The development of weather radar as a research and operational tool for hydrology in South Africa

An overview of weather radar-related developments in South Africa, specific ally aimed at hydrological research and operations, is given. Hydrometeorol ogical applications of weather radar have their roots in the country's long -standing research effort on rainfall enhancement from summertime convectiv e storms. This: programme has developed the necessary infrastructure, exper tise and related hardware and software to collect and archive high-quality radar data, analyse the information and conduct comparisons with convention al measurements on catchment scales. The high spatial and temporal resoluti on, and realtime nature of radar data have distinct advantages over even de nse raingauge networks when catchment rainfall under convective conditions is estimated for flood hydrology. These advantages are highlighted by two c ase studies presented. The information gained from radar data has also prov ided insight into the structure of rain-producing systems, enabling the mor e accurate modelling of the phenomenon. Shortcomings of weather radar data for hydrological applications are described and the ongoing research effort s to address these shortcomings are highlighted. These include methods to r educe the impact of ground clutter, anomalous propagation, hail and the bri ght band on rainfall estimates. It also includes methods to extend the usef ul range of radar data for rainfall estimation, necessitated by the less-th an optimal radar spacing over South Africa. Furthermore, some of the plans to optimise the use of the radar infrastructure are highlighted with specif ic reference to the radar networking system and how radar rainfall estimate s might be integrated with satellite rainfall estimates and measurements by conventional gauges. (C) 2001 Elsevier Science B.V. All rights reserved.