Landslide hazard zoning along Himalayan Kaghan Valley of Pakistan��by integration of GPS, GIS, and remote sensing technology

This paper presents a methodology for developing a landslide hazard zonation map by integration of global positioning system (GPS), geographic information system (GIS), and remote sensing (RS) for Western Himalayan Kaghan Valley of Pakistan. The landslides in the study area have been located and mapped by using GPS. Eleven causative factors such as landuse, elevation, geology, rainfall intensity, slope inclination, soil, slope aspect, distances from main road, distances from secondary roads, and distances from main river and those from trunk streams were analyzed for occurrence of landslides. These factors were used with a modified form of pixel-based information value model to obtain landslide hazard zones. The matrix analysis was performed in remote sensing to produce a landslide hazard zonation map. The causative factors with the highest effect of landslide occurrence were landuse, rainfall intensity, distances from main road, distances from secondary roads, and distances from main river and those from trunk streams. In conclusion, we found that landslide occurrence was only in moderate, high, or very high hazard zones, and no landslides were in low or very low hazard zones showing 100% accuracy of our results. The landslide hazard zonation map showed that the current main road of the valley was in the zones of high or very high hazard. Two new safe road routes were suggested by using the GIS technology.     

Engineering geological mapping developed in the Fortaleza Metropolitan Region, State of Ceara, Brazil

Engineering geological mapping was carried out, at a scale of 1:100,000, in the Fortaleza Metropolitan Region, located in northeastern Brazil, to provide engineering geological information as an aid in planning land use and occupation. In this study, eight basic maps were produced drawing: urban areas, lithology, unconsolidated materials in addition to geomorphological map showing slopes, water resources, engineering geological zoning and distribution of geological–geotechnical environmental problems based on information collected through field and laboratory investigations. The region was divided into nine engineering geological zones analyzed in terms of geohazard susceptibility and foundation, excavation and waste disposal conditions.     

Groundwater vulnerability assessment in shallow aquifer of Kathmandu Valley using GIS-based DRASTIC model

In this paper, groundwater aquifer vulnerability map has been developed by incorporating the major geological and hydro-geological factors that affect and control the groundwater contamination using GIS based DRASTIC model. This work demonstrates the potential of GIS to derive a map by overlying various spatially referenced digital data layers that portrays cumulative aquifer sensitivity ratings across the Kathmandu Valley, Nepal, providing a relative indication of groundwater vulnerability to contamination. In fact, the groundwater is the major natural resources in Kathmandu for drinking purpose. The decline in groundwater levels due to the over exploitation and thus extracted water from shallow aquifer has been contaminated by the infiltration of pollutants from polluted river and land surface is continuous and serious. As the demand for water for human and industrial use has escalated and at the same time, the engineering and environmental costs are much higher for new water supplies than maintaining the existing sources already in use. Management of groundwater source and protecting its quality is therefore essential to increase efficient use of existing water supplies. Aquifer vulnerability maps developed in this study are valuable tools for environmental planning and predictive groundwater management. Further, a sensitivity analysis has been performed to evaluate the influence of single parameters on aquifer vulnerability assessment such that some subjectivity can be reduced to some extent and then new weights have been computed for each DRASTIC parameters.     

城市生活垃圾填埋场浅论

城市生活垃圾的处理为城市管理的一大难题 ,垃圾填埋场地的合理选择与布局直接关系到场地四周的环境质量。加强场址的地质环境研究工作 ,有助于防止和减少填埋场对地质环境及生态环境的危害。     

Assessment of geo-environmental problems of the Zonguldak province (NW Turkey)

The Zonguldak province is a coastal settlement area that has been suffering from serious natural and human-induced environmental problems sourced by its geology and geomorphology. Since the province locates at the heart of a coal-producing basin, the geo-environmental problems related to mining activities such as esthetic degradation, disposal of mining wastes and subsidence of the abandoned coal galleries are badly affecting every day life in Zonguldak province. Disposal of municipal wastes is also a big problem since only one municipality out of 32 has a sanitary disposal area. The rest of the municipalities dispose their solid wastes to rivers or to the sea. The province has also some health problems, which are pointed out in the literature, related to coal mining and geologic environment. These are cytogenetic damage in peripheral lymphocytes and pheumoconiosis (most commonly seen at coal workers), goiter and cancer. Landslides are the most important hazards in the area since 13% of the total surface of the Zonguldak is affected by landslides. In this study, considering the hazard potential special attention is given to deep landslides and using the stepwise forward conditional logistic regression technique, the landslide susceptibility map for the Zonguldak province is produced. The results showed that the most important independent variables governing the landslides are slope gradient, volcanic, and sedimentary rocks of Eocene and clastic and carbonate units of Cretaceous. The landslide map is used as a base map for the production of geo-hazard reconnaissance map on which areas subjected to other important geo-hazards (flood, earthquake and subsidence) are also shown to provide guidance for both existing settlement areas to take the necessary preventive measures and for new developing settlement areas to avoid the problematic areas.     

