water and greater n values at higher water. With these 

 adjustments, the model was able to duplicate the calibration 

 data in the Saugus-Pines river system. 



b. Storage in both channel and ponds in upper reaches of both 

 rivers was adjusted in order to match elevations, particularly 

 those measured at Atlantic Lobster and Broad Sound Tuna. Very 

 little bathymetric data and no tidal data were available for 

 these areas. Therefore, storage was at first estimated from 

 USGS topographic maps and then changed during the calibration 

 process. The final storage areas selected remained reasonable 

 based upon the available data. 



c. As was mentioned previously, data from the Boston gage were 

 adapted for use as boundary conditions for the model. Since 

 the tide in the study area conforms so closely with that 

 measured at Boston, only minor alterations to the Boston tide 

 were necessary. The calibration process found that Boston data 

 should be multiplied by 0.984 and shifted forward in time by 



5 min before being used as boundary values. 



31. The results of the calibration process are depicted in Figures 13- 

 17. These figures show excellent agreement between numerical and measured 

 water levels during a period of large tidal range. 



Model Verification 



32. A 32-hour period from 1000 15 August to 1800 16 August 1984 was 

 chosen to verify the hydrodynamic model. This time period was chosen because 

 good data were available from the five study area tide gages as well as from 

 the N0S gage at Boston. Also, since the calibration was preformed for a 

 spring tide, a neap tide with a lower high tide and a small range (4.8 and 8.2 

 ft NGVD, respectively) was chosen to verify the model. The results for the 

 five study area gages are shown in Figures 18-22. These results show ex- 

 cellent agreement between numerical and measured water levels for all five 

 locations. 



Simulation of Event Ensemble by the Hydrodynamic Model 



33. The 150 selected events were simulated on a CYBER 205 computer in 

 three sets of 50 by the calibrated and verified storm surge model. The simu- 

 lations of the individual events varied from 13 to 75 hours prototype time de- 

 pending upon the number of high tides that needed to be modeled. For each of 

 the 150 surge plus tide time-histories, all highs with still-uater levels 



30 



