Application of GIS-based statistical modeling for landslide susceptibility mapping in the city of Azazga,Northern Algeria

Landslide susceptibility mapping is a necessary tool in order to manage the landslides hazard and improve the risk mitigation. In this research, we validate and compare the landslide susceptibility maps (LSMs) produced by applying four geographic information system (GIS)-based statistical approaches including frequency ratio (FR), statistical index (SI), weights of evidence (WoE), and logistic regression (LR) for the urban area of Azazga. For this purpose, firstly, a landslide inventory map was prepared from aerial photographs and high-resolution satellite imagery interpretation, and detailed fieldwork. Seventy percent of the mapped landslides were selected for landslide susceptibility modeling, and the remaining (30%) were used for model validation. Secondly, ten landslide factors including the slope, aspect, altitude, land use, lithology, precipitation, distance to drainage, distance to faults, distance to lineaments, and distance to roads have been derived from high-resolution Alsat 2A satellite images, aerial photographs, geological map, DEM, and rainfall database. Thirdly, we established LSMs by evaluating the relationships between the detected landslide locations and the ten landslides factors using FR, SI, LR, and WoE models in GIS. Finally, the obtained LSMs of the four models have been validated using the receiver operating characteristics curves (ROCs). The validation process indicated that the FR method provided more accurate prediction (78.4%) in generating LSMs than the SI (78.1%),WoE (73.5%), and LR (72.1%) models. The results revealed also that all the used statistical models provided good accuracy in landslide susceptibility mapping.

     

Landslide susceptibility mapping of the Sea to Sky transportation corridor, British Columbia, Canada: comparison of two methods

The Sea to Sky corridor stretches over a distance of 135?km into British Columbia’s Coast Mountains. The corridor has witnessed hundreds of historical and pre-historic landslides. In the last 154?years, 155 landslide events have been reported. The most common types of landslides are rockfalls and debris flows, which are small in volume, but can be quite damaging. These are more abundant in the southern part of the corridor where infrastructure is built close to steep slopes. Two different methods were adapted to create debris flow and rockfall/rock slide susceptibility maps. Both qualitative heuristic and fuzzy logic susceptibility maps showed a similar distribution of susceptibility zones, especially high susceptibility. Correlation of high susceptibility zones with occurrence of historical and mapped geological landslide events was very good. Success rate curves were calculated for extrapolated zones of initiation for debris flow and rockfall/rock slide deposits. Success rate curves were better for debris flow than rockfall/rockslide maps.     

襄渝线汪家沟隧道出口增设棚洞设计

由于具有突发性、危害性大等特点,崩塌落石病害一直为山区既有线路病害防治中的重点。以既有襄渝线王家沟隧道工程为背景,在既有线崩塌落石病害采用棚洞结构进行防护方面做了一些新的尝试,解决了既有线与临近增建二线相邻且间隔较大条件下崩塌落石病害防护工程综合设计技术问题,可为我国山区铁路崩塌落石灾害防护治理工程提供有益的参考和借鉴。     

Rapid susceptibility mapping of earthquake-triggered slope geohazards in Lushan County by combining remote sensing with the AHP model developed for the Wenchuan earthquake

A rapid-response mapping model can be used to study the susceptibility of areas of interest to geohazards (which are commonly regarded as among the most damaging natural hazards), assuming that the model is stable (i.e., that it is generally applicable to any such area). Applying a predefined predictive geohazard-susceptibility model to an area with geoenvironmental conditions similar to those of the area for which it was originally formulated is an effective method of testing the stability of the model. In this paper, the analytic hierarchy process (AHP)-based model developed for the Wenchuan earthquake was used to study susceptibility to earthquake-triggered slope geohazards in Lushan County. Upon integrating the results of a literature review, site investigation, and remote sensing interpretation, seven main factors that influence earthquake-triggered slope geohazards were identified, including peak ground acceleration, distance from a stream, distance from a highway, slope gradient, slope position, normalized difference vegetation index, and micro-landform. In order to reduce the subjectivity of the expert evaluation method usually applied in the AHP, these factors were ranked by relative importance using regression analysis. The weight of each factor was then calculated by the AHP. The susceptibility mapping model was obtained on the ArcGIS platform, utilizing map overlaying. Finally, the results were re-classified to obtain a map of slope geohazard susceptibility. The accuracy of the AHP model was evaluated using both qualitative and quantitative methods. In the qualitative method, the modeled distribution of susceptibility was compared with the actually distribution of geohazards in the study area (identified through remote sensing interpretation), and the areas with high and very high geohazard susceptibilities in the model were found to match well with the actual locations of slope geohazards. In the quantitative method, statistical data showed that over 66% of the geohazards were located in areas of high or very high susceptibility according to the model, while only about 16% were located in areas of very low or low susceptibility, and the density of slope geohazards was about 125 times greater in the areas with very high susceptibility than in the areas with very low susceptibility. Also, the AUC value of the ROC curve for the model suggested that it has high predictive power (a predictive accuracy of 84.8%). In conclusion, it was possible to make accurate predictions about the slope geohazards in earthquake-prone areas located in mountainous regions based on geospatial data, and a high correlation between the susceptibility map generated by the AHP-based model and the true distribution of slope geohazards was observed. Therefore, the AHP-based model used here could be applied to map the slope geohazard susceptibility in other mountainous regions which may be prone to slope geohazards during earthquakes.     

