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Spatial Variability of Soil Parameters of the vanGenuchten Model at a Regional Scale

机译：vanGenuchten模型的土壤参数在区域尺度上的空间变异性

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摘要

Spatial heterogeneity of soil water retention curves (SWRC) plays an important role in modelling the movement of water and solutes in soils. To characterize the spatial variability of SWRC parameters fitted by the van Genuchten (VG) equation, and then identify factors that closely correlated with the VG parameters, we collected undisturbed and disturbed soil samples from the upper 0–5 cm soil layer at 382 sampling sites across the entire Loess Plateau of China (_620 000km2). We determined the SWRC and six other soil properties as well as nine environmental factors for each site. Results showed that the saturated water content (θs) and a curve-shape parameter that is related to soil pore size distribution (n) were weakly spatially variable (coefficient of variation (CV)¼15%), and that the residual soil water content (ur) and a scaling parameter that is related to the inverse of the air entry pressure (a) were moderately (CV¼96%) and strongly variable (CV¼136%), respectively. Semivariograms of √ θr and log(a) were best-fitted by an isotropic exponential model, while those of us and log(n) were fitted by an isotropic spherical model. Fractal analysis indicated that log(a) demonstrated the most short-range variation, while log(n) reflected the importance of long-range variation. Bulk density and the contents of clay, silt, sand and soil organic carbon contributed greatly to the variations in the VG parameters (except a). However, the vegetation, topographic and climatic elements as well as land use also usually explained some of the variation. The VG parameters, at the regional scale, demonstrated different characteristics of spatial variation, which comprehensively reflected the combined effects of processes involving the soil, vegetation, topography and climate as well as effects of land use, which is often determined by human activity.
机译：土壤保水曲线（SWRC）的空间异质性在模拟土壤中水和溶质的运动中起着重要作用。为了表征由范·格努赫滕（VG）方程拟合的SWRC参数的空间变异性，然后确定与VG参数密切相关的因素，我们从382个采样点的0-5 cm上部土壤层收集了未扰动和扰动的土壤样本跨越中国整个黄土高原（_620 000平方千米）。我们确定了每个站点的SWRC和其他六个土壤属性以及九个环境因子。结果表明，饱和水含量（θs）和与土壤孔径分布（n）相关的曲线形状参数在空间上是微弱的变化（变异系数（CV）¼15％），而土壤残留水含量（ ur）和与进气压力（a）的倒数相关的缩放参数分别适度（CV¼96％）和强变量（CV¼136％）。 √θr和log（a）的半变异函数通过各向同性指数模型拟合最佳，而我们和log（n）的半变异函数通过各向同性球形模型拟合。分形分析表明，log（a）表现出最大的短程变化，而log（n）反映了长程变化的重要性。体积密度以及粘土，粉砂，沙子和土壤有机碳的含量极大地影响了VG参数的变化（a除外）。但是，植被，地形和气候要素以及土地利用通常也可以解释其中的一些变化。在区域范围内，VG参数显示出不同的空间变化特征，这些特征综合反映了涉及土壤，植被，地形和气候的过程的综合影响以及土地利用的影响，而土地利用的影响通常由人类活动决定。

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  • 来源
    《Clean》 |2015年第2期|271-278|共8页
  • 作者

    Yunqiang Wang; Ming’an Shao; Xiangwei Han; Zhipeng Liu;

  • 作者单位

    State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, Shaanxi 710075, China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, China;

    Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China;

    Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China;

    State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, China;

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  • 正文语种 eng
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  • 关键词

    Fractal dimension; Geostatistics; Loess Plateau; Residual maximum likelihood; Soilwater retention curve;

    机译：分形维数地统计学黄土高原;残留最大可能性;土壤保水曲线;

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