GROUNDWATER RESOURCES AND POTENTIAL IN WADI GARAWI, EAST EL TEBEN, EASTERN DESERT, EGYPT: INFERENCES FROM GEOELECTRICAL INVESTIGATIONS | ||||
| Journal of Egyptian Geophysical Society | ||||
| Volume 9, Issue 1, 2011, Page 37-50 PDF (544.16 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jegs.2011.384436 | ||||
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| Author | ||||
| A.M.M. Al Temamy | ||||
| Geophysics Department, Desert Research Center. | ||||
| Abstract | ||||
| Sustainable development of groundwater aquifers requires a permanent source of groundwater and a mechanism for recharging the aquifer. In this study, geoelectric methods were used to address the sources of groundwater and the mechanics of recharge in Wadi Garawi. To fulfill the objective of this study twenty Vertical Electrical Soundings and Two-Dimensional electrical imaging profiles were measured. Results of the VES data and the constructed cross-sections indicate the presence of three main geoelectrical units (A, B and C) which correspond to Quaternary, Pliocene and Eocene deposits, respectively. Three water-bearing formations in the area of study are detected. These formations are represented by geoelectrical layer “A3” (a part of the Quaternary alluvial deposits), geoelectrical layer “B2” (Pliocene sand and sandstone) and geoelectrical layer “C1” (Eocene limestone). The interpreted results of the 2-D imaging profiles and the VES curves are consistent with: (1) small thicknesses for the Pliocene aquifer in the south compared to those in the north, (2) fault control in the western part that is responsible for terminating the Pliocene aquifer against the Pliocene clay (second site). Five normal faults were detected from the constructed cross-sections. These faults contribute to the groundwater potential in the area and act as conduits facilitating groundwater recharge at some regions and as impervious boundaries at other sites. These effects can be illustrated by the increment of the thickness of the Quaternary aquifer in the western part comparable with the eastern part. The Quaternary aquifer in the west is recharged by the seepage from the Nile River, which has the same level as the groundwater. On the other hand, in the east the aquifer is recharged from occasional surface water flooding. Different aquifers are interconnected hydrogeologically due to the structural effect, i.e. between the Quaternary aquifer (layer A3) and the Pliocene aquifer (layer B2) in the west, and between the Pliocene aquifer (layer B2) and Eocene water-bearing (layer C1) in the east. The uplifted clay layer (B3) at the middle of the study area subdivided the sources of recharge along the Pliocene aquifer into two different zones. A permanent recharge from the Quaternary aquifer that is feeded by the seepage from the River Nile in the west and a seasonal one from the Eocene interconnected water-bearing limestone (low potential) that feeds through deep structures and fractures. The fault reduces the thickness of uplifted Pliocene aquifer to a small value (8.5 m at VES 3); hence, low potential for groundwater is expected at this site. Also, the Quaternary aquifer was not detected in the southern soundings due to the impact of faulting. As the Quaternary aquifer has a greater thickness (more than 20 m) and recharged by seepage from the Nile River, a permanent source of recharge for groundwater is guaranteed. At the same time the western part of the Pliocene aquifer is feeding from the Quaternary aquifer. This in turn will store a permanent source of groundwater which is considered one of the essential requirements of sustainable development. Therefore, the western part is more suitable for the sustainable development in the area of study. | ||||
| Keywords | ||||
| Aquifer; recharge; imaging profile; Vertical Electrical Sounding (VES); faults; seepage; water flood; fracture; development; interconnected water-bearing | ||||
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