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1.
《Engineering Geology》2004,73(3-4):193
In two events, on November 15 and 17, 2000, near the Mangart Mountain (2679 m a.s.l.), NW Slovenia, two translational landslides (debris flow slides) with a total volume of more than 1.5 million m3 occurred on the Sto
e slope composed of morainic material filled with silt fraction. The first landslide was associated with a dry and the second landslide with a wet debris-flow, respectively. The rain gauging station in the village of Log pod Mangartom recorded 1638.4 mm of rainfall (more than 60% of the average annual precipitation) in the 48 days before the events (rainfall intensity of 1.42 mm/h in 1152 h). The recorded rainfall depth has a recurrence interval of more than 100 years. Other recorded rainfall depths of shorter duration (481.6 mm in 7 days, 174.0 mm in 24 h, 70 mm in 1 h) have recurrence intervals of much less than 100 years. A hydrological analysis of the event showed that the increase in runoff coefficients during the wet period in autumn 2000 before the landslide was as high as two- to threefold. An analysis using natural isotopes of δ18O and tritium of water samples from the Sto
e landslide area has shown permanent but slow exfiltration of underground waters from a reservoir in the slope. In the case of low-intensity and long-duration rainfall in autumn 2000, relatively low permeable (10−7 m/s) morainic material was nearly saturated but remained stable (average porosity 21%, water content 20%, liquid limit 25%) until high artesian pressures up to 100 m developed in the slope by slow exfiltration from the relatively high permeable (10−5 m/s) massive dolomite. The Sto
e landslide (two debris flow slides) was triggered by high artesian pressures built in the slope after long-duration rainfall. The devastating debris-flows formed from the landslide masses by infiltration of rainfall and surface runoff into the landslide masses and by their liquefaction. 相似文献
2.
A catastrophic earthquake with a Richter magnitude of 7.3 occurred in the Chi-Chi area of Nantou County on 21 September 1999.
Large-scale landslides were generated in the Chiufenershan area of Nantou County in central Taiwan. This study used a neural
network-based classifier and the proposed NDVI-based quantitative index coupled with multitemporal SPOT images and digital
elevation models (DEMs) for the assessment of long-term landscape changes and vegetation recovery conditions at the sites
of these landslides. The analyzed results indicate that high accuracy of landslide mapping can be extracted using a neural
network-based classifier, and the areas affected by these landslides have gradually been restored from 211.52 ha on 27 September
1999 to 113.71 ha on 11 March 2006, a reduction of 46.24%, after six and a half years of assessment. In accordance with topographic
analysis at the sites of the landslides, the collapsed and deposited areas of the landslide were 100.54 and 110.98 ha, with
corresponding debris volumes of 31,983,800 and 39,339,500 m3. Under natural vegetation succession, average vegetation recovery rate at the sites of the landslides reached 36.68% on 11
March 2006. The vegetation recovery conditions at the collapsed area (29.17%) are shown to be worse than at the deposited
area (57.13%) due to topsoil removal and the steep slope, which can be verified based on the field survey. From 1999 to 2006,
even though the landslide areas frequently suffered from the interference of typhoon strikes, the vegetation succession process
at the sites of the landslides was still ongoing, which indicates that nature, itself, has the capability for strong vegetation
recovery for the denudation sites. The analyzed results provide very useful information for decision-making and policy-planning
in the landslide area. 相似文献
3.
