2 . Exi s ting Protective Beaches . 



Restoration and widening of beaches have come into increasing use in 

 recent years. Examples are Corpus Christi Beach, Texas (U.S. Army Engineer 

 District, Galveston, 1969); Wrlghtsvllle Beach and Carolina Beach, North 

 Carolina (Vallianos, 1970); and Rockaway Beach, New York (Nerseslan, 1977). 

 Figures 6-13 to 6-20 illustrate details of these projects with before-and- 

 after photos. Table 6-2 presents a fairly complete listing of beach restora- 

 tion projects of fill lengths greater than 1.6 kilometers (1 mile) that have 

 been completed in the United States. In 1968, beach widening and nourishment 

 from an offshore source was accomplished by a pipeline dredge at Redondo 

 Beach, California. As previously mentioned, this was one of the first 

 attempts to obtain beach fill from a high wave energy location exposed 

 offshore using a pipeline dredge (see Ch. 6, Sec. III,2,b). The largest beach 

 restoration project ever undertaken in the United States was recently 

 completed in Dade County, Florida (see Ch. 6, Sec. III,2,c). Of the projects 

 mentioned, Carolina Beach, Redondo Beach, and the Dade County beaches are 

 discussed below. 



a. Carolina Beach, North Carolina . A protective beach was part of the 

 project at Carolina Beach (Figs. 6-17 and 6-18 illustrate the planning and 

 effects of such a protective beach at Corpus Christi, Texas). The project 

 also included hurricane protection; however, the discussion of protective 

 beach planning in this chapter includes only the feature that would have been 

 provided for beach erosion control. The report on which the project is based 

 was completed in 1961 (U.S. Army Engineer District, Wilmington, 1961), and the 

 project was partly constructed in 1965. 



The predominant direction of longshore transport is from north to 

 south. This conclusion was based on southerly growth of an offshore bar at 

 Carolina Beach Inlet and on shoaling at Cape Fear, 19 kilometers (12 miles) 

 south of Carolina Beach. Subsequent erosion south of Carolina Beach Inlet and 

 accretion north of the jetty at Masonboro Inlet, about 14 kilometers (9 miles) 

 north of Carolina Beach, have confirmed the direction. The long-term average 

 annual deficiency in material supply for the area was estimated in the basic 

 report at about 10 cubic meters per linear meter (4 cubic yards per linear 

 foot) of beach. This estimate was based on the rate of loss from 1938 to 

 1957, from the dune line to the 7-meter (24-foot) depth contour. Carolina 

 Beach Inlet, opened in 1952, apparently had little effect on the shore of 

 Carolina Beach before 1957; therefore, that deficiency in supply was con- 

 sidered the normal deficiency without regard to the new inlet. 



For planning, it was estimated that 60 percent of the material in the 

 proposed borrow area in Myrtle Sound (behind Carolina Beach) would be 

 compatible with the native material on the beach and nearshore bottom and 

 would be suitable for beach fill. This estimate assumed that 40 percent of 

 the borrow material was finer in size characteristics than the existing beach 

 material, and therefore would be winnowed due to its incompatibility with the 

 wave climate. The method of Krumbein and James (1965) was considered for 

 determining the volume of fill to be placed. However, insufficient samples 

 were taken from the foreshore and nearshore slopes to develop characteristics 

 of the grain-size distribution for the native beach sand. 



6-16 



