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基于遥感技术的藏东南地区冰川泥石流危险性评价
Alternative TitleHazard Assessment of Glacial Debris Flows in Southeast Tibet Based on Remote Sensing Technology
Language中文
李炫
Thesis Advisor范建容
2016-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline地图学与地理信息系统
Keyword藏东南地区 遥感 冰川泥石流 危险性评价
Other Abstract

藏东南地区分布着我国一半以上的海洋型冰川,受季风气候和全球变暖的影响,区域内冰川消融退缩加上丰富的降雨一遇到松散的固体物质就极易形成泥石流灾害,冰川泥石流灾害已成为藏东南地区经济发展的重要阻碍,做好藏东南地区的冰川泥石流危险性评价具有重要的实践意义。本文针对区域内冰川泥石流大量存在(冰水泥石流和冰湖溃决泥石流)的特点,选取藏东南然乌-通麦段作为研究区,在国内外学者对冰川泥石流形成机制研究成果总结分析的基础上,从地形地貌、地质构造、气象条件和人类活动等多个方面选取评价指标,建立了适合研究区的冰川泥石流的危险性评价指标模型,借助于遥感技术快速方便的特性,综合应用GIS空间分析方法和地理统计方法快速有效的获取相关参数,并结合模糊综合评价模型实现了然乌-通麦区段冰川泥石流的危险性评价。具体的研究工作如下:(1)确定了然乌-通麦区段流域划分的合理阈值,实现了基于DEM数据流域单元的快速分划。综合应用河网密度法和均值变点法,依次递增集水阈值大小,根据集水阈值大小与河网密度之间的关系,从不同的角度确定出阈值为4000(即累积栅格值),有效的防止了流域阈值选取的不确定性。(2)确定了波段比值阈值法最为适合研究区冰川信息的提取,实现了研究区冰川积雪地的提取。通过分析研究区Landsat8遥感数据上冰川积雪地的光谱特征,运用影像数据的第3和第6波段建立雪被指数通过目视判读确定研究区的冰川提取阈值,同时对比监督分类方法和非监督分类方法提取的冰川结果,最终认为波段比值阈值法在阈值取0.4的时候能比较完整的提取出研究区的冰川信息,得到研究区的总冰川区面积为967.13km2,占总流域面积的18.44%。(3)通过总结前人对冰川泥石流的研究成果,并分析研究区冰川泥石流灾害的形成条件,建立了研究区冰川泥石流危险性评价模型,实现了然乌-通麦区段的冰湖溃决危险性评价和冰川泥石流危险性评价。考虑到气象条件是泥石流爆发的驱动因子,主要应用MODIS地表温度和TRMM降雨数据提取相应的气象指标参与危险性评价,有效的弥补了该区段气象资料匮乏的缺陷。在评价因子提取的基础上,运用模糊综合评价方法,将研究区的冰湖溃决危险性划分为高度危险、中度危险、低度危险、极低危险四个等级,将研究区的冰川泥石流危险性划分为高度危险、中度危险、低度危险三个等级,划分的结果表明:研究区大部分冰湖溃决的危险性极低,然乌-通麦段流域冰川泥石流危险性以高度-中度危险居多,并运用已知灾害点对评价结果加以检验得到76.19%的已知泥石流点处于高度危险区域,这一结果表明研究结果具有一定的参考价值。

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There are more than half of maritime glacier in china concentration distributed in the Southeast Tibet. Affected by monsoon climate and global warming, shrinking glaciers in this area coupled with abundant rainfall once encountered any loose solid substance would be easily formed debris flows. Glacial debris flows have become an important obstacle in economic development of Southeast Tibet. So, the hazard assessment in this area is of great practical significance.This paper considering the large number of glacial debris flows in this area, choose Ranwu to Tongmai as study area. On the basis of glacier formation mechanism research summary of domestic and foreign scholars, evaluation indexes are determined from multiple aspects including: topography, geological structure, weather conditions and human activities. Considering the convenience of remote sensing, we established the evaluation model for glacial debris flows in study area. Comprehensive application of GIS(Geographic Information System) and geostatistical methods to obtain the relevant parameters and combine with fuzzy comprehensive evaluation model we achieved the hazard assessment of glacial debris flows and glacial lake outburst in study area. The main research content is as follows:(1) Determination of watershed division reasonable threshold, so we get the distribution of drainage area based DEM data. Comprehensive application of the mean change point method and drainage density method and ascend order the size of catchment threshold, according to the relationship between the catchment drainage density and threshold size we work out the threshold value is 4000 which is value of cumulative grid.(2) Determination of the most suitable method for glacier information extraction in study area is the band ratio threshold method. And we extract the glacier snow area. By analyzing the spectral characteristics of the Landsat-8 remote sensing data, we use band 3 and band 6 of landsat-8 data to calculate the NDSI(Normalized Difference Snow Index). Finally we concluded that the band ratio threshold method could extract the glacier information completely when the threshold is equal to 0.4. and we get the area of glaciers in the study area is 976.13km2, 18.44% of the total study area.(3) Summarizing the previous studies of glacier debris flow and analyzing the formation conditions of glacier debris flow, we built the hazard assessment model of glacier debris flows. So we achieved the hazard assessment of glacial debris flows and glacial lake outburst in study area. In consideration of the weather conditions is the driving factor in outbreak of debris flow, we used MODIS land surface temperature product and TRMM precipitation data to extract corresponding meteorological indicators and combined with fuzzy comprehensive evaluation model the glacial lake outburst risk in study area are classified as high risk, moderate risk, low risk, extremely low risk while the glacial debris flows are classified as high risk, moderate risk, low risk. According to the result, most of the glacial lake outburst are extremely low risk, many of the glacial debris flows are high-moderate risk. Using known hazards to test the evaluation result, 76.19% known hazards is in high risk area which confirmed that this study have some reference value. 

Subject Area测绘科学技术 ; 环境科学技术
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/17205
Collection数字山地与遥感应用中心
Affiliation中国科学院•水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
李炫. 基于遥感技术的藏东南地区冰川泥石流危险性评价[D]. 北京. 中国科学院研究生院,2016.
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