Field investigations and hydrological modelling of dryland agriculture in the Berg Rivers catchment are yielding new insight into the origin of salts and the behaviour of a sensitively balanced water system and will form the subject of a workshop to be held at the University of Stellenbosch this week.

Since the mid 1970s, authorities have been struggling with problems of increased salinity in the Berg River - a major source of drinking water for the City of Cape Town and several towns on the West Coast.

Previously natural dryland salinity (predominantly NaCl salts trapped in Proterozoic Malmesbury-shale sediments) was identified as the source of some of the salts affecting water quality. The hypothesis is that the clearing of natural vegetation for the purpose of agriculture enhanced the mobilisation and discharge of these salts.

According to CSIR principal researcher, Dr Nebo Jovanovic, the results of field investigations so far is yielding new insight into the origin of salts and the behaviour of the system.

Hydrological modelling serves to quantify salt discharges for combinations of land use and management conditions. The research will result in the development of guidelines for regulating land use in terms of salt generation capacity to be adopted by the Department of Agriculture. The guidelines will be based on the knowledge gained from on-farm experiments and hydrological modelling, he says.

A three-day workshop, hosted by the University of Stellenbosch, the Friedrich Schiller University (Germany) and the CSIR will give an overview of the latest research on dryland salinity, land use and hydrological modelling in the Berg River catchment. The workshop will also include a field trip to farms in the study area in the catchment between Malmesbury and Moorreesburg.

Dr Willem de Clercq from the University of Stellenbosch will give the historic background and Jovanovic will present new findings on the geohydrology of the Berg River. CSIR hydrogeologist Richard Bugan will talk about the state of hydrological modelling applied to the rivers catchment. Dr Francois Engelbrecht, atmospheric modeller at the CSIR, will deal with the implications of short- and long-term climate variability.

From the Friedrich Schiller University in Germany, Prof W Flugel and Dr Jorg Helmschrot will talk about new developments in modelling and the challenges we face in South Africa. Other speakers from the Agricultural Research Council and the Department of Soil Science at the University of Stellenbosch will focus on land use practices and the endemic renosterveld.

The workshop is a result of the collaborative research between South Africa and Germany, funded by the National Research Foundation (NRF) and the German government. The research presented at the workshop stems from two projects funded by the Water Research Commission, namely Management of human-induced salinisation in the Berg River catchment (South Africa) and Optimised monitoring of groundwater - surface water - atmospheric parameters for enhanced decision making.

The workshop will take place from 3 to 4 March at the University of Stellenbosch , with a field trip organised for Friday 5 March. Researchers, scientists and interested parties are welcome to contact Jovanovic for more information or to attend the workshop and field trip.