River Flood Routing using The Multiple-reach Muskingum Model

The hydrological flood routing methods have many applications due to their simplicity and accuracy. Amongst these methods, the Muskingum routing model is more commonly used for river flood routing. In this model, it is assumed that the coefficients and parameters are spatially and temporally constant for a specific river. In this study, it has been shown that to increase the accuracy of traditional or single-reach Muskingum model results, a river may be split to several reaches and for each reach, the Muskingum procedure can be implemented separately. In this case, the multiple-reach Muskingum parameters will be obtained. The optimum number of reaches for a river are different and is probably dependent on the geometrical and bed slope changes through the river and should be obtained by optimization. By implementing the multiple-reach Muskingum model for the Karoun river, between Karoun and Gotvand hydrometric stations, it was shown that in this river the three-reach Muskingum model has considerably more accuracy than the single-reach method which causes the sum of squared error to decrease from 1750000 to nearly 1000000 (m3/s)2.