HYDROCHEMICAL STUDy OF GROUNDWATER ON . NUBIAN SANDSTONE AQUIFER IN AFRICA (CASE STUDY ELDAKHLA OASIS

Abstract

The Nubian Sandstone Basin is considered one of the most important groundwater basins in North Africa and the Arab Region. It extends across the borders of four African Countries, Egypt, Sudan, Chad and Libya. The Dakhla Oasis constitutes one of the main five distributed Oases in western Desert of Egypt.

The Nubian Sandstone basin occup1es an area of more than 2."5 million Km2 and under lies the common border area between Egypt, Sudan, Libya and Chad. The basin extends approximately between latitudes 15. and 30. Nand longitudes 20• and 34•E. The Dakhla area a depression occupies an area between latitudes 25.15" and 26. and longitudes 28.15" and 29• 30"E.

The present study revealed that the Nubian Sandstone basin in the study area is a part of huge groundwater reservoir extending to cover the Wadi El Gedid area and El-Uwienat. The upper part is Nubian Sandstone rocks, it belongs to Cretaceous time.

The Cretaceous rocks in the depression are divided into 4 units, which are from top to bottom, chalk and chalky limestone, greenish and gray leafy clay, clays with Exogyra Overwegi and Nubian Sandstone. The hydrogeology of the study area where the aquifer system in Nubian Sandstone basin is divided into various groundwater basins hydraulically connected in various degrees to the major Nubian basins in the countries sharing the regional aquifer.