Simulating the hydrology and water resources of large basins in southern Africa

There are a number of problems associated with developing water resources management strategies in the large basins of Africa where data are scarce. This paper reports on some initial applications of drought assessment methods and a hydrological model in the Zambezi and Congo basins, using global rainfall data sets as the main input information. The drought analyses using CRU and GHCN rainfall data for the Zambezi show broad agreement, but some important local variations. The results are related to FAO crop production statistics, but further testing of alternative drought indices is required. Gauged streamflow data (12 sites) and CRU rainfall data were successfully used to calibrate and validate the Pitman monthly time-step rainfall-runoff model for many parts of the Congo basin. Problems were experienced in one of the headwater tributaries and in the ungauged central parts of the basin. Further work will include assessments of future climate change scenarios and their uncertainty.