A comparative study on machine learning modeling for mass movement susceptibility mapping (a case study of Iran)

Mass movements are among the most dangerous natural hazards in mountainous regions. The present study employs machine learning (ML) models for mass movement susceptibility mapping (MMSM) in Iran based on a comprehensive dataset of 864 mass movements which include debris flow, landslide, and rockfall during the last 42 years (1977–2019) as well as 12 conditional factors. The results of validation stage show that RF (random forest) is the most viable model for mass movement susceptibility maps. In addition, MARS (multivariate adaptive regression splines), MDA (mixture discriminant additive), and BRT (boosted regression trees) models also provide relatively accurate results. Results of the AUC for validation of produced maps were 0.968, 0.845, 0.828, and 0.765 for RF, MARS, MDA, and BRT, respectively. Based on MMSM generated by RF model, 32% of study area is identified to be under high and very high susceptibility classes. Most of the endangered areas for mass movement are in the west and central parts of the Chaharmahal and Bakhtiari Province. In addition, our findings indicate that elevation, slope angle, distance from roads, and distance from faults are critical factors for mass movement. Our results provide a perspective view for decision makers to mitigate natural hazards.

     

Inpho与Photomod软件在无人机数字正射影像图制作中的对比

当前利用无人机快速获取影像数据,制作正射影像图已成为常态,如何选择合适的航测成图软件进行生产成为生产单位考虑的问题。通过结合生产项目,进行测区试验,对常用于数字正射影像图制作的Inpho和近年推出的Photomod软件进行空三解算、DTM制作及滤波、正射纠正、镶嵌匀色等各功能的对比,分析该两种软件在各个处理流程下的优缺点,为测绘生产单位选择航测成图软件提供借鉴。     

陕西泾阳县地质灾害发育特征及形成条件

泾阳县是咸阳市辖县之一,地质构造复杂,大断裂发育,岩土体结构类型较复杂,人类活动强度大,降水量大且集中,地质灾害发育。该文分析了泾阳县地质灾害的类型、规模、发育特征和分布特征,进而分析了地质灾害的形成条件。分析表明,地质灾害发育的控制因素主要有地形地貌、地质构造、地层和岩土体结构、坡体地质结构等,而地下水和植被是地质灾害的影响因素,人类工程活动、大气降雨和地震是地质灾害的促发因素。     

LD岩土胶结剂加固黄土试验研究*

 土体化学加固是利用化学材料发生反应生成凝胶并胶结土粒的特性来达到加固土体的目的。对黄土而言，化学加固后改善了土的结构状态，不仅使土的承载力提高，而且使其湿陷性、崩解性和压缩性等不良工程地质性质也大为改观。本文介绍了兰州大学最新研制的LD系列岩土胶结剂固化黄土的加固机理.。通过强度优选试验、崩解试验、抗冻试验对LD系列岩土胶结剂固化黄土的工程性质进行试验研究，并对影响固化黄土强度的主要因素进行分析。试验结果证明，LD-3#，4#胶结剂固化黄土的物理、力学、水理、抗冻等方面的性能都有大幅度的提高，是加固黄土的新型材料。     

落石运动模式与运动特征现场试验研究

落石试验是寻找落石运动敏感因素、探求运动规律和获取运动参数的较好方法.为厘清落石形状、块度大小和运动模式对其运动特征的影响规律,进行了112块落石现场试验;以落石形状、质量和运动弹跳次数为变量,统计分析了水平运动距离、运动速度的变动规律.试验结果表明:不管何种形状落石,运动模式均为滚动和弹跳,无明显滑动段;切坡平台和公...     

