Providing hydrological information and data analysis tools for the determination of ecological instream flow requirements for South African rivers

The new South African Water Act and the inclusion of a component that stipulates that some water has to be reserved to maintain the ecological functioning of rivers has stimulated a renewed interest and need for detailed hydrological data. This has occurred at a time when many of the countries rivers are already affected by impoundments, abstractions, return flows and land-use change impacts. The need to relate the ecological requirements of rivers to the characteristics of the natural flow regime and to convey the details of flow regimes to non-hydrological specialists has presented hydrologists with an exciting challenge. It is rewarding to discover that the status of hydrological research and practice in South Africa, and the methodologies that were already available, were more than capable of responding to this challenge and that the hydrological tools required to assist with the implementation of the new act were either already available or could be developed rapidly.