The beach of Pevensey Bay (UK) is a shingle barrier beach under threat from flooding and coastal erosion. Today, the beach is managed in an adaptive manner developed by Pevensey Coastal Defence, where management activities respond to changes in risk and beach recharge and beach recycling is undertaken.
Based on: Sutherland, James, and Ian Thomas. "The Management of Pevensey Shingle Barrier." Ocean & Coastal Management 54 (2011): 919-29.
Pevensey Bay, located between Eastbourne and Cooden in East Sussex on the southern coast of England, surrounds a nine kilometre beach under threat from flooding and coastal erosion. The beach is a shingle barrier beach, a mix of sand, gravel and cobbles protecting important animal habitats, properties, roadways and other infrastructure. Additionally, approximately 50 km2 of valued low-lying conservation and agricultural land could be flooded should the beach become breached at high spring tide. The challenge facing local authorities and residents is that each wave of sea water on the barrier beach takes more sediment away than it brings, resulting in a net loss of coastal land as time progresses. This issue is compounded by sea level rise, and both contribute to increased risk of flooding and loss of land through erosion.
In general, the strategy of the Pevensey Bay beach management plan can be classified as “hold the line”, which involves strengthening and upgrading the existing coastal defences. In Pevensey, it was decided to thicken the barrier beach through beach nourishment, recharge, and recycling to bring more protection from breaching.
In response to the flood and erosion risk, the UK Environmental Agency has tasked the Pevensey Coastal Defence consortium to manage the barrier beach of Pevensey Bay. The consortium implements activities in response to assessed risk that are determined through monitoring. This strategy is representative of an adaptive management approach whereby risk and uncertainty are managed through an continuative process of informed decision making that responds to regular monitoring.
Pevensey Coastal Defence was able to meet their tactical objectives by following a three-part process of measurement, benchmarking and implementation. The three stages helped maintain the natural and social health of the Pevensey Bay. Firstly, both the Environmental Agency and Pevensey Coastal Defence performed cross-shore profiles and beach surveys several times a year to get a better understanding of the level of erosion. The measured values are compared, or benchmarked, to set threshold values of various coastal state indicators that would indicate existing and predicated erosion and flooding. Finally, the differences between measurements and thresholds let decision makers compare intervention strategies as well as the locations to implement these strategies. Considered and implemented strategies include variations of beach nourishment, recharge, recycling and re-profiling through the use of dump trucks or boats. This last stage has a temporal factor with different strategies being more efficient and environmentally sound at different times of the year.
A study of the Pevensey Bay barrier beach concludes that early decisions made during the adaptive management process should carefully consider several coastal state indicators and thresholds that will determine when to intervene and by how much. Additionally, Pevensey Bay, like other similar shrinking beach areas, is best protected by beach recharge sourced from external sediment reservoirs in tandem with beach recycling, all the while considering the health and impact on natural systems.