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.

     

GIS-based landslide hazard zonation: a case study from the Parwanoo area,Lesser and Outer Himalaya,H.P., India

GIS-based landslide hazard zonation has been carried out for a tectonically active region of the Himalayas, which is under pressure for rapid economic development. Thematic layers of slope, fault, geology, land use, flow accumulation, drainage and roads were prepared based on topographic maps, satellite imagery, published geological maps and ground truth. Five classes of landslide hazard were identified; 24% of the total area falls into the Very high or High hazard zones where 54% of the observed landslides were recorded.      

Landslide assessment for land use planning and infrastructure management in the Paphos District of Cyprus

The Paphos District has been described as one of the most landslide-prone areas of Cyprus, with landslides impacting villages, roads and other infrastructure. With increasing levels of development and investment in infrastructure, Cypriot authorities are investigating ways to assess landslide susceptibility, hazard and risk for planning purposes. A 2-year project has catalogued over 1,840 landslides, investigated the spatial distribution of key landslide attributes, and used the results to develop maps of landslide susceptibility across large areas of the Paphos District. To gain a better understanding of the materials and failure mechanisms involved, 20 of these landslides were selected for further study, including engineering geological mapping, ground investigation, laboratory testing, development of ground models and slope stability analysis at specific locations. The results enabled soil parameters to be reviewed, thus strengthening the interpretations derived from field observations. The use of the mapping outputs is discussed in terms of planning and engineering applications and recommendations are made for strengthening and expanding the landslide database.     

Engineering geology maps: landslides and geographical information systems

IAEG Commission No. 1—Engineering Geological Maps—is developing a guide to hazard maps. Scientists from 17 countries have participated. This paper is one of a series that presents the results of that work. It provides a general review of GIS landslide mapping techniques and basic concepts of landslide mapping. Three groups of maps are considered: maps of spatial incidence of landslides, maps of spatial–temporal incidence and forecasting of landslides and maps of assessment of the consequences of landslides. With the current era of powerful microcomputers and widespread use of GIS packages, large numbers of papers on the subject are becoming available, frequently founded on different basic concepts. In order to achieve a better understanding and comparison, the concepts proposed by Varnes (Landslide hazard zonation: a review of principles and practice, 1984) and Fell (Some landslide risk zoning schemes in use in Eastern Australua and their application 1992; Landslide risk assessment and acceptable risk. Can Geotech J 31:261–272, 1994) are taken as references. It is hoped this will also add to the international usefulness of these maps as tools for landslide prevention and mitigation. Six hundred and sixty one papers and books related to the topic are included in the references, many of which are reviewed in the text. This report is being continually updated and further references can be seen on the IAEG website () under Commission No. 1.     

Landslide hazard zonation of the Khorshrostam area, Iran

 Landslide hazard zonation is a method to evaluate the risk where there is the potential for landslides. The factors contributing to the hazard in an area can usually be identified, results of the investigations frequently being presented as a landslide hazard zonation map indicating zones of similar risk of the occurrence of a landslide. Korshrostam is one of the areas most susceptible to landslides in Iran with more than 13% of its surface being affected by landslide activity. The effects include damage or disturbance to villages, farmlands and roads as well as the exacerbation of erosion of the land surface and consequently an increase in the rate of sedimentation in the water flowing into the reservoir of the Manjil dam. The method of landslide zonation used in this study was based on a simple grid unit. A number of factors contributing to the likelihood of landsliding were considered, including lithology, slope, tectonic activity, land use and groundwater. For each grid unit, the incidence of landsliding and an assessment of the likely contributory factors were recorded in terms of a surface percentage index (SPI). A computer program was written using fuzzy sets to calculate the hazard potential index (HPI) for each unit. This was used to prepare the landslide hazard zonation map. Received: 10 June 1999 · Accepted: 16 September 1999     

The Third Hans Cloos Lecture. Urban landslides: socioeconomic impacts and overview of mitigative strategies

