Space Solution of Kinematic‐Wave Model by Time Iteration

Abstract

A kinematic-wave model was developed to solve for time to advance to specified locations along the furrow where infiltration was measured as a function of ponding time and wetted perimeter. Time step increased during advance to take advantage of the more slowly changing flow profile. In an earlier model developed by Rayej and Wallender, the system of nonlinear flow equations was solved implicitly for flow area and time step using the double-sweep technique. Coding requirements were extensive and computation time was protracted, however. Performance of the time-iteration model was compared with the double-sweep model. Advance trajectories for both uniform and nonuniform soils are essentially the same for both time-iteration and double-sweep methods. For both models, advance time decreases as space step decreases for both soil types. Computation time for the time-iteration model is one-third and one-fourth of the computation time for the double-sweep model for uniform and nonuniform soil, respectively. As expected, the number of nodes decreases as the space step increases and computation time decreases.