Analysis of time-varying rainfall infiltration induced landslide 总被引：5，自引：0，他引：5
Chen Chien-Yuan Chen Tien-Chien Yu Fan-Chieh Lin Sheng-Chi 《Environmental Geology》2005,48(4-5):466-479
A case study of rainstorm-induced landslide is modeled following the hourly rainfall time series from the stage of infiltration
caused by induced slope movement and soil saturated to excess pore pressures—Transient Rainfall Infiltration and Grid-based
Regional Slope-Stability Analysis (TRIGRS). The grid-based landslide stability analysis was conducted to model the increased
pore pressures and runoff in the study area under the specified rainfall conditions. The generated time variances of pore
pressures help determine landslide characteristics and mechanisms under rainfall conditions. Inputs of soil properties and
permeability parameters for landslide stability analysis in the study area were prepared by TRIGRS adopted for transient infiltration
analysis. Results of the analyses show that under heavy rainfall conditions, the infiltrated slope is unstable and the time
of debris masses movement initiated is correlated to the recorded time. In the initiated landslide, characteristics and effects
are considered and reflected in the numerical modeling under combinations of topography, land use, climatic and geological
conditions. Results reveal that there is a plane failure surface and a potential circular failure surface at the study site
besides the rock topple failures in the crest. A grid-based slope-stability analysis incorporated with the GIS spatial functions
is more advantageous than the traditional two-dimensional analysis for specified slope profiles to determine the whole behavior
of a slope. 相似文献
4.
Sandra G. Catane Hillel B. Cabria Cristituto P. Tomarong Jr Ricarido M. Saturay Jr Mark Albert H. Zarco Winston C. Pioquinto 《Landslides》2007,4(1):85-90
On 17 February 2006, a rockslide-debris avalanche cascaded down the steep slope of Mt. Can-abag, burying the entire village
of Guinsaugon in St. Bernard, Southern Leyte, Philippines. Casualties include 139 dead with 980 still missing and presumed
dead, making it perhaps the most catastrophic landslide in Philippine history. The landslide started at the ridge top along
a fault plane associated with the active Philippine Fault Zone. It started as a block slide that transformed into an avalanche.
The entire event lasted for only a few minutes. Estimated maximum landslide velocity is 120–130 m/s. The landslide left behind
a deep, wedge-shaped scarp. The central part of the deposit exhibits a hummocky topography typical of avalanches, in contrast
to the flatter surface of the debris-flow-type marginal deposit. High amounts of soil in the matrix were derived from the
scouring of ancient landslide deposits and rice fields in the valley. The landslide has a total area of 3.2 km2 and a runout distance of 4.1 km. Estimated volume of debris is approximately 20 Mm3. At least four streams were dammed by the landslide debris. Intense precipitation and earthquakes preceding the landslide
are the potential triggers. Preliminary back analyses assuming a planar and wedge slip surface yielded very low factors of
safety even under dry conditions. A more rigorous analysis of the failure mechanism of the landslide is needed. 相似文献
5.
Continuous 5-day (August 4–9, 2019) torrential rainfall in the monsoon season triggered more than 90 landslides on northwest-southeast extended mountain range of Mon State, Myanmar. In this study, remote sensing images, DEM, and limited fieldworks were used to create the landslide inventory. The topography features of these landslides are analyzed via ArcGIS. The largest one occurred on 9 August 2019 and caused 75 deaths and 27 buildings were damaged. This landslide occurred on gentle topography (slope angle, 23°) with long run-out, in which the angle of reach was relatively low (10°). The volume was 111,878 m3 was mainly composed of weathered granite and red soil and the sliding depth was approximately 7.5 m. Topographic characteristics including the relative slope height, angle of reach, and slope angle of source area of 35 landslides with areas?>?4000 m2 were analyzed. The spatial distribution characteristics and topographic features of the 35 landslides below are distinguished: (1) the concentration of most of landslides on southwest-facing slopes showing the heterogeneous spatial distribution of landslide; (2) an uncommon landslide distribution in which more than half of landslide originates from upper slope; (3) the range of the angle of the source area (17°–38°) compatible with the internal friction angle of soils in tropical regions (17°–33°); and (4) the tangent of the angle of reach is generally smaller than 0.5 (angle of reach?<?27°) shows a relative high mobility and the relation between landslide mobility and the slope angle of the landslide source area is similar to the one of earthquake-triggered landslides, even though the triggering mechanism, landslide type, and landslide volume are dramatically different.
相似文献6.
