Kinematic wave solution of circular channel flow for urban drainage

摘要

In urban drainage, the circular channel is often used. The kinematic wave theory has been applied to approximate the unsteady flow in sewer by many computer packages for drainage design, e.g. HEC, SWMM and MOUSE among others. In the application of kinematic wave theory, one of key things is the derivation of kinematic wave parameters. This paper considered (a) circular channel with constant Manning roughness coefficient, and (b) circular channel with variable Manning roughness coefficient. For case (b), an equation that can describe the variation of Manning roughness coefficient with flow depth is presented. The examination of the "old" kinematic wave parameters shows that they do not give good agreement to the "true" relationships between discharge and flow area. "New" kinematic wave parameters that give better agreements are recommended to replace the old parameters. Similarly, the time of travel formulas that are based on the new parameters are recommended to replace the formulas that are based on the old parameters, and are used for estimating the time of travel in circular channel subject to a uniform lateral inflow and a constant upstream inflow.