In addition to the natural processes that cause erosion, human alterations are affecting erosion rates. Some of the engineering solutions designed to protect certain portions of the shoreline accelerate the erosion of nearby areas by impeding beach sand supplies. Clearance of dune-stabilizing vegetation and destruction of the dunes themselves remove a substantial source of protection against high water and storm waves. While coastal erosion affects all regions of the United States, erosion rates and potential impacts are highly localized. Average coastline recession rates of 25 feet per year are not uncommon on some barrier islands in the Southeast, and rates of 50 feet per year have occurred along the Great Lakes.
Severe storms can remove even wider beaches, along with substantial dunes, in a single event.
In undeveloped areas, these high recession rates are not likely to cause significant concern, but in some heavily populated locations, one or two feet of erosion may be considered catastrophic. Therefore, the impacts of erosion are not necessarily measured in terms of the highest recession rates, but may be measured against the social and economic costs to the areas affected. Forecasting tools are improving, yet the public often does not heed warnings of impending danger.