天水锻压机床厂滑坡变形破坏机制及形成演化 总被引：4，自引：1，他引：3
天水锻压机床厂滑坡(1.4×106 m3)发生于1990年8月11日, 滑坡体主要由次生黄土组成, 滑床为第四系黄土和新近系泥岩, 滑坡沿黄土-泥岩接触面发生, 属黄土接触面滑坡。通过野外调查和工程钻探对锻压机床厂滑坡变形破坏机制及形成演化进行研究, 结果表明, 该滑坡变形破坏方式表现为滑移-拉裂式, 受区内二元斜坡结构控制, 是在工程切坡和降雨、灌溉等诱发因素作用下形成; 其形成演化经历了高陡边坡形成期→滑坡孕育期→滑动面贯通临界期→滑坡启动下滑堆积期→滑坡复活变形期等过程。该滑坡目前处于欠稳定状态, 遇地震或强降雨等作用, 极有可能再次复活下滑。研究成果可为该类滑坡的防治预警提供理论依据。 相似文献
7.
2008年5月12日的汶川大地震引发了大规模同震山体滑坡,随后的强降雨又引发新的山体滑坡,滑坡形成的松散固体物质成为后续泥石流灾害的主要物质来源。为探究强震区泥石流流域崩滑体时空演变特征,文章以北川县魏家沟等8条泥石流流域为例,选取8期遥感影像（2008年震后、“9.24”泥石流发生后、2010年、2011年、2013年、2014年、2015年、2016年）,分别解译崩滑体,统计其空间分布特征。此外,利用归一化植被指数（NDVI）计算研究区内植被覆盖度（VFC）及植被覆盖度恢复率（VCRR）。结果表明:研究区内崩滑体发育面积在强降雨作用后达到峰值,随后呈稳定恢复状态,面积逐年减小。崩滑体在高程900~1 100 m范围、坡度30°~45°范围、坡向90°~135°范围、距沟道150 m范围内发育面积最大。流域内植被覆盖度在2008年“9.24”泥石流灾害后最低,随后呈稳定恢复。自震后到2010年的时期内,植被覆盖度恢复率中等以下区域较多,植被恢复程度较低。2011年之后,流域内大多区域处于植被覆盖度恢复率中等以上等级,植被恢复程度较高。到2016年,研究区植被覆盖度已恢复至较高水平。研究表明:除地层岩性、微地貌等因素影响外,植被对泥石流活动性具有一定的抑制作用。 相似文献
8.
Following a heavy rainstorm on 29 June 1999, hundreds of slope failures occurred in granitic mountains in Hiroshima Prefecture, Japan. Among these events, a highly mobile landslide (termed the Kameyama landslide in this paper), which occurred in Kameyama area of Hiroshima city, was the most catastrophic, and was investigated in detail. The displaced soil mass from the source area of this landslide traveled about 300 m and deposited a volume more than 10 times as great as that in the source area. The landslide originated in and traversed a valley-shaped concave slope covered by pre-existing colluvial debris deposits. In addition, a spring was visible in the source area and very shallow ground water was observed in an observation pit dug in the source area. Thus, it is inferred that the ground-water table rose quickly during the rainfall, and that this rise triggered the slope failure in the source area. Based on a field survey along the landslide cross section, a possible explanation for the mechanism of the landslide was obtained: the displaced soil mass from the source area impacted the debris deposit in the path of the landslide, thus triggering liquefaction failure of the saturated part of debris. The original landslide and the liquefied debris then moved downslope as a single mass. To examine this assumption, ring-shear tests were performed on samples taken from the source area. Undrained ring-shear tests on the saturated samples showed that the sample is highly liquefiable, and liquefaction failure could have been triggered in the debris deposits by a very small impact from the displaced soil mass of the initial failure. In addition, laboratory tests simulating the impacts on the debris deposits at natural water content, i.e., unsaturated (at the survey time, 2 days after the failure) showed that although shear failure could be caused by the assumed impact force, the displaced soils stopped after a few centimeters displacement, indicating that existence of a saturated zone in debris deposits is prerequisite for this kind of failure. 相似文献
9.
