How Beaches Are Protected
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Every second of every day rivers dump sand, silt, and other sediments into oceans. What happens to these sediments? Ocean waves deposit some of them along coastlines. This forms a sandy beach. Beach sand may also include weathered shells or other hard parts of ocean animals. Along some coastlines ocean currents and waves deposit sand and dirt just offshore from the mainland. Over many years these deposits may build into a new land-form called a barrier island. A long chain of barrier islands run down the Atlantic coast of the United States. The chain includes the Golden Isles, the popular name for several of the barrier islands along the Georgia coast. All ocean beaches change with the seasons and from day to day. Waves may pick up beach sand then deposit it farther down the beach. Tides also move sand as they advance and retreat. Winds blow sands into small hills called dunes. The dunes are always changing shape and size. Beaches also change from year to year. Today on the eastern shores of Georgia's coastal islands, ocean waves and currents are washing away more beach sand than they are depositing. Thus the beaches are slowly eroding away. The ocean is depositing sands in the marshes and in open waters to the west of the islands. Why do beaches erode in some places and build up in others? Remember that beaches are part of a system that includes the land, rivers, and oceans. Any change in the system may change beaches too. Remember that beach sand typically comes from rivers. Any change in the flow of a river can affect the beaches it feeds. On the Nile River in Egypt the Aswan Dam has blocked much of the sediment flow. As a result beaches near the mouth of the Nile have been eroding. How can beach erosion be slowed or stopped? Communities have tried many different solutions. One simple idea is to dump new sand on eroded beach. This is called beach nourishment. It restores a beach for at least a short period of time. Ocean currents and waves carry away beach sand. Beach nourishment often must be repeated to be effective. It works best when the cause of the erosion has been removed. A sea wall is a tall wall built along the rear edge of a beach. A sea wall is designed to receive waves at high tide. The waves lose much of their energy when they hit the wall. Their erosive power is reduced.