共查询到20条相似文献，搜索用时 31 毫秒
1.
The occurrence of wet-snow avalanches is, in general, poorly understood. For 20 years (winters of 1975–1976 to 1994–1995),
the avalanche activity has been observed in the Dischma valley near Davos (Eastern Swiss Alps). The study area comprises a
large starting zone of north-easterly aspect (2,300 m a.s.l.) with several avalanche paths. We have analyzed the occurrence
data in combination with meteorological and snowpack data collected at an elevation of 2,090 m a.s.l. During the 20-year observation
period, almost 800 wet-snow avalanches were observed, about 4.5 times more loose snow avalanches than slab avalanches. Considering
both types of avalanches jointly, snow depth, precipitation and air temperature showed the highest correlation with avalanche
activity. Most loose snow avalanches occurred when air temperature was high and/or after a precipitation period. Slab avalanches
occurrence was primarily related to warm air temperatures and snowpack properties such as the isothermal state and the existence
of capillary barriers. Radiation did not show up as a significant variable. The results suggest that in a transitional snow
climate wet-snow avalanches are, as dry snow avalanches, often related to precipitation events, and that wet slab instability
strongly depends on snowpack properties in relation to warming of the snowpack and melt water production. 相似文献
2.
Snow avalanches are a major natural hazard for road users and infrastructure in northern Gaspésie. Over the past 11 years, the occurrence of nearly 500 snow avalanches on the two major roads servicing the area was reported. No management program is currently operational. In this study, we analyze the weather patterns promoting snow avalanche initiation and use logistic regression (LR) to calculate the probability of avalanche occurrence on a daily basis. We then test the best LR models over the 2012–2013 season in an operational forecasting perspective: Each day, the probability of occurrence (0–100%) determined by the model was classified into five classes avalanche danger scale. Our results show that avalanche occurrence along the coast is best predicted by 2 days of accrued snowfall [in water equivalent (WE)], daily rainfall, and wind speed. In the valley, the most significant predictive variables are 3 days of accrued snowfall (WE), daily rainfall, and the preceding 2 days of thermal amplitude. The large scree slopes located along the coast and exposed to strong winds tend to be more reactive to direct snow accumulation than the inner-valley slopes. Therefore, the probability of avalanche occurrence increases rapidly during a snowfall. The slopes located in the valley are less responsive to snow loading. The LR models developed prove to be an efficient tool to forecast days with high levels of snow avalanche activity. Finally, we discuss how road maintenance managers can use this forecasting tool to improve decision making and risk rendering on a daily basis. 相似文献
3.
The search to improve protective techniques against natural phenomena such as snow avalanches continues to use classic methods to calculate flexible structures. This paper deals with a new method for designing avalanche protection nets; this method is based on a coupled analysis of both the net structure and the snow mantel using a coupled Lagrangian‐discrete approach. This has led to the development of computational software so that avalanche nets can be easily designed. This tool provides for the evolving forces acting on several parts of the net as a function of the snow situation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
4.
Nesibe Köse Abdurrahim Aydın Ünal Akkemik Hüseyin Yurtseven Tuncay Güner 《Natural Hazards》2010,54(2):435-449
Many parts of our planet are exposed to natural disasters such as snow avalanches, floods and earthquakes. Detailed knowledge
on these natural disasters is crucial for human safety. On December 25–26, 1992, two avalanches occurred at Kayaarkası-Kastamonu
in northern Turkey. The first avalanche took place at night of 25–26 December and caused no damage. The second avalanche took
place at morning of 26 December, killed four people and did damage to properties. The purpose of the present study is to determine
the effects of the snow avalanches on tree rings and to investigate the boundaries and velocities of the avalanches using
a numerical simulation model and the tree-ring data. Increment cores from 71 trees in the avalanche-impacted area and the
control site were sampled to obtain individual standard chronologies. In the analyses, trees were grouped as (1) heavily damaged
by the avalanche, showing a decrease in tree-ring widths since the event, (2) trees heavily damaged by the avalanche, showing
an increase in tree-ring widths a couple of years later the event and (3) trees that were not damaged by the avalanche. In
this study, one of the most important results is the precise determination of the temporal and spatial patterns of the undocumented
avalanche (the first avalanche) event. Avalanches were numerically simulated using dynamical avalanche simulation software
ELBA+. Comparison of the simulation model with tree-ring analysis revealed valuable results about the boundaries of the zone
of influence of the avalanches. 相似文献
5.