Vegetation recovery and landscape change assessment at Chiufenershan landslide area caused by Chichi earthquake in central Taiwan 总被引：1，自引：1，他引：0
This study discusses vegetation recovery and land cover change with reference to the Chiufenershan landslide, a major disaster
caused by the Chichi earthquake, 21 September 1999. Image classification technology, landscape indicators from multi-temporal
remotely sensed data and a field survey provide the data. Image differencing methods and threshold values coupled with pre-
and post-quake satellite images were used. Multi-temporal images in combination with various vegetation indices were drawn
on to classify land cover patterns and discuss differences and suitability of indices. Landscape indicators and field investigations
fed into an investigation of vegetation recovery and landscape change. The study results show that the best image classification
system is original wavebands coupled with a cropping management factor index (CMFI). The land cover analysis shows that areas
of forest and grass are increasing and areas of landslide are decreasing. From the field investigation, because the left and
right sides of the landslide area were not disturbed by the earthquake, their calculated similarity index is the highest (30.08%).
Miscanthus floridulus is the most dominant pioneer plant at the landslide collapse area with an importance value index (IVI) of 63.6%. 相似文献
10.
《地学前缘(英文版)》2018,9(6):1871-1882
A combined cluster and regression analysis were performed for the first time to identify rainfall threshold that triggers landslide events in Amboori, Kerala, India. Amboori is a tropical area that is highly vulnerable to landslides. The 2, 3, and 5-day antecedent rainfall data versus daily rainfall was clustered to identify a cluster of critical events that could potentially trigger landslides. Further, the cluster of critical events was utilized for regression analysis to develop the threshold equations. The 5-day antecedent (x-variable) vs. daily rainfall (y-variable) provided the best fit to the data with a threshold equation of y = 80.7–0.1981x. The intercept of the equation indicates that if the 5-day antecedent rainfall is zero, the minimum daily rainfall needed to trigger the landslide in the Amboori region would be 80.7 mm. The negative coefficient of the antecedent rainfall indicates that when the cumulative antecedent rainfall increases, the amount of daily rainfall required to trigger monsoon landslide decreases. The coefficient value indicates that the contribution of the 5-day antecedent rainfall is ∼20% to the landslide trigger threshold. The slope stability analysis carried out for the area, using Probabilistic Infinite Slope Analysis Model (PISA-m), was utilized to identify the areas vulnerable to landslide in the region. The locations in the area where past landslides have occurred demonstrate lower Factors of Safety (FS) in the slope stability analysis. Thus, rainfall threshold analysis together with the FS values from slope stability can be suitable for developing a simple, cost-effective, and comprehensive early-warning system for shallow landslides in Amboori and similar regions. 相似文献
11.
The debris flow, which was triggered in the Wenjia Gully on August 13, 2010, is an extreme example of mass movement events, which occurred after the Wenchuan earthquake of May 12, 2008. This Earthquake triggered in the Wenjia Gully the second largest co-seismic landslide, which can be classified as a rockslide-debris avalanche. A lot of loose sediments was deposited in the basin. In the main so called Deposition Area II of this landslide, with a volume of 30?×?106?m3, flash floods can easily trigger debris flows because of the steep bottom slope and the relative small grain sizes of the sediments. The largest debris flow of August 13, 2010 destroyed the most downstream dam in the catchment during a heavy rain storm. The debris flow with a peak discharge of 1,530?m3/s and a total volume of 3.1?×?106?m3 caused the death of 7 persons, 5 persons were missing, 39 persons were injured and 479 houses buried. After three rainy seasons, only 16?% of the landslide-debris deposition was taken away by 5 large-scale debris flow events. Since the threshold for rainfall triggered debris flows in the Wenjia Gully and other catchments drastically decreased after the Wenchuan Earthquake, new catastrophic events are expected in the future during the rainy season. 相似文献
12.