As a result of population pressures, hillsides in the world’s urban areas are being developed at an accelerating rate. This development increases the risk for urban landslides triggered by rainfall or earthquake activity. To counter this risk, four approaches have been employed by landslide managers and urban planners: (1) restricting development in landslide-prone areas; (2) implementing and enforcing excavation, grading, and construction codes; (3) protecting existing developments by physical mitigation measures and (4) developing and installing monitoring and warning systems. Where they have been utilized, these approaches generally have been effective in reducing the risk due to landslide hazards. In addition to these practices, landslide insurance holds promise as a mitigative measure by reducing the financial impact of landslides on individual property owners. Until recently, however, such insurance has not been widely available and, where it is available, it is so expensive that it has been little used.      

Predicted effects of residential development on a northern Idaho landscape under alternative growth management and land protection policies

Land use change driven by exurban development can lead to dramatic alterations in the structure and function of landscapes. Residential development outside of urban and suburban zones can disrupt agricultural and forest management operations and ecosystem processes, increase community wildfire hazard, deplete groundwater resources, and lead to social conflict. We assessed two policy tools, urban growth boundaries and agricultural use zoning, for their potential to help manage growth and sustain the rural landscape. Using a survey-based model, we simulated the effects of the two policy tools on land use change and compared the results with predictions of land use change for two rural counties (4794 km²) in northern Idaho developed in a previous project. We measured the effects of predicted exurban development using four measures: number of housing units predicted on productive agricultural lands, number of housing units predicted on a groundwater resource area, changes to a wildfire hazard index for residential structures, and the social acceptability of residential development patterns given current development preferences. The two policy tools impose in substantially different landscape-level residential development patterns when compared to the baseline change prediction and each other. Each tool resulted in a variety of tradeoffs between negative and positive effects among our measures of impact. Our findings demonstrate the importance of using multiple indicators to evaluate growth management and land protection policy tools for making land use planning decisions.     

Landslide hazard assessment and judgment of reliability: a geomechanical approach

Landslide hazard maps are often defined as reliable a posteriori, in accordance with the real landslides occurring from the time of the map production. However, to be useful for planning, a reliability judgment concerning the hazard mapping should be a priori, based on data uncertainty characterization, and must be driven by the knowledge of the slope instability mechanisms. The landslide hazard assessment, when based on the deterministic diagnosis of the processes, may really lead to really providing clues about how and why the slope could fail (landslide susceptibility) and, possibly, when (landslide hazard). Such deterministic assessment can be pursued only through the interpretation and the geo-hydro-mechanical modelling of the slope equilibrium. In practice, though, the landslide hazard assessment is still seldom dealt with slope modelling, in particular when it addresses intermediate to regional zoning. The paper firstly offers an overview of the key steps of a methodology called the multiscalar method for landslide mitigation, MMLM, which that is a methodological approach for the intermediate to regional landslide hazard assessment using the hydro-mechanical diagnoses of landsliding. The validation of the MMLM to the geologically complex outer sectors of the Southern Apennines (Daunia-Lucanian mountains; Italy) is also delineated, together with a practical approach to incorporate a reliability judgment in the landslide susceptibility/hazard mapping.     

A method for quick assessment of earthquake-triggered landslide hazards: a case study of the Mw6.1 2014 Ludian,China earthquake

Rapid assessment of the distribution of earthquake-triggered landslides is an important component of effective disaster mitigation. The effort should be based on both seismic landslide susceptibility and the ground shaking intensity, which is usually measured by peak ground acceleration (PGA). In this paper, we address this issue by analyzing data from the Mw6.1 2014 Ludian, China earthquake. The Newmark method of rigid-block modeling was applied to calculate the critical acceleration of slopes in the study area, which serve as measurement of slope stability under seismic load. The assessment of earthquake-triggered landslide hazard was conducted by comparing these critical accelerations with the distribution of known PGA values. The study area was classified into zones of five levels of landslide hazard: high, moderate high, moderate, light, and very light. Comparison shows that the resulting landslide hazard zones agree with the actual distribution of earthquake-triggered landslides. Nearly 70% of landslides are located in areas of high and moderately high hazard, which occupy only 17% of the study region. This paper demonstrates that using PGA, combined with the analysis of seismic landslide susceptibility, allows a reliable assessment of earthquake-triggered landslides hazards. This easy-operation mapping method is expected to be helpful in emergency preparedness planning, as well as in seismic landslide hazard zoning.

