Understanding barrier beaches – a scoping study

Barrier beaches around the UK are important, not only in terms of defences against flooding but also in their own right as important coastal geomorphological features. A lack of detailed understanding of how these beaches evolve and of models to predict their performance as flood defences, together with constraints on acceptable methods of intervention, make the successful and cost-efficient management of barrier beaches a challenging task for coastal managers. The need for better management of such beaches as both flood defences and natural heritage areas will inevitably increase in the face of rising sea-levels. A team from HR Wallingford, the University of Southampton, and the Channel Coastal Observatory, with the support of funding from Defra/EA (project FD 1924 - Understanding Barrier Beaches: A Scoping Study) has mapped, classified and reviewed barrier beaches. Importantly, the scoping study has documented management techniques, and identified what future research is required. Main points *What are they? Describe a typical barrier beach and explain briefly their geomorphological and other attributes – photo of Chesil here. *Why this study? BBs often form a natural food defence to low-lying and behind them. but not naturally of an adequate standard to protect e.g. residential properties They are sometimes overtopped by large waves, leak and or roll-back landward, and such events are likely to become more frequent as sea levels rise. All these events can give rise to unacceptably high flood-risks, often justifying improving the standard of protection they provide, although the natural heritage interests of such beaches can constrain what type of intervention is acceptable. * Aims of this study To justify and provide a scope for further research into barrier beaches so that their processes and evolution can be better understood and predicted, and appropriate methods for their management recommended. *Main outputs of study Cataloguing of UK barrier beaches, including an on-line database / GIS system that provides details of these beaches (location, sediment type, add extra details); Review of BB management methods used based on consultation with “owners” of the beaches (includes monitoring and appropriate analysis); Review of scientific literature and of existing predictive process methods for overtopping, leaking and morphological change of barrier beaches; Recommendations for a future staged research programme to improve both predictive methods and to produce “Best Practice” guidance for cost-effective and environmentally acceptable management of barrier beaches as natural flood defences (including monitoring their condition, performance and the flood defence standard they offer).