Parametric estimation of the van Genuchten’s equation based on hybrid genetic algorithm

The van Genuchten equation is the most commonly used soil characteristic curve equation,and its parameter value precision directly affects the soil water movement equation computation precision.In this paper,the parameter optimized model for van Genuchten equation was established,and the hybrid genetic algorithm which combines genetic algorithm with Levenberg-Marquardt optimization algorithm was used to solve it.A series of numerical experiments were conducted to verify the model.The results show that the hybrid genetic algorithm has the higher convergence efficiency than the ordinary genetic algorithm,moreover the number of convergence iteration also reduces greatly.The hybrid genetic algorithm has the higher estimate parameter precision than the nonlinear simplex method and the damped least squares method,moreover,do not need the initial parameter value.Therefore,the hybrid genetic algorithm can be can be used to estimate van Genuchten equation parameters as a new method.