Assessing landslide susceptibility using Bayesian probability-based weight of evidence model

This study aims to demonstrate the application of a Bayesian probability-based weight of evidence model to map landslide susceptibility in the Tevankarai stream watershed, Kodaikkanal, India. Slope gradient, relief, aspect, curvature, land use, soil, lineament density, flow accumulation and proximity to roads were the landslide conditioning factors we considered in order to assess susceptibility. The weight of evidence model uses the prior probability of occurrence of a landslide event to identify areas prone to landslides based on the relative contributions of landslide conditioning factors. A pair-wise test of conditional independence was performed for the above factors, allowing the combination of conditioning factors to be analyzed. The contrast (difference of W ⁺ and W ^?) was used as weight for each factor’s type. The best observed combination consisted of the relief, slope, curvature, land use and distance to road factors, showing an accuracy of 86.1 %, while the accuracy of the map with all factors was 83.9 %.     

川藏公路南线八宿—林芝段滚石灾害的工程地质调查与评价

对川藏公路南线八宿一林芝段沿线山地灾害的工程地质调查表明，滚石对公路的危害性非常突出，鉴于滚石事件自身的特点应将之作为一个专门的灾种给予高度的重视。通过对滚石灾害的影响因素分析，给出了相应的灾害评价方法，并对19个滚石灾害点进行了灾害评价。针对灾害的相对严重程度，对各段滚石区防护措施的设置提出了初步建议。     

Landslide susceptibility maps using different probabilistic and bivariate statistical models and comparison of their performance at Wadi Itwad Basin,Asir Region,Saudi Arabia

The purpose of the current study is to produce landslide susceptibility maps using different probabilistic and bivariate statistical approaches; namely, frequency ratio (FR), weights-of-evidence (WofE), index-of-entropy (IofE), and Dempster–Shafer (DS) models, at Wadi Itwad, Asir region, in the southwestern part of Saudi Arabia. Landslide locations were identified and mapped from interpretation of high-resolution satellite images, historical records, and extensive field surveys. In total, 326 landslide locations were mapped using ArcGIS and divided into two groups; 75 % and 25 % of landslide locations were used for training and validation of models, respectively. Twelve layers of landslide-related factors were prepared, including altitude, slope degree, slope length, topography wetness index, curvature, slope aspect, distance from lineaments, distance from roads, distance from streams, lithology, rainfall, and normalized difference vegetation index. The relationships between the landslide-related factors and the landslide inventory map were calculated using different statistical models (FR, WofE, IofE, and DS). The model results were verified with landslide locations, which were not used during the model training. In addition, receiver operating characteristic curves were applied, and area under the curve (AUC) was calculated for the different susceptibility maps using the success (training data) and prediction (validation data) rate curves. The results showed that the AUC for success rates are 0.813, 0.815, 0.800, and 0.777, while the prediction rates are 0.95, 0.952, 0.946, and 0.934 for FR, WofE, IofE, and DS models, respectively. Subsequently, landslide susceptibility maps were divided into five susceptibility classes, including very low, low, moderate, high, and very high. Additionally, the percentage of training and validating landslides locations in high and very high landslide susceptibility classes in each map were calculated. The results revealed that the FR, WofE, IofE, and DS models produced reasonable accuracy. The outcomes will be useful for future general planned development activities and environmental protection.     

Defining the suitability of new crushed rock aggregate source areas in the North of Kocaeli Province using GIS

This study evaluated the current crushed rock aggregate resources and defined the suitability of potential crushed rock aggregate resource areas in the north of Kocaeli Province by using the geographical information system (GIS). Evaluation of the current aggregate market showed that almost 80 % of the total annual production (14.35 million tonnes) is supplied by the quarries located in Gebze and 20 % of the total annual production (3.65 million tonnes) is supplied by the quarries located in Hereke. The commercial crushed rock aggregate is totally supplied from the limestone and dolomite type carbonate rocks in the northern Kocaeli region. Defining the suitability of potential crushed rock aggregate resource areas was achieved by using GIS methods. First, an aggregate bedrock potential map was developed by using the geological map of the area and categorized as high, moderate and low bedrock potential areas. The high potential areas, which comprised almost 25 % of the northern Kocaeli region, contain carbonate rocks with varying physical, chemical and engineering properties. Secondly, the suitability of the bedrock potential areas was checked by considering the land-use, distance to the county centres and distance to major roads and highways layers in the weighted overlay function of the GIS. The resulting final map contained not suitable, low suitability and suitable areas for crushed rock aggregate. The suitable areas were grouped into three zones according to their geographic distributions. Further, the most promising crushed rock aggregate areas were defined based on the previous field work and surveys in the suitable areas.     

