Hydrogeochemical characterisation and evaluation of groundwater resources and review of groundwater management schemes in Kamiesberg, Northern Cape

Abstract

Kamiesberg, located in the semi-arid regions of South Africa, depends primarily on subsurface water resources for domestic, agricultural and industrial use. In order to assess geochemical evolution of groundwater and to identify salinization, a constant threat, regular monitoring is required. Here we evaluate decadal hydrogeochemical data collected by water management schemes applied in Kamiesberg to improve our understanding of the success of groundwater supply and management schemes in sustainable use of groundwater resources. IC and ICP-MS results proved a distinct Na-Cl character of the groundwater as well as elevated salinity of 100-350 mS/m towards the interior, along the Kamiesberg Mountains, and 730-1165 mS/m towards the west coast. Several towns are subjected to microbial contamination as well as fluoride concentrations above the allowable drinking water limit. Municipal water chlorination may be a contributing factor to increased chloride levels (>400mg/L). Potable water quality at towns served with treated (desalinated) water complies with the national drinking water standard for major element composition, emphasising necessity for wider distribution of desalinated and disinfected potable water. Soils analysed for U mainly indicated concentrations higher than the world mean value of 0.7-9mg/L, however, no correlation between U levels in groundwater and host rock was established.