不同结构土壤斥水性对坡面侵蚀过程的综合影响及其作用机理研究

Soil water repellency is one of the most critical influences on soil erosion, which affect the process of erosion by increasing aggregate stability, promoting the formation of soil crusts，reducing soil infiltration and so on. However, most studies evaluated the relation between water repellency and erosion just from one or two sections of erosion process. As a result, the combined effect is still unclear because the results from these studies were contradicted. To understand it more comprehensively and thoroughly, typical soils with different texture and water repellency level will be selected, the Physical and chemical properties of which will be analyzed to understand the factors affecting repellency. After that, aggregate breakdown and soil infiltration will also be simulated in laboratory to understand the mechanism between repellency and each sub-procedure. At last, simulate rainfall will be designed. The process of aggregate breakdown, splash, crust, infiltration, runoff and sediment will be monitored completely. The combined effects of water repellency on soil erosion will be understudied better.

斥水性是影响土壤侵蚀的重要因素，斥水通过增强团聚体稳定性、促进结皮形成、降低土壤入渗等多个途径影响土壤侵蚀过程。但是目前关于斥水性与土壤侵蚀关系的研究大多从团聚体稳定性或土壤入渗等单方面进行分析，斥水性在不同方面加剧或减弱土壤侵蚀的作用并不相同。由于缺乏对土壤侵蚀作用的全面研究，斥水性对土壤侵蚀的综合影响及作用机理尚不完全清楚。为进一步明确斥水性对土壤侵蚀的综合作用，本研究选取不同结构及斥水强度的典型土壤，分析土壤斥水性的影响因素，通过室内团聚体破碎模拟、土壤入渗模拟等方法研究斥水性对土壤侵蚀子过程的影响及作用机制。在此基础上通过模拟降雨试验，全面监测降雨过程中团聚体破碎、溅蚀发生、结皮形成、土壤入渗、径流产生及冲刷等过程，通过数据挖掘与分析，从总体上揭示斥水性对不同土壤侵蚀过程的影响及其机理。

土壤斥水性是影响土壤侵蚀的重要因素，通过增强团聚体团聚体稳定性、降低入渗、增加产流等方式影响土壤侵蚀过程。本研究选取了我国中南地区几种不同类型及利用方式土壤，通过土壤斥水性性质分析，探究土壤斥水性分布规律及其影响因素，结合室内模拟降雨试验，阐明了土壤斥水性对坡面侵蚀过程的综合影响，主要结论如下：1. 受长期耕作影响，耕地土壤的斥水性最低，表层土壤斥水性高于表下层，黄褐土斥水性高于其他类型土壤；斥水性受到多个因素的影响，不同土地利用方式下土壤斥水性影响因素有所差异，斥水性受到土壤机械组成和游离铁、铝氧化物的显著影响。2. 斥水性显著影响水稳性团聚体含量，斥水性强的土壤湿筛后WSA、MWD、GMD等值也越高，对不同破碎机制下团聚体稳定性也有着一定影响，总体上看斥水性越强的土壤其团聚体水稳性也更强，更不易被破坏分散。3. 土壤溅蚀过程呈现为倒“V”形状，即一个陡涨陡落的特点，累计溅蚀量随降雨历时变化规律呈现对数函数模型，在一定雨强范围内，斥水性对土壤溅蚀有着显著影响，斥水性越大土壤发生溅蚀的程度也越大；土壤斥水性显著影响产流的初始阶段，可以加快坡面径流、增加坡面产流；通过侵蚀产沙数据分析发现，斥水性会显著降低坡面侵蚀产沙，对坡面侵蚀产沙有显著的抑制作用。