Use of Geomorphological Information in Indirect Landslide Susceptibility Assessment

The objective of this paper is to evaluate the importance of geomorphological expert knowledge in the generation of landslide susceptibility maps, using GIS supported indirect bivariate statistical analysis. For a test area in the Alpago region in Italy a dataset was generated at scale 1:5,000. Detailed geomorphological maps were generated, with legends at different levels of complexity. Other factor maps, that were considered relevant for the assessment of landslide susceptibility, were also collected, such as lithology, structural geology, surficial materials, slope classes, land use, distance from streams, roads and houses. The weights of evidence method was used to generate statistically derived weights for all classes of the factor maps. On the basis of these weights, the most relevant maps were selected for the combination into landslide susceptibility maps. Six different combinations of factor maps were evaluated, with varying geomorphological input. Success rates were used to classify the weight maps into three qualitative landslide susceptibility classes. The resulting six maps were compared with a direct susceptibility map, which was made by direct assignment of susceptibility classes in the field. The analysis indicated that the use of detailed geomorphological information in the bivariate statistical analysis raised the overall accuracy of the final susceptibility map considerably. However, even with the use of a detailed geomorphological factor map, the difference with the separately prepared direct susceptibility map is still significant, due to the generalisations that are inherent to the bivariate statistical analysis technique.     

陕西凤县滑坡易发性评价研究

滑坡易发性评价是滑坡早期预警的基础,为了探索适用于秦岭山区的区域滑坡易发性评价方法,本文在陕西凤县1:5万详细调查的基础上,针对山区地质灾害调查的特点,对传统信息量模型进行改进,利用ArcGIS软件基于改进的信息量模型完成了凤县滑坡易发性评价。结果显示:凤县地质灾害分布主要与植被覆盖率、河流侵蚀和人类工程活动相关。根据评价结果将凤县滑坡易发性划分为四个等级:高易发区面积165 km2,占全县总面积的5.2%;中易发区面积686 km2,占21.5%;低易发区面积1195 km2,占37.5%;基本安全区面积1141 km2,占35.8%。根据此评价结果,为陕西凤县土地利用规划和滑坡防治提供依据,并为秦岭山区的区域滑坡易发性评价提供思路和方法。     

基于RS与GIS的层次分析法在滑坡危险性评估中的应用——以四川宣汉天台乡滑坡为例

基于遥感(RS)和地理信息系统(GIS)技术,采用多层次分析(AHP)法,以四川宣汉天台乡为研究区,根据该区实际情况,选取线性构造、道路、土地利用、坡度、坡向5种影响滑坡灾害发生的因素作为评价因子,进行区域滑坡危险性评估。在ArcGIS的空间分析环境中运行权重叠加,把研究区划分成滑坡极易发生区、易发生区、一般发生区、可能发生区、难发生区和极难发生区。通过实地调查和与研究区的滑坡灾害实证研究结果进行比较,发现评估结果与实际状况较为吻合,研究方法能够准确地评估区域滑坡灾害危险性的程度。     

不同区域地质灾害评价方法的组合效应分析

区域地质灾害发生机理复杂,国内外主要的评价思路是建立以方法本身为基础的评价模型,这种评价思路会引起与区域地质灾害危险性自身的“不兼容”性,可以通过合理利用不同方法进行组合的评价模式来减小这种“不兼容”性.通过分析现有评价方法的适宜性,针对其不同的优缺点,提出了利用不同区域地质灾害评价方法进行组合评价应当遵循的基本原则,包括扬长避短原则、互扬互抑原则、提高资料的利用率原则、提高评价结果的精度原则.以青川县滑坡危险性评价为例,对这些原则的具体应用进行了分析,结果表明,利用模糊综合评判分别与AHP法和信息熵进行组合评价,其结果的精度要高于单独模糊综合评判法,但由于历史监测数据不充分,使得利用专家知识和经验的模糊综合评判与AHP的组合评价法的精度要高于基本监测数据的模糊综合评判和信息熵的组合评价法.     

