in Figure 63. Also given is total transport in 10 6 cubic meters per 

 second as a function of time across the transect lines indicated in 

 the figure. 



2. Hurricane Camille . 



Hurricane Camille traversed the extensive low-lying marsh area 

 of the Mississippi Delta, moving over the shallow waters of Breton 

 and Chandeleur Sounds for 4 hours prior to landfall near Bay St. 

 Louis, Mississippi, at approximately 0400 G.m.t., 18 August 1969. The 

 radius to maximum winds was about 37 kilometers. The atmospheric 

 pressure drop across the storm was 90 millibars. The maximum sus- 

 tained winds were approximately 60 meters per second with the highest 

 wind gusts estimated at 90 meters per second. 



The surge simulation extended over a 48-hour period beginning at 

 0000 G.m.t. on 17 August. A time step of 60 seconds was selected for 

 numerical stability. The boundary conditions are the same as those 

 used in the Carla simulation. The Camille winds are analytically 

 deformed as shown in Figures 43 through 45. The bottom drag coeffi- 

 cient was increased to 5 x 10" 3 at computational grid points in the 

 area bounded by 6 <_ i £ 11 and 14 <^ j < JM to simulate the larger 

 resistance associated with the low flooded marsh lying northeast of 

 the simulated Mississippi Delta (see Figures 28 and 65). 



Figure 64 shows the observed and computed water levels at se- 

 lected grid points along the coast. At Pascagoula, Mississippi, the 

 water level increased from 2.2 to 4.5 meters in a 2-hour period 

 indicating a strong convergence. In fact, the simulated hydrography 

 at the approximate location of the maximum surge (Bay St. Louis) 

 showed a similar convergence with the sea level rising from 2.9 to 

 7.0 meters in the same time period (figure not presented). The water 

 surface topography in 1 -meter contour increments at selected times 

 from 24 to 36 hours illustrating the surge development is shown in 

 Figures 65 through 73. The effect of the delta, modeled as a wall 

 protruding from the coast, is visible in these figures by the presence 

 of high water along the eastern side of the wall. The track of the 

 storm with respect to the delta is such that the circulation is 

 inhibited in this area resulting in the setup. The water velocity, 

 V , at the selected times and grid points as shown in Figure 74 are 

 in accord with these observations. The computed maximum coastal 

 surge envelope east of the delta presented in Figure 75 shows that 

 the calculated peak surges are approximately that observed in the 

 Gulfport to Pascagoula area (U.S. Army Engineer District, New Orleans, 

 1970). A test run employing a constant wind-stress coefficient, K , 

 of 3 x 10~ 6 with the same boundary conditions produced a similar 

 maximum surge envelope. There is qualitative agreement between the 

 observed and predicted surge envelopes. This is shown by the rela- 

 tively low water elevation of 2.7 meters near Hopedale, Louisiana, 



108 