奎屯河新龙口右岸山体崩塌原因及再次失稳可能性分析 总被引：1，自引：0，他引：1
奎屯河新龙口段山体历史上多次发生山体塌滑破坏,最近一次山体崩塌较为反常地发生在1月寒冷季节,而不是通 常的7、8月雨季,针对该段山体频繁发生破坏而且还出现反季节崩塌这种特殊情况,从区域地质背景、地震作用、地形地貌、气 候及降水等几个方面分别详细论述了产生崩塌的原因,同时指出这次反季节崩塌产生的触发原因在于气候反常造成雪水入 渗、短时间内发生多次冻融,裂隙中液态水结冰产生膨胀力诱发了此次山体崩塌。采用赤平投影分析论证了潜在崩塌的可能 性问题,指出发生此次崩塌后的右岸山体仍然未达到稳定状态,还可能再次发生破坏,同时应用实体比例投影法圈定了最有 可能破坏的山体位置并对崩塌方量进行了计算,从而对山体潜在崩塌可能性及规模有了一定把握,对该段山体崩塌的防治具 有实际的工程意义。 相似文献
6.
Snow depth records from daily measurements at climatological stations were obtained from Environment Canada and were processed and analyzed. It was identified that there are 549 stations, each with at least 20 years of useable annual maximum snow depth data. Both the Gumbel distribution and generalized extreme value distribution were used to fit the annual maximum snow depth, considering several distribution fitting methods. Statistical analysis results indicated that, according to the Akaike information criterion, the Gumbel distribution is preferred for 72 % stations. The estimated return period value of annual maximum snow depth at stations was used to calculate their corresponding ground snow load. The at-site analysis results were used as the basis to spatially interpolate the ground snow loads for locations tabulated in the National Building Code of Canada (NBCC) since a code location and a climatological site are usually not co-located. For the interpolation, the ordinary co-kriging method with elevation as co-variate was used because a cross-validation analysis by using several deterministic and probabilistic spatial interpolation techniques indicated that the ordinary co-kriging method is preferred. A comparison of the newly estimated ground snow loads to those locations tabulated in the 1995 edition and 2010 edition of the NBCC was also presented. 相似文献
7.
Estelle Arbellay Markus Stoffel Armelle Decaulne 《Boreas: An International Journal of Quaternary Research》2013,42(3):568-574
Dendrogeomorphic research has long relied on scarred trees to reconstruct the frequency of mass‐movement processes. Injuries have mostly been dated macroscopically by counting the tree rings formed after wounding. Tree‐ring anatomical anomalies induced by cambial injury, in contrast, have only recently been recognized as proxy records of past events. We investigated 12 sub‐arctic downy birch (Betula pubescens Ehrh.) trees scarred by snow avalanches in Norway and Iceland. Earlywood vessel lumina were measured for each tree in the xylem tissue bordering the scars. Seven successive rings were examined, namely two control rings laid down prior to wounding and five rings in the wound xylem. We provide evidence that snow‐avalanche‐induced wounding resulted in atypically narrow earlywood vessels over at least two years. Our data demonstrate that wound‐associated vessel anomalies represent tangible markers of mass‐movement processes, and as such make a viable tool for reconstructing past events. Similar dendrogeomorphic studies based on tree‐ring anatomy can be readily conducted with other mass‐movement processes, as well as with other broad‐leaved tree species. Ultimately, this new approach will foster increment coring over more invasive sampling techniques. 相似文献
8.
P. Höller 《Natural Hazards》2014,71(3):1259-1288
Snow gliding is a downhill motion of snow on the ground; it is able to affect afforestation (uprooting of plants) and to cause soil erosion. Once the glide motion turns into an avalanche movement, the process is called a glide avalanche. Winters with continuing snow gliding and a high activity of glide avalanches might be called ‘glide winters’. The most recent ‘glide winter’ in the European Alps was 2011/2012. Glide avalanches have the ability to cause damage to buildings and infrastructure. This review describes the progress in research, from basic snow glide measurements via the design of sophisticated models through to comprehensive investigations concerning glide avalanche formation. However, despite the great progress made in this field of research, there are still some unsolved problems, such as the influence of soil conditions on snow gliding or the prediction of glide avalanches. 相似文献
9.
