Delineation of groundwater protection zones: Towards a groundwater management plan in the Sutherland area, South Africa
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Date
2022
Authors
Mulder, DaniƩl
Journal Title
Journal ISSN
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Publisher
University of the Free State
Abstract
The water resources of the largely groundwater-dependent Central Karoo region have been put under much strain as a result of continuous drought over the past seven years (DWS, 2021a). Rainfall patterns have been erratic, with the lowest recorded rainfall in decades. Hence, there has been limited recharge to the respective aquifers, resulting in declining groundwater levels and a decrease in borehole yields. The town of Sutherland relies solely on groundwater for its water supply. It was reported by the DWS (2021a) that in the long term, continuous water level monitoring of the production boreholes has indicated a general drop in water levels and a correlating decline in yields. In addition to dropping water levels, there has been a large increase in the number of privately owned boreholes drilled within the town area. Previously, these boreholes mostly targeted shallow water strikes within the fractured aquifer. However, with the declining water levels noted above, these boreholes have become increasingly low yielding and, in some cases, even dry. The response to this has been private drilling continuing past the shallow fractures to deeper water strikes in the aquifer, likely contributing towards a general drop in water levels within production boreholes close to town. The existing water supply boreholes are located within a 1-km radius of the town where the significant increase in groundwater use is occurring. Furthermore, historically, other than wellhead protection, the supply boreholes have been unprotected against contamination and the impact of other groundwater users. Figure 1 depicts one of the existing production boreholes and wellhead protection with a residential area in the background. In 2021, the expansion of the existing town supply with newly developed boreholes and wellfields targeted relatively undeveloped and undisturbed areas. This presented the opportunity to delineate protection zones and to develop standard operating procedures for sustainable aquifer management that will prevent the deterioration of groundwater quality and the aquifer itself through contamination and over-abstraction.
Description
Dissertation (M.Sc.(Geohydrology))--University of the Free State, 2022