Comparison of optimal design of Unit Hydrograph using Simulated Annealing and Genetic Algorithm (case study: Kameh Watershed)

One of the most important steps in analysis of hydrology and produce design hydrographs is Unit Hydrograph. Unit hydrograph is used for determination of flood in storms with different duration and intensity. This paper presents an optimization model of producing unit hydrograph using SA (Simulated Annealing) Algorithm and Genetic Algorithm. Gamma, Log-normal and First passage time probability distributions are used in this study. In this model, the objective function is to minimize the sum of squares of the deviation between predicted and actual direct runoff hydrographs per unit area of the watershed. The predicted direct runoff hydrograph per unit watershed area is estimated using unit hydrograph and probability distribution function. Also there are no constrains in the optimization model using SA and Genetic algorithms and probability distribution functions, and the number of variable to be estimated by optimization is equal to probability distribution parameters. So, the proposed method is a simple method. Results show that Log-normal and First passage time distributions can be used to predict the peak discharge more or less correctly. Also comparison of obtained results from SA Algorithm and Genetic Algorithm show that SA Algorithm has better results in predicting optimal solution. Therefore, this model may be applied for quick and approximate estimation of unit hydrograph and simulation of runoff hydrograph.