土壤优先流的离子显色示踪技术与分形模型模拟方法研究

Abstract

为获得优先流的非均匀运动模式、提高优先流模拟预测的精度，本文运用碘-淀粉显色示踪技术，将优先流流场从流动背景中显示出来，通过数字图像分析技术和采样分析，获得优先流流场及流场内的土壤含水率和溶质浓度的非均匀分布模式；在此基础上，分别运用活动流场模型和二域模型对试验条件下的水流运动和溶质运移结果展开模分析，并通过相对标准偏差分析定量评价活动流场模型和二域模型模拟预测优先流发展的有效性。相对标准偏差分析显示，相对于二域模型，活动流场模型对土壤水流运动和溶质运移的模拟预测精度均较高。研究结果表明，活动流场模型较好的捕捉到了土壤优先流的整体非均匀信息。 To capture the heterogeneous flow pattern and enhance the prediction accuracy of preferential flow in unsaturated soil, the iodine-starch staining method was applied to visualize the preferential flow pattern from the background in this research. The digital imaging procedure was conducted to obtain the heterogeneous distribution pattern of preferential flow paths, and soil sampling was conducted to obtain the heterogeneous distributions of soil water content and solute concentration in the preferential flow region. The measured distributions of soil water content and solute concentration resulted from preferential flow were simulated and predicted using the active region model (ARM) and the mobile-immobile region model (MIM). The modeling efficiency using ARM and MIM were quantitatively evaluated and compared using the relative root mean square error (RRMSE) analysis. The model evaluation and comparison revealed that, ARM produced more accurate infiltration depth, and soil water and solute concentration distributions predictions, showing the ARM captured the macroscopic behavior of preferential flow and transport well.