基于GIS技术的巴东新城区滑坡灾害危险性区划

基于ArcGIS8软件平台开发了三峡库区巴东县新城区滑坡灾害信息系统,通过全面分析巴东新城区滑坡灾害的地形条件,工程地质岩组、构造与斜坡结构类型、人类工程活动、水的作用等影响因素,建立了相应的滑坡灾害危险性评价指标体系。采用基于GIS技术的信息量模型和敏感性评价方法,实现了巴东县新城区滑坡灾害危险性区划,其中,高危险区面积3.30km^2,占7.196;中危险区面积5.77km^2,占12.4％;低危险区面积16.40km^2,占35.3％;基本安全面积21.05km^2,占45.2％,可以作为巴东新城区城镇建设规划和减灾防灾的参考依据。     

Comparing Landslide Hazard Maps

The objective of the method explained in this paper isto obtain a better insight in the decision rulesapplied by geomorphologists in the direct mapping oflandslide hazard. This can be obtained by forcinggeomorphologists to specify for each unit (polygon) intheir hazard map the criteria that they used toclassify the unit as high, medium or low hazard. Whenthis is done systemically for an entire area, it ispossible to analyze those criteria statistically, andto evaluate whether they can be grouped into generaldecision rules, or whether these criteria arecompletely site specific. The same area in the Alpagoregion in Italy was mapped at 1 : 5000 scale by threeteams of experts individually. The different methodsare presented and the results are compared.     

Overview Landslide Hazard Assessment of China

In recent years, China has suffered serious geological disasters, most of slope movements due to complex geology, geomorphology, unusual weather conditions, and large-scale land explorations during high speed economic development. According to geological hazard investigations organized by the Ministry of Land and Resources of China, there are 400 towns and more than 10000 villages under the threatening of those landslide hazards. This paper presents the overview landslide hazard assessment in terms of GIS, which aims to evaluate the overview geohazard potentials, vulnerabilities of lives and land resources, and risks in conterminous China on the scale of 1 : 6 000 000. This is the first overview landslide hazard potential map of China.     

基于粗糙集的支持向量机滑坡易发性评价

区域滑坡易发性评价对灾害中长期预测预报具有重要意义。以三峡库区秭归至巴东段为研究区,利用粗糙集理论对20个初始评价因子进行属性约简,去掉冗余或干扰信息,得到13个核心评价因子,并以此作为支持向量机的输入特征集,构建支持向量机模型,实现滑坡易发性评价。在易发性分区图中高易发区占8.2%,主要分布在童庄河右岸、归州河沿岸、青干河左岸、树坪至范家坪长江右岸、牛口到东壤口长江左岸和巴东附近;不易发区占 52.7%,主要分布于店子湾至巴东旧城以及远离长江水系及植被覆盖度高的区域。通过验证与分析,粗糙集-支持向量机模型在高中易发区中的预测精度为85.6%,其预测能力优于支持向量机模型;与野外调查对比,预测结果与实际情况吻合较好。研究表明,应用粗糙集和支持向量机相结合进行滑坡易发性评价具有预测能力强、计算效率高等优点。     

Validation of Landslide Susceptibility Maps; Examples and Applications from a Case Study in Northern Spain

A procedure for validating landslide susceptibility maps wasapplied in a study area in northern Spain and the results obtained compared. Validationwas used to carry out sensitivity analysis for individual variables and combinationsof variables. The validity of different map-making methods was tested, as well as theutility of different types of Favourability Functions. The results obtained show thatvalidation is essential to determine the predictive value of susceptibility maps. Italso helps to better select the most suitable function and significant variables, thus improving the efficiency of the mapping process. Validation based on a temporal strategy makes it possible to derive hazard maps from susceptibility maps.     

