The surge -elevations determined from this investigation will he 

 used in development of the open-coast surge frequency. The following 

 terminology is introduced to give special meaning to a hypothetical 

 htirricane with a central pressure index (CPl) frequency probahility of 

 once in 100 years. A hurricane possessing this particular characteristic 

 will be designated as a "Beta Hurricane" and included in this type of 

 hypothetical hurricane is the Standard Project Hurricane (SPH). The 

 Beta Hurricane is an SPH if, and only if, the storm generates the maximum 

 surge at a specific location under investigation. Maximiim surges are, of 

 course, produced by an appropriate combination of all parameters involved 

 for the particular basin under consideration. The "Standard Project 

 H\irricane" as defined by the Corps of Engineers is the most severe storm 

 that is reasonably characteristic of the location being investigated. 



Historically, it does not appear from a study of past hurricane 

 records that storms occur more frequently at any specific location along 

 the Texas Coast than at any other. On this basis, and for the purposes 

 of this study ,_ it will be assumed that hurricanes approach and cross the 

 coast uniformly. 



Section II. OPEN-COAST SURGE FREQUENCY 



1. General 



In the development of the open-coast surge frequencies, it is con- 

 sidered that the disturbance of the sea surface can be separated into 

 three component parts or causes, i.e., hurricane winds, other high winds, 

 and astronomical forces, although these are actually inseparable. Maximum 

 surge heights which have been produced, but are less than 2 feet above "the 

 mean sea level datum are disregarded in the present study. Water level 

 elevations in this range can be attributed primarily to light winds and 

 the astronomical forces. Very high surges are produced by hurricanes, 

 and surges lying in the range of two feet to the high surges, and caused 

 by strong winds and tropical depressions, are designated a non-hurricane 

 sxirge. Of course, there is considerable overlap of hurricane surges into 

 the non-hurricane surge range, however, these can be combined in the 

 final analysis. A hurricane is a storm that has cyclonic wind patterns 

 and has ma:ximum wind velocities that equal or exceed 75 miles per hour. 



2. Historical Hurricane Data 



Many hurricanes of record approached and crossed the Texas Coast prior 

 to the 20th century. The data of surge heights and hurricane parameters 

 for these early storms are so limited that they would be ineffectual in 

 the present study. Since 1900, great strides have been taken to record 

 the various characteristics of hurricanes, and the art of measurement and 

 procurement of the data has improved substantially over the years. 



