土壤孔隙结构调控斥水性土壤水分运动的作用机理研究

土壤斥水性能够直接影响土壤水分的入渗、再分布和蒸发过程。土壤斥水性和水分运动又均受土壤孔隙结构的调控，导致斥水性土壤水分运动比亲水性更为复杂，目前大多关于斥水性土壤水分运动研究仅考虑斥水性强弱的影响，具有片面性。本研究通过向不同结构土壤添加斥水性物质，进行土柱控制试验和数值模拟，并借助X-ray CT技术分析土壤孔隙结构对斥水性土壤水分运动的作用机制。具体研究目标包括：1）量化土壤孔隙结构和斥水性相关指标，揭示土壤孔隙结构对斥水性强弱程度的驱动作用；2）探究土壤斥水性与水力学参数之间的关系，基于Hydrus模型建立考虑土壤斥水性的水分运动模型，进一步明确土壤斥水性通过改变水力学性质对水分运动的影响；3）分析比较不同孔隙结构下斥水性土壤水分运动差异，并结合目标1中的研究内容，阐明土壤孔隙结构对水分运动的调控作用。研究结果对完善土壤水分运动基础理论和提高其模拟精度具有重要意义。

Soil water repellency can directly affect the processes of soil water infiltration, redistribution, and evaporation. Soil pore structure can influence soil water repellency and movement, which leads that the soil water movement under water repellent soil is more complex than under hydrophilic soil and it is a unilateral study of the hydrophobic soil water movement only considering the degree of soil water repellency. We will add different contents of a kind of hydrophobic substance to carry out a controlled soil column experiment indoors and numerical simulation. The X-ray CT technique will be applied to study the mechanism of the impact of soil pore structure on soil water movement for water repellent soil. The specific objectives of this study are: 1) to quantify soil pore structure and water repellency and then reveal the driving effect of soil pore structure on the degree of soil water repellency; 2) to establish the relationship between soil water repellency and soil hydraulic parameters and built soil water movement model using Hydrus Model that is tested by the measured value of soil water content. Furthermore, we assess the mechanism of the effect of soil water repellency on soil water movement by changing hydraulic properties; 3) to reveal the regulatory effect of soil pore structure on hydrophobic soil water movement through comparing the difference of soil water movement under different soil pore structure and combining the content of objective one. The studies have important implications for improving the basic theoretical knowledge on soil water movement and the accuracy of the simulation for the soil water movement.