Appraisal of overland flow modeling using HEC-HMS and a variable parameter Muskingum method

Abstract

The present study was undertaken with the objective of evaluating the simulation capabilities of the variable parameter Muskingum discharge (VPMD) routing methods, proposed) for channel routing and that of the kinematic wave based method adopted in the US Army Corps of Engineers HEC-HMS model for simulating overland flow over unit width plane strips. The solutions obtained from the above two methods were also compared with the corresponding benchmark solutions obtained by solving the full Saint-Venant equations. A total of 60 simulations were made by each of these three methods for evaluating their performances. Accordingly, a total of 60 unit width overland flow strips with the length of 100 m each were considered for study. Each of these strips were characterized by a set of uniform Manning’s roughness coefficient and uniform slope with the former selected from six values varying from 0.02 to 0.4 and the latter selected from ten overland flow plane slopes varying from 0.0005 to 0.005. The comparison of the VPMD and HEC-HMS based solutions with the corresponding benchmark solutions of the Saint-Venant equations reveal that the overland flow simulated using the VPMD method is more accurate and robust in comparison with the corresponding solutions based on the Kinematic Wave method of the HEC-HMS model in simulating the benchmark solutions for a wide range of flow conditions, except for the flow conditions characterized by the criterion , where k is the kinematic wave number and F is the Froude number. Further, the severe restriction on the temporal grid size as employed in the HEC-HMS model for obtaining stable solutions is not needed for obtaining solutions using the VPMD method.