and 180 sec (C-language version) on a 386-based 25-MHz processor with a math 

 coprocessor. On a 486 -based 25 -MHz processor, the run times were less than 

 half the preceding values. 

 Results 



177. DYNLETl provides calculation results of stage, velocity, and 

 discharge at any cross section (Part IV). From examination of survey maps, 

 the velocity gaging stations INLET3 and MIDIS3 were located inside cross 

 sections at Nodes 4 and 26, respectively, and the tide gages US Coast Guard 

 (USCG) , Pot Nets Point, Vines, Massey Ditch, and Dewey Beach were located 

 inside cross sections at Nodes 12, 22, 23, 26, and 28, respectively (Fig- 

 ure 12). These were used in the comparisons. The number "3" on the station 

 names INLET3 and MIDIS3 denotes the third velocity gage in a string of three. 

 Velocity gage station MIDIS3 was located in a narrow strait between islands, 

 thereby connecting two large water masses in the double back-bay area in a 

 region not too distant from where the tidal flow must turn relatively sharply 

 toward or away from the inner inlet throat. Measurements at Gage MIDIS3 

 therefore provide a severe test of any model. 



178. For comparison with measured velocities, calculated values at 

 several stations at Nodes 4 and 26, corresponding to the locations of Gage 

 INLET3 and MIDIS3, are plotted on Figures 13 and 14. 



Additional plots are given in Appendix B. Because the location of the gage 

 sites could not be identified with a particular station on the cross sections, 

 it is expected that one or more of the computed plots would represent model 

 results at or near the location of the gage. Computed values are plotted as 

 solid lines, and the measured values are plotted as dashed lines. These 

 figures indicate that DYNLETl reproduced the ranges, magnitudes, and phases of 

 the average velocities with almost no adjustment of the bottom friction 

 coefficient, as described previously. 



179. For comparison of computed and measured stages, values of water 

 surface elevation at several data points at Nodes 12, 22, 23, 25, and 28, 

 corresponding to the location of tide gages USCG, Pot Nets, Vines, Massey, and 

 Dewey, were plotted. Two of these, one at Gage USCG and one at Gage Dewey, 

 are shown on Figures 15 and 16. The remainder of the plots are contained in 

 Appendix B. The agreement between the computed and measured values ranges 

 from good to excellent at all gages except Massey. There is poor agreement 



70 



