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Figure 6. Numerical grid for storm surge model 



area using altered Boston water levels to drive the boundary. The procedure 

 used to alter the Boston water levels to produce the desired results is 

 described in the section on model calibration. 



26. The final grid configuration has 2,025 cells arranged in 45 rows 

 and 45 columns. The cells with the finest resolution are 500 ft square and 

 cover most of the areas of interest: Roughans Point, Point of Pines, the 

 Saugus-Pines Inlet, and the initial reaches of both rivers. The cells with 

 the coarsest resolution, located near the boundary, are approximately 1,500 

 by 700 ft. The grid is orientated to match the predominant direction of the 

 river system, since the initial reaches of the rivers form nearly 90-deg 

 angles. 



Wind Forcing 



27. Wind speed and direction are required inputs to WIFM for the model- 

 ing of storm surge. For this study a spatially constant but temporally vary- 

 ing wind forcing was used. The wind data were supplied by WED using raw data 

 from Logan International Airport and a wind data analysis computer program 



24 



