中国科学院水利部水土保持研究所机构知识库

水资源短缺是黄土高原地区农业生产和生态环境建设主要的限制因子。 土壤水分入渗过程不仅决定着土壤对雨水和灌溉水等有限水源的利用程度，而且也深刻影响着地表径流和土壤侵蚀强度。土壤表面电场对团聚体稳定性具有重要影响，团聚体破碎后土壤孔隙将发生重要变化，并影响水分入渗过程。然而，目前关于土壤电场作用对黄土母质发育土壤水分入渗过程的影响尚不清楚，同时考虑表面电场作用后
经典土壤水分入渗模型的适用性还有待进一步验证。因此，本研究采用室内一维定水头土柱模拟试验，通过定量调控土壤表面电场，研究了不同土壤电场强度对水分入渗速率、湿润锋运移、累积入渗量的影响，并采用 Kostiakov 模型和 Philip 模型对土壤水分入渗过程进行拟合。结果表明：（1）湿润锋运移速度、入渗速率和累积入渗量均随入渗电解质浓度的减小、表面电位（绝对值）和电场的增大而降低，这表明土壤表面电场对土壤水分入渗具有重要的、不可忽略的影响。（2）当电解质浓度 < 0.01 mol·L-1，塿土和褐土的电位绝对值大于 233 mV 和 223 mV 时， 土壤水分入渗特性参数随时间的变化曲线较为接近， 表明 233 mV和 223 mV 分别是影响两种土壤水分入渗过程的临界电位值。（3） Kostiakov 模型和 Philip 模型对于塿土和
褐土入渗过程的模拟均有较好的适用性，但通过进一步分析其拟合统计特征值（决定系数 R2、残差平方和、均方根误差 RMSE 值），发现 Kostiakov 模型的拟合结果更优。该研究结果可为黄土高原土壤水分入渗的内部调控新技术提供理论参考。
 

【Objective】The Loess Plateau of China is one of the world’s most severely eroded regions. In this region water shortage is the main limiting factor in agricultural production and ecological environment construction. Therefore, it is of great significance to improve utilization efficiency of the limited water resources in the region to the maintenance of regional ecological environment security and efficient development of green agriculture. The process of soil water infiltration not only determines utilization rate of the limited water sources, such as precipitation and irrigation, but also profoundly affects intensity of surface runoff and soil erosion. Soil water infiltration is mainly affected by soil organic matter content, bulk density, texture, structure stability and soil porosity, water quality and so on. Recent researches have demonstrated that soil surface electric field influences soil water infiltration by affecting stability of soil aggregates and distribution of soil pores. Although quite a number of studies have been reported on water infiltration, water availability and their affecting factors in soils developed from Loess, it is still not clear that how soil interfacial properties (surface electric field and surface potential of soil particles) vary in the process of water infiltration and affect water infiltration characteristics and
how applicable the classical soil water infiltration model is when effect of the surface electric field is taken into account. So further studies need to be done. 【Method】 In this study, two representative Loess soils, Lou soil and Cinnamon soil, were used. According to the double layer theory of charged particles, the surface electric field of soil particles could be quantitatively adjusted by applying a series of electrolyte solutions different in concentration. Soil water infiltration rate, moisture front migration and cumulative infiltration in the two soils was determined. The Kostiakov model and the Philip model was used to fit the process of soil water infiltration. 【Result】 Results show: (1) Wetting front movement, infiltration rate and cumulative infiltration decreased with decreasing electrolyte concentration and increasing surface potential (absolute value), which indicates that surface electric field of soil particles strongly affects soil water infiltration; (2) When electrolyte concentration in the bulk solution was less than 0.01 mol·L-1 or absolute surface potential value of the Lou soil and Cinnamon soil was more than 233 mV and 223 mV, the temporal variation curves of soil water infiltration in the two soils were close to each other, which indicates that 233 mV and 223 mV is the critical potential value of the soil water infiltration process in Lou soil and Cinnamon soil, respectively; and (3) The Kostiakov model and the Philip model were both applicable to simulating infiltration processes in Lou soil and Cinnamon soil. Further analyses of the fitting parameters—correlation coefficient (R2), residual sum of squares, and root mean square error (RMSE) shows that the Kostiakov model was more suitable than the Philip model.【Conclusion】All the findings demonstrate that the process of soil water infiltration is greatly influenced by soil surface electric field. There are critical surface potentials controlling water infiltration. The findings provide a theoretical reference for development of new techniques to regulate water infiltration based on soil internal forces.