Different types of Optimizing the Parameters of Hydrological Routing Methods using Particle Swarm Optimization (PSO) Algorithm for Flood Routing in the Karun River

Optimizing the parameters of hydrological routing methods has a special place in increasing the accuracy of estimating outflow hydrograph and also calculating the peak area of flood hydrograph in engineering works. In the present study, since the range of changes in the inflow of the third flood (computational flood) is between the range of changes of the inflow of the first and second floods (base floods), For this reason, in order to increase the flood routing accuracy by using hydrological routing methods (linear Musking method, Working values, convex and modified Att-Kin), instead of using the parameters (X, K, ∆t) of a baseline flood, the arithmetic mean and the geometric of the two baseline flood parameters is discussed in 8 different modes using the Particle Swarm Optimization (PSO) algorithm. In other words, the use of all 8 modes presented in the present study has increased the accuracy of hydrological routing methods in estimating the peak area of flood hydrographs between Mollasani (upstream) and Ahwaz (downstream) hydrometric stations of the Karun River. Thus, in the best case presented in the present study (mode 8), the mean relative error of the computational flood peak area relative to the conditions in which the first baseline flood is used alone, for the mentioned methods are 66, 66, 25 and 18%, respectively, and in conditions When the second baseline flood is used alone, it has improved by 43, 43, 4 and 9%, respectively.