EVALUATION OF TWO PARAMETER ESTIMATION TECHNIQUES OF THE MUSKINGUM METHOD

Abstract

This study involves the assessment of the performance of a widely used Muskingum method for routing a flood in a channel reach which differ from each other in the form of nonlinear storage equations. This analysis also involves the comparison of the performance of this nonlinear Muskingum method witl that of the physically based Variable Parameter Muskingum Discharge method known as the VPMD method when applied for routing a given inflow hydrograph in the same channel reaches. The performance of nonlinear Muskingum method advocated by Gill(1978), is assessed by first by calibrating the parameters of the method for a given set of hypothetical inflow-outflow hydrographs each routed in different hypothetical rectangular channel reaches characterised by different channel slopes and Manning's roughness and its performance is compared with the corresponding performance of the VPMD in reproducing the same-set of benchmark hydrographs for calibration and verification. In all our simulation runs it was found that the Variable Parameter Muskingum method is showing overall better performance in reproducing the routed hydrograph close to the St. Venants Solution when compared with the Nonlinear Muskingum method. Unlike the physically based method there is no applicability criteria to assess the applicability of the non linear Muskingum method. It has to be routed and tested. This study reveals that a Physically based channel routing method such as the Variable Parameter Muskingum Discharge method with a prior knowledge about its applicability based on some established criterion is preferable than a semiempirical method such as the nonlinear Muskingum methods.