NUMERICAL-METHODS USED TO MODEL UNSTEADY CANAL FLOW

This paper presents a critical review of numerical methods used to model unsteady flow in canals. The significance of the various forms of the governing equations is outlined, and the problems associated with the evaluation of boundary drag and head loss are introduced. The attributes of the numerical solution techniques are described. These attributes include applicability, accuracy. convenience, and robustness. Both legitimate and nonlegitimate methods of achieving robustness are considered. Approximate hydrologic techniques are viewed from the perspective gained by a review of the complete equations. Characteristic and finite-difference techniques for solving the full equations are compared. Practical difficulties in detecting bore-wave formation during a simulation are noted. Specific techniques are recommended for difficult problems.such as the computation of very shalloW floWS. Practical considerations concerning testing of the techniques and a cautionary note for users of computer-simulation models are given.