Beach Nourishment Experience in the United States: Status and Trends in the 20th Century

摘要

Beach erosion is a worldwide problem that is particularly noticeable along developed shorelines that front open-ocean costs. Engineered response to the coastal erosion problem in the United States features the imposition of hard structures (such as seawalls and groins), and soft structures such as beaches and dunes. Beach nourishment has become the shore protection measure of choice because it is a multipurpose approach that provides economic and environmental advantages to threatened coastal systems. Experience with the procedure in the US over the last century identifies trends towards improved methods of fill placement, better design strategies, and recognition of increased potential of performance associated with larger fill densities. Maintenance volumes (expressed in terms of total volume per unit length per year) for Atlantic, Gulf and Pacific coast nour- ishment programs decrease from north to south along the Atlantic coast and from Atlantic coasts to Gulf coasts. Planning long-term nourishment requirements requires differentiation of volumetric maintenance needs from initial construction. Of the 1 x 10~9 m~3 (one billion cubic meters) of sediments removed from America's beaches by engineering works and anthropogenic activity in the past century, about 650 x 10~6 m~3 (six-hundred fifty million) have been returned to the beaches. There is thus a sediment deficit that needs to be mitigated over the long term.