and examination of the field records indicates that the total measured ebb and 

 flood flows at some gaging stations are not balanced. This discrepancy in the 

 field data may act to reduce agreement between measurements and model. 



146. The model also provides discharges at all nodes. Comparison of 

 the computed and measured discharges at the inlet throat (Node 6) is given in 

 Figure 10. Measured discharges were computed manually by the USAGE District, 

 Wilmington, from the measured velocities, and some error may be expected owing 

 to estimation of effective channel cross section. Figure 10 indicates that 

 DYNLETl gave a maximum (flood) flow of 48,031 cfs at the inlet throat, whereas 

 the maximum flood flow from measured velocities at gaging stations was 

 estimated at 42,129 cfs. Similarly, the maximum ebb flow was computed as 

 -42,613 cfs, and the estimated value from the measurements was -44,225 cfs. 



147. The plot of the cross section at Node 1, the sea boundary, is 

 shown in Figure 11 as an example of how DYNLETl processes cross -sectional 

 data. Data points describing the horizontal locations and elevations of the 

 channel bottom divide the cross section into subchannels, and the average 



30 

 20 



- 





^/^ 



Compute J 



Measured 



-^ 



/ 





\ 



-\\ 







\ 



- \ 









■ v^ 



J/ 







1 



1 



1 



1 



14 16 



Time in Hours 



Figure 10 . Computed and measured discharges , Masonboro Inlet 



56 