     

哈尔滨市城乡土地优化利用规划研究

以哈尔滨市为例,针对城乡土地利用存在的土地供需矛盾突出、公共空间缺乏、乡村建设用地利用效率低等问题,提出坚持科学发展观,优化土地利用的有效途径,加强城乡统筹,优化土地利用格局;突出以人为本,创造宜居生活空间;坚持可持续发展,集约高效利用城市土地。     

地理信息系统/遥感技术支持下三峡库区青干河流域滑坡危险性评价

以统计模型为基础、地理信息系统作为工具的滑坡灾害评价模式已经得到普遍认可和使用,数字高程模型(DEM)、遥感影像、区域地质调查资料已经成为区域滑坡评价研究的因子数据源。选择三峡库区青干河流域顺向坡滑坡多发地段为研究区,在滑坡编目数据库基础上,通过:(1)数字高程模型获取高程、坡度、地形聚水能力因子;(2)遥感影像获取植被指数;(3)区域地质调查资料、数字高程模型计算斜坡类型定量因子TOBIA指数及获取岩石地层单元因子。采用二分类变量逻辑回归评价方法对上述6种因子建立滑坡危险性评价模型,开展地理信息系统/遥感技术支持下顺向坡滑坡危险性评价研究。研究结果表明,根据模型概率值分布和已知滑坡发育关系,可以将研究区划分为高危险区、中等危险区、低危险区3个等级,高危险区包含70%已知滑坡,中等危险区包含14%已知滑坡,评价结果和实际滑坡发育情况吻合,合理地反映区内滑坡灾害发育的总体特征。     

Landslide hazard and risk zonation—why is it still so difficult?

The quantification of risk has gained importance in many disciplines, including landslide studies. The literature on landslide risk assessment illustrates the developments which have taken place in the last decade and that quantitative risk assessment is feasible for geotechnical engineering on a site investigation scale and the evaluation of linear features (e.g., pipelines, roads). However, the generation of quantitative risk zonation maps for regulatory and development planning by local authorities still seems a step too far, especially at medium scales (1:10,000–1:50,000). This paper reviews the problem of attempting to quantify landslide risk over larger areas, discussing a number of difficulties related to the generation of landslide inventory maps including information on date, type and volume of the landslide, the determination of its spatial and temporal probability, the modelling of runout and the assessment of landslide vulnerability. An overview of recent developments in the different approaches to landslide hazard and risk zonation at medium scales is given. The paper concludes with a number of new advances and challenges for the future, such as the use of very detailed topographic data, the generation of event-based landslide inventory maps, the use of these maps in spatial-temporal probabilistic modelling and the use of land use and climatic change scenarios in deterministic modelling.     

基于GIS和信息量的滑坡灾害易发性评价——以三峡库区万州区为例

 以滑坡灾害发育较多的三峡库区万州区为研究区,基于指标因素状态分级和因素相关性分析结果,选取坡度、坡向、坡体结构、地层岩性、地质构造、水的作用以及土地利用7项影响因素,以全区700多个滑坡灾害点为样本数据,依据各因素状态下发生的滑坡频率曲线和信息量曲线的突变点为等级划分的临界值来确定因素状态,并在此基础上建立易发性评价指标体系。基于GIS的栅格数据模型,应用信息量理论开展研究区易发性评价,研究结果表明：易发性高和较高的区域主要分布在土地利用总体规划中的建设用地、侏罗系中统上沙溪庙组第二、三段(J2s2,J2s3)、库水变动带和河网影响带以及万州城区。统计结果表明,处在高易发和较高易发区面积为1 210 km2,其中高易发区和较高易发区分别占研究区总面积的9.71%和25.9%,研究区易发性评价精度高达87%。本文完整的论述了县域滑坡灾害易发性评价的理论方法和技术路线,并以三峡库区万州区为例开展滑坡灾害易发性评价、结果分析以及预测精度评价等,为该区域滑坡灾害防治规划与预测预报提供技术支持,为全国范围内县域滑坡灾害易发性评价提供理论指导和技术参考。     

