CONTRIBUTIONS TO THE HYDROGEOLOGY OF NUBIA SANDSTONE AQUIFER IN THE MIDDLE PART OF DARB EL-ARBEAIN, SOUTH WESTERN DESERT, EGYPT. EZZAT A. KORANY1, R. G. FATHY2 and MOHAMED EL. NAGATY2 Ain Shams University, Faculty of Science, Geology Department 1 General Authority for Rehabilitation Projects and Agricultural Development (GARPAD) 2 Recently the Nubia sandstone water bearing rocks are encountered in the subsurface at Darb El-Arbeain area, southeast of Western Desert, Egypt. They form a characteristic aquifer system built up of successive and connected units. They are defined into; Paleozoic Mesozoic sandstone Layer and Upper Cretaceous sandstone rock units, overlying directly the Pre-cambrian basement rocks and capped by the confining layers of Dakhla Shale Formation. During the period 99 / 2000 17 wells were drilled in the area lying at the middle part of Darb El -Arbeain. They are designed as productive pumped wells to provide the groundwater from Nubia sandstone aquifer for the agriculture development projects. The present work aims at investigating, for the first time, the hydrogeological conditions of the Nubia sandstone aquifer system as based on; lateral and vertical facies distribution, structure implications, hydraulic parameters and hydrogeochemical classification of groundwater and their quality evaluation. The obtained results were subjected to numerical analyses and graphical presentations. They provide proper contributions to the hydrogeology of the Nubia sandstone aquifer in a part of the Western Desert of Egypt.