A geohydrological situation analysis for the construction of a groundwater management plan for the Sasolburg industrial and mining area

[摘要] English: The Department of Water Affairs in South Africa has recently moved towards the management ofregions on a catchment and subcatchment scale. The Taaibos and Leeu Spruit catchments wereidentified as catchments where groundwater research was needed. The final objective of this workwould be the implementation of a Catchment Management PlanThese catchments house several influences on groundwater quality. These include the urban area ofgreater Sasolburg, several chemical industries (petrochemical, fertilizers, plastics ete), miningactivities, power stations and agriculture.A groundwater situation analysis was therefore undertaken to highlight all relevant groundwatercomponents.To achieve this, the study included a literature study, the creation of a database, fieldwork includingsampling of 101 sites in the catchment for inorganic analysis, sampling of 10 sites for toxicitytesting to indicate true toxicity of the water, aerial geophysics over a portion of the catchment andresistivity soundings at points surrounding the industries.Based on information gathered by this work it was possible to identify the principal aquifers in thearea and classify them according to methods set out by Parsons (1995). The chief controls ongroundwater movement and pollution sources on each site were identified. It was found that adolerite sill of variable depth and thickness was the main control of groundwater movementunderlying the industrial areas.The collected data and sampling highlighted the most important pollution sources. Use of toxicitytesting showed the potential of these tests in indicating the true toxicity of samples. These resultswith, simplified numerical modelling in the area gave an indication of pollution migration and areasof concern.The area was subdivided into groundwater management areas based on the activities in each area.Three zones were defined representing the industrial and mining areas, a buffer zone and the areasto be protected respectively. In each zone different quality guidelines were proposed.A Threat Action Guide spreadsheet was developed to identify and prioritize areas of concern. Ituses water quality data for different parameters, the aquifer classification, the water qualityguideline for the zone and the distance to the nearest area of concern as inputs. A threat index isthereby calculated using various empirical equations and this index then suggests differentgeneralized management options to be followed.The situation analysis has provided an overview of this heterogeneous area and put a basicframework in place on which the eventual Groundwater Management Plan will be based.

[发布机构] University of the Free State