elevation, therefore allowing a significant amount of wave energy into the 

 protected area. The beach response to these types of structures is usually a 

 salient; these structures may be advantageous for sites where the interruption 

 of the horizon by a structure is considered unaesthetic. Unless otherwise 

 noted, reef breakwaters have been grouped with detached breakwaters, and 

 pocket beach breakwaters with headland breakwaters, throughout this report. 

 For projects with relatively short alongshore distances to protect, a single 

 breakwater is often sufficient. For longer length projects, a series of 

 structures may be required to protect the project beach; this series is termed 

 a segmented system. 



3. Unlike shore -perpendicular structures (i.e., groins), which impound 

 sediment and ultimately starve downdrift beaches, detached breakwaters can be 

 designed to allow material to pass through the sheltered region, minimizing 

 their impact on adjacent shorelines. Onshore, shore -parallel structures such 

 as seawalls, revetments, and bulkheads are designed to prevent retreat of the 

 landward region they protect and do nothing to reduce erosion of the beach. 

 Beach- fill reduces the storm impacts to upland structures, while providing a 

 recreational beach; however, the quantities of replenishment required for 

 maintenance may be cost-prohibitive. The use of detached or headland break- 

 waters in combination with beach-fill may provide a cost-effective alternative 

 to beach- fill alone for many coastal regions. 



4. Although the breakwater appears to have advantages over the other 

 traditional forms of shore protection mentioned above, use of this form of 

 shore protection has been minimal in the United States. Seventeen detached 

 breakwater projects (46 breakwater segments) exist along 9,200 km of the 

 continental US and Hawaiian shorelines. Seventy-one additional segments 

 either are in the early stages of construction or are planned for construction 

 within the next few years by the US Army Corps of Engineers* (Gorecki and 

 Pope in preparation). Comparatively, at least 4,000 detached breakwater 

 segments exist along Japan's 9,400-km coast (Seiji, Uda, Tanaka 1987; Japanese 

 Ministry of Construction (JMC) 1986) ; 15 segments provide protection to the 

 300 km of Israeli Mediterranean shoreline (Goldsmith and Sofer 1983) ; and 



Personal Communication, 1989, Edward Fulford, Chief, Coastal Planning Section, 

 formerly US Army Engineer District (USAED) , Baltimore, Baltimore, MD, and 

 Thomas Bender, Chief, Coastal Engineering Section, USAED, Buffalo, Buffalo, NY. 



