The constant movement of sand is a natural cycle that results in an ever-changing beach profile and coastline. As part of this cycle, beaches experience regular phases of erosion and accretion.
Accretion is the build-up of sand and typically occurs during the calmer summer months, when sand is gradually returned onshore and the beach width increases. In contrast, erosion is the loss of sand offshore into sand bars and occurs during the stormy winter months.
Erosion can happen slowly or rapidly depending on the conditions at the site and can result in a dramatic change, often resulting in loss of beach and erosion escarpments (scarps) along the front of sand dunes. Nearshore, beach and dune systems can take a considerable time to recover from a major storm.