Beach Erosion: Causes and Stabilization

Abstract

Natural and human-related causes of beach erosion are discussed and illustrated by examples. Sea level rise, trapping of sand by natural inlets and migration of natural inlets are the most pervasive natural causes. Construction of navigation works, followed by reduction in sediment delivery to the coast and subsidence induced by ground fluid extraction are the most prevalent human-related causes. Application of the Bruun Rule to sea level rise is discussed including its limitations and extensions to include beach nourishment and barrier islands. Prediction of shoreline changes caused by natural phenomena on decadal scales can only be accurately calculated with historical data. However, predictions of shoreline and volume changes due to human-induced effects such as construction of a littoral barrier or a beach nourishment project can reasonably be calculated with analytical and numerical models. Societal responses to beach erosion are expensive and limited to: retreat, stabilization with structures, nourishment and combinations of the last two. Each beach is unique thus placing a need to understand the cause of the erosion, develop a prognosis for “without response” conditions and prescribe the best approach for the future. Fortunately, long-term shoreline changes are available in some areas as are the effectiveness of some stabilization projects to guide this process. It is concluded that it will be possible to maintain some highly developed areas for one or two centuries with available technology and resources. Some areas will undoubtedly require abandonment within this period.