Nearly all of South Africa's water requirements are drawn from surface resources. It is generally accepted that demand will exceed the exploitable resources within the next 40 years. A reliable means of evaluating surface water resources is therefore essential to planners, designers and managers of water supply schemes.
This paper discusses the problems involved in a country-wide appraisal of surface water resources, with reference to a recently undertaken survey of South Africa. The paper describes how spatial and temporal extrapolation of stream flow observations was accomplished with the aid of a deterministic rainfall-runoff model which takes into account landuse changes. Also described are the techniques employed for statistical analysis of low records to provide information for determination of storage yield at virtually any locality in the country. Some results of the new water resources survey are presented.
A general co-ordinated optimization planning policy for the distribution of mine service water is described. The optimization is aimed at minimizing the non-linear cost functions which include the procurement, desalination and distribution of the water. Constraining parameters include : yields of the sources, requirements of the demand zones, qualities at the sources and the demands and desalination requirements. Non-linear functions are mathematically handled using the separable programming technique. Computer solutions using linear programming and separable programming are discussed. The technique is applied to a mine on the Witwatersrand Reef, South Africa.