Probabilistic coastal flood forecasting

The project described in this paper included development of surge ensemble modelling for the UK, and demonstration of probabilistic coastal flood forecasting for an area in the Irish Sea. Its purpose was to develop, demonstrate and evaluate probabilistic methods for surge, nearshore wave, and coastal flood forecasting. The main features that distinguish these methods from existing UK practice are in the use of hydraulic models extending through to action at coastal defences, and the use of ensemble and other probabilistic approaches throughout. Estimation of high overtopping as an indicator of coastal flooding involves transformation of wave forecasts through the nearshore and surf zones, and the combined effects of waves and sea level in causing overtopping; with sufficient accuracy and reliability for acceptance, and sufficient lead time for actions to be taken to reduce potential losses.