A large landslide formed at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, at 1430?hours local time, when rapid failure occurred after several days of preliminary movements. The landslide has an area of 0.3?km2, a runout distance of 1.2?km and an estimated volume of about 10?Mm3. The landslide caused nearly 2,300 inhabitants to be evacuated, with high economic losses. The most probable trigger of the landslide was the cumulative precipitation over the preceding 20?days (having a return period of more than 100?years), which followed a long period of 4?C5?months of heavy rainfall (of about 150% of the average rainfall of the period). This report presents a summary of our findings pertinent to the landslide??s activities based on our field investigations. In particular, this report covers (1) details of land deformation caused by the landslide, (2) geology pertinent to landslide development, (3) identification of the landslide mechanism and its triggering factors based on the analysis of the boring core specimens and landform features, as well as the available video of the event, and (4) preliminary evaluation of the stability of the original slope before the landslide using the finite element-based shear strength reduction method. The aim of the paper was to describe the landslide and explain its mechanism of occurrence. 相似文献
13.
南京猪头山滑坡属于典型的覆盖层滑坡,2003年5月边坡发生缓慢变形失稳,没有对周围造成很大的危害,故未引起足够重视,2016年6~7月间受强降雨的影响再次发生大规模的滑动。研究发现,该滑体的地层具有特殊地质结构,在强降雨条件下会产生暂时性承压水,在其承压水的渗透力及浮托力作用下,其稳定性将会大大下降,因此该滑坡的再滑动与降雨密切相关。本文运用数值模拟方法分析了滑坡变形过程与降雨时长及降雨强度之间的关系,结果表明猪头山山前缓坡的稳定性随降雨时长和降雨强度增大逐渐降低,且具有一定的突变性,其滑坡面的位置位于坡体填土层的下部,较好地揭示了猪头山降雨型滑坡形成的机理以及滑坡再滑动机制。这一研究为所在地区的降雨性滑坡预报和治理提供了科学依据。 相似文献
14.
四川都江堰三溪村710高位山体滑坡研究 总被引：2，自引：0，他引：2
2013年7月10日上午10时,四川都江堰市中兴镇三溪村受极端暴雨影响发生高位山体滑坡灾害,滑坡-碎屑堆积体方量超过150104m3,其中1#滑坡-碎屑堆积体长度1.26km,造成三溪村一组重大人员伤亡。笔者在野外实地调查和室内研究分析的基础上,总结了都江堰三溪村滑坡的基本特征,研究了其启动运动机制和滑动速度,主要认识如下:（1）该滑坡为一处高位山体滑坡,后缘白垩系砂砾岩地层高速滑动后剧烈撞击-铲刮-偏转后铲动坡体上的松散堆积层而形成高位山体滑坡-碎屑流灾害。（2）根据滑坡的运动及堆积特征,将1#滑坡划分为砂砾岩滑动区、碰撞铲刮区和碎屑流堆积覆盖区3部分。（3）7月8日8时至10日8时,中兴镇三溪村的持续强降雨天气过程（都江堰市3d的降雨量相当于该地区年降雨总量的44.1%）,直接触发了滑坡的发生。（4）三溪村滑坡的发生受2008年汶川地震、特殊的岩土体性质、地形地貌条件以及极端暴雨事件的综合影响,地震、地形为其发育提供了基础条件,极端暴雨事件为其直接诱发因素。（5）建议加强高位山体滑坡的研究,尤其是远程滑坡-碎屑流的早期识别和预警。 相似文献
15.
