Surface Water Flooding

The Surface Water Flooding component of our Hazard Impact Model project is led by the Centre of Ecology and Hydrology in collaboration with the Health and Safety Laboratory, Environment Agency, Met Office and the Flood Forecasting Centre.

The Surface Water Flooding component forecasts hazard, impact and risk information based on Met Office predictions of likely rainfall. These forecasts are used by hydrometeorologists at the Flood Forecasting Centre to improve their understanding of flood risk and potential impact, and to support their issuing of guidance through the Flood Guidance Statement to emergency responders.

The Hazard

The flooding hazard is based on the Centre of Ecology & Hydrology's Grid-to-Grid model, which converts probabilistic rainfall forecasts - based on the high-resolution Met Office Global and Regional Ensemble Prediction System (MOGREPS-UK) - into surface water runoff.

G2G

Impacts and Vulnerability

Impacts were grouped into four categories. Vulnerability was assigned by the function of a building and by a person's age and health. 

The impact data are combined with the Environment Agency’s Flood Map for Surface Water dataset to create a pre-calculated Impact Library of potential flood impact information. This is matched to probabilistic Grid-to-Grid surface runoff forecasts to produce scenario maps of flood impact severity. These maps are combined to produce county-level risk scores using the Flood Forecasting Centre's Flood Risk Matrix that links potential impact and likelihood to give an overall assessment of flood risk severity.

SWF_workflow2

The Surface Water Flooding Hazard Impact Model is currently in a trial phase at the Flood Forecasting Centre, where it is being applied alongside existing tools to assist in the provision of flood guidance.