The hydrochemistry of rivers in KwaZulu-Natal
The chemistry of the major elements of KwaZulu-Natal river water draining the eastern Drakensberg Escarpment was monitored in October 2003 and compared to data obtained previously along the western Drakensberg Escarpment, i.e. the Caledon and Upper Orange Rivers. The data obtained in these two surveys reveal no significant differences in the Mg, Ca, Na, K and HCO3- content of rivers draining similar lithologies, despite slightly different climatic regimes and different suspended loads. The implication is that lithology is the dominant control on the major element chemistry of river water draining the Drakensberg. However, in the north-western part of KwaZulu-Natal, drought-stricken at the time of sampling, evaporation-induced concentration results not only in evaporite formation, but dramatic changes in river and stream water chemistry. Elevated levels of minor constituents such as NO 3- also indicate that in cultivated areas anthropogenic activities have an impact on water quality and composition.