岷江上游泥石流易发性评价及沟谷趋势预测

发布时间：2018-01-24 18:58

本文关键词： 岷江上游泥石流易发性信息量地貌信息熵　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：选择岷江上游泥石流沟为研究对象,旨在通过分析研究区泥石流的环境分析,探讨泥石流的发育特征,同时在环境分析基础上选择适宜的评价因子,应用信息量法对区域泥石流进行易发性定性定量评价,并利用地貌信息熵的计算来进行泥石流沟谷发育特征预测。主要成果如下:(1)对岷江上游泥石流的环境分析基础上,从泥石流空间分布、流域形态和物源特征三个方向进行探讨,得到岷江上游泥石流发育特征:研究区泥石流主要呈条带状沿河,大断裂,高山峡谷集中发育;沟道完整系数小,主沟纵比降与主沟长度和流域面积呈负相关关系;崩滑堆积体、山体失稳、坡面侵蚀三类物源类型。(2)通过对泥石流致灾因子的讨论,归纳出泥石流的形成条件:地貌多为小起伏山地区(200~500m)、岩性主要为三叠系和志留系的泥灰岩、页岩、千枚岩夹结晶灰岩、身处大断裂、坡度20°~40°、植被指数0.4~0.75的林地裸地区,泥石流灾害在以上区域占了较大面积。(3)基于因子相关性分析结果,选取坡度、坡向等9个要素作为泥石流灾害易发性评价因子,应用信息量模型,分析各因子对泥石流发生的贡献,对研究区进行泥石流易发性区划,研究结果表明:降雨量、坡度和植被覆盖率为泥石流的发生提供较大的信息量,基于信息量分区得到在降雨量稀少的干旱河谷、植被覆盖较低的陡坡下,是泥石流的高易发区,多表现在坡面侵蚀的物源和流通区,茂县~汶川~理县沟谷地带常见;低易发区主要分布在高海拔的清水区,多为冰原覆盖,较少发育泥石流灾害;中易发区主要在地形起伏较大的流通区;总的易发程度主要由河谷下游堆积区向各支流上游积雪清水区过渡分布,同时评价结果对泥石流防治中拦挡坝选址有一定的工程指导意义。(4)基于划定的泥石流子流域进行地貌信息熵计算,探讨出流域沟谷发育趋势研究,结果表明:岷江上游泥石流主要处于壮年偏幼年沟谷演化阶段,该阶段沟谷受侵蚀强烈,地表起伏大,为泥石流的形成提供充足的动力条件;壮年期泥石流沟也有一定数量分布,侵蚀强度中等,松散物质开始堆积;老年期泥石流数量少且沟槽较为稳定。
[Abstract]:The debris flow gullies in the upper reaches of Minjiang River were selected as the research object. The purpose of this study was to analyze the environment of debris flow in the study area, and to explore the development characteristics of debris flow, and to select appropriate evaluation factors on the basis of environmental analysis. The qualitative and quantitative evaluation of the susceptibility of regional debris flow was carried out by using the method of information quantity. The main results are as follows: 1) based on the environmental analysis of debris flow in the upper reaches of Minjiang River, the spatial distribution of debris flow. The characteristics of debris flow in the upper reaches of Minjiang River are discussed in three directions: the debris flow in the upper reaches of Minjiang River is mainly along the river, the large fault and the high mountain gorge are concentrated in the study area; The raceway integrity coefficient is small, and the main channel longitudinal ratio drop is negatively related to the main ditch length and watershed area. Landslide accumulation, mountain instability, slope erosion three types of material source type. 2) through the discussion of debris flow disaster factors. The forming conditions of debris flow are summarized as follows: the geomorphology is mostly 200 ~ (500) m ~ (-1) in the small undulating mountain area, and the lithology is mainly composed of mudstone of Triassic and Silurian system, shale and phyllite intercalated with crystalline limestone, which is located in a large fault. In the bare area with a slope of 20 掳~ 40 掳and a vegetation index of 0.4 ~ 0.75, the debris flow disaster occupies a large area in the above area.) based on the results of factor correlation analysis, the slope is selected. Slope direction and other nine factors are used as risk assessment factors for debris flow. The contribution of each factor to debris flow occurrence is analyzed by using information quantity model, and debris flow vulnerability regionalization is carried out in the study area. The results show that rainfall, slope and vegetation coverage provide a large amount of information for the occurrence of debris flow. It is the high prone area of debris flow, and it is often seen in the gully area of Maoxian ~ Wenchuan ~ Lixian. The low risk area mainly distributes in the high elevation clear water area, mostly covers by the ice sheet, develops the debris flow disaster less; The middle prone area is mainly in the circulation area where the topography fluctuates greatly; The total vulnerability is mainly distributed from the accumulation area in the lower valley to the clear snow cover area in the upper reaches of the tributaries. At the same time, the evaluation results have a certain engineering guidance significance for site selection of blocking dam in debris flow prevention and control. (4) based on the calculation of geomorphological information entropy of the delineated debris flow subbasin, the trend of valley development in the basin is discussed. The results show that the debris flow in the upper reaches of Minjiang River is mainly in the stage of the evolution of the gully in the middle of the age, and the erosion of the valley is strong and the surface undulation is large, which provides sufficient dynamic conditions for the formation of the debris flow. The debris flow trenches also have a certain number of distribution in the prime period, the erosion intensity is medium, loose material begins to accumulate; The amount of debris flow in the old age is less and the trench is more stable.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.23

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