It is customary to assume that the system is initially in a state of 

 equilibrium and V = 0, and S is uniform along the traverse line at the 

 start of the computational scheme. Thus, computations should be initiated 

 for conditions prior to the arrival of strong winds over the Continental 

 Shelf. Although the real system would seldom, if ever, be in a complete 

 initial state of equilibrium, errors in assuming it to be are of little 

 consequence in the computational scheme after several time steps in the 

 calculations, because the effects of the forcing functions will eventually 

 predominate . 



To demonstrate the computational procedures, the storm surge in the 

 Gulf of Mexico resulting from Hurricane Camille (1969) is calculated. 

 Hurricane Camille was an extremely severe storm that crossed the eastern 

 part of the Gulf of Mexico with the eye of the storm making landfall at 

 Bay St. Louis, Mississippi, at about 0500 Greenwich Mean Time (GMT) on 

 18 August 1969. Unusually high water levels were experienced along the 

 gulf coast during the passage of Camille because of the intense winds and 

 relatively shallow water depths which extend far offshore. The storm surge 

 is calculated and compared with the peak surge generated by Camille. 



Information published by the U.S. Weather Bureau for Hurricane Camille 

 in HUR 7-113 (1969) indicates that R = 14 nautical miles and Wp = 13 knots 

 would be representative of these values which are assumed to be invariant 

 while the storm moved over the Continental Shelf. The wind data and track 

 for Hurricane Camille have been published by the Weather Bureau in HUR 

 7-113A (1970). The track, together with the traverse line used in the 

 present calculations, is shown in Figure 3-47. Overwater wind speeds and 

 directions are shown in Figure 3-48. A profile of the seabed along the 

 traverse line is shown in Figure 3-49. 



Tide records from the region affected by the storm show the mean water 

 level to be about 1.2 feet above normal before being affected by the storm. 

 This value is taken to represent the initial water level. The range of 

 astronomical tides in this location is about 1.6 feet. A constant value of 

 0.8-foot above MSL is used in the computations; the final surge hydrograph 

 at the coast can be subsequently corrected to account for the predicted 

 variations of the tide. Variations in the initial water level and astro- 

 nomical tides may be added algebraically to the storm surge calculations 

 without seriously affecting the final results. The atmospheric pressure 

 difference, P„ - P„. is needed for evaluating the pressure setup com- 

 ponent, S^p. Data given in HUR 7-113 (1969) suggest that p^ = 26.73 

 inches of mercury and p^ = 29.92 inches of mercury are representative for 

 the hurricane. All of these values are assumed to remain constant for the 

 calculations . 



The wind data, basin profile, and hurricane characteristics provide 

 the basic information needed in making an estimate of the peak storm surge 

 associated with Hurricane Camille. The time intervals, distance increments 

 along the traverse line, etc., are given in the computational steps to 

 follow. 



3-109 