Regional landslide-hazard assessment for Seattle, Washington, USA 总被引：13，自引：6，他引：13
Rex L. Baum Jeffery A. Coe Jonathan W. Godt Edwin L. Harp Mark E. Reid William Z. Savage William H. Schulz Dianne L. Brien Alan F. Chleborad Jonathan P. McKenna John A. Michael 《Landslides》2005,2(4):266-279
Landslides are a widespread, frequent, and costly hazard in Seattle and the Puget Sound area of Washington State, USA. Shallow
earth slides triggered by heavy rainfall are the most common type of landslide in the area; many transform into debris flows
and cause significant property damage or disrupt transportation. Large rotational and translational slides, though less common,
also cause serious property damage. The hundreds of landslides that occurred during the winters of 1995–96 and 1996–97 stimulated
renewed interest by Puget Sound communities in identifying landslide-prone areas and taking actions to reduce future landslide
losses. Informal partnerships between the U.S. Geological Survey (USGS), the City of Seattle, and private consultants are
focusing on the problem of identifying and mapping areas of landslide hazard as well as characterizing temporal aspects of
the hazard. We have developed GIS-based methods to map the probability of landslide occurrence as well as empirical rainfall
thresholds and physically based methods to forecast times of landslide occurrence. Our methods for mapping landslide hazard
zones began with field studies and physically based models to assess relative slope stability, including the effects of material
properties, seasonal groundwater levels, and rainfall infiltration. We have analyzed the correlation between historic landslide
occurrence and relative slope stability to map the degree of landslide hazard. The City of Seattle is using results of the
USGS studies in storm preparedness planning for emergency access and response, planning for development or redevelopment of
hillsides, and municipal facility planning and prioritization. Methods we have developed could be applied elsewhere to suit
local needs and available data. 相似文献
16.
Landslides are mainly triggered by decrease in the matric suction with deepening the wetting band by rainfall infiltrations. This paper reports rainfall-induced landslides in partially saturated soil slopes through a field study. A comprehensive analysis on Umyeonsan (Mt.) landslides in 2011 was highlighted. The incident involves the collapse of unsaturated soil slopes under extreme-rainfall event. Fundamental studies on the mechanism and the cause of landslides were carried out. A number of technical findings are of interest, including the failure mechanism of a depth of soil and effect of groundwater flow, the downward movement of wetting band and the increase of groundwater level. Based on this, an integrated analysis methodology for a rainfall-induced landslide is proposed in this paper that incorporates the field matric suction for obtaining hydraulic parameters of unsaturated soil. The field matric suction is shown to govern the rate of change in the water infiltration for the landslide analysis with respect to an antecedent rainfall. Special attention was given to a one-dimensional infiltration model to determine the wetting band depth in the absence of the field matric suction. The results indicate that landslide activities were primarily dependent on rainfall infiltration, soil properties, slope geometries, vegetation, and groundwater table positions. The proposed methodology has clearly demonstrated both shallow and deep-seated landslides and shows good agreement with the results of landslide investigations. 相似文献
17.
Analysis of an anti-dip landslide triggered by the 2008 Wenchuan earthquake in China 总被引：2，自引：0，他引：2
Runqiu Huang Jianjun Zhao Nengpan Ju Guo Li Min Lee Lee Yanrong Li 《Natural Hazards》2013,68(2):1021-1039
The Guantan landslide, with a total displaced mass of about 468 × 104 m3, was triggered by the 2008 Wenchuan earthquake and succeeding rainfall in Jushui Town, Sichuan Province, China. The landslide occurred on an anti-dip hard rock slope with a weak rock founding stratum of 200 m in thickness. To investigate the failure mechanism of the Guantan landslide, dynamic behaviors of hard and soft rock slopes were investigated by means of large scale shaking table tests. The laboratory models attempted to simulate the field geological conditions of the Guantan landslide. Sinusoidal waves and actual seismic waves measured from the Wenchuan Earthquake were applied on the slope models under 37 loading configurations. The experimental results indicated that deformation mainly developed at a shallow depth in the upper part of the hard rock slope and in the upper (near the crest) and lower (near the toe) parts of the soft rock slope. An equation for predicting the depth of sliding plane was proposed based on the location of the maximum horizontal acceleration. Finally, it was concluded that the failure process of the Guantan landslide occurred in three stages: (1) toppling failure caused by compression of the underlying soft rock strata, (2) formation of crushed hard rock and sliding surface in soft rock as the result of seismic shocks, particularly in the horizontal direction, and (3) aftershock rainfall accelerates the process of mass movement along the sliding plane. 相似文献
18.
