SPATIAL AND TEMPORAL TRENDS IN GROUNDWATER SALINITY IN BAHRAIN

In Bahrain, groundwater in the Dammam aquifer is the only natural sour ce of fresh water to meet the increasing demands for water. Prolonged over-exploitation of the aquifer has led to continuous deterioration o f groundwater quality. In this study, a countrywide hydrochemical surv ey has been conducted to investigate the aquifer deterioration process , A total number of 254 water wells have been sampled to assess the pr esent groundwater salinity in terms of TDS, with 110 of these samples being further analyzed for major ion concentrations. The results are u sed to define the spatial trend of quality deterioration, where five z ones of aquifer salinization are identified. Sources and mechanisms of salinization are also discussed. Furthermore, temporal changes in gro undwater quality over the period 1979-1992 are examined using base-lin e data from a previous survey. The effectiveness of past management sc hemes to control quality deterioration are evaluated. The study reveal s that the quality of the aquifer recharge flow received in Bahrain fr om Eastern Saudi Arabia by lateral under-flow has been significantly i nfluenced by inland mixing with higher concentration waters. Spatial a nd temporal analyses conducted in this study indicate that abstraction rate is a key factor in the management process to control groundwater quality. Accordingly, further measures required to restore groundwate r quality are suggested.