基于小流域的地震扰动区降雨型滑坡泥石流危险性评价方法

地震扰动区存在大量震裂松散坡体,在持续或者密集的降雨条件下极易转化为滑坡灾害。同时,滑坡又会给泥石流提供大量松散固体物质,增加泥石流的危险性。因此,在震区,灾害通常以"链"的形式出现,比单一灾种危害性大。为了更有效地对地质灾害危险性进行评价,笔者将滑坡、泥石流作为灾害链,综合地加以分析和研究。选择5·12汶川大地震中受灾严重的都江堰市白沙河流域的17条泥石流沟作为研究区,建立滑坡-泥石流危险性评价耦合模型,研究24 h不同降雨量条件下小流域滑坡泥石流危险性的变化。耦合模型包括了坡体稳定性评价模型,水文模型及以泥石流规模、发生频率、流域面积、主沟长度、流域高差、切割密度、不稳定斜坡比为评价因子的泥石流危险性评价统计模型。研究结果表明:随着降雨量的增大,参与泥石流活动的松散物质方量持续增加,但当24 h降雨量超过200 mm后,泥石流沟的危险度等级不再发生变化;17条泥石流沟中4条为中危险度,12条为高危险度,1条为极高危险度。这说明研究区地质灾害问题相当严峻,在多雨季节存在泥石流群发的可能性,直接威胁到居住在泥石流沟附近的人民群众生命财产安全;因此,对于有直接危害对象的高危险度及其以上的泥石流沟,应该按照高等级设防标准进行工程治理及发布预警报。同时也说明,将滑坡、泥石流作为灾害链研究具必要性和可行性。     

基于加权证据权模型的青藏高原东部巴塘断裂带滑坡易发性评价

巴塘断裂带位于青藏高原东部,呈北东—南西向展布,全新世活动强烈,沿断裂带崩塌、滑坡、泥石流等地质灾害极为发育。基于遥感解译和野外地质调查,在巴塘断裂带两侧10 km范围内识别出滑坡93处;在分析滑坡空间发育特征的基础上,选取地形地貌(地面高程、地形坡度和地形坡向)、地形湿度指数、地层岩性、活动断裂、降雨量、水系、人类工程活动和植被覆盖等10个因素作为滑坡易发程度的主控因素,采用加权证据权法建立滑坡易发性评价模型,开展巴塘断裂带滑坡易发性评价;成功率(ROC)曲线检验结果表明此次滑坡易发性评价的准确率为82.3%。采用基于自然断点法将滑坡易发程度划分为极高易发、高易发、中等易发和低易发4个级别,结果表明滑坡易发性受巴塘断裂带和河流控制显著,极高易发区和高易发区主要分布在巴塘断裂带、金沙江和巴曲河谷及一级支流两侧,中等易发区主要分布在巴曲各支流中上游,低易发区主要分布在人类工程活动弱的高山地带以及地形相对平缓的区域。滑坡易发性评价结果很好地反映了巴塘断裂带现今滑坡发育分布特征,对该区重大工程规划建设和防灾减灾具有科学指导意义。     

滑坡灾害空间预测支持向量机模型及其应用

随着GIS技术在滑坡灾害空间预测研究中的广泛应用,滑坡灾害空间预测模型成为研究的热点问题。在总结滑坡灾害空间预测研究现状的基础上,简要介绍了两类和单类支持向量机的基本原理。以香港自然滑坡空间预测为例,采用两类和单类支持向量机进行滑坡灾害空间预测,并与Logistic回归模型进行了比较。结果表明,两类支持向量机模型优于Logistic回归模型,而Logistic回归模型优于单类支持向量机模型。     

基于GIS的兰州滑坡与泥石流灾害危险性分析

频繁发生的灾害愈来愈对人类社会造成巨大影响, 遥感、地理信息系统、全球定位系统和网络技术日益在减灾行动中发挥重要的作用. 兰州区域地质岩性、构造断裂、地震活动带、地表侵蚀强烈和地形起伏破碎等因素造成了兰州滑坡与泥石流灾害的发育, 夏季暴雨、人类工程活动等诱发下灾害频繁, 风险加剧. 针对兰州地区滑坡与泥石流等山地灾害对区域社会经济的影响, 通过建立区域滑坡与泥石流灾害的空间数据库, 在GIS技术辅助下实现了专家经验模型和Logistic模型对滑坡与泥石流灾害危险性的预测, 其中滑坡Logistic模型准确性达到85.3%, 专家经验模型准确性达到74.2%; 泥石流Logistic危险性预模型准确性达到80.5%, 专家经验模型准确性达到90.5%. 随着研究的深入, 综合遥感、地理信息系统、全球定位系统和网络技术的灾害研究与应用将在灾害防治中发挥重要的作用.     

