Paper No. 296-2
Presentation Time: 9:00 AM-6:30 PM
AN INTEGRATED APPROACH (REMOTE SENSING, GEOPHYSICS, STABLE ISOTOPES, FIELD AND HYDROCHEMISTRY) FOR IDENTIFICATION OF POTENTIAL AQUIFER ZONES IN WADI QENA BASIN, EASTERN DESERT, EGYPT
Wadi Qena basin represents one of the most promising regions for future development in Egypt. Fresh water supplies are crucial for such plans. We provide an integrated remote sensing (Landsat-8, SRTM, Radarsat-1, Geoeye), geophysical (aeromagnetic, gravity data), isotopic (δ18O, δ2H), field (stratigraphic and structural interpretation) and geochemical (major dissolved ions) approach to delineate zones of potential groundwater resources in Wadi Qena basin. Four water-bearing horizons were sampled: fractured crystalline aquifer, Nubian Sandstone Aquifer System (NSAS), Post Nubian Aquifer System (PNAS) and the Quaternary aquifer (QT). Findings include: (1) spatial analysis of remote sensing data in a GIS environment refers to an extensive control by faults (dextral faults trending NE-SW and sinistral faults [i.e. Najd system] trending NW-SE) and intensive surface water supply from the east through Wadi Fattera, Wadi El Gedami and other smaller wadis (2) analysis of geophysical data indicates that these faults extend to the subsurface and control the water-bearing horizons, (3) Two end members, two mixed groups and one evaporated group could be identified including: group (I) the highly depleted fossil Nubian waters (range: δ18O from -6.39 to -6.74 and δ 2H from -48.21 to -52.46); group (II) modern waters (range: δ18O from -1.41 to -1.51 and δ2H from -5.46 to -6.04); group (III) mixed between NSAS and modern waters (range: δ18O from -4.82 to -5.05 and δ2H from -33.28 to -38.54);group (IV) mixed between NSAS, PNAS and QT waters; and group (V) samples which have a considerable deviation from the Global Meteoric Water Line (GMWL) along an evaporation line (range: δ18O from -0.58 to -4.55 and δ2H from -19.59 to -38.68) (4) Group (III) samples tap the NSAS and are located along the main channel of Wadi Fattera (area 3648 Km2) providing evidence for modern recharge of the NSAS, (5) Group (IV) samples tap the QT and PNAS aquifers and are located along the delineated deep-seated faults providing evidence of upward leakage of the deep NSAS into the shallower QT and PNAS aquifers, (6) these findings are supported by hydrochemical facies and the chlorinity-δ 18O relationships. The present study improves our understanding of the role of structural control and modern recharge in exploration for aquifer potential in arid environments.