GROUNDWATER MODELING AT THE GOLAN HEIGHTS BASALT AQUIFER, ISAREL

The Golan Heights lies in the north of Israel at the eastern side of the Jordan river (33^o00’N 36^o30’E). It is a part of the Hauran, a large Plio-Pleistocene volcanic province that extended also eastward into Syria. The basalt rocks serve as a regional aquifer that is being exploited both by Israel and Syria due to the high quality of the water (i.e., [Cl]<25 mg/l). This study defines the boundaries of the aquifer, divide it into sub-basins and quantify the flow fields at each. In this study, water samples from springs and boreholes have been collected and analyzed and the water balance has been re-assessed. A structural map of the basalt base topography was drawn. This map exhibits for the first time the pre-basaltic topography, which was shaped by faults and erosion. A numerical model was built for a quantitative evaluation of the flow field using the MODFLOW code. The computed groundwater flow field is supported by both the water balance and the isotopic composition analyses (¹⁸O, ²H and ³H).

Result indicates that the regional basalt aquifer is divided into two basins: the Kinneret (“Sea of Galilee”) basin and the Yarmouk basin. The eastern water divide lies evidently adjacent to the international border. The Kinneret basin lies on the north and middle parts of the Golan Heights yielding 80*10⁶ m³/y. It is divided into two sub-basins, separated by a pre-basalt structural ridge that serves as hydraulic barrier. Flow direction in both sub-basin is westward, into the Jordan Rift Valley, feeding large springs on the western slopes of the Golan Heights (50*10⁶ m³/y), seeping into perennial rivers (10*10⁶ m³/y), and into the Kinneret lake and the Jordan River (20*10⁶ m³/y).

The southern and the easternmost parts of the Golan are small portion of the Yarmouk basin. In this area, water flows southward feeding the upper Wadi Raqqad springs in Syria. In the southernmost part of the Golan, basalt aquifers are mostly perched and local.