Shepway Strategic Flood Risk Assessment (SFRA)

Project name

Shepway Strategic Flood Risk Assessment (SFRA)

Location

Shepway District, Kent

Client

Shepway District Council (SDC) & Environment Agency

Description of Project

With over 40km of coastal frontage and a collection the low lying marshland within the district, SDC & the EA jointly commissioned Herrington Consulting to undertake a detailed SFRA to examine the impacts of both breach events and wave overtopping along the various defended and un-defended coastal frontages.

Considerations

Given the vast size of the continuous flood compartment that forms the Shepway District, the main consideration was being able to construct a numerical flood model that could accurately represent a series of flood event scenarios, whilst maintaining a high level of detail. A detailed 2D grid (25m in size), was built to represent the entire flood compartment and a series of breach and wave overtopping scenarios, 28 in total, were tested. These scenarios comprised multiple breach locations, present day and climate change conditions and provided the LPA with accurate outputs in the form of GIS mapping layers.

Numerical Modelling

Suite of wave overtopping models used, 2D hydrodynamic TUFLOW model used to determine flood depth, velocity, flow paths and hazard rating.

Outcome

The detailed outputs comprised two separate combined hazard maps, one for the current day and one including an allowance for the impacts of climate change. The various maps and accompanying report have been vital in enabling SDC planners to apply the Sequential Test within the areas of the district that are at risk of flooding and to enable clear decisions to be made. Consequently, the highly accurate results have also been used to aid the Environment Agency when reviewing countless Flood Risk Assessments within the district.