Effects of human activities on the Waterval River, Vaal River catchment, South Africa

Abstract

Rand Water's chemical water quality data from 1991 to 2000 were used to assess the water quality of the Waterval River, which contributes about 111 x 10⁶m³ of water to the Vaal River annually. Due to a biological community's ability to reflect water quality changes over time, biomonitoring was undertaken to support chemical water quality monitoring. Aspects of the riverine habitat, invertebrates and fish were investigated to give baseline information on the area. Human activities such as mining, industry, agriculture, rural and urban settlements are currently responsible for the deterioration of the ecological integrity of this river system. Habitat degradation was especially evident in the upper reaches of the Waterval River, as indicated by the South African Scoring System, version 4, Average Score Per Taxon and Biotic Integrity scores. In general, the ratings achieved were lower than those expected for the available habitat, which suggests that human activities have influenced the biotic community. By selectively addressing the areas of concern, the state of the environment can be improved, using the current assessment as a benchmark to measure the success or shortcomings of any actions in the years to come.