Structural constraints on the groundwater regime of the Cretaceous aquifers in Central Sinai, Egypt

The Lower Cretaceous aquifer is one of the most important water bearing formations not only in Sinai but also in the Middle East because of its high hydraulic parameters and good water quality. This aquifer is dominated by a thick sequence of well sorted and permeable sandstones The Lower Cretaceous aquifer is generally crossed by two main E-W trending, down to the north normal right-lateral oblique-slip faults; the Ragabet El-Naam Fault (RANF) to the south and Minsherih-Abu Kandu Shear Zone (MAKZ) further north. In Central Sinai, the water flow pattern and hydrochemistry of the Lower Cretaceous aquifer are controlled by the fault-fold patterns. Across the RANF the water flow is retarded behind the fault zone and deviates toward its central segment where the groundwater spills-out northward at Nekhel City. In contrast, the MAKZ defines a barrier for the northward flowing groundwater where the Lower Cretaceous aquifer south of the fault is blocked by the Upper Cretaceous to Eocene limestone and shale to the north. The water type changes across the fault zones from meteoric water to water of marine origin at the RANF and north of MAKZ respectively with sporadic occurrences of old marine water types limited to NW-trending structural lows. Generally the northward flow pattern of the Lower Cretaceous aquifer shows an eastward deviation to Gulf of Aqaba-Dead Sea rift and southwestward deviation to Gulf of Suez rift. Such deviations are controlled by the fault patterns characterizing north and west Sinai provinces. (c) 2012 Elsevier Ltd. All rights reserved.