SHALLOW GEOPHYSICAL TECHNIQUES FOR GROUNDWATER AQUIFER EXPLORATION, AIN ALSOKHNA AREA, WEST GULF OF SUEZ, EGYPT | ||||
| Journal of Egyptian Geophysical Society | ||||
| Volume 14, Issue 1, 2016, Page 131-141 PDF (941.38 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jegs.2016.385664 | ||||
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| Authors | ||||
| A.A.A. Othman1; Th.H. Abd El-Hafez1; M.A.S. Yousse2; M.E.M. Sabra3 | ||||
| 1Geology Department, Faculty of Science, Al-Azhar University, Cairo, Egypt | ||||
| 2Nuclear Materials Authority, Exploration Division, P. Box 530, Maadi, Cairo, Egypt. | ||||
| 3Egyptian Mineral Resources Authority, P. Box 11517, Abbasiya, Cairo, Egypt | ||||
| Abstract | ||||
| Eight seismic refraction profiles, five vertical electrical soundings (VES) and four geophysical well logging tools were acquired along the western side of Gulf of Suez, Egypt, in order to study the aquifer's geometry, groundwater level, and locate promising sites for future water drilling wells. The well logging measurements included natural gamma ray (GR), self potential (SP), electric resistivity (16″ and 64″), density and neutron. The seismic primary wave velocity distribution different velocities ranging between 500 – 625 m/s, 1300 – 1600 m/s and 2400 – 3000 m/s. The obtained results showed that the first low velocity range may indicate non-saturated zone which is directly affected by surface water that appears along the studied area. The second and third velocities ranges may show water level at saturated zone and the lithologic interfaces. The estimated thickness of the unsaturated zone varies between 1 m and 3.5 m. The thickness of the top saturated zone ranges between 9.5 m and 26 m which represent the gradual increase of seismic velocity layers with depth. This increase may be due to the dense rocks which change vertically from alluvial at the surface to compacted sediments and then to sandstone at depth. The true resistivities of the aquifer show two zones; the first zone is a surficial resistive layer of dry alluvium, unconsolidated with consolidated Wadi sediments, which have average resistivity of more than 440 Ω.m then lower resistivities reaching to 21 Ω.m in the second zone which constitutes the main aquifer in the third and fourth geoelectric layers. The geophysical well logging tools confirmed the water depths obtained from the seismic refraction analysis and vertical electrical soundings. The water table levels start below 17, 40, 15 and 45 m at wells no. 1, 2, 3 and 4, respectively. In addition, they give more detailed explanation about the subsurface lithologies and their physical properties through varying lithologies with depth such as porosity, clean or radioactivity, density and electrical resistivity. The integration of these results confirms the existence of a groundwater aquifer within this interval. The combination between the three executed geophysical methods indicated that the subsurface lithology of the area is composed of three layers. The first top layer is formed from unconsolidated and consolidated Wadi sediments (non-saturated zone) and the second saturated zone is a fractured rock composed mainly of saturated sandstone and considered a promising layer for groundwater accumulation. The surface level of groundwater was increased toward the west and decreased toward the east of the studied area. The obtained results show that for any future drilling for groundwater, a number of VES positions may be considered as potential locations, especially at VES 3. | ||||
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