In this investigation > stirge frequency estimates are based on actual 

 hurricanes of record, but extended by logic and mathematical relations to 

 cover hypothetical hurricanes. Nineteen actual hurricanes, experienced on 

 the Texas Coast over a period of G6 years of record (19OO-I965) are used 

 in conjunction with this analysis. These hurricanes were selected because 

 the parameters which define the storm intensity have been historically 

 recorded, and because, in the derivation of the hypothetical hurricane 

 model, a parametric study is employed. If there were sufficient data of 

 surge heights at all desirable locations in the sea and in adjoining bays 

 and low-lying terrain, it would be better indeed to treat such a problem 

 by the methods described in pure statistics. However, this is not the 

 case because recorded surge heights are meager, tide recording stations 

 are limited in nximber, and the years of record are relatively few. There- 

 fore, it is not only necessary, but mandatory, to resort to methods of 

 logic or reasoning for resolution of the problem. 



The present study originated in connection with the authorized Texas 

 Coast Hiirricane Studies because of the difficulties encountered in deriv- 

 ing surge frequency estimates for various locations within Galveston Bay. 

 It would indeed be more appropriate to base surge-frequency relationships 

 within the bay system on actual records; however, only two water-level 

 recording stations located near Galveston Island have records adequate for 

 carrying out this type of analysis. Since these recorders are located in 

 the lower region of the bay and near the eastern part of the island, they 

 give no indication of surge-frequency relationships in other parts of the 

 bay. Water surface elevations in a semi enclosed bay can vary significantly 

 throughout the bay, and the extent of variation/is dependent upon the 

 geometry of the basin and the forcing functions involved. To resolve the 

 problem, the surge frequency must be determined at numerous positions 

 within the confines of the estuary. Because of insufficient observed 

 water levels in Galveston Bay, the surge frequencies at all locations 

 of interest must be determined from hurricane surge heights resolved from 

 a numerical scheme using prescribed hurricane parameters. Resolution of 

 the surge heights in Galveston Bay has been treated by Reid and Bodine 

 (I96&) by employing a finite-difference numerical method for solving the 

 linearized hydrodynamic transport equations. The parametric studies re- 

 lated to the above work can be used in determining the surge frequencies 

 at various positions within the bay. 



The surge frequencies that may be expected for hurricanes in a bay 

 system are coupled with the surge frequencies on the open coast for a 

 particular location. The amplitude of the surge, however, can vary sig- 

 nificantly from a position in the sea to a position in the bay. Marinos 

 and Woodward (1968) used those parameters that govern the intensity of 

 a hurricane in conjunction with the Bathystrophic Storm Tide theory* to 

 predict the ' surge that may be expected from hypothetical hurricanes at 

 the open coast of Texas . 



*Bathystrophic Storm Tide theory takes into account the coriolls effect 

 on the wind stress as it acts on the water. 



