EVALUATION OF ENVIRONMENTAL ISOTOPIC AND SALINAR COMPOSITION OF GROUNDWATER IN OASES OF THE WESTERN DESERT, EGYPT

Representative water samples were collected from different eases in th e western desert of Egypt to examine characteristics of Egyptian groun dwater. Chemical data recognized two basic groundwater types; alkali b icarbonate and alkali chloride, where sodium has the highest concentra tion. For each region the median SD, delta(18)O and ionic strength of water calculated from their chemical analyses are recorded and plotted . Generally, the results of isotopic content measurements of the groun dwaters from the different eases in the western desert indicate the fo ssile origin of these waters. The values of delta D and delta(18)O of the western desert eases' waters are characteristic of old paleowaters from the Nubian sand aquifer. Modern sparse rainfall data suggest tha t any precipitation will exhibit moderate to large positive isotopic c ontent enrichments and cannot be a source for these waters. They have been in no connection with the Nile water, moreover the change in isot opic composition is due to evaporation which is now ineffective at dee per levels.