ON THE MUSKINGUM-CUNGE FLOOD ROUTING METHOD

For practical problems, efficient but accurate solution methods are us ually preferred to computationally expensive but extremely accurate on es. The Muskingum-Cunge (M-C) method is an efficient technique often a pplied to solve flood routing problems. There are two free parameters in the M-C method: the spatial step and the temporal step. The accurac y of the method wholly depends on the Courant number (essentially the ratio of these step sizes). It is not known which combination of spati al and temporal step yields the best solution. In this study, the conc ept of column holdup (which is quite often employed in solute transpor t problems) and the results from the truncation error analysis of the kinematic wave equation are combined to obtain a straightforward condi tion leading to optimal spatial and temporal steps. It is found that a simple explicit scheme is the best method to solve the complete diffu sion wave equation starting from the kinematic wave equation. The sche me attains third-order accuracy if the optimal Courant number is 1/2.