The Floodrelief Internet-based Flood Forecasting Decision Support System

For operational flood forecasting and operational decision-makers, ready access to current and forecasted meteorological conditions is essential for initiating flood response measures and issuing flood warnings. Effective flood forecasting systems must provide reliable, accurate and timely forecasts for a range of catchments; from small rapidly responding urban areas, to large, more slowly responding fluvial systems, often within the same region. Using meteorological observations and quantitative precipitation forecasts to produce hydrological flood forecasts provides valuable increases in lead-time that can be exploited to mitigate the effects of a flood event. However while the value of accurate meteorological forecasts is widely recognised real-time flood management decisions must be based on an understanding of the uncertainties and associated risks. The need to address these requirements has led to the development within EU 5th framework project FLOODRELIEF of an internet-based decision support system to provide highly accessible real-time flood management tool. This decision support system has been designed together with FLOODRELIEF forecasting end-users to provide flood management and forecast information in a flexible, efficient and easily understood manner to operational users and decision makers. Comprehensive facilities for accessing and presenting both meteorological observations and numerical weather forecasts are available. The system has been integrated with a highly portable, low cost operational numerical weather forecasting system THOR. The THOR system has been developed within the FLOODRELIEF project to provide quantitative precipitation forecasts at different resolutions using dynamical downscaling. Ensemble forecasting using different forecasting inputs provides a flexible Proc. International Conference “Innovation, advances and implementation of flood forecasting technology” 17-19 October 2005, Tromsø, Norway. 2 method of estimating uncertainty. For example, alternative rainfall forecasts using mesoscale meteorological forecasts or weather radar forecasts can be used by operational forecasters to models to estimate an uncertainty range. In this manner a direct and intuitive estimate of forecast uncertainties that can be communicated to flood managers and decisionmakers, is achieved. This decision support system is applied to regional flood forecasting in the UK, in the FLOODRELIEF study catchment, the Welland and Glen.