土壤水蚀过程中的重力侵蚀模拟研究

Water Erosion is main cause of soil loss, also it is one of most important soil erosion processes. During the soil erosion process, water erosion is always accompanied with gravitational erosion. Because the study of mechanism and process simulation of gravitational erosion fall far behind of water erosion and that causes difficulty of improving accuracy of soil erosion process simulation forecast. Insufficiency of systemic experimental observation data of gravitational erosion is main cause led to lag behind of study on gravitational erosion. It is considered to be the fundamental research work which is urgent to be strengthened that carrying out research and experiment of gravitational erosion, and applying experimental results to simulation of soil erosion in basin. The project is based on laboratory experiments to simulate occurrence of gravitational erosion in process of water erosion, explore control method of causes of occurrence conditions for gravitational erosion, study on effect of influencing factors of g gravitational erosion such as gradient of ditch, water content of soil, dredging and erosion of runoff, rain intensity etc. and quantify contribute rate of main influencing factors for gravitational erosion occurrence, defined gravitational erosion critical conditions, and base on that we built complete soil erosion process model contains gravitational erosion process. Research is considered to have practical significance in promoting development of gravitational erosion experimental research, explore mechanism of gravitational erosion, improving simulation accuracy of soil erosion process.

水力侵蚀是土壤流失的主要原因，也是土壤侵蚀最重要的过程之一。在土壤侵蚀过程中，水力侵蚀总是与重力侵蚀相伴发生。由于重力侵蚀的机理及过程模拟研究明显落后于水力侵蚀，造成土壤侵蚀过程模拟预报精度难以提高。而缺乏系统的重力侵蚀实验观测资料，是重力侵蚀研究滞后的主要原因。开展有关重力侵蚀的实验模拟研究，并将实验成果应用于流域土壤侵蚀过程的模拟，是土壤侵蚀研究中亟待加强的基础性研究工作。本项目通过室内实验，模拟水力侵蚀过程中重力侵蚀的发生，探索重力侵蚀发生条件的控制方法，研究重力侵蚀的影响因素- - 沟坡坡度、坡高、土壤含水量、径流淘蚀、降雨强度等对重力侵蚀的影响，量化主要影响因素对重力侵蚀发生的贡献率，界定重力侵蚀发生的临界条件，并以此为基础构建包含重力侵蚀过程的完整土壤侵蚀过程模型。研究成果在促进重力侵蚀实验研究发展，探索重力侵蚀发生机理，提高土壤侵蚀过程模拟计算精度等方面具有实际意义。

在土壤侵蚀过程中，水力侵蚀常与重力侵蚀相伴发生。由于重力侵蚀发生的随机性和不确定性，使得难以进行有效的实验模拟和观测，从而影响了重力侵蚀发生机理及模型模拟的研究。开展水力侵蚀过程中重力侵蚀的实验观测及模拟研究，是土壤侵蚀研究中亟待加强的基础性研究工作。本研究利用人工降雨系统和变坡土槽，开展了桂林当地红壤的探索性实验，归纳出了降雨历时递进实验和降雨过程断续实验相结合的实验方案。通过将所归纳出的实验方案在供试黄土侵蚀实验中的应用，并结合三维数字扫描技术，获得了水力侵蚀过程中坡面细沟及沟道发育过程的实验观测数据，分析了坡度、雨强、降雨历时对侵蚀过程中重力侵蚀发生的影响。本研究提出了较为可行的重力侵蚀实验模拟方案，对水力侵蚀过程中的重力侵蚀进行了界定，归纳出了区分重力侵蚀产沙量与水力侵蚀产沙量的方法，丰富了水力侵蚀过程中重力侵蚀的模拟研究成果。