Regional land pattern assessment: development of a resource efficiency measurement method

Debate on the sustainability of human settlements has recently been focused primarily on the urban portion of the land use pattern. However, urban areas rely on suburban, rural, and other less densely settled lands for their existence. In order to quantify the impacts of various land patterns on their supporting resources, these exurban lands must be included in any sustainability assessment. This need for a regional view has resulted in a measurement method that enables comparisons of relative sustainability between various regional land use patterns. Existing methods employed to assess urban sustainability are reviewed and compared with the regional characteristic curves method, introduced here, that takes a more holistic regional view. Results from the application of the method are presented, displaying the spatial dimension it brings to the analysis of illustrative primary metrics as well as demonstrating its ability to spatially quantify change in these metrics over time.     

Identification of landslide hazard and risk ‘hotspots’ in Europe

Landslides are a serious problem for humans and infrastructure in many parts of Europe. Experts know to a certain degree which parts of the continent are most exposed to landslide hazard. Nevertheless, neither the geographical location of previous landslide events nor knowledge of locations with high landslide hazard necessarily point out the areas with highest landslide risk. In addition, landslides often occur unexpectedly and the decisions on where investments should be made to manage and mitigate future events are based on the need to demonstrate action and political will. The goal of this study was to undertake a uniform and objective analysis of landslide hazard and risk for Europe. Two independent models, an expert-based or heuristic and a statistical model (logistic regression), were developed to assess the landslide hazard. Both models are based on applying an appropriate combination of the parameters representing susceptibility factors (slope, lithology, soil moisture, vegetation cover and other- factors if available) and triggering factors (extreme precipitation and seismicity). The weights of different susceptibility and triggering factors are calibrated to the information available in landslide inventories and physical processes. The analysis is based on uniform gridded data for Europe with a pixel resolution of roughly 30 m × 30 m. A validation of the two hazard models by organizations in Scotland, Italy, and Romania showed good agreement for shallow landslides and rockfalls, but the hazard models fail to cover areas with slow moving landslides. In general, the results from the two models agree well pointing out the same countries with the highest total and relative area exposed to landslides. Landslide risk was quantified by counting the number of exposed people and exposed kilometers of roads and railways in each country. This process was repeated for both models. The results show the highest relative exposure to landslides in small alpine countries such as Lichtenstein. In terms of total values on a national level, Italy scores highest in both the extent of exposed area and the number for exposed population. Again, results agree between the two models, but differences between the models are higher for the risk than for the hazard results. The analysis gives a good overview of the landslide hazard and risk hotspots in Europe and allows a simple ranking of areas where mitigation measures might be most effective.     

Reliability of landslide isopleth maps

  Following very heavy rainfall on 19/20 July 1983, 109 landslides occurred in the east of Findikli, Rize, north-east Turkey. The movements took place in completely weathered andesitic, dacitic and granitic rocks as well as slope debris. They extended over an area of approximately 25 km². The paper discusses the contour (isopleth) map prepared using data from the 1983 landslides and discusses its value for landslide hazard zoning. It is concluded that on the basis of 12 years of field evidence, a contour map derived from a precise inventory map can be a useful tool. Received: 28 November 1998 · Accepted: 15 May 1999     

Assessment and validation of GIS-based landslide susceptibility maps: a case study from Feltrino stream basin (Central Italy)

