摘要
以模拟农田尺度降雨入渗—重分布条件下阿特拉津(atrazine)在非饱和土壤中的淋溶动态为数值算例,通过在北京东郊的一块27m×27m的农田采集100个土壤样品,测定其主要理化性质,间接计算获得各土壤样品的vanGenuchten型水力学参数、溶质运移的弥散度及atrazine在土壤中吸附的分配系数,进而基于柱模型假设,运用HY DRUS 1D软件得到不同时刻采样区内土壤水负压和atrazine浓度的平均分布。在此基础上,重点探讨了应用幂平均算法计算不同的等价有效参数对农田尺度下土壤水负压和atrazine浓度平均分布的数值模拟精度的影响。就所设计的降雨入渗—重分布条件下atrazine淋溶的算例而言,土壤水力学参数、溶质运移参数和吸附特性参数取几何平均或调和平均作为有效参数值,空间平面上呈正态分布的土壤水负压的初值采用算术平均值作为流场模拟的初始条件,可以获得满意的数值模拟结果。
The heterogeneity of agricultural soils leads to the complexity of flow and solute transport. To improve the efficiency of numerical simulation, some parameters must be upscaled. In this study, we take the numerical simulation of atrazine leaching through unsaturated soils at field scale as an example, by taking 100 soil samples from a field plot with an area of 27 m×27?m, located in the eastern suburb of Beijing, and analyze their main physicochemical properties. The hydraulic parameters of the van Genuchten's type for all soil samples are generated by using pedotransfer function, and the dispersivities of atrazine transport are indirectly estimated by using the hydraulic information. The adsorption coefficients of atrazine on the soil texture are indirectly calculated, too.On the assumption of column model, the atrazine leachs in the soil on the condition that the rainfall infiltration-redistribution is simulated. Firstly, the dynamics of the soil water matric potential and the atrazine concentration in individual soil column are simulated by using 100 simulations of HYDRUS-1D software, and then their mean spatial distribution is obtained from the results. Secondly, the dynamics of soil water matric potential and atrazine concentration in an equivalent porous media is simulated by using the effective parameters and one simulation of HYDRUS-1D. In this paper, the emphasis is put on discussing the effect of the equivalent effective parameters, being calculated by the power law averaging technique, on the numerical simulation of the mean distribution of soil water matric potential and atrazine concentration at field scale. It is shown that the upscaled numerical simulation of high accuracy can be obtained, when the geometry mean or harmonic mean values of hydraulic parameters, transport parameters and adsorption parameters are taken as their effective parameters, while the arithmetic mean of soil water matric potential of normal distribution under initial condition is taken as its equi
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2005年第2期222-232,共11页
Advances in Water Science
基金
国家自然科学基金资助项目(40271058)~~
关键词
土壤
阿特拉津
淋溶
农田尺度
有效参数
幂平均算法
数值模拟
soil
atrazine
leaching
field scale
effective parameters
power averaging technique
numerical simulation
