Prefeasibility study for managed aquifer recharge within the Greater Kruger National Park, Limpopo province, South Africa
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Date
2022-02
Authors
Holloway, Michael Thomas
Journal Title
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Publisher
University of the Free State
Abstract
The Greater Kruger National Park (GKNP) is located in South Africa, which is a relatively dry country and among the 20 most water-scarce countries in the world. Two study sites for a prefeasibility study are situated along the western borders of the GKNP, located within the private game park boundaries of Olifants West Nature Reserve (Balule) and Timbavati Game Reserve (Motswari), north of Hoedspruit. Warm summer with seasonal rainfall on hot afternoons and winters that are mild and dry with almost no rainfall characterises the climate of the study areas. Except for Water Research Commission (WRC) reports and selected geological reports on regional geology surrounding the study areas, few hydrogeological studies have been conducted in the study areas. This dissertation investigates the prefeasibility of progressing to a full feasibility study for Managed Aquifer Recharge (MAR) through a combination of literature investigations and diagnosis of multiple field visits to collect hydrogeological information within the study areas. National guidelines on MAR have been consulted throughout the dissertation and study to guide the investigation on the potential for success to feasibility within the study area for MAR. The study involved an in-depth hydrocensus of both study sites to identify all possible boreholes, as well as establish a monitoring network of selected boreholes to monitor the effect of regional groundwater use on the hydrogeological setting. Geochemical analysis was conducted on both groundwater sites and surface water sites to class the water quality against water types and drinking water guidelines for usage within communities and game reserves/lodges. Geophysical surveys and available literature were assessed to characterise the hydrogeological flow regimes within the study areas, to develop a conceptual model for further understanding of the study areas hydrogeology, as well as to complete specific elements of a prefeasibility study check-list. In accordance with the prefeasibility check-list, many aspects were investigated to determine the success and need for a MAR scheme. Water level monitoring of selected boreholes indicated that over a period of two-and-a-half years, an overall decrease in the water table for boreholes at a higher elevation. This decrease in water level indicated that the aquifer is dewatering as a result of either below average annual rainfall recharge or over-abstraction of groundwater users of the aquifer. Chemistry results of groundwater and surface water sites indicated that the surface water (or source water) is much more desirable than the groundwater, which is typically characterised by elevated electrical conductivity (EC), fluoride (F) and nitrate (NO3) across both study sites. Surface water was more ideal and only displayed elevated aluminium. Through geophysical methods and literature studies, potential MAR sites were identified for both study areas, whereby an Aquifer Storage Transfer and Recovery (ASTR) method can be implemented for recharging groundwater into dolerite dykes and mapped lineaments, upgradient of abstraction boreholes to increase water security and improve the natural groundwater quality setting. MAR schemes are initially more expensive to establish than conventional methods such as water treatment facilities, however, the annual operating expenses are much lower and can see a faster return on investment than treatment options. The MAR method proposed is non-invasive and opportunistic for flood water runoff from within drainage channels, whereby potential groundwater zones of MAR correlate to. It is recommended that this dissertation complete the purpose of a prefeasibility study and precedes a feasibility study in the future.
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Keywords
Dissertation (M.Sc. (Geohydrology))--University of the Free State, 2022, Greater Kruger National Park (GKNP) -- South Africa