Numerical Solution of Muskingum Equation

It has been specified in several past publications that the computational time interval should be taken equal to or greater than 2KX to avoid computing negative outflows; K and X are parameters in the Muskingum equations. It is suggested herein that such a specification may need to be imposed only on the first computational time interval; subsequent time intervals can be selected as small as one may practically desire. The first time step, of the order of 2KX, is identified with the time lag parameter previously advocated by the writer. The proposed method of computation is explained by solving a numerical example. Using a time lag of 4.57 hr in this example, the outflow hydrograph is computed with a time step of 1 hr. The computed hydrograph is realistic and satisfies the flow continuity requirement.