Predicting coastal evolution using a sediment budget approach; a case study for southern England

Despite the fact that coastal evolution occurs over a range of temporal and spatial scales, most existing modelling tools for predicting coastal evolution are founded on the science of the small-scale coastal processes. This paper discusses the role of a variety of approaches to predicting coastal evolution and considers that the ability to predict long-term (e.g. 50–100 years plus) larger-scale changes in coastal systems is of paramount importance to coastal managers if the ultimate aim of developing long-term sustainable management of the coast and its resources is to be achievable. The advantages of asediment budgetary approach to predicting coastal evolution are discussed and it is suggested that such an approach is better suited to predicting long-term and large-scale coastal behaviour than existing hydrodynamic and physical models. The procedure for developing a conceptual sediment budget model for predicting coastal evolution is outlined, based upon the identification of littoral cells, and consideration of sediment sources, throughputs and sinks. This modelling procedure is then applied to a “real case” coastal unit located in central southern England, namely Poole Bay, in order to exemplify its benefits and the type of results achievable. From the model, it is suggested that the most appropriate strategy for Poole Bay is one of continued beach replenishment, with maintenance of the existing seawall and groyne defences.