nonoperational. A modified version of the lumped-parameter model has been 

 incorporated as the Automated Coastal Engineering System (ACES) (Leenknecht, 

 Szuwalski, and Sherlock 1990) model, hereafter referred to as the ACES Lumped- 

 Parameter Model (ALPM) . However, the input data structure of the ALPM model 

 is different from its predecessor model , and many modifications have been 

 introduced so that the ALPM can no longer be considered to be the same as the 

 GLPM, although it is in the same class. It was found in this review that in 

 all GITI model studies of Masonboro Inlet, the field data, particularly the 

 water surface elevations at tide gages, were adjusted to obtain calibration. 



149. It should be noted that the major parameter determining the 

 magnitude of flow in the GLPM is the bay area. By computing the bay area from 

 the tidal range, tidal duration, and tidal prism, as has been done in the 

 Masonboro Inlet case, the procedure, in effect, provides the solution as input 

 to the model . 



GLPM 



150. The GLPM is described in GITI Report 14 (Seelig, Harris, and 

 Herchenroder 1977). This model is a lumped-parameter model and can be traced 

 to a simple, physically appealing one -dimensional quasi-steady state analyti- 

 cal model introduced by Keulegan (1967). The solution of Keulegan was based 

 on a channel of constant cross -section and constant friction factor. However, 

 the GLPM goes beyond Keulegan' s simple analytical model and uses a composite 

 channel made up of subchannels of variable width and length. 



151. Application of the GLPM model to Masonboro Inlet using the 

 September 1969 data is of interest. Comparisons of the cross sections as 

 given in Seelig, Harris, and Herchenroder (1977) with the cross sections 

 obtained from hydrographic maps from the USAGE District, Wilmington, show that 

 the natural cross section was simulated by four rectangular subchannels. The 

 maximum (flood) flow was computed as 55,000 cfs at the inlet throat by Seelig, 

 Harris, and Herchenroder, to be compared with the maximum flood flow of 

 42,000 cfs estimated from measured velocities at gaging stations. 



152. The data used by Seelig, Harris, and Herchenroder (1977) was 

 modified in an attempt to find an approximate estimate of the flow. There- 

 fore, direct comparison of results with the DYNLETl model cannot be made. 



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