THE FAULT PATTERN IN THE NORTHERN NEGEV AND SOUTHERN COASTAL-PLAIN OFISRAEL AND ITS HYDROGEOLOGICAL IMPLICATIONS FOR GROUNDWATER-FLOW IN THE JUDEA-GROUP AQUIFER

On the basis of a broadly expanding data base, the hydrogeological pro perties of the Judea Group sequence in the northern Negev and southern Coastal Plain of Israel have been reassessed. The updated subsurface model is based on data derived from water- and oil-wells and on recent large-scale geophysical investigations. A new regional pattern of fau lts extending through the subsurface of the study area has been reveal ed. In view of the reassessed geological and hydrological subsurface s etting, it appears that the Judea Group aquifer should not be regarded as one continuous and undisturbed hydrological unit; owing to the occ urrence of regional faults, its subaquifers are locally interconnected . These subaquifers, which contain mainly high-quality water, are juxt aposed, as a result of faulting, against Kurnub Group sandstones conta ining brackish paleowater. The latter Group is faulted against late Ju rassic formations containing highly saline groundwater. In the Beer Sh eva area, the Judea Group aquifer is vertically displaced against the Senonian and Eocene Mt. Scopus and Avdat Groups, which also contain br ackish and saline water. In the southern Coastal Plain, major faults l ocally dissect also the Pleistocene Kurkar Group, facilitating inflow of Mg-rich groundwater deriving from Judea Group dolomites. The new ge ological evidence and its hydrogeological implications provide new sol utions for previously unexplained salinization phenomena.