Landslides in the Mailuu-Suu Valley, Kyrgyzstan—Hazards and Impacts

Mailuu-Suu is a former uranium mining area in Kyrgyzstan (Central Asia) at the northern border of the Fergana Basin. This region is particularly prone to landslide hazards and, during the last 50 years, has experienced severe landslide disasters in the vicinity of numerous nuclear waste tailing dams. Due to its critical situation, the Mailuu-Suu region was and still is the target area for several risk assessment projects. This paper provides a brief review of previous studies, past landslide events and a discussion on possible future risk scenarios. Various aspects of landslide hazard and related impacts in the Mailuu-Suu Valley are analyzed in detail: landslide susceptibility, historical evolution of landslide activity, size-frequency relationship, river damming and flooding as well as impacts on inhabited areas and nuclear waste storage zones. The study was carried out with standard remote sensing tools for the processing of satellite imagery and the construction of digital elevation models (DEMs). The processed inputs were combined on a GIS platform with digital landslide distribution maps of 1962, 1977, and 2003, digitized geological and geographic maps, and information from landslide monitoring and geophysical investigation.As a result, various types of landslide susceptibility maps based on conditional analysis (CA) are presented as well as predictions of future landslide activity and related damming potential and their possible impact on the population. For some risk scenarios, remediation and prevention measures are suggested.     

甘肃舟曲南峪江顶崖古滑坡发育特征与复活机理

江顶崖古滑坡位于甘肃舟曲白龙江左岸,区内地形地貌和地质构造复杂,多高山峡谷且河流纵坡降大,晚第四纪以来强烈活动的坪定—化马断裂带从区内通过,造成地层岩性极为破碎,古滑坡发育,且复活特征明显。在遥感解译和现场调查的基础上,对江顶崖古滑坡的发育特征和复活机理进行分析,认为江顶崖古滑坡堆积体方量为41×106～49×106m3,为在地质历史上形成的巨型古滑坡,位于坪定—化马断裂带及其次级断裂形成的断裂带内。根据滑坡不同位置和坡体结构特征,将江顶崖古滑坡共划分为古滑坡崩塌区、滑坡岩体变形区、古滑坡堆积区等3个大区,以及4个古滑坡复活区等7个区域,坡体内断错陡坎和拉裂缝极为发育。江顶崖古滑坡的中部复活区是主要变形和破坏区,1991年和2018年的复活区均位于该区域内,2018年复活滑坡体体积为480×104～550×104m3,为缓慢滑动的牵引式滑坡。江顶崖古滑坡复活机理复杂,在断裂活动和地震作用下形成的破碎岩土体和斜坡结构特征为滑坡复活提供了内因,强降雨作用增加了坡体自重并弱化了岩土体的力学强度,在暴雨期形成的强烈河流侵蚀作用进一步切割坡脚,从而诱发滑坡的复活;因此,江顶崖古滑坡是在内外动力耦合作用下形成的典型古滑坡复活案例。目前江顶崖古滑坡区域内的4个滑坡复活区仍处于蠕滑状态,在强降雨和河流侵蚀等作用下极可能再次发生复活,并造成堵江和毁坏国道等灾害事件。     

城市垃圾性质及其填埋场的工程地质评价

卫生填埋是现阶段处理城市垃圾的主要方法,正确评价,选择填埋垃圾的工程性质对填埋场的设计极为重要;填埋场是一个综合性污染源,若处理不当,会产生严重的环境工程地质问题,做好填埋场的工程地质研究,对于水资源及环境保护具有重要意义,本文对城市垃圾的工程性质进行了分析,评价,从环境工程地质学的角度对合肥市清溪路垃圾埋场的地基勘察,主要工程地质问题及应采取的工程措施进行了探讨。     

