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Learn-Assess making such on-site detention a necessity. Home Leaminl! Center Back Shoreline Protection Quasi-natural methods such as beach nourishment or artificial sand-dune building are often used to attempt to restore an eroding beach as well as protect development. Long reaches of shore can be protected by artificial nouri !bre nt !t a rd a i..el y low cost per linear foot. In addition, nourishment can widen a beach and increase its recreational value. A well-known beach nourishment project is the 10.5 miles of beach restoration in Dade County, Florida, which includes Miami Beach. However; these methods provide only temporary solutions to chronic long-term erosion caused by the diminishing supply of sediment in the littoral system. They also require periodic renourishing during their 15- to 50-year life span. Even so, they are more cost-effective than large structures, such as groin fields or segmented offshore breakwaters. These structures can also build or increase beach width as well as provide protection, but erosion can occur downdrift if they are not properly designed. Structures like seawalls, bulkheads, and revetments protect development, but are not intended to renourish or widen the beach. Erosion can occur in front of them because the natural movement of the shoreline has been affected. Such structures as breakwaters and jetties, which are designed to protect harbors and navigation channels from wave action or to stabilize inlets, can also cause erosion on the downdrift side if they do not include a sand-bypassing system. Because of their high cost, few shoreline protection projects have been built without federal assistance, although most coastal states and many communities have participated in various ways. Page 17 006