A New Approach to Determine Reference Discharge for Muskingum- Cunge Routing Method (Case Study: Dinehvar River, Kermanshah Province)

In order to predict the magnitude, velocity, and form of the flood wave with respect to time, the flood routing methods are used. There are several ways to accomplish the flood routing which are divided into two general categories, including hydraulic and hydrological routing methods. Among the various hydrologic routing methods, the Muskingum- Cunge method has been applied more frequently because no need to calibration process of output hydrograph. The accuracy of this method depends on the choice of reference discharge and geometrical parameters. In this study, a new model was proposed for calculating the reference discharge based on the comparison of Muskingum- Cunge method and MIKE11 hydrodynamic model for Dinehvar River, in Kermanshah Province. The results showed that the output hydrograph obtained by the proposed reference discharge was in good agreement with the output of MIKE11 model so that for the 200 years flood hydrograph, the RMSE and E criteria values were equal to 1.64 m3s-1 and 0.99, respectively. Furthermore, comparison of the proposed relationship with other researcher’s findings showed that the proposed relation not only was a function of the peak discharge but also was a function of peak time and base time of the input hydrograph.