中文摘要：

为了研究优先通道发育程度对不同降雨强度下优先流特征的影响，该文选取不同深度的田间原状土样，在不同降雨强度下进行土壤优先流的室内物理模拟试验，并采用双渗透介质模型Hydrus-1D对优先流发育过程进行数值模拟。结果表明：优先通道越发育，其优先流程度越高。降雨强度对优先流速率及其增加幅度的影响随土壤优先通道发育程度的增加而增加。优先通道发育的土柱，降雨强度越大时，其土柱下端初始出流时间越短，而优先通道一般发育的土柱，其土柱下端初始出流时间均随降雨强度增加呈先减小而后增加的规律。当降雨强度小于土柱最大导水能力（原状土柱表面出现积水时的导水能力）时，优先流速率随降雨强度增加而显著增加，而当降雨强度接近或大于其最大优先导水能力时，优先流速率增加缓慢或趋于稳定。土壤优先通道对降雨入渗的导水能力（即优先流速率与降雨强度之比）随降雨强度增加而变小。双渗透介质模型能较理想地模拟优先流发育过程，对土壤基质向大孔隙排水过程的模拟较差，但模型不适用于裂隙发育的土壤。各土柱的优先流程度为93.6%～99.9%。在研究降雨强度对优先流的影响规律时，该研究考虑了优先通道发育程度对此规律的影响，丰富了优先流理论，同时对农业节水、土壤污染迁移、地下水污染风险评价以及滑坡机理等研究方面具有重要的科学意义。

英文摘要：

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 wit