pile groin was constructed about 350 feet northeast of the inlet 

 centerline on the Gulf side to stop further erosion of beach front and 

 to protect nearby summer homes. 



"The Pass remained partially closed until July 1958 while the Corps of 

 Engineers was preparing recommendations for its stabilization. Their 

 report was published in April 1958. The report proposed constructing 

 steel sheet pile bulkheads along both sides of the pass, north and 

 south of the highway bridge, installation of a second sill across the 

 Gulf entrance, and periodic deposition of sand on the Gulf beach area 

 southwest of the pass to replace material lost through littoral drift 

 processes. These recommendations were implemented between July 1958 

 and May 1959, with the exception of beach nourishment. 



"The Pass has remained open since 1959 in a relatively stable condi- 

 tion to this date. Anticipating the gradual weakening of the steel 

 bulkheads through corrosion, Texas Parks and Wildlife Department 

 constructed a concrete retaining wall behind the southwest steel bulk- 

 head in 1966. A similar concrete wall was installed behind the south- 

 east bulkhead in 1972. These concrete walls extend from the highway 

 bridge to a point 600 feet south." 



b. Beach Changes . Between 1882 and 1974, beaches within about 10 miles 

 north and 7 miles south of the pass eroded at a rate of about 5 feet per year 

 (Morton, 1975); however, erosion rates since the pass was created have been 

 greater, although estimates differ. Morton (1975) found that rates varied 

 between 15 and 25 feet per year; rates developed for the Galveston County 

 Shore Erosion Study being conducted by the Galveston District varied between 7 

 and 14 feet per year. The volume losses associated with this erosion were 

 established from the following analysis of beach profiles. 



Profiles near Rollover Pass were published by Lockwood, Andrews, and 

 Newnam, Inc. (1974), and profiles for the High Island area by the U.S. Army 

 Engineer District, Galveston (1975). The annual rates of volumetric change 

 per longshore foot of beach were plotted from a planimeter of the area between 

 the earliest profile and the latest profile at each station (Fig. 60). At 

 High Island, the average rate of volume change between 1967 and 1973 was 2.3 

 cubic yards per foot per year. The rate for the two profiles just updrift of 

 Rollover Pass was about 1.5 cubic yards per foot per year. If an average rate 

 of about 2 cubic yards per foot per year is assumed to represent the noninlet- 

 related beach erosion, profile data show that higher rates occur downdrift at 

 least as far west as station 2000W (see Fig. 60). Although no profile data 

 between stations 2000W and 14000W were available, the plot of shoreline reces- 

 sion rates shows that erosion can be assumed to decrease linearly toward 

 station 14000W. Thus, the shaded area in Figure 60 represents the annual 

 volume loss from the longshore transport system due to inlet processes, i.e., 

 about 26,000 cubic yards. 



c. Tide Characteristics. 



(1) Summary of Hydraulic Data Collection . The earliest tide measure- 

 ments in the vicinity of Rollover Bay were reportedly obtained between 1887 

 and 1890 but were not published (U.S. Army Engineer District, Galveston, 

 1942). Since other preinlet data were available, no attempt was made to 

 locate these measurements. 



67 



