A review of sediment/water quality interaction with particular reference to the Vaal River system

The effects of sediment on water quality are reviewed, particularly in relation to the Vaal river system, the most important water resource in South Africa. Increased turbidity, the most obvious visual effect, was counteracted in the lower Vaal river by increasing salinity, which had resulted in blooms of rooted underwater macrophytes through greater light penetration. The role of sediment in modifying the impact of pollutants on the aquatic environment is also discussed. Sorption of pollutants on sediments played an important part in the dynamics of organic and inorganic compounds in the Vaal system.