The quality of the Florisbad spring-water in relation to the quality of the groundwater and the effects of rainfall

Abstract

The spring-water, groundwater and rainfall were examined as part of a study to determine aspects of the environment in which faunal remains at Florisbad were fossilised. A 1988 analysis of the Florisbad spring and exploration pit-water showed a 27% higher TDS in the pit-water after a high rainfall period, despite the two being located only 22 m apart. An extended qualitative water-sampling programme in 1999 confirmed a difference, but in this instance the TDS of the same exploration pit was 49% lower than that of the spring-water after a low rainfall period. This was contrary to the norm where high recharge usually results in low TDS and low recharge results in high TDS. Results also showed extreme TDS variations of up to 6 times higher between individual pit-waters 54 m apart. The fluctuation in the quality of the pit-water, in relation to the stable spring-water, led to the conclusion that the two should be separate entities. It was further concluded that the mineralisation of the pit-water originated either directly, or indirectly, from a source other than the spring-water. Long-term rainfall appears to have only a slight effect on the quality of the spring-water and possibly no effect on the quality of the pit-water, while short-term rainfall appears to have little effect on the spring-water quality, but has a decided influence on the pit-waters. Aspects relating to water quality and water monitoring at Florisbad are discussed and a comprehensive historic record of the spring-water quality and composition is also given. Investigations on the origin/s of the groundwater mineralisation are continuing. The results clearly indicate that the spring-water does not currently carry sufficient mineralisation for fossilisation.


WaterSA Vol.27(1) 2001: 39-48