American Society of Civil Engineers


The Impact of Anthropogenic Activities on Coastal Erosion


by Orville T. Magoon, (President, Coastal Zone Foundation, P.O. Box 279, Middletown, CA 95461), Billy L. Edge, (W. H. Bauer Professor of Dredging Engineering, Ocean Engineering Program, Department of Civil Engineering, Texas A & M University, College Station, TX 77845), and Katherine E. Stone, (Myers, Widders, Gibson & Long P.O. Box 7209, Ventura, CA 93006)
Section: Part V Coastal, Estuarine, and Environmental Problems, pp. 3934-3940, (doi:  http://dx.doi.org/10.1061/40549(276)308)

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Document type: Conference Proceeding Paper
Part of: Coastal Engineering 2000
Abstract: From the earliest time, civilizations have been dependent on coastlines. Fishermen built their huts, tended their nets and gained access to the great food supply of the oceans at the coastlines. Kings and Lords recognized the values of the sea’s products for food and the relevance of bays and river mouths for commerce and eventually as staging areas for their military. The coasts have always had an important recreation value. Most experts agree that wide sandy beaches are the best form of coastal protection. In modern times we have come to realize that everyone benefits from the coast, thus all must share in the responsibility for maintaining the coast. As civilization demands more from the coast and interrupts the supply of sand to the coast by constructing cities and harbors, dams and flood control works and navigation structures, the coastal erosion induced by storm waves is often exacerbated. Until recently, planners and designers did not understand that the works of civilization at some distance from the coast could cause devastating erosion of coastal shores and beaches. Plains and hills or mountains that had once easily eroded during severe rain storms and supplied great quantities of silica sand to wash to the shore are now covered with parking lots, streets, homes and buildings, and other structures. Sands are mined from rivers, streams and beaches for fill and aggregate, for glass bottles and for sandboxes. In tropic latitudes, increased turbidity and reduced water quality has had a negative impact on the health of reefs and calcium carbonate beach sand production. These cumulative actions all reduce the supply of sand to coastal beaches, which in turn would have provided much needed recreational areas, good shore protection, and an environmentally valuable habitat. Although the short-term impact of an individual development may be difficult to quantify, the cumulative effect of sand-reducing activities is catastrophic over the long term, costing billions of dollars in public and private property damage. Compounding this problem is the fact that laws, regulations, and coastal remedial works have usually focused on the immediate reach of coast affected and have not addressed the basic cause of the problem: the prevailing lack of sufficient supply of sediment to the coast. Some of the major factors in reducing sediment supplies both along the coastal and over entire drainage basins are described in the following four paragraphs.


ASCE Subject Headings:
Coastal processes
Beach erosion
Human factors
Storms
Wave action