ANALYSIS FOR GROUNDWATER OCCURRENCES IN ASSUIT AREA, UPPER EGYPT | ||
| Journal of Egyptian Geophysical Society | ||
| Volume 8, Issue 1, 2010, Pages 83-94 PDF (3.84 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jegs.2010.380905 | ||
| Abstract | ||
| Integrated geophysical investigation has been carried out using both gravity and electrical resistivity techniques to evaluate the groundwater resources and the geologic factors affecting their occurrence. The geophysical survey includes analyzing the Bouguer anomaly map and thirty three VES’es to delineate the Pleistocene-Recent aquifer extension, and the subsurface geologic structures. The gravity study shows the expected horizontal as well as vertical extension of the subsurface aquifer, which corresponds to the general low gravity effect within the Nile Valley. Also, the gravity study reveals the existence of a number of faulting features that are dissecting the sedimentary sequence and play an important role in replenishment the upper Pleistocene groundwater aquifer either through surface infiltration or subsurface discharge from the deeper Nubian aquifer. The interpretation of the resistivity data indicated the presence of three main geoelectrical units of varying resistivity ranges. Using the results obtained from the interpretation of the resistivity data, the depth to the top of the aquifer unit, its thickness and the distribution of the interpreted true resistivity have been mapped to show their horizontal as well as the vertical variations within the study area. The average thickness of the water bearing horizon is ranging from 70 to 170 meters within the close proximity to the Nile River. The aquifer’s interpreted resistivity ranges from 10 to 80 Ohm.m depending generally on its lithological composition and groundwater salinity. | ||
| Keywords | ||
| Residual and regional gravity; first & second vertical derivatives; VES | ||
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