Shoreline Position (ft) 



300- 



200 



100 



Measured 01/23/86 

 Measured 07/29/87 

 Calculated 07/29/87 



Holly Beach, LA 



500 



1000 1500 2000 2500 



Distance Alongshore (ft) 



3000 



Fig. 9. Preliminary results of model calibration 



the three eastern breakwaters has remained about the same as that measured in 

 the 1987 surveys, with only small salients apparent. 



Predictions of shoreline change with the calibrated model do not depart 

 from the 12/88 survey that showed a persistent elongation of the salients for 

 the three western breakwaters and a reduced or negligible amount of sediment 

 accumulation behind the three eastern structures. As a further exercise, on 

 the assumption of continued deterioration of the breakwaters, transmission 

 coefficients were increased by 0.1, except for the severely damaged eastern- 

 most breakwater, which was assigned K T = 0.9. After three years of simula- 

 tion, the shoreline at the three eastern breakwaters retreated to the revet- 

 ment, whereas the salients at the three western breakwaters persisted, but 

 with smaller areas, closely reproducing qualitative features of the 12/88 

 survey. 



56 



