基于GIS的汶川地震地质灾害危险性评价研究

【作者】 赵彬；

【导师】 李家存； 赵文吉；

【作者基本信息】 首都师范大学 ， 地图学与地理信息系统， 2011， 硕士

【摘要】 地震引发了大量的地质灾害,对人民的生产、生活造成了巨大的危害和损失。所以对地质灾害进行危险性评价并进行地质灾害危险性区划,对于提高警惕,避开地质灾害高危区或者加强高危区的防范,减少地质灾害造成的危害与损失具有重大的现实意义。地质灾害的发生与地质环境条件密切相关,它们是地质灾害发生的物质基础。基于地质灾害的空间分布规律,统计分析地形地貌、地质构造等地质环境条件与地质灾害的空间相关性。利用ArcGIS的空间分析功能和图解建模方式构建地质灾害敏感性与危险性评价模型。围绕数据获取、相关性分析、评价模型建立与区划等问题,基于GIS建立地质环境条件因子提取、敏感性评价、危险性区划等流程并制定技术路线。地震诱发的地质灾害类型主要为崩塌与滑坡,本文以二者为研究对象,研究内容如下：地质环境条件因子的提取与分析。以“5.12”汶川地震重灾地区——汶川为例,收集了研究区1：50000比例尺DEM、遥感影像、地质构造、降雨等基础地理资料。根据地震地质灾害空间分布规律与特征,结合统计曲线特征与相关性程度,筛选出影响因子大,冗余度低的因子作为地质灾害评价因素。在地质灾害与地质环境条件的提取、量化与空间表达的基础上建立地质灾害评价空间数据库。地震地质灾害敏感性区划与分析。总结了国内外地质灾害评价中的的研究方法与现状,基于GIS建立地质灾害敏感性评价模型,对比分析不同模型的优势与精度。采用制图综合对地质灾害敏感性进行区划与制图,并分析成因。地震地质灾害诱发因素分析及危险性区划。地质灾害的发生不仅与地震有关,还与降雨、人为活动等因素相关。统计分析三者与地质灾害的空间分布,进行汶川地震地质灾害的危险性区划。通过对以上内容的研究,取得如下研究成果：基于地质灾害空间分布规律与特征,分别统计分析了每个地质环境条件因子与地质灾害的相关性。地质灾害的高发区分别为：高程1.2-2.4km之间,坡度45°-60°之间,地形起伏度在400-500m之间,千枚岩与岩浆岩中地质灾害分布广泛。对比分析了两种地质灾害敏感评价模型。结果表明：信息量模型操作简单,易于判断因子的影响程度,评价精度低；逻辑回归模型具有筛选变量的能力,评价精度较高,计算过程较为复杂。基于逻辑回归模型进行敏感性评价与综合制图,结果表明：地质灾害极高敏感区占8.9%,该区处于元古界较硬的花岗岩层、构造发育、地形切割强烈、山高坡陡、农耕、采矿、修筑公路、土地开发利用等人类工程活动强度大,地质灾害发育密度大。地质灾害高敏感区占16%,该区位于志留系茂县群千枚岩分布较多的地层,地震断层破碎带发育,修建道路切割坡脚,形成大量的有效临空面,地质灾害发育密度较大。地质灾害中敏感区占19%,低敏感区占22.2%,该区由于远离河流和道路,所以坡度变化较小,地质灾害发育密度较小。地质灾害不敏感区占33.9%,该区地质构造完整,主要为三叠系须家河组砂岩夹页岩,地势陡峻但人居分散,人口密度小,人类工程经济活动强度小,地质灾害造成的危害很小。根据以上区划结果,要加强地质灾害极高敏感区的环境保护与防护,减少地质灾害的发生统计了地震烈度、年降雨量与道路与地质灾害的空间分布,初步从宏观角度分析了三者对地质灾害的致灾作用。基于敏感性区划,尝试分析了汶川地震地质灾害的危险性空间区划。结果表明：地质灾害极高危险区位于岷江与二河交汇处,地质灾害危险区划与敏感性区划具有很好的对应关系。更多还原

【Abstract】 The earthquake triggers a large number of geological disaster(landslide, rockfall and so on) which caused tremendous damage and loss in recent years. It is necessory to evaluate the geological disaster hazard to alarm the dangrous, and keep people away from the hazzrd area or take some measures, which to reduce the harm caused by geological disasters.Environment conditions are relative to geological disaster, which are the material basis of geological disaster. Based on the geological disaster distribution character, this paper use frequency analysis method to analyse the spatial relationship between them. Using spatial analysis and graphical modeling function of ArcGIS software to evaluate the geological disaster susceptibility and hazard assessment. Basee on GIS make a workflow about data acquisition, correlation analysis, evaluation model and zoning issues.The types of geological disaster caused by earthquake including landsldie and rockfall mainly, this paper take them as geological disaster to study the geological disaster hazard. It conatins the following part:conditioning factors extraction and analysis. Take wenchuan district which attacked heavily during the "5.12" Wenchuan earthquake as study area. Based on the geological disaster investigation, built the geological disaster inventory,1:50000 DEM, remote sensing images, lithological map, and other basic geographic information data. According to the spatial distribution of geological disaster character, this paper combine with statistical correlation curve and select the conditioning factors with strong power and low redundancy as the geological disaster hazard assessment factors. After spatializing them, build up a spatial database for geological hazard assessment finally.Goelogical disaster susceptibility analysis. First review the geological disaster assessment methods and recent development both domestic and abroad. then. set up two models based on GIS. assess the susceptibility of the two methods, and make the susceptibility map.Earthquake induced geological hazard assessment and analysis. geological disaster not only associate with earthquakes, but also related with rainfall, human activities. With statistical method to analyse those triggering factors’relationship with geological disasters, then establish the weighd based on information theory. Give the zoning of geological disaster hazard and mapping the area.On the above contents, this study get achieved the following result: It based on spatial distribution of geological hazards and characteristics, statistical analysis of geological environmental conditions of each factor and the correlation of geological disasters. The main geological environment between high incidence of geological disasters factors as:elevation between 1.2～2.4km, slope between 45°～60°, relief amplitude between 0.4～0.5km, Phyllite and magmatic rocks have more geological disasters.Compare between the susceptibility model, finding that:the information model is simple and easy to evaluate the weight of those factors, while the logistic regression model has the ability to select factorsis with complicated process. However, the later model has higher accuracy.The susceptibility result indicates that:the most susceptibility class covered 8.9%, this area contains hard proterozoic granite lithology, structural development, terrain cutting strongly, high mountains and steep slopes, and frequent human engineering activities, which caused high geological disasters density. The median class covered 16%, this group filled with Silurian Maoxian phyllite, due to the slope by the road development caused a large number of effective free surface. The normal class covered 19% and low with 22.2%, whoes groups are far away from rivers, roads and low topographic relief. The extremely low class covered 33.9%, whose group including Wolong Nature Reserve, with Complete the geologic structure, mainly Triassic sandstone Xujiahe shale, steep terrain but little human settlement, and low-intensity of the population density, economic activities and human engineering. So we have to strengthen the environment protection and safety of highset susceptibility area.Select the seismic intensity, rainfall and human activity as the Disastrous factors for Hazard assessment. Statistics of the three factors’spatial distribution with disasters, and their impact from macro perspective. Based on the susceptibility division, trying to analyze the earthquake hazard distribution. The results showed that:the most dangerous area located at junction of Minjiang river and Second river, thehazard area has good correspondence with the susceptibility division.更多还原