基于斜坡单元的山区城镇滑坡灾害易发性评价：以康定为例

山区地质灾害易发性评价对城镇地质灾害风险管理具有重要意义。本文以康定市为例,以斜坡单元为最小评价单元,选取高程、坡度、坡向、曲率、工程地质岩组、距道路距离、距断裂距离、距水系距离和斜坡结构等9个滑坡影响因子,根据各因子滑坡面积比曲线与证据权值曲线的突变点,划分滑坡影响因子二级状态,并对各影响因子进行相关性分析,剔除相关性较高的距道路距离因子,在此基础上,采用证据权模型进行滑坡易发性评价。对已有治理工程的斜坡单元,本文尝试利用折减系数法对其易发性进行进一步评价。结合现场调查,将研究区滑坡易发性程度划分为：极高易发、高易发、中等易发、低易发。评价结果表明,自然工况下极高易发区主要位于康定市炉城镇以及研究区北侧二道桥村一带,高易发区主要位于雅拉河、折多河与瓦斯沟河谷两侧,对治理工程所在的斜坡单元进行折减后,极高易发区面积由11.21%降至8.42%,滑坡比率由4.03降低至2.3,研究结果符合实际情况,模型精度达77.8%。评价结果较好地反映了康定市区的滑坡易发性分布情况,可为城镇精细化评价提供一定的参考依据。     

小浪底水库区垣曲段近岸区地质灾害类型及防治措施

小浪底库区垣曲段近岸区地质环境条件比较复杂，库区近岸以崩塌、滑坡、黄土湿陷为主的地质灾害较为发育，水库蓄水升至275m水位后，必将引起库岸再造，库区水位以下岩土均被软化，引发水下崩塌、滑坡、沿河黄土岸坡也会不断崩塌后退，直接危及沿岸居民区及沿河工矿企业及公路的安全。文章总结了库区近岸各种类型地质灾害发育特征及其成因，通过对库区近岸崩塌、滑坡形成条件的分析，基本查明了区内崩塌，滑坡发育的基本规律，对库区环境地质问题进行了分区，并对主要居民区环境地质问题进行了评价，运用工程地质类比法及理论计算法，对主要居民区是否受到坍岸危害，进行了最终坍岸宽度计算，对区内环境和地质问题进行了预测，在对区内各主要居民点及库区近岸区环境地质条件分析后，提出了以勘查与治理，运用生物工程及灾情预估等内容的减灾防灾对策。     

Initiatives for earthquake disaster risk management in the Kathmandu Valley

Situated over the Himalayan tectonic zone, Kathmandu Valley as a lake in geological past has a long history of destructive earthquakes. In recent years, the earthquake risk of the valley has significantly increased due mainly to uncontrolled development, poor construction practices with no earthquake safety consideration, and lack of awareness among the general public and government authorities. Implementation of land use plan and building codes, strengthening of design and construction regulations, relocation of communities in risky areas, and conduction of public awareness programs are suitable means of earthquake disaster risk management practice. Kathmandu, the capital of Nepal, is still lacking earthquake disaster risk management plans. So, this paper highlights some initiatives adopted by both governmental and nongovernmental organizations of Nepal to manage earthquake disaster risk in the Kathmandu Valley. It provides some comprehensive information on recent initiatives of earthquake disaster risk management in the valley and also highlights the outcomes and challenges.     

SBAS-InSAR技术在西藏江达县金沙江流域典型巨型滑坡变形监测中的应用

滑坡是一种破坏力极强的地质灾害,对滑坡易发区域进行长期有效的时序形变监测是研究机理和防灾减灾的重要途径,小基线雷达干涉测量技术（SBAS-InSAR）在滑坡等地质灾害形变监测中的应用为当前地灾防治提供了新的手段。文章使用SBAS-InSAR技术对西藏江达县金沙江流域发生的典型滑坡灾害进行了时序形变特征分析。首先,基于2017年7月—2018年12月的23景Sentinel-1A影像数据,获取了江达县东部及其周边区域在时间跨度内的形变分布图以及时序形变特征;在此基础上,结合区域内沃达和白格2处滑坡的实地勘探资料和现有研究成果验证了形变探测结果的准确性;另监测数据显示沃达滑坡中部及前缘位置存在明显形变,且部分位置的形变量超过100 mm,白格滑坡的残留体同样存在较大的形变,尤其是边界区域存在明显的形变漏斗,最大形变量超过110 mm。同时在金沙江流域西岸存在2处滑坡隐患区域,累计沉降量均超过45 mm,最大形变速率分别为?53 mm/a和?45 mm/a。基于数据分析和现场勘查,表明SBAS-InSAR技术在滑坡灾害的形变监测方面是一种有效手段,另江达县金沙江多处岸坡在不断发生形变,应进一步加强该区域地质灾害形变监测,必要时提前开展防治工作。     

