Real-Time Flood Forecasting Systems: Perspectives and Prospects

Advances in flood forecasting concern much more than innovation in model formulation. This paper aims to provide a perspective on developments in the UK over the last twenty years, initially by reviewing models in current operational use but progressing to discuss updating methods, the use of weather radar and lastly the introduction of integrated flood forecasting systems. Updating methods allow real-time measurements, for example of river level received via telemetry, to be used to improve model performance. Weather radar allows point measurements of rainfall, from an often sparse raingauge network, to be complemented by spatially continuous measurements of the rainfall field and thereby, provide improved input to flood forecasting models. Most recently, flood forecasting systems have been developed capable of coordinating the construction of forecasts at many points across a possibly complex region and being generic in their use of models and their configuration to any set of river networks without expensive recoding. These developments are examined with an acknowledged emphasis on procedures developed at the Institute of Hydrology and particularly those methods which are incorporated in its River Flow Forecasting System or RFFS. However, these methods are reviewed with reference to techniques developed elsewhere and which are in use operationally, thereby providing an overview of the present state-of-the-art in the UK. Prospects for future improvement are considered, focusing on the potential value of digital terrain models to formulate a new generation of distributed model appropriate for operational use in combination with radar rainfall and satel-lite-derived thematic data, for example on land-use.