A Comparison Between HEC-2 and FLDWAV

A comparison was performed between FLDWAV, currently a beta program developed by the National Weather Service, and the more widely used HEC-2 program. Espey, Huston & Associates, Inc. performed the comparison, as part of a study for the City of Oklahoma City on the North Canadian River. The City plans to place several low-head dams on the river for aesthetic and recreational purposes. Because these dams are to have hinged crest gates that respond to upstream flooding, FLDWAV was selected as the hydraulic model to perform necessary analyses. Previous HEC-2 models served as a baseline for input and a basis of comparison to the results produced by FLDWAV.

FLDWAV is a hydraulic model that combines of the capabilities of the DAMBRK and DWOPER models. It is a one dimensional, dynamic, unsteady flow model, which among other capabilities calculates water surface elevations and flow at each cross section throughout a storm event. HEC-2 provides a single elevation for a specified steady flow condition. FLDWAV, beyond HEC-2's capabilities, allows the user to model the effects of dynamic systems (such as movable gates on a dam) on a river system. FLDWAV also has the capacity to dynamically model a river network system such as a main river stem with tributaries. This paper addresses solutions to problems encountered in using and comparing the two models. Several issues include using HEC-2 to generate FLDWAV geometric river sections, the importance of setup parameters, dam and bridge input options, and routing differences between the two models. 12 pp., 6 references.