Landslide susceptibility studies focus on producing susceptibility maps starting from landslide inventories and considering the main conditioning factors. The validity of susceptibility maps must be verified in terms of model accuracy and prediction skills. This paper deals with a GIS-based landslide susceptibility analysis and relative validation in a hilly-coastal test-area in Adriatic Central Italy. The susceptibility analysis was performed via bivariate statistics using the Landslide-Index method and a detailed (field-based) landslide inventory. Selection and mapping of conditioning factors and landslide inventories was derived from detail geomorphological analyses of the study area. The susceptibility map was validated using recent (shallow) landslides in terms of both model accuracy and prediction skills, via Success rate and Prediction rate curves, respectively. In addition, a pre-existing official landslide inventory was applied to the model to test whether it can be used when a detailed (field-based) inventory is not available, thereby extending its usability in similar physiographic regions. The outcome of this study reveals that slope and lithology are the main conditioning factor of landslides, but also highlights the key role of surficial deposits in susceptibility assessment, for both their type and thickness. The validation results show the effectiveness of the susceptibility model in both model accuracy and prediction skills given the good percentage of correctly classified landslides. Moreover, comparison of the susceptibility map with the official Regional landslides inventory proves the possibility of using the developed susceptibility model also in the absence of detailed landslide mapping, by considering inventories that are already available.     

区域滑坡空间预测方法研究及结果分析

区域滑坡空间预测是通过分析滑坡在区域空间分布的丛集性及规律性,圈定出滑坡相对危险性区域。通过MAPGIS软件平台及其二次开发的滑坡灾害分析系统,采用半定量和定量两种方法对浙江省永嘉县区域滑坡进行了预测。半定量方法采用反映历史滑坡强度的袭扰系数和滑坡易发程度指数来评价,编制了危险性预测分区图;定量化方法采用信息量模型来评价,采用规则网格作为预测单元,运用该模型对永嘉县区域滑坡进行了空间定量预测,并依信息量法的结果编制了该区的危险性划决预测分区图,为政府部门进行土地规策、避免在滑坡易发区进行大规模土地开发和工程建设提供了科学依据。同时通过两种方法的预测结果,对比分析了滑坡的形成和各影响因素的关系,为滑坡的有效防治提供了参考。     

珠江三角洲“耕保型村庄”的发展诉求与耕地保护经济补偿——以佛山市南海区平沙村为例

2013年以来“城乡统一的建设用地市场”已成为土地制度改革的中心议题，但这一制度仍受困于“计划性”的城乡建设用地的指标总控以及耕地（尤其是基本农田）指标控制。基于此，对于基层政府而言，辖区内的基于城乡建设用地的利益格局与基于基本农田保护的责任格局产生了智识与政策层面上的双重分裂，而“耕保型村庄”长期作为一个失语者则未得到应有的追踪与调研。文章以珠江三角洲的佛山市南海区为例，借由案例村庄的深度访谈来折射其对于农村土地制度改革（尤其是农村集体经营性建设用地）的期望以及对于耕地保护经济补偿的诉求，期望能对新一轮次的城乡统筹发展与村庄规划有所启发。     

Transition of the satoyama landscape in the urban fringe of the Tokyo metropolitan area from 1880 to 2001

An explicit understanding of past landscapes is a basic and important issue, which enables deeper understanding of current landscapes in a longer context and gives useful suggestion to today's landscape planning. In this paper, transition of the traditional Japanese agricultural landscape (satoyama landscape) over a relatively long temporal scale (1880–2001), and its inherent dynamics in each of four socioeconomically based time periods in two topographically different areas around the Tokyo metropolitan area was studied. Information derived from historical records and interviews was used to differentiate four socioeconomic periods, and to support and explain the results of the analysis. Old maps and aerial photographs were used to create land use maps, which were analyzed using GIS. The results illustrated drastic landscape change from agricultural to urban landscape, with unique land use and transition patterns in each study area. A large part of both study areas was affected by bi-directional conversion between woodlands and crop fields in the early part of the study period, in the form of shifting agriculture. Our results also showed that the landscapes are becoming less dynamic and it may suggest reconsideration for land use planning, which will lead to more stabilized landscapes.