【作者】 赵超；

【导师】 徐向舟；

【作者基本信息】 大连理工大学 ， 水文学及水资源， 2011， 硕士

【摘要】 黄土高原沟坡区重力侵蚀严重,研究重力侵蚀问题对于该地区的防灾减灾和可持续发展具有重大的现实意义。本文首先回顾了前人在黄土沟坡重力侵蚀成因机理、模型试验方法以及数值模拟等方面取得的研究成果,并根据研究背景区域现场调查结果和相关的文献资料,建立了黄土沟坡概化模型。然后利用沟坡模型试验的设备和技术,模拟研究了不同坡度、坡高组合条件下黄土沟坡的重力侵蚀过程。最后分析了黄土沟坡的重力侵蚀发生过程、重力侵蚀影响因素以及模型出水口的产流、产沙过程。研究取得了如下主要成果：(1)提出了一种适用于沟坡地形重力侵蚀动态、定量观测的方法——“MX-2010-G型地貌仪”观测法。该地貌仪可根据重力侵蚀发生前后坡体的体积差定量计算出重力侵蚀量。另外,由于地貌仪对沟坡地貌变化过程进行了全程录像,且地貌矢量图是根据录像截屏处理得到,因此,地貌仪又实现了对沟坡地形的动态观测。(2)采用模型试验方法成功地模拟了黄土沟坡的重力侵蚀过程。试验中发现：在模拟降雨条件下,黄土沟坡模型的重力侵蚀现象与原型接近；从试验中观测到的重力侵蚀发生时间,单次重力侵蚀发生量与坡面宽度、高度的对比关系等方面来看,模型试验的结果与原型都比较吻合。(3)研究了重力侵蚀与坡度、坡高以及下垫面含水量等影响因素之间的关系。坡度是重力侵蚀重要的限制性因素,坡度决定重力侵蚀发生的类型和规模；坡高是重力侵蚀重要的影响因素,当沟坡坡度相同时,崩塌量和重力侵蚀总量都与坡高成正相关趋势,滑塌侵蚀量则受坡高的影响较小；在其它降雨要素相同时,下垫面含水量是沟坡重力侵蚀重要的触发因素,其变化与沟坡地貌发育以及重力侵蚀过程基本一致。(4)观测了黄土沟坡的产流、产沙过程。累积径流量与降雨历时呈显著的线性函数关系,累积产沙量与降雨历时呈显著的幂函数关系；含沙量和输沙率均随降雨历时呈现上升趋势,特别是次降雨的中后期,含沙量和输沙率的增大趋势都比较明显；次降雨重力侵蚀总量与含沙量呈成正相关关系,重力侵蚀对高含沙水流的形成起着十分重要的作用。更多还原

【Abstract】 The study of gravitational erosion in gully region is of great practical significance for its disaster prevention and mitigation, and sustainable development. This study presents an approach for simulating the gravitational erosion of loess gully that is different from any previously attempted. Firstly, the generalized scheme of loess gully is established, based on the previous laboratory studies, the field investigations of the background region, and the relevant literature. Then a series of model experiments in various initial dimensions are operated to simulate the process of gravitational erosion by the equipment and technology of gully model experiment. Finally, the process of gravitational erosion, the relationship between the gravitational erosion and its influence factors, and the process of the runoff and sediment yield are analyzed. The results can be summarized as follows:(1) This study proposes an observation method, which is suitable for the dynamic and quantitative observation of gravity erosion in gully terrain. The volume of gravity erosion can be quantitatively calculated by the MX-2010-G topography meter according to the topography before and after gravity erosion. Simultaneously, the dynamics of gully can be observed for the whole video recording by the MX-2010-G topography meter.(2) Model experiment method is successfully used to simulate the gravitational erosion of loess gully. According to the model experiment, we conclude that the model experiment and prototype of loess gully are similar, whether the phenomenon of gravitational erosion or the test results.(3) There are many influence factors for the generation of the gravitational erosion. Based on the model experiments, some factors, such as the slope gradient, height and soil moisture of underlying surface and so on, are discussed in this paper. The conclusions are as follows:(a) The slope gradient is the restrictive factor which determines the type and intensity of the gravitational erosion; (b) When the grade are the same, the total volume of collapse and gravity erosion are positively correlated with the height, however the total volume of landslide is less affected by the height; and (c) The soil moisture of underlying surface is the important triggering factor for the occurrence of gravitational erosion, which is basically consistent with the landform development and the process of the gravitational erosion.(4) Combining the gravitational erosion and observation results of the outlet of the models, the process of runoff and sediment yield is researched in this study. The conclusions are as follows:(a) Cumulative runoff is significantly relative to rainfall duration in linearity, while cumulative sediment yield has a power function relationship with rainfall duration; (b) Sediment concentration and sediment transport rates increases with the rainfall duration, and it’s more obvious in the late of each rainfall; (c) Gravitational erosion has a positive correlation with sediment concentration, and it also plays an important role in the hyperconcentrated flows.更多还原