A surface water flooding impact library for flood risk assessment

Abstract

The growing demand for improved risk-based Surface Water Flooding (SWF) warning systems is evident in EU directives and in the UK Government’s Pitt Review of the 2007 summer floods. This paper presents a novel approach for collating receptor and vulnerability datasets via the concept of an Impact Library, developed by the Health and Safety Laboratory as a depository of pre-calculated impact information on SWF risk for use in a real-time SWF Hazard Impact Model (HIM). This has potential benefits for the Flood Forecasting Centre (FFC) as the organisation responsible for the issuing of flood guidance information for England and Wales. The SWF HIM takes a pixel-based approach to link probabilistic surface water runoff forecasts produced by CEH’s Grid-to-Grid hydrological model with Impact Library information to generate impact assessments. These are combined to estimate flood risk as a combination of impact severity and forecast likelihood, at 1km pixel level, and summarised for counties and local authorities. The SWF HIM takes advantage of recent advances in operational ensemble forecasting of rainfall by the Met Office and of SWF by the Environment Agency and CEH working together through the FFC. Results are presented for a case study event which affected the North East of England during 2012. The work has been developed through the UK’s Natural Hazards Partnership (NHP), a group of organisations gathered to provide information, research and analysis on natural hazards for civil contingencies, government and responders across the UK.