土壤水分运动空间变异性尺度效应的染色示踪入渗试验研究
Characterizing scale-dependent heterogeneity of soil water movement through dying infiltration experiments
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摘要: 探讨了土壤水非均匀流动特性和描述方法,通过染色示踪剂调查了三种试验尺度条件下非均匀流动模式,并采用随机层叠模型对不同实验尺度条件下非均匀流动模式进行了模拟。随机层叠模型中具有对数正态分布性质的随机层叠发生器被用来描述水流入渗过程,不同的方法被用于模型参数求解。试验观测和模拟计算结果均表明,尺度特性是非均匀流动的重要影响因素之一,准确的描述不同研究尺度下的非均匀流动特征,须同时考虑流动在水平和垂直方向的变异性。随着研究尺度的增加,流动的非均匀性变异程度更加明显。Abstract: To address the flow heterogeneity issue,the objective of this study are to investigate heterogeneity of soil water flow at different measurement scales using dying infiltration experiments and characterize the heterogeneity information included in different scales with the random cascade model. The random cascade model with a lognormal distribution is used to simulate the infiltration process in soils,and the different methods are applied to estimate the model parameters. Results based on the experimental data and the model simulations show that the measurement scale is important factors affecting the flow patterns in soils. To accurately describe flow transport processes at different scales,it is necessary to consider heterogeneities in the vertical and horizontal directions. As the measurement scale increases,the effect of multi-dimensional heterogeneities on the flow processes in soils becomes more significant.