The Hydrogeological Charaterization of Vegter Region 39 : Eastern Upper Karoo

Abstract

Over the past 50 to 60 years the Geological Survey and Department of Water and Sanitation (DWS) have carried out numerous local groundwater investigations as well as a number of regional surveys and studies. A large volume of data, reports, and information have thus been accumulated to which other organizations have contributed as well. The last 10 to 15 years saw the establishment of an electronic National Groundwater Archive (NGA) currently containing in excess of 200 000 boreholes. Despite the amassed data and information, the goal of characterising the country's groundwater resources still remain out of reach. The focus of this study was to establish a methodology for the delineation of hydrogeological regions within the eastern upper Karoo, South Africa, based on the method that was employed by Vegter (2001). The methodology is based on three parameters, namely water level, strike depth, and EC. The delineation of the sub-regions will provide a rough estimate for the siting of boreholes and additionally provide more manageable hydrogeological units for future events. Satisfactory model calibration was achieved, although the lack of appropriate data necessitated various assumptions in the model setup. The application of the calibrated model assisted in the interaction as well as the estimation of the available groundwater in the region.