兰州皋兰山黄土滑坡特征及灾度评估研究 总被引：5，自引：0，他引：5
皋兰山滑坡是西北地区非常典型的黄土滑坡,由3个次级滑坡构成,形成条件可概括为:新构造作用促使皋兰山强烈隆起,形成高达200～300m以上陡峻的自然斜坡,平均坡度在33.7°,临空条件好;构成斜坡的基岩为泥岩,其上覆盖很厚的黄土层,泥岩表面风化、破碎严重,不透水,黄土垂直节理发育,有利于地表水的渗入,在黄土与泥岩的接触面构成抗剪强度低值带;在地下水对下部软弱层侵润作用下,其抗剪强度大大降低;地震是促使滑坡产生的突发因素;同时,由于斜坡前缘建房开挖边坡及公园建设加载和绿化灌溉等,导致坡体稳定性明显降低,出现失稳破坏。通过野外勘查和位移监测及稳定性计算表明:目前滑坡总体上处于稳定状态,局部滑坡体复活变形迹象渐趋明显,其中变形最严重的是位于斜坡中下部并紧邻市区的Ⅰ3滑坡、Ⅰ4滑坡和Ⅲ滑坡。文章还对滑坡潜在损失进行了初步评估,并提出了防治方案和建议。 相似文献
19.
This paper deals with landslide hazards and risk analysis of Penang Island, Malaysia using Geographic Information System (GIS)
and remote sensing data. Landslide locations in the study area were identified from interpretations of aerial photographs
and field surveys. Topographical/geological data and satellite images were collected and processed using GIS and image processing
tools. There are ten landslide inducing parameters which are considered for landslide hazard analysis. These parameters are
topographic slope, aspect, curvature and distance from drainage, all derived from the topographic database; geology and distance
from lineament, derived from the geologic database; landuse from Landsat satellite images; soil from the soil database; precipitation
amount, derived from the rainfall database; and the vegetation index value from SPOT satellite images. Landslide susceptibility
was analyzed using landslide-occurrence factors employing the probability-frequency ratio model. The results of the analysis
were verified using the landslide location data and compared with the probabilistic model. The accuracy observed was 80.03%.
The qualitative landslide hazard analysis was carried out using the frequency ratio model through the map overlay analysis
in GIS environment. The accuracy of hazard map was 86.41%. Further, risk analysis was done by studying the landslide hazard
map and damageable objects at risk. This information could be used to estimate the risk to population, property and existing
infrastructure like transportation network. 相似文献
20.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(10):925-934
Detailed geomorphological mapping carried out in 5 sample areas in the North of Lisbon Region allowed us to collect a set of geological and geomorphological data and to correlate them with the spatial occurrence of landslide. A total of 597 slope movements were identified in a total area of 61.7 km2, which represents about 10 landslides per km2.The main landslide conditioning factors are: lithology and geological structure, slope angle and slope morphology, land use, presence of old landslides, and human activity.The highest landslide density occurs in Cretaceous marls and marly limestones, but the largest movements are in Jurassic clays, marls and limestones.The landslide density is higher on slopes with gradients above 20 °, but the largest unstable area is found on slopes of 10 ° to 15 °, thus reflecting the presence of the biggest slope movements. There is a correlation between landslides and topographical concavities, a fact that can be interpreted as reflecting the significance of the hydrological regime in slope instability.Concerning land use, the highest density of landslides is found on slopes covered with shrub and undergrowth vegetation.About 26% of the total number of landslides are reactivation events. The presence of old landslides is particularly important in the occurrence of translational slides and complex and composite slope movements.20% of the landslide events were conditioned by anthropomorphic activity. Human's intervention manifests itself in ill-consolidated fills, cuts in potentially unstable slopes and, in a few cases, in the changing of river channels.Most slope movements in the study area exhibit a clear climatic signal. The analysis of rainfall distribution in periods of recognised slope instability allows the distinction of three situations: 1) moderate intensity rainfall episodes, responsible for minor slope movements on the bank of rivers and shallow translational slides, particularly in artificial trenches; 2) high intensity rainfall episodes, originating flash floods and most landslides triggered by bank erosion; 3) long-lasting rainfall periods, responsible for the rise of the groundwater table and triggering of landslides with deeper slip surfaces. 相似文献