对土壤侵蚀研究的几点思考

土壤侵蚀是现代地理环境条件下改变地貌景观的主要过程,也是引起土壤质量退化、沙漠化与石漠化的核心因素,与土壤、生态、水文等多个地表过程密切相关。虽然土壤侵蚀研究需要气候、地质、地貌、土壤、水文、生态等相关学科的基本知识,分析土壤侵蚀发生、发展过程的动力机制,但需要明确界定土壤侵蚀研究的时空尺度。土壤侵蚀与水土保持之间相互联系、相互促进。土壤侵蚀研究的时间尺度以次降雨、月、年为主,研究主题为次降雨侵蚀过程、土壤侵蚀季节变化与年际变化,时间尺度不宜超过100年。土壤侵蚀研究的空间尺度以小流域为主,基于土壤侵蚀垂直分带性,可以进一步分为样点、坡面、沟坡与小流域。在不同空间尺度上,研究内容与研究方法差异明显。土壤侵蚀过程包括土壤分离、泥沙输移和泥沙沉积,各个过程的主控因素存在差异,研究成果积累差异明显,研究重点会随着时空尺度的变化而有所不同。在土壤侵蚀过程研究中,应充分理解分离控制和输移控制及其时空转换阈值。虽然土壤侵蚀研究已经取得了大量成果,但在细沟网络结构及其时空变化、泥沙沉积过程、沟蚀形成与演变动力机制、重力侵蚀发育过程动力学机理、小流域土壤侵蚀过程模型等诸多方面,亟待加强研究。

Several Ideas Related to Soil Erosion Research

Soil erosion is a key process to alter landforms under modern geo-environmental conditions. It is also the main element to soil degradation,desertification and rocky desertification and is closely related to earth surface processes of soil,ecology and hydrology. The knowledge of climatology,geology,geomorphology,pedology,hydrology,and ecology are needed to analyze the dynamic mechanisms of soil erosion occurring and development. However,the boundaries of temporal and spatial scales need to be identified clearly. Soil erosion is closely related to soil and water conservation and they are stimulated to each other. The temporal scale of soil erosion research focuses on rainfall event,month,and year. The main topics are erosion processes of rainfall event,seasonal and inter-annual variations in soil erosion. The time scale should be less than 100 years. The spatial scale of soil erosion research should be focus on small watershed. Based on the vertical distribution of soil erosion in small watershed,site,hillslope,gully and small watershed are commonly selected to study soil erosion. Nevertheless,the contents and methods are quite different from different scales. Soil erosion includes three sub-processes of soil detachment,sediment transport and sediment deposition. The key influencing factors and the research accumulations of these sub-processes are significantly different. The studying topics change with the temporal and spatial scales. The detach-limited and transport-limited as well as their altering threshold conditions should be always remind in mind to understand your experimental results. The future studies should be enhanced on rill network and its temporal-spatial variations,sediment deposition,dynamic mechanism of gully formation and evolution,mechanism of gravity erosion development,process-based soil erosion model for small watershed.