An application of the interaction matrices method for slope failure susceptibility zoning: Dogankent settlement area (Giresun, NE Turkey)

Large-scale instability phenomena frequently occur in slopes in such geologically complex areas as Dogankent in NE Turkey. This study presents an application of the interaction matrices (IM) methodology, as a semi-qualitative method sensitive to large-scale slope instability. For both rock and soil slopes, the main interactive factors were distance from faults, degree of weathering and slope angle. Using IM, a slope failure susceptibility map was created for the Dogankent area and checked again field evidence. The results indicated that IM could be a useful method for slope stability assessment.      

大同市0．5m分辨率真彩色数字正射影像图制作

指出数字正射影像是利用像控点和数字高程模型,对影像同时进行倾斜改正和投影差改正,之后经影像镶嵌和匀光匀色后裁切而成。以大同市0．5m分辨率真彩色数字正射影像图制作项目为例,介绍了大同市勘察测绘院数字正射影像图的生产制作经验,以供类似项目参考借鉴。     

岩土数值模拟：方法论的思考

从地球系统科学的角度，通过地学、力学等多学科交叉，评述岩土数值模拟发展的内在历程，做了方法论意义上的思考，认为当前4种研究特点可代表岩土数值模拟的近期发展方向，并提出可靠度理论与力学数值模拟技术相结合是解决当今岩土工程问题的最主要的研究方法和发展方向。     

基于天宝UASMaster正射影像图制作

介绍了UASMaster正射影像图制作流程,对流程中关键的步骤原理进行了简要分析,并对实际生产过程中可能存在的问题进行了探讨,最后结合具体工程项目,对成果的精度进行了分析。结果表明:UASMaster可满足大比例尺正射影像图制作的精度要求。     

基于信息量法的重庆云阳县(三峡库区)地质灾害易发性评价

云阳县地处重庆市东部,属三峡库区,构造上位于川东弧形构造带东北段,褶皱形态以宽平的屉形向斜和狭窄的高背斜相间排列,组成隔挡式构造。区内地貌以中-高山峡谷地貌为主,第四纪以来一直处于间歇性抬升状态,地形切割强烈,长江河道从境内穿过,河流水系发育,年降雨量大,地质环境条件脆弱,地质灾害发育。论文基于Arcgis平台,运用信息量法全面分析了影响云阳县地质灾害发育的地形条件、地层岩性、地质构造、河流水系、人类工程活动等因素,建立了云阳县地质灾害易发评价指标体系。评价结果表明,高易发区面积576 km²,占比15.8％,中易发区面积1801.68 km²,占比49.41％；评价结果可为云阳县区域地质灾害防治提供依据,也可为三峡库区地质灾害易发性评价提供参考。     

基于多源遥感数据的浏阳500kV线路工程地质灾害风险评价

以浏阳500kV线路工程沿线为研究区,收集和整理相关资料,地质灾害类型主要为滑坡,确定了坡高、坡度、坡向、坡形、距离水系距离5个具有代表性的影响因素作为评价因子。通过层次分析法,对各个评价因子赋予权重。运用ArcGIS10的表面分析、距离分析、重分类、加权叠加、重采样等工具,对各评价因子的多源遥感数据进行分析,获得研究区的地质灾害风险评价图。对研究区进行地质灾害风险评价,将此区域内的地质灾害风险等级划分为:低风险、中等风险、高风险、极高风险四类。     

公路沿线遭遇滚石的风险分析——案例研究

具有国防意义的川藏公路南线是中国内地连接西藏的主要交通要道，也是进藏公路中最危险的一条。在对该公路的典型地质灾害段(八宿-林芝段)进行工程地质调查后，由现场调查、专家经验、理论分析等综合集成对滚石发生频率进行了估计，并获得了19个滚石区在不同人类活动特征下遭遇滚石的年平均概率。通过遭遇滚石的概率及承灾体的易损性分析，还得到了车辆和行人经过不同滚石区时遭遇滚石而致命的风险。相应的风险评价结果表明：(1)经过滚石区Rm4，Rm5，Rs1，Rs4，Rs5，Rs10和Rm7时因滚石而致命的风险水平是比较高的：(2)由于八宿一林芝间的交通条件和人类活动特征变化不大，不同滚石区间的危险性评价在一定程度上与风险评价是一致的：(3)考察区公路沿线滚石致命的风险远远高于发达国家或地区滑坡灾害的风险。