雷达数据辅助下的滑坡易发性评价

岩土体含水量对滑坡,尤其是土质滑坡的稳定性具有极大的影响。本文以三峡库区秭归段内土质滑坡作为研究对象,利用Sentinel-1雷达数据反演地表岩土体含水量来替代传统的湿度指数因子,在保持其他因子不变的情况下,构建二元逻辑回归模型进行滑坡易发性评价。结果表明,利用成功率曲线对结果进行分析,采用岩土体含水量因子时预测精度达到80.2%,高于采用地形湿度指数的77.2%。利用雷达数据反演得到的岩土体含水量代替地形湿度指数进行滑坡易发性评价精度较高、预测能力较强。     

基于信息量、逻辑回归及其耦合模型的滑坡易发性评估研究:以青海沙塘川流域为例

滑坡易发性定量评估是预测滑坡发生空间概率的重要手段,基于统计分析原理的评估方法目前在国内外应用最为广泛,且不同评估方法的对比研究逐渐成为热点。以青海沙塘川流域黄土梁峁区为例,剖析了信息量模型和逻辑回归模型在滑坡易发性评估中的优越性和局限性,并探索提出基于二者的耦合模型。考虑坡度、坡向、起伏度、岩性、与干流距离、与支流距离和植被指数等7个影响因素,对比分析了基于信息量、逻辑回归及二者耦合模型的滑坡易发性评估的技术流程及结果。3种模型的成功率分别为:耦合模型成功率(78. 9%)>信息量模型成功率(71. 8%)>逻辑回归模型成功率(70. 8%)。在沙塘川流域黄土滑坡的易发性评估中,信息量和逻辑回归模型的表现基本相当,但信息量-逻辑回归耦合模型的成功率明显提升。该研究结果可为黄土高原区滑坡易发性定量评估提供借鉴。     

我国登陆台风影响区地质灾害易发性分析

地质环境脆弱的地区,台风的特大暴雨可以诱发山体滑坡和泥石流等地质灾害,造成严重人员伤亡。本文分析了我国登陆台风影响区域内的地质灾害时空分布特点,利用信息量方法,通过灾害的易发性区划来分析登陆台风影响区地质灾害特征,进而比较台风和非台风影响条件下地质灾害产生的地理条件和信息量差异。分析结果表明,在台风强降雨条件下,地质灾害的触发地质环境条件较非台风降雨触发地质灾害明显降低,地质灾害脆弱性明显增加。     

Use of GIS Technology in the Prediction and Monitoring of Landslide Hazard

Technologies such as Geographical Information Systems (GIS) have raised great expectations as potential means of coping with natural disasters, including landslides. However, several misconceptions on the potential of GIS are widespread. Prominent among these is the belief that a landslide hazard map obtained by systematic data manipulation within a GIS is assumed to be more objective than a comparable hand-made product derived from the same input data and founded on the same conceptual model. Geographical data can now be handled in a GIS environment by users who are not experts in either GIS or natural hazard process fields. The reality of the successful application of GIS within the landslide hazard domain seems to be somewhat less attractive than current optimistic expectations.In spite of recent achievements, the use of GIS in the domain of prevention and mitigation of natural catastrophes remains a pioneering activity. Diffusion of the technology is still hampered by factors such as the difficulty in acquiring appropriate raw data, the intrinsic complexity of predictive models, the lack of efficient graphical user interfaces, the high cost of digitisation, and the persistence of bottlenecks in hardware capabilities.In addition, researchers are investing more in tuning-up hazard models founded upon existing, often unreliable data than in attempting to initiate long-term projects for the acquisition of new data on the causes of catastrophic events. Governmental institutions are frequently involved in risk reduction projects whose design and implementation appear to be governed more by political issues than by technical ones. There is an unfortunate general tendency to search for data which can be collected at low cost rather than attempting to capture the information which most readily explains the causes of a disaster.If the technical, cultural, economic and political reasons for this unhealthy state cannot be adequately tackled, the International Decade for Natural Disaster Reduction will probably come to an end without achieving significant advances in the prediction and control of natural disasters.     

