非饱和土壤溶质迁移转化模型参数优化估算

在分析非饱和土壤中水分和溶质迁移转化规律的基础上,采用与坐标网格相适应的分块连续作用的水动力函数,研究模型参数最优化估算技术.运用Gauss-Newton最小化计算的Levenberg-Marquardt修正法来实现反求模型的迭代问题.该方法被应用于估算一维土柱和二维土槽试验研究模型的参数,探讨了参数给定与估算数量对参数的置信区间和预测效果的影响.经验证表明,参数优化估算技术是可行的,以此参数进行模型预测,其结果是可信的.

Parameter estimation for the model of contamination transport and transformation in unsaturated soil

Parameter estimation is the key job of mathematics simulation and calculation,and its most complex problem is the simulation of water movement and contamination transferring in unsaturated soil. On the basis of analyzing movement and transference,the hydrodynamic functions of piecewise-continuous which is suitable for coordinate grid is adopted,and a contamination distributing equation about soluting concentrations in the liquid,solid,and gaseous phases in variably saturated soil is established. The inverse problem mode is adopted to discuss the optimization estimation technique of the model parameters. The Levenberg-Marguardt modification of the Gauss-Newton minimization algorithm is used to calculate iterative problem of the model parameters. The experiment model parameters of one-dimensional soil column and two-dimensional large tilting soil tank are estimated by the method,and the effect of the given parameter and estimation amount on parameter's confidence intervals and forecast result are discussed. The identified and analyzed results shows that the parameter estimation technique is feasible and the forecast result is dependable. The parameter estimation technique is used to simulate the transferring and transforming of pollutants in unsaturated soil.