Combining regional and local scale coastal flood risk assessment and hazard modelling

This paper presents a method to combine regional- and local-scale flood risk assessment with numerical modelling of coastal inundation under sea defence breaching. We review existing coastal defence inspection reports, and by combining structure condition, deterioration, hinterland significance and inundation probability, we generate a risk score for each stretch of coastal defence in North Wales and North-West England. A frontage in North-East Wales deemed to be at high risk was used for a detailed hazard study using a flood model (LISFLOOD-FP), where a 0.5% probability flood was modelled under various sea-level rise and defence breaching scenarios. Flood hazard ratings given partial and total failure of the sea wall under present day, 2050 and 2100, and H++ sea-level scenarios are simulated to identify future flood risk to key infrastructure within the coastal community.