14,000 

 13,000 



26,080 yd^/yr 



• 



1956-76 



Shore 



ine 



Erosion 



Rate 



(ft/yr) 





(Based 



on Aerial 



Photo A 



lolysis 



for 





SWG) 













X 



Erosion 



Rote 



yd 



Vft/yr) 







2 3 4 5 6 7 8 

 Erosion Rote (yd 3 /ft/yr) 



Figure 60. Comparison of beach profile and 

 aerial photo erosion rates. 



Tide data were collected in Rollover Bay between September 1936 and 

 October 1937 by the Galveston District as part of a comprehensive measurement 

 program. The first tidal data collected after Rollover Pass opened in 1955 

 were obtained from May 1956 to April 1957 from an SWG gage located in Mud 

 Bayou, about 10 miles east of Rollover Pass. Between 21 November 1956 and 19 

 February 1957 gages were also operated in the Gulf of Mexico at Gilchrist and 

 in Rollover Bay. Gages usually provide an excellent record of the hydraulics 

 of a bay; however, the tide curves in the U.S. Army Engineer District, 

 Galveston (1958) revealed a serious malfunction in the Rollover Bay gage, 

 making the bay data unusable. In October 1962, the Galveston District began a 

 comprehensive tide gaging program to continuously monitor watiic levels at many 

 coastal locations. Tide data from the SWG South Jetty and Marsh Point (East 

 Bay) gages are complemented by NOS data collected at Gilchrist (East Bay) in 

 March and April 1965. 



Tidal currents were measured in the pass on 4 and 5 May 1965 by the 

 Galveston District in connection with a physical modeling program of a 



68 



