Comparison of PSO and GA in Calibration of Clark's IUH Storage Coefficient

Evaluation of watershed hydrograph is prerequisites for the appropriate design of soil and water resources management programs in the watershed. Therefore, in ungauged watershed, simulation of storm water hydrograph is important for designing flood control measures, determining flood-plain boundaries and watershed management plan. The Clark method is one of the most applicable techniques for simulation direct hydrograph whose efficacy depends upon the accuracy in estimating storage coefficient. However, very limited studies have been conducted to using optimization method for Clark parameter estimation. Therefore, this study is focused on parameter estimation methods of GA and PSO for estimating the k parameter (storage coefficient of Clark model) and compare with graphical method. The Tamar watershed located in Golestan Province with 1515 km2 selected for this purpose. After collected physiographic, rainfall and runoff data for eight storms, the Clark's time-area model was employed for simulation of flow hydrograph and routed to the watershed outlet. The results of study revealed that the Clark’s IUH resulted from PSO optimization method for estimation storage coefficient (K) has better performance with efficiency coefficient of 0.64 than GA and graphical method (efficiency coefficient of 0.60 and 0.52, respectively). The results also, showed that Clark IUH model predicted all hydrograph component with good accuracy.