erode below mean sea level. These channels are quickly healed; and (c) broad overwash 

 wbere the foredune ridge is completely breached for 1 mile or longer. These breaches are 

 mostly evident in central and southern Padre Island, but are less significant in the northern 

 part. 



Bodine (1969) analyzed data from 19 Texas hurricanes, and presented models of 

 expected frequency of storm surges for various heights at different coastal locations. These 

 data are presented in Table 1. The frequency of surges for a given height decreases from the 

 northeast coast to the southern tip. A surge equal to or greater than the Mustang Island 

 surge of Hurricane Celia can be expected to reoccur, on the average, every 10 years at the 

 same location. As noted, the natural dune line in that area was hardly affected by Celia, 

 although low, duneless areas (old hurricane channels) were scoured out by the surge 

 floodtide and ebbtide. In contrast, the surge of Hurricane Carla is shown in Table 1 as the 

 storm surge of the century; the 12.3-foot recorded surge near the eye of the hurricane has 

 been exceeded only once in Texas during this century— the 1915 storm at Galveston with 

 12.7 feet (Bodine, 1969). As discussed earlier, the well developed foredune ridge of Mustang 

 Island and northern Padre survived Hurricane Carla, and although severe erosion of the dune 

 face occurred, it kept the surge from broadly overwashing the island. Whether an artificial 

 dune line can do the same is conjectural, and would depend greatly on dimensions of the 

 dune line at the time of the storm. The 5-year-old dunes would not have withstood the more 

 than 100-foot dune-face erosion associated with Carla, since the dune ridge is narrow at 

 present although its height is over 14 feet MSL. However, the effects of a 10- or even a 

 20-year storm surge would be minimal. 



Table 1. Average expected height of storm surges on open beaches for selected yearly 

 intervals at certain Texas gulf coast localities. 



Intervals (years) 



Surge height (feet) 



Sabine 



Galveston 



Freeport 



Port O'Connor 



Mustang Island 



Port Isabel 



2 



3.7 



3.1 



2.8 



2.8 



2.7 



2.6 



5 



5.4 



4.5 



4.4 



4.4 



3.9 



3.7 



10 



8.0 



7.0 



6.0 



6.0 



5.5 



5.5 



20 



10.3 



9.4 



8.2 



8.2 



7.8 



7.4 



50 



13.5 



11.5 



10.3 



10.3 



9.8 



9.2 



100 



15.0 



12.6 



11.4 



11.5 



11.0 



10.2 



1,000 



17.0 



14.1 



12.8 



13.0 



12.0 



11.3 



(Bodine, 1969) 

 4. Natural Barrier Island System. 



Godfrey and Godfrey (1972) and Dolan (1972a, b) stated that for some east coast 

 barrier islands, e.g., the Outer Banks of North Carolina, a well developed and continuous 

 vegetated foredune system is not a natural condition, and that the islands have always been 



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