用MatLab确定土壤水分特征曲线参数

Determination of Parameters of Soil Water Characteristic Carve by MatLab

土壤水分特征曲线是定量研究土壤水运动的重要参数。目前,土壤物理学家普遍采用vanGenuchten模型(简称VG模型)来描述土壤水分特征曲线(h-θ曲线),本文讨论了如何确定模型参数的方法。根据中国科学院栾城试验站大田土壤剖面所采土样实测土壤负压h和土壤含水率θ数据,VG模型中的参数利用MatLab非线性拟合函数来确定,通过用四参数模型计算,计算的θ值与实测的θ值拟合较好,误差相对较小。通过长江河口地区土样检验表明,用MatLab方法确定VG模型参数,计算值与实测值拟合也较好,且计算值与实测值的残差平方和范数<0.001。

Soil water characteristic curve is an important parameter for studying soil water movement quantificationally. Now, generally soil physicists use van Genuchten model （shortened as VG model） to describe the curve （h-θ curve）. How to determine parameters of the VG model was explored in this paper. Based on the data of soil negative pressure h and soil water content θ measured at the Luancheng Agricultural Ecosystem Station, Chinese Academy of Sciences, the nonlinear simulation function of MatLab was used to determine parameters of the VG model, The θ values calculated through the four-parameter model fitted quite well the measured θ values, with relatively limited error, Soil samples collected from the estuary of the Yangtze River were used to verify the findings, showing that the values calculated using the VG model, of which parameters were defined by the MatLab method, fitted the measured data quite well too with the norm of residual error square sum less than 0.001.