Application and validation of bivariate GIS-based landslide susceptibility assessment for the Vitravo river catchment (Calabria,south Italy)

The Calabria (Southern Italy) region is characterized by many geological hazards among which landslides, due to the geological, geomorphological, and climatic characteristics, constitute one of the major cause of significant and widespread damage. The present work aims to exploit a bivariate statistics-based approach for drafting a landslide susceptibility map in a specific scenario of the region (the Vitravo River catchment) to provide a useful and easy tool for future land planning. Landslides have been detected through air-photo interpretation and field surveys, by identifying both the landslide detachment zones (LDZ) and landslide bodies; a geospatial database of predisposing factors has been constructed using the ESRI ArcView 3.2 GIS. The landslide susceptibility has been assessed by computing the weighting values (Wi) for each class of the predisposing factors (lithology, proximity to fault and drainage line, land use, slope angle, aspect, plan curvature), thus evaluating the distribution of the landslide detachment zones within each class. The extracted predisposing factors maps have then been re-classified on the basis of the calculated weighting values (Wi) and by means of overlay processes. Finally, the landslide susceptibility map has been considered by five classes. It has been determined that a high percentage (61%) of the study area is characterized by a high to very high degree of susceptibility; clay and marly lithologies, and slope exceeding 20° in inclination would be much prone to landsliding. Furthermore, in order to ascertain the proposed landslide susceptibility estimate, a validation procedure has been carried out, by splitting the landslide detachment zones into two groups: a training and a validation set. By means of the training set, the susceptibility map has first been produced; then, it has been compared with the validation set. As a result, a great majority of LDZ-validation set (85%) would be located in highly and very highly susceptible areas. The predictive power of the model is considered reliable, since more than 50% of the LDZ fall into 20% of the most susceptible areas. The reliability of the susceptibility map is also suggested by computing the SCAI index, true positive and false positive rates; nevertheless, the most susceptible areas are overestimated. As a whole, the results indicate that landslide susceptibility assessment based on a bivariate statistics-based method in a GIS environment may be useful for land planning policy, especially when considering its cost/benefit ratio and the need of using an easy tool.     

基于GIS和层次分析法的沙溪流域滑坡地质灾害易发性评价

滑坡是沙溪流域主要地质灾害类型之一,开展滑坡灾害易发性评价可为区域地质灾害防治提供数据基础和决策依据。通过沙溪流域生态地质调查,分析了滑坡灾害分布规律和影响因素之间的关系,选取岩性建造、地貌、坡度、坡向、降雨量、距河流距离和距断层距离7项指标,利用层次分析法及地理信息系统空间分析技术,开展沙溪流域滑坡地质灾害易发性评价。结果显示: 沙溪流域滑坡易发性影响因子依次为岩性建造、多年年均降水量、地形地貌、坡度、距河流距离、距断层距离和坡向; 沙溪流域滑坡灾害易发性与坡度、岩性建造、年均降水量表现出明显正相关,即坡度越大、岩性建造性质越软弱、越易风化,年均降水量越多,越易引发滑坡灾害; 滑坡灾害易发性与断裂构造、河流距离与滑坡灾害易发性呈负相关,即距离越近越容易诱发地质灾害; 流域整体以低易发区和极低易发区为主,高易发区主要分布在沙溪流域中南部、东部及东北部地区。这为沙溪流域地质灾害防治提供了基础数据和决策依据。     

