Structural Controls on Groundwater Flow in Basement Terrains: Geophysical, Remote Sensing, and Field Investigations in Sinai

Abstract

An integrated [very low frequency (VLF) electromagnetic, magnetic, remote sensing, field, and geographic information system (GIS)] study was conducted over the basement complex in southern Sinai (Feiran watershed) for a better understanding of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17-18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways for surface water infiltration. Findings include: (1) spatial analysis in a GIS environment revealed that the distribution of the water-bearing features (conductive features) corresponds to that of fractures, faults, shear zones, dike swarms, and wadi networks; (2) using VLF (43 profiles), magnetic (7 profiles) techniques, and field observations, the majority (85 %) of the investigated conductive features were determined to be preferred pathways for groundwater flow; (3) northwest-southeast-to north-south-trending conductive features that intersect the groundwater flow (southeast to northwest) at low angles capture groundwater flow, whereas northeast-southwest to east-west features that intersect the flow at high angles impound groundwater upstream and could provide potential productive well locations; and (4) similar findings are observed in central Sinai: east-west-trending dextral shear zones (Themed and Sinai Hinge Belt) impede south to north groundwater flow as evidenced by the significant drop in hydraulic head (from 467 to 248 m above mean sea level) across shear zones and by reorientation of regional flow (south-north to

Aquifer recharge, depletion, and connectivity: Inferences from GRACE, land surface models, and geochemical and geophysical data

“…7), mostly filled by Paleo zoic-Lower Cretaceous sandstones in the Kufra subbasin and by Paleozoic-Upper Cretaceous sandstone in the Dakhla subbasin (Thorweihe and Heinl, 2002). Structures like the Pelusium megashear system, which are subparallel to groundwater flow direction, act as preferred pathways for groundwater flow, whereas others that intersect the flow at high angles impound groundwater up gradient (Gudmundsson, 2000;Babiker and Gudmundsson, 2004;Mohamed et al, 2015).…”

Flash floods mitigation and assessment of groundwater possibilities using remote sensing and GIS applications: Sharm El Sheikh, South Sinai, Egypt

“…Hydrogeologically, the Miocene aquifer is considered as the main water bearing formation in the study area. Additionally, two formations are bearing groundwater including the Quaternary alluvial sediments and the fractured basement Yousif and Hussien Bulletin of the National Research Centre (2020) 44:50 (Aglan 2015;Mohamed et al, 2015;Isawi et al 2016). The Miocene aquifer is composed of limestone, dolomitic limestone, and coarse grained sandstone with shale intercalations.…”

Fault zone hydrogeology in arid environments: The origin of cold springs in the Wadi Araba Basin, Egypt

“…The NAS in the WAB is under pressure exerted by the weight of the overlying impermeable steeply dipping lower Senonian shales and gently dipping upper Senonian carbonates (Figures 3, 4 and 5a,b). Moreover, the low hydraulic conductivity of faults zones (i.e., reverse faults along the two sides of the WAB [Figure 3]) act as a natural barrier to the groundwater flow in the NAS (Mohamed et al, 2015; Tóth, 2009). The combination of the abovementioned two hydrological parameters lead to elevated groundwater table upslope of the fault zone and ultimately groundwater discharge takes place along the spring locations.…”