农业工程学报Issue(20)：118-127,10.DOI:10.3969/j.issn.1002-6819.2014.20.015
降雨强度对优先流特征的影响及其数值模拟
Effect of precipitation intensities on preferential flow and its numerical modeling
摘要
Abstract
The preferential flow is common in the soil with preferential paths, which affects soil water infiltration greatly. Although previous studies have made a great progress in preferential flow, the effect of preferential paths on preferential flow has not been reported, and a great effort is necessary to understand how precipitation intensities affect preferential flow. Therefore, in this paper, five undisturbed soil columns were sampled at the depth of 0-100 cm with different distribution of preferential paths from the Experimental Station of the Institute of Hydrogeology and Environmental Engineer, Chinese Academy of Geological Science (Hebei, China) and from Luancheng Experimental Station of Chinese Academy of Science (Hebei, China). Tests of different precipitation intensities, i.e., 0.23-0.24, 0.07-0.11, and 0.008-0.042 cm/min, were done to investigate preferential flow of the five soil columns. And the Hydrus-1D software coupling a dual-permeability model was applied to simulate the preferential flow of the soil columns under differential rainfall intensities. The results showed that the preferential paths played a vital role in development of the preferential flow since the levels of preferential flow were higher with more preferential paths in the soils. The relative transport abilities of preferential paths, which were defined by the ratio of velocity of preferential flow to rainfall intensity, increased with heavier rainfall. When the rainfall intensities were larger than the maximal coefficients of hydraulic conductivity of the intact soil columns, the velocities of preferential flow increased remarkably with increase of rainfall intensities. However, when the rainfall intensities were smaller than the maximal coefficients of hydraulic conductivity, the velocities of preferential flow increased little or no change. The effect of rainfall intensities on theνand increased ranges ofνwas related to the development of preferential paths in the intact soil columns, i.e., the effect can be stronger with the higher degree of preferential paths. In the soil columns with better development of preferential paths, the initial times of soil water flowing out at the bottom of the soil columns were shorter when rainfall intensities were larger, while in the soil columns with well developed preferential paths, the initial times of soil water flowing out at the bottom of the soil columns decreased firstly with a higher rainfall intensity, and then increased. The dual-permeability model described preferential flow well but couldn’t simulate the process that soil water in the soil matrix flowed out horizontally to preferential paths after the rainfalls. As such the model was not suitable for the soils with plenty of soil fissures. The percentage of preferential flow obtained from the results of modeling was 93.6%-99.9%, which was in agreement with the tested results in undisturbed to disturbed soil. It suggested the model could simulate the preferential flow well. However, the results may be affected by size of columns since the characteristics of preferential flow varied with study scales. Therefore, further studies were needed to improve the understanding of preferential flow in larger scales. The results here will be useful to evaluate the groundwater recharge, water saving methods and movement of soil pollutants in arable land.关键词
土壤/水/孔隙结构/优先通道/优先流/降雨强度/双渗透模型/Hydrus-1DKey words
soils/water/pore structure/preferential path/preferential flow/precipitation intensity/dual-permeability model/Hydrus-1D分类
农业科技引用本文复制引用
吴庆华,朱国胜,崔皓东,张家发,张发旺..降雨强度对优先流特征的影响及其数值模拟[J].农业工程学报,2014,(20):118-127,10.基金项目
国家重点基础研究发展计划（“973”计划）（2010CB428802）；国家自然科学基金项目（51279016）；国家“十二五”科技支撑计划（2011BAB10B04）；中央级公益性科研院所基本科研业务费 （）
