Abstract:

In order to solve the problem of unstable parameter calibration results of conceptual hydrological model, the linearized calibration method of Xin’anjiang daily model parameters was put forward. Firstly, this method was compared with the SCE-UA method and the Simplex method through an ideal model. The average values of objective function obtained by the 3 methods were 0.02, 0.10 and 8.39 m³/s, respectively and the average iteration numbers were 8, 637 and 327, respectively. Moreover, the parameter variances obtained by the linearized calibration method were much smaller than those of other two methods. These results demonstrated that the linearized calibration method can find the true parameter values. It also has higher accuracy and convergence speed with more stable calibration results. Then the performance of the new method in model parameter calibration was examined using the measured data of Jianyang and Changtan River basin. The results showed that the stable optimal parameter values could also be quickly got. All of the objective function values of the 10 runs in Jianyang River basin were 100.35 m³/s and the iteration numbers were all within 8. In the validation phase of the two river basins, the relative errors of runoff depth were all within 9.68% and the values of determination coefficient were all above 0.819. It can be concluded that the linearized calibration method can solve the problem of unstable calibration results about nonlinear model parameters without producing unrelated local optima. Furthermore, it is not influenced by the different initial parameter values and has high computation accuracy and needs small iteration numbers. Hence, the linearized calibration method is an effective global optimization method.

Key words: parameter optimization, linearized calibration method, Xin’anjiang model, daily model