Updated flood risk assessment

Flood modelling uses predicted river flows, rainfall, and coastal levels combined with topographic data and flow equations to generate flood risk information (such as depth, velocity, flood levels, and hazards). Our team of specialists updated the coastal flood modelling for Shanklin to ensure it uses the latest information and software available.

The main coastal threat to Shanklin is erosion of the sea defences due to their current poor condition. Our latest modelling predicts that failure of the coastal defences would lead to the loss of the beach amenity and access to the esplanade. This which would have significant knock-on impacts to the area. We estimate that 76 residential and 55 non-residential properties are at risk of flooding from failure of the sea wall. The below map shows the anticipated flood extent in the event of defences failing.

Preventing this scenario can be achieved through either Option 3, Option 4 or Option 5*. Increasing the height of the coastal defences does not provide any additional erosion protection over Option 3, it only provides a greater level of protection against flooding associated with waves overtopping the sea wall.

Modelling results tell us that the risk of flooding from wave overtopping is low given the existing height of the defences and raised floor levels of properties. Modelling suggests that 5 non-residential properties and 0 residential properties in Shanklin would remain at risk of internal flooding from overtopping after completion of Option 3.

*Option 3 - Keep the existing defence level
*Option 4 - Raise the level of the defence in stages into the future
*Option 5 - Raise the defence level now