Specific regional hydrological aspects Geophysical investigations of the hydrogeological basins in the central Jordan Valley

In the present study the natural water resources along the central Jordan Valley and the future development of these resources (Fig. 3.2.1-1) were investigated. The hydrogeological modeling of the area was examined against the background of the geological history of the Dead Sea Rift Valley. The reconstruction of major geological events in the history of the basin enables the identification of tectonic and sedimentary processes which defined the regional hydrogeological system. Thus, events such as compression and decompression and the resulting folding and faulting which occurred during the uplift of the eastern and western borders of the Dead Sea basin, seawater invasion, fast subsidence of the basin floor and the sedimentary events which followed, had to be considered both in time and space. The characterization of the hydrogeological system was done by combining multidisciplinary geoscience methods such as classic field geology, geochemical and geophysical field methods, and climatological analysis of precipitation systems. The interpolation of various models yielded several data sets. In this particular chapter only the geophysical results are presented. The Dead Sea Rift is a unique region in which powerful tectonic processes created a deep (about -400 m msl) and narrow valley, bordered on its eastern and western margins by high mountainous ridges (up to about +1000 m msl). An active transform fault, which runs along its central part, shifts the eastern (Arabian) plate about 105 km. northwards relative to the western one (African). This structural complexity bears naturally upon the hydrogeological and hydrochemical system. Thus, the western aquiferous complex includes the Upper Cretaceous calcareous karstic formations and younger rock-units and recent alluvial sequences. The eastern water-bearing strata are of Jurassic age and younger, ending with the same alluvial complex. On both sides of the Rift, the regional aquifer occurs in the Upper Cretaceous karstic limestone and dolomite formations.