EVALUATION OF OVERLAND FLOW MODELING USING HEC-HMS AND A VARIABLE PARAMETER MUSKINGUM METHOD

Abstract

The present study was undertaken with the objective of comparing the simulation capabilities of the Variable Parameter Muskingum Discharge (VPMD) routing method, proposed by M.Perumal for channel routing , and that of the kinematic wave based method adopted in the U.S.Army Corps of Engineers HEC-HMS model, for simulating overland flow plane strips. The solutions obtained from the above two methods were also compared with the corresponding solutions given by the full Saint-Venant equations, for obtaining the benchmark solutions required for comparison. A total of 60 simulations were made by each of these three methods for evaluating their performances. Accordingly, total of 60 unit width overland flow strips with the length of 100 m. Each of these strips were characterized by 6 uniform Manning's roughness coefficients varying from 0.02 to 0.4 and 10 overland flow plane slopes varying from 0.005 to 0.0005. The comparison of the VPMD and HEC-HMS based solutions with the corresponding benchmark solutions of Saint-Venant equations reveal that the VPMD method is more accurate and robust in comparison with 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 KFo < 1, 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 solution is not needed for obtaining the VPMD solution.