A PRELIMINARY LIMNOLOGICAL STUDY OF BUFFELSPOORT DAM AND ITS CATCHMENT

SUMMARY

A limnological survey of the Buffelspoort Dam and its catchment between 1973 and 1975 showed that the water of the area contained extremely low concentrations of dissolved minerals and that there was no point source of nutrient supply to the dam. The anion and cation dominance in the catchment water may be summarized as HCO3 >Cl >SO₄NO₃ and Na⁺ >Mg⁺⁺ >Ca⁺⁺ >K⁺, respectively, and this water may be classified as soft bicarbonate water. The impoundment was warm monomictic and had an extensive anaerobic hypolimnion during summer stratification. Changes in water transparency were related to the seasonal fluctuation in water content and the hydrological cycle. Nutrient concentrations in the dam displayed seasonal trends which were related to stratification, hydrological events and phytoplankton activity. On the basis of its nutrient content and chlorophyll a concentrations the impoundment can be classified as mesotrophic. The further development of holiday resorts in the catchment poses a cutrophication hazard, especially if expansion results in the installation of sewage treatment plants.