Abstract
Time-domain electromagnetic (TEM) soundings and vertical electrical soundings (YES) were conducted to assess the subsurface groundwater contamination in Al Quwy'yia area through tracing the conductivity changes caused by leachate contamination of groundwater. Most of the contamination sources are coming from the incomplete sanitary system and the illegal dumping of wastewater along the lowland area outside the town. Contamination of the groundwater poses a major threat because most of the local inhabitants rely on ground water to supply up to 60% of their water needs for various life activities. TEM and YES data sets have been acquired along four longitudinal profiles to cover the most urban area of Al Quwy'yia. The combined inversion of YES and TEM data sets increase the resolving certainty of the subsurface resistivity models. The basement rock has the highest resistivity values, whereas the uncontaminated limestone has moderate resistivity response in comparison with the contaminated zones, which have a lower resistivity response. The constructed cross-sections and resistivity slice maps along the area provide valuable information about the shallow seepage from the septic tanks, as well as the deep infiltration from the dump site at the southern part of the study area.