HYDROGEOLOGICAL STUDIES ON THE NUBIA SANDSTONE AQUIFER IN BAHARIYA AND FARAFRA DEPRESSIONS, WESTERN DESERT, EGYPT

Abstract

This study concerns mainly with the groundwater occurrences, movements and qualities within the Nubia aquifer system in Bahariya and Farafra depressions. To achieve these aims the following techniques are applied; field investigations of the morphologic features, the surface geologic succession, structures, surveying of the water points, measuring of the piezometric heads and well discharges, carrying out pumping and recovery tests, collecting and analysis of about fifty six groundwater samples, field measuring of their pH and electrical conductivity. Rock samples of twinty six deep wells in Bahariya and Farafra depressions were collected and subjected to petrographical examination. Based on the rock properties and geophysical logging, the penetrated Nubia succession in Farafra is subdivided into successive rock units represented from top to base by symbols (A), (B), (C), (D) and (E). They are correlated with the similar rock units represented by symbols (S3), (C2), (S2), (Cl) and (Sl) in Bahariya depression respectivily. Subsurface mapping for the defined successive Nubia rock units in Bahariya and their extension in Farafra depression are constructed indicating minor domal and basinal structures and crestal shifting by depth for the main surface structures. The defined sandstone Nubia rock units are classified into water bearing zones separated by confining and semiconfining clay and/or shale units. The hydraulic parameters of the Nubia sandstone water bearing zones are estimated by pumping and recovery tests in Bahariya and Farafra depressions.