坡面水蚀动力与细沟发育形态的相互作用机制及其影响因素研究

Severe soil erosion not only deteriorates ecological environment of the Loess Plateau, but also threatens the ecological security of the lower reaches of the Yellow River. Quantitatively revealing mechanisms of slope erosion processes has significant roles on erosion control and regional sustainable development of the Loess Plateau. Black loam, loessial soil and sand loess are selected as soil samples. Based on the field survey and observations of the field runoff plots, slope erosion processes and mechanisms are investigated through the indoor and field artificial rainfall experiments, combined with microtopography scanning technology and geographic information technology. The analysis is focused on the interation mechanisms between rill flow dynamic characteristics and rill development configuration. Also,their responses to the combined effects of rainfall, slope gradient, slope length ,topsoil characteristics and topsoil crust are investigated. Moreover, the the impacts of the interaction between water erosion dynamics and rill development configuration on slope sediment erosion-removal processes are investigated. And three-dimensional dynamic simulation based on self-organisation theory is carried out to explore the developmental form of rill erosion and related sediment yield processes. All these investigations can supply scientific base to the quantified descriptions of slope erosion process mechanisms and are benefit to the improvement of slope soil erosion prediction.

严重的水土流失不仅造成黄土高原生态环境恶化，而且威胁黄河下游生态安全，定量研究坡面侵蚀过程与机理，对黄土高原水土流失综合防治与区域可持续发展具有非常重要的意义。以黑垆土、黄绵土和沙黄土为研究对象，在野外调查和野外径流小区观测的基础上，通过室内和野外人工模拟降雨试验，结合微地貌扫描技术与地理信息技术，系统进行坡面水蚀过程与机理研究，揭示坡面细沟流水动力学特性与细沟发育形态相互作用机制及其对降雨、坡度、坡长、土壤特性和表土结皮等因素综合作用的响应规律，探讨细沟发育形态变化的临界条件，分析坡面水蚀动力与细沟发育形态的相互作用及其对坡面泥沙侵蚀-搬运过程的影响规律，并基于自组织理论探讨坡面细沟发育形态与细沟侵蚀产沙过程的三维动态模拟，以期深化坡面细沟侵蚀过程机理研究，为定量刻画坡面侵蚀过程机理和提高坡面土壤侵蚀预报水平提供科学依据。

坡面水土流失是造成黄土高原生态环境恶化的重要因素，定量研究坡面侵蚀过程与机理，对黄土高原水土流失综合防治与区域可持续发展有重要意义。项目通过室内人工模拟降雨试验与野外调查，结合微地貌扫描技术，系统进行了坡面水蚀过程与机理研究，揭示了坡面细沟流水动力学特性与细沟发育形态相互作用机制及其对影响因素的响应规律，结果表明细沟内水流流速沿坡长发生变化，在开始的1-3米内一直增加，在距离坡顶3米处左右达到最大，之后出现小幅度减小的趋势，坡度是影响细沟发育的主要因素，相关系数高达0.97。探讨了细沟发育形态变化的临界条件，发现坡面跌坎发生的临界流速在0.19～0.21 m/s之间，当坡面径流流速大于临界值时，会有细沟产生。分析了坡面细沟发育对坡面产沙过程的影响规律，t检验表明坡度和细沟形成对含沙量的增加有显著影响，单位水流功率与径流含沙量之间关系最为显著。在本基金的资助下共发表论文18篇（其中5篇SCI 论文），超额完成了研究任务（基金预期发表10-12篇，其中SCI论文4-6篇），培养了硕士研究生3名。通过本项目研究可深化坡面细沟侵蚀过程机理研究，为定量刻画坡面侵蚀过程和提高坡面土壤侵蚀预报水平提供科学依据。