Real-time hazard impact modelling of surface water flooding: some UK developments

Following recent UK floods (summer 2007 and Cornwall 2010) and the UK Government’s Pitt Review, forecasting and warning of surface water flooding (SWF) has received much attention. To support effective mitigation actions there is a growing demand for more robust, accurate and timely forecast and alert information on surface water flooding and its impacts at local, regional and national scales. The Natural Hazards Partnership (NHP) aims to provide co-ordinated information on natural hazards from across UK government departments, agencies, trading funds and public sector research establishments. Under NHP, a Hazard Impact Model framework is being developed and SWF is one of three initial hazards being trialled. In contrast to rainfall threshold based methods, the NHP prototype SWF approach is based on dynamic gridded surface runoff estimates from the Grid-to-Grid model which is already used for operational fluvial flood forecasting. Methodologies for generating dynamic maps of the possible impact have been derived using national datasets of population, infrastructure, property and transport. The prototype approach is explained and illustrated through a case study along with a perspective on future developments.