estimating hypo-hurricanes is generated internal to the program. In 

 subsequent discussions of an example problem, the basic input to the 

 computer will be more clearly demonstrated. 



3. Example Problem 



For illustration purposes, the peak surge will be determined at the 

 mouth of the Chesapeake Bay using characteristics given by Graham and 

 Nunn (1959) for a storm with a large radius and a moderate forward speed. 

 It is not implied here that this storm is a Standard Project Hurricane 

 (SPH) , since a study would be needed to determine if it produced the 

 highest possible peak surge at this location. The parameters taken are 

 as follows : 



CPI = 27.57 inches of mercury 



Pj^ = 29.92 inches of mercury 



R =35 nautical miles 



Vp = 22 knots (25.3 miles per hour) 



Vy_ = 102 miles per hour 



The isovel pattern considered appropriate for the above parameters is 

 given by Graham and Nunn (1959) on their Figure 33. 



Figure 3 shows the Chesapeake Bay Entrance and the offshore hy- 

 drography over the Continental Shelf. The line along which computations 

 are carried - the traverse line - corresponds to a latitude of 37°00'. 

 This traverse line represents a line which, on the average, is about per- 

 pendicular to the bed contours. The path of the storm is taken parallel 

 to and about 35 nautical miles south of the traverse line. Since com- 

 putations of the surge would be invalid within the Bay, the last raw 

 data position is at the mouth at a longitude of 76°00'. Figure 4 shows 

 the approximate bed profile along the traverse line from the mouth of 

 Chesapeake Bay seaward to the 600-foot depth contour. Experience has 

 shown that a point where the depth is 300 feet is usually sufficient for 

 commencing the computation from the seaward position to the most landward 

 point. Setup in regions deeper than this depth are generally negligible. 

 This will become evident by the example. The discrete points in space 

 in which raw data is supplied and the corresponding depths below mean 

 sea leval are taken as shown on page 53 in the Appendix. 



By positioning the isovel so that the maximum wind lies on the 

 traverse line, and winds are about zero at the most landward position, 

 the values of wind (W) , radius (r) , and theta (0) can be plotted as a 

 function of distance from the mouth of the Bay seaward. For the example, 

 this is shown on Figure 5 where time in hours indicates the position 

 relative to the mouth after an elapse of time. The method of evaluating 

 W, r and G along the traverse line is shown on Figure 6. 



28 