Causes of large-scale landslides in the Lesser Himalaya of central Nepal

Geologically and tectonically active Himalayan Range is characterized by highly elevated mountains and deep river valleys. Because of steep mountain slopes, and dynamic geological conditions, large-scale landslides are very common in Lesser and Higher Himalayan zones of Nepal Himalaya. Slopes along the major highways of central Nepal namely Prithvi Highway, Narayangadh-Mugling Road and Tribhuvan Highway are considered in this study of large-scale landslides. Geologically, the highways in consideration pass through crushed and jointed Kathmandu Nappe affected by numerous faults and folds. The relict large-scale landslides have been contributing to debris flows and slides along the highways. Most of the slope failures are mainly bechanced in geological formations consisting phyllite, schist and gneiss. Laboratory test on the soil samples collected from the failure zones and field investigation suggested significant hydrothermal alteration in the area. The substantial hydrothermal alteration in the Lesser Himalaya during advancement of the Main Central Thrust (MCT) and thereby clay mineralization in sliding zones of large-scale landslide are the main causes of large-scale landslides in the highways of central Nepal. This research also suggests that large-scale landslides are the major cause of slope failure during monsoon in the Lesser Himalaya of Nepal. Similarly, hydrothermal alteration is also significant in failure zone of the large-scale landslides. For the sustainable road maintenance in Nepal, it is of utmost importance to study the nature of sliding zones of large-scale landslides along the highways and their role to cause debris flows and slides during monsoon period.     

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。     

基于要素分析和二元统计模型的区域滑坡危险等级制图——以国道212线陇南段为例

国道212线陇南段是我国地质灾害最发育的地区之一,绘制该区的滑坡危险等级地图对灾害管理和发展规划是极其必要的。基于滑坡的野外调查、机理研究和室内试验等工作,分析了滑坡与各种要素的相关性,选择控制滑坡的9个重要要素作为评价要素,利用GIS和二元统计的信息值模型和滑坡先验风险要素模型绘制了研究区的滑坡危险等级地图。最后,选用区内11个具有明显滑动位移的活动滑坡与滑坡危险等级地图比较,检验其可靠度。结果表明,活动的滑坡绝大部分都位于危险等级很高和高的范围内,说明两种模型的评价结果与研究区实际情况相吻合,同时也反映出信息值模型与实际情况更加相符。     

Landslide susceptibility mapping using the weight of evidence method in the Tinau watershed, Nepal

Mountainous areas in Nepal are prone to landslides, resulting in an enormous loss of life and property every year. As a first step towards mitigating or controlling such problems, it is necessary to prepare landslide susceptibility maps. Various methodologies have been proposed for landslide susceptibility mapping. This study applies the weight of evidence method to the Tinau watershed in west Nepal. A landslide susceptibility map is prepared on the basis of field observations and available data of geology, land use, topography and hydrology. Predicted susceptibility levels are found to be in good agreement with the locations of past landslides. The results show that about 30?% of the area is highly susceptible to landsliding. The present results provide useful information to the authorities concerning the landslide susceptibility zones and possible improvements for disaster management activities and sustainable development.     

一种基于多源数据融合的滑坡地形深度学习识别模型研究

传统高位远程滑坡识别依赖地质专家人工判别,识别效率较低。研究实现一种基于深度学习的滑坡地形自动识别模型,以提高大范围区域潜在滑坡隐患点筛查工作的效率。该模型以目标区域的遥感图像、DEM数据、地质分区、河流水系等地质观测数据为输入,针对不同类型观测数据差异巨大的问题,设计构建特征分支网络,精确提取对应的滑坡特征。对光学影像数据采用深层网络架构提取复杂特征,对海拔、地质构成、河流和断裂带分布等结构化数据采用浅层网络架构提取特征。随后设计特征融合模块,融合两个网络的提取结果获得全面的滑坡灾害特征。模型基于提取的滑坡特征进行滑坡区域语义分割,实现精准的像素级别滑坡地形分类和定位。通过实验验证,该模型对滑坡区域的识别准确率（ACC）达到了0.85,可为滑坡自动识别提供技术支撑。     

Estimation of Seismic Landslide Hazard in the Eastern Himalayan Syntaxis Region of Tibetan Plateau

The eastern Himalayan syntaxis is one of the most tectonically active and earthquake-prone regions on Earth where earthquake-induced geological disasters occur frequently and caused great damages. With the planning and construction of Sichuan-Tibet highway, Sichuan-Tibet railway and hydropower development on the Yarlung Zangbo River etc. in recent years, it is very important to evaluate the seismic landslide hazard of this region. In this paper, a seismic landslide hazard map is produced based on seismic geological background analysis and field investigation using Newmark method with 10% PGA exceedance probabilities in future 50 years by considering the influence of river erosion, active faults and seismic amplification for the first time. The results show that the areas prone to seismic landslides are distributed on steep slopes along the drainages and the glacier horns as well as ridges on the mountains. The seismic landslide hazard map produced in this study not only predicts the most prone seismic landslide areas in the future 50 years but also provides a reference for mitigation strategies to reduce the exposure of the new building and planning projects to seismic landslides.