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Beach Nourishment

sand beaches shoreline erosion

Beach nourishment is the artificial process of adding sediment to a beach for recreational and aesthetic purposes, as well as to provide a buffer to coastal erosion. The sand may be dredged from nearby and pumped onto the beach, or transported in from outside areas. It is considered a soft method of stabilizing the shoreline, as opposed to rock and concrete structures meant to capture sand or protect the shore from wave erosion.

Fixed seawalls, groins, breakwaters, and jetties frequently result in net loss of beach area and may have a negative effect for beach recreation and appearance. They also tend to affect adjacent stretches of the shoreline, frequently in a negative manner. Beach nourishment can often achieve many of the same goals as fixed structures without some of the negative aspects. In an effort to restore their beaches in a manner that least impacts the environment, many communities have elected to employ beach nourishment.

The demand for beach nourishment comes from beachfront property owners and communities that rely on beaches for recreation and as a source of economic revenue. Because shorelines are constantly changing with the environment, people living near them are often faced with situations where they find it necessary to protect their shores from what they believe are adverse modifications.

More than 70% of Earth's shorelines are retreating due to rising sea levels. As shorelines move landward, structures located on or near the beach may be destroyed. In addition, communities may lose significant amounts of income if they lose the use of their beaches. It is, in fact, the interaction of the natural migration of the beach with the placement of beachfront structures that creates the demand for shoreline protection. If no homes, roads or businesses were built in the coastal area, beach retreat might be seen more as the fundamental process that it is and not as a threat that should be thwarted. Shorelines moving landward do not necessarily mean that beaches will vanish.

Beach nourishment is much more than dumping additional sand onto the beach. Mathematical models, although controversial, have been developed to determine how much sand is needed and its most beneficial placement. They also forecast how long until the next round of nourishment is required, for a nourished beach erodes as fast, if not faster, than the original beach. The first beach nourishment project took place on Coney Island, New York, in 1922 and it is an on-going project. In 1997, new technology using multibeam surveying equipment was introduced in Denmark to save on surveying costs and produce more accurate surveys for use in beach modeling.

Nourishment is required every few years to keep beaches from retreating and the cost is typically millions of dollars per nourishment event. Such a project often seems to present greater benefits than the fixed structure method. However, the life of the nourishment project can rarely be predicted with accuracy and the costs are often borne by the taxpaying public rather than those property owners that benefit most directly. Proponents of beach nourishment would argue that restored beaches might draw more economic development to an area. Critics would counter that the existing and increased development at the shoreline are responsible for establishing the need for nourishment, and that the cost of protecting structures on a retreating shoreline will eventually exceed the value of the property, no matter what type of erosion control is selected.

Beach ecosystems may be negatively impacted by nourishment. For example, vegetation and animals may be buried by the sand placement. Turtles cannot use the beach for laying eggs if the new beach is too steep. Grain size of the new sand must be considered, because it is best for the beach ecosystem if the new sand and original sand are similar in grain size. Otherwise, for example, the new sand may contain excessive amounts of mud, or the construction process may muddy the water, harming organisms. Collection of the fill material from the borrow pit may also impact the flora and fauna of that area. Environmental impacts are repeated each time the beach requires nourishment.

Beach nourishment has become the preferred method of erosion control for many U.S. beaches. Nourishment provides continued use of recreational beaches and protects structures near the shoreline. While the advantages of this engineering method over other techniques of shoreline protection, such as seawalls and breakwaters, have been recognized, issues regarding the environmental, economic, and social impacts of beach nourishment remain. Ultimately, the continued rise of sea level due to global climate change may make beach nourishment untenable.

Resources

Books

Commission on Engineering and Technical Systems, National Research Council. Beach Nourishment and Protection. Washington D.C.: National Academy Press, 1995.

Keller, Edward. Environmental Geology. Upper Saddle River, NJ: Prentice-Hall, Inc., 2000.

Other

Geological Society of America (GSA). Beach Nourishment: The Wave of the Future for Erosion Control (Part A). Southeast Section Annual Meeting Abstracts. 2001 [cited October 19, 2002]. <www.gsa.confex.com/gsa/2001SE/finalprogram/session_77.htm>.


Monica Anderson

KEY TERMS

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Beach nourishment

—The artificial process of adding sediment to a beach to improve recreation and appearance and to provide a buffer to coastal erosion.

Borrow pit

—An excavated area for the collection of fill materials such as sand or gravel.

Breakwater

—An offshore structure built to dissipate the force of waves.

Groin

—A wall built perpendicular to the shore to trap sediment or prevent erosion.

Jetty

—A structure that extends from the shore, usually to protect the entrance to a harbor from sediment buildup.

Seawall

—A man-made wall, frequently with a steep face, built along the coastline to prevent erosion by waves.

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