基于灰色关联度模型的区域滑坡敏感性评价

数理统计和机器学习模型如支持向量机(support vector machine,SVM)等,在区域滑坡敏感性评价中得到广泛的应用.但这些模型的建模过程往往较复杂,如在对机器学习进行训练和测试时难以选取合理的非滑坡栅格单元,而且有较多的模型参数需要确定.为提高滑坡敏感性评价建模的效率和精度,提出基于灰色关联度的敏感性评价模型.灰色关联度模型能有效计算各比较样本与参考样本之间的定量的关联度,具有建模过程简洁和评价精度高的优点,该模型目前在区域滑坡敏感性评价中的应用还没有引起研究人员的足够关注且有待进一步拓展.拟将灰色关联度模型用于浙江省飞云江流域南田—雅梅图幅(南田地区)的滑坡敏感性评价,并将得到的评价结果与SVM模型的敏感性评价结果作对比分析.结果显示,灰色关联度模型在高和极高敏感区的滑坡预测精度优于SVM模型,而在中等敏感区的滑坡预测精度略低于SVM模型;整体而言,灰色关联度模型对整个南田地区滑坡敏感性分布的预测精度略高于SVM模型.对两个模型建模过程的对比结果显示,灰色关联度模型建模较简单,具有比SVM模型更高的建模效率,为滑坡敏感性评价提供了一种新思路.     

不同组合模型区域滑坡易发性及精度分析

为探索区域滑坡易发性评价模型的适用性和评价结果的合理性,以滑坡灾害高发的白龙江流域为研究区,首先选取坡度、地形起伏度、距断层距离、地层岩性、流域沟壑密度、植被指数等6项影响滑坡发生的孕灾因子作为易发性的评价指标,以研究区2 093处滑坡灾害点为样本数据,依据各指标条件下的信息量值、确定性系数值和证据权重值曲线突变规律,并结合滑坡面积及分级面积频率比曲线作为等级划分的临界值来确定因子分级状态;其次,基于指标因子状态分级和相关性分析结果,采用信息量法、确定性系数法、证据权法分别与逻辑回归组合的3种模型开展区域滑坡灾害易发性评价,并从模型结果、适用性和精度等方面采用多手段对3种组合模型进行比较和讨论。研究结果表明：在区域滑坡易发性评价方面,3组模型均表现较为理想,信息量和逻辑回归组合模型的预测精度为94.6%,其预测精度和准确性优于其他2种组合模型。笔者以白龙江流域中游及其岷江支流段为例,开展滑坡灾害易发性评价模型适用性、评价结果分析以及预测精度评价对比和研究等,成果可为该区地质灾害防灾减灾和国土空间用途管制规划决策提供参考。     

Regional Assessment of the Effects of Land-Use Change on Landslide Hazard By Means of Physically Based Modelling

Physically based models are capable of evaluating the effects of environmental changes through adaptations in their parameters. For landslide hazard zonation, this gives them an edge over traditional, statistically based techniques that require large datasets and often lack the objectivity to achieve the same purpose. Therefore, physical models can be valuable tools for hazard assessment and planning purposes.The usefulness of the model prognosis depends largely on the ability of the physical model to mimic the landscape system. This implies that the model should be calibrated and validated and that the imposed changes do not lead to a radical departure from the present situation.Under the recognition of these constraints, a physically based model has been applied to a 1.5 km² catchment in the Alcoy region (SE Spain) to evaluate the effects of land use change on landslide activity. The model couples a transient, distributed hydrological model with a probabilistic assessment of the slope stability. Thus, it is able to assess the spatial and temporal activity of slope instability. For the present situation, validation demonstrates that the probability of failure returns a conservative estimate of the spatial frequency of landsliding. The model has subsequently been applied to two hypothetical land use change scenarios that extrapolate present and likely trends. For these scenarios, the model results indicate a marginal decrease in the spatial frequency of landsliding (aerial extent of instability). However, the decrease in the temporal activity (is total duration of instability over a given period) is substantial under the altered land use conditions. The forecasted change in landslide activity not only affects the relative weight of slope processes in the region. It also has implications for the perceived hazard levels and the landslide hazard zonation of the area.