INVESTIGATION OF CHANNEL SEEPAGE AREAS AT THE EXISTING KAFFREIN DAM SITE (JORDAN) USING ELECTRICAL-RESISTIVITY MEASUREMENTS

A geoelectrical resistivity survey was carried out in the existing Kaffrein dam site, near the Dead Sea, Jordan, in order to investigate channel seepage and the hydrological conditions of the alluvial deposits in the upstream as well as downstream areas of the dam. The data from the electrical resistivity survey were interpreted by the classical curve matching and computer modelling techniques. Fifteen vertical electrical soundings (VES), utilising the Schlumberger array, ABEM TERRAMETER SAS 300 B and SAS 2000 booster, were conducted in the area. The lengths of these soundings extend up to 800 m. Interpretation of resistivity data has confirmed the existence of low to moderate resistivities (54-108 OMEGA.m) at depth (in the alluvial deposits), which may be attributed to the presence of water percolations that flow also beneath the axis of the dam. Shallow boreholes (< 20 m) drilled in the downstream area to monitor seepage, have confirmed the findings of the resistivity survey. This study demonstrates the usefulness of electrical resistivity measurements in detecting seepage zones under the dams.