Hydrogeological and remote sensing investigation of the fractured carbonate aquifer, East El Minia, Eastern Desert, Egypt

Abstract

Groundwater resources in the Sahara are the backbone of the sustainable agricultural development. However, the assessment of groundwater dynamics, particularly the role of structural control on groundwater flow and recharge mechanism in Saharan karst aquifers (KA) is poorly constrained due to sparse hydrological data. The KA in East El-Minia area (EMA), in the Eastern Desert of Egypt is highly affected by a set of major faults related to the post-Eocene tectonics and Red Sea rifting system. The present study integrates field observations, Phased Array type L-band Synthetic Aperture Radar images (PALSAR), digital elevations models, geophysical, stable isotope and geochemical data to identify the structural control on groundwater flow and the recharge mechanisms in the KA. Analysis of the PALSAR data indicated that the area was affected by a set of NW trending normal faults and related grabens while the aeromagnetic data showed consistency of subsurface faults with the surficial trend. Isotopic data of groundwater from the KA indicated two mixing groups with three recharge sources. Group I, groundwater samples with mixed isotopic signature between Nubian Sandstone paleo-water and modern meteoric water with slightly depleted isotopic signature (δ18O: 3.2‰ to - 1.22‰, δ2H: 18.55‰ to - 1.44‰).Group II, mixed water signatures between the old and modern Nile water endmembers with slightly enriched signatures (δ18O: 0.02‰–0.55‰, δ2H: 4.91‰ to 27.03‰).Finally, mass balance calculations indicated that the mixing in Group I is dominated by Nubian-paleowater and rainwater, while in Group II samples are dominated by Nile water which indicates that NW faults control the recharge from the Nile at El Sareiryia watershed while impeding the recharge from the Nile at El Tahnwia. Our findings shed light on the role of structural control on groundwater dynamics in the KA in arid regions.