Studies of mineralization in South African rivers

Abstract

Several South African rivers are polluted by mineral salts of diffuse source. This pollution can be related to geological phenomena and to irrigation practices. Mineralization is problematic in that it can render surface waters unsuitable for irrigation as well as for urban and indus¬trial use. A mathematical simulation model is being developed for the Great Fish and Sundays River systems in the Eastern Cape to predict the consequences of different mineralization processes in terms of salt concentration patterns in these rivers for different system operation policies and subject to different extraneous events, such as rainfall sequences. This model is to be verified for the Fish and Sundays Rivers and then applied to two other rivers where mineralization is of concern, namely the Berg and Bree Rivers in the Western Cape. The modelling study requires a large amount of data, in particular, records of river flow associated with chemical water quality, physical and chemical characteristics of irrigated soils, ground-water chemical quality and rainfall. A large scale data collection programme has been established for each of the above mentioned river systems and in each case the programme is expected to be of three or four years' duration to permit useful modelling results.