Comparison of the Kinematic Wave and Dynamic Wave Techniques for Flood Routing and Constructing a Downstream Hydrograph in a Reach of the Doab Samsami River

Different hydraulic and hydrological methods are used in flood routing for construction of the downstream hydrograph of a river. Hydraulic flood routing methods، initially based on the Saint-Venant equations، are developed using the continuity equation and employing the terms of the momentum equation، consist of three models: kinematic wave، diffusion wave، and dynamic wave. The objective of this study was to evaluate the accuracy of the kinematic wave and dynamic wave methods. This project was implemented in a 3. 5 km reach of the Doab Samsami River، which is a tributary of the Karoon River. Fourteen cross sections were surveyed in the reach and their Manning''s roughness coefficients were estimated based on the expert judgment. A computer program was developed for flood routing with the kinematic wave method. For the dynamic flood routing، the unsteady flow analysis of the HEC-RAS software was used. The developed hydrographs using the two methods were compared with the actual hydrograph at the downstream station using the RMSE criterion. Results indicated that the kinematic wave and the HEC-RAS models were very close، indeed. Therefore، based on the simplicity of the method، and also the limited data requirement of the kinematic wave method، its use is strongly recommended for similar studies، and also for flood routing in rivers with larger gradients.