“自然-人为”耦合驱动的流域水沙运移尺度效应及其尺度依存

流域水沙运移具有明显的尺度效应特征，这已被国内外众多研究者揭示。目前，流域径流和输沙的尺度效应研究多为连续尺度上，且径流和输沙变化的驱动因素研究集中的土地利用变化方面。本项目拟以多级尺度典型流域为研究对象，开展“自然-人为”耦合作用下的流域水沙运移的尺度变异规律研究，探究气候变化、土地利用变化、径流和输沙过程变化等几个过程突变规律和协同变化机制；在定量评估气候变化和人类活动对侵蚀产沙作用份额的基础上，通过扩展研究区域，揭示黄土区流域在离散尺度上的尺度效应，辨析连续尺度与离散尺度的尺度效应异同和各自尺度依存的尺度域；基于流域泥沙输移尺度依存和分形特征，探讨一定尺度域内侵蚀产沙的尺度转换途径。该研究对于系统认识黄土区流域侵蚀产沙过程的尺度效应、科学评价自然-人为作用对其贡献率以及丰富水文过程尺度转换途径研究具有重要理论意义，同时对指导区域土地管理与规划以及综合治理措施配置有重要现实意义。

A number of researchers from home and abroad have revealed the fact that runoff and sediment delivery in watersheds have significant characteristics on scale effect. Currently, scale effects on runoff and sediment delivery are studied mostly at continuous scales of watersheds. Moreover, factors of driving forces on runoff and sediment delivery are focused on factors related to land use change. This project intends to investigate scale effect variation on runoff and sediment delivery under ‘natural-artificial’ coupling drive in typical multi-scale watersheds, and to explore variation of processes, such as climate change, land use change, runoff and sediment delivery and their co-variation mechanism. In addition, on the basis of quantitative assessment on the effect of climate change and human activities on sediment delivery, a number of new watersheds in the Loess Plateau will be selected to study, with the aim of revealing characteristics of scale effect at discrete scales. Also, it will be distinguished that similarities and differences of scale effect and their scale-dependence domains between continuous and discrete scales. Furthermore, based on dependence of sediment delivery ratio on scale and its fractal characteristics, the scale-up/down approaches of sediment delivery are planning to discuss at certain scales. This study has important theoretical significance on systematic understanding of scale effect on erosion and sediment delivery in loess areas and also on scientific assessing the effect of ‘natural-artificial’ coupling drive and enriching scale-up/down approaches of sediment delivery and hydrological processes. Meanwhile, this study has important practical significance on guiding regional land management and planning as well as comprehensive control measures and allocation.