D. M. McClung 《Natural Hazards》2011,59(3):1635-1645
In North America and Europe, most fatalities due to snow avalanches occur in the backcountry during recreational pursuits.
Of these, more than 90% of the fatal avalanches are triggered by the victims themselves. This pattern suggests that the primary
cause of avalanche fatalities for human-triggered avalanches is a failure in human perception. For the latter, people thought
that the state of stability or instability of the snow cover was different than it actually was. In this paper, the strength
and weight of evidence used to make decisions in backcountry travel are discussed from: (a) the perspective of the favored
hypothesis to proceed for good recreational enjoyment based on stability evaluation and (b) the null hypothesis based on an
assessment of instability. Based on the facts about snow slab avalanche release, it is argued that instability analysis is
the best framework for avalanche forecasting, whereas human action is most closely related to the favored hypothesis (stability
evaluation). Using scaling laws derived from: (a) fracture mechanics about the size of imperfections causing avalanches and
(b) avalanche dimensions, it is suggested that a snow slab could show stability over more than 99% of the total area. From
the concepts of Bayesian probability, it is shown that overconfidence about stability can arise when the weight of the likelihood
is high and the weight of prior is low. Similarly, underconfidence (excessive conservatism) often results when the weight
of the prior is high with little regard for the likelihood, which may be low. Overconfidence about stability is considered
to be a prime source of accidents. 相似文献
10.
Mircea Voiculescu 《Natural Hazards》2009,51(3):459-475
Snow avalanches represent an undeniable reality in the Southern Carpathians both as a geomorphic process and as a type of
hazard. Before the 1990s, few researchers focused on avalanches in Romania. However, after 1990, avalanches became an increasingly
important topic of Romanian research including research on their management implications. This study focuses on the Făgăraş
massif, a representative mountain unit in the Southern Carpathians that is dominant due to its glacial and periglacial relief,
high altitudes and high occurrence of avalanche hazards. Three main research issues are considered. First, types of avalanches
are delineated along with affected areas of the Balea glacial valley (on the northern slope) and the Capra glacial valley
(on the southern slope) using data from a research centre for snow and avalanche monitoring that was created in the Balea
glacial cirque in 2003. Second, the impact of avalanches on human activities is considered including transportation use of
the Transfăgărăşan Highway that traverses the highest elevations in Romania and winter recreation activities such as skiing,
snowboarding, climbing and hiking. The impacts on forests are also considered. Third, the needs and gaps of avalanche management
are considered, specifically in the Făgăraş massif and also more generally in the mountains of Romania. 相似文献
11.
Dynamical models for calculating snow avalanche motion have gained growingimportance in recent years for avalanche hazard assessment. Nevertheless, inherentuncertainties in their input-data specification, although well acknowledged, areusually not explicitly incorporated into the analysis and considered in the mappingresults. In particular, the estimate of avalanche release conditions is affected bystrong uncertainties when associated to a return period. These sources of error arenormally addressed through sensitivity analysis or conservative parameters estimate.However, each of these approaches has limitations in assessing the statistical implications of uncertainties.In the present paper the problem of release scenarios randomness is looked at following a Monte Carlo procedure. This statistical sampling-analysis method allows the evaluation of the probability distributions of relevant variables for avalanche hazard assessment – such as runout distance and impact pressure – once the release variables – essentially releasedepth and release length – are expressed in terms of probability distributions, accounting explicitly for inherent uncertainties in their definition. Both the theoretical framework of this procedure and its application to a real study case are presented. As initial step of this research in the present work the attention is mainly focused on flowing avalanches descending on open slopes. Therefore, the one-dimensional version of VARA dynamic models is usedfor avalanche simulations. 相似文献
12.
Iuliana Armaş 《Environmental Earth Sciences》2014,71(11):4637-4646
The aim of this study is to quantify the landslide risk for individual buildings using spatial data in a GIS environment. A landslide-prone area from Prahova Rivers’ Subcarpathian Valley was chosen because of its associated landslide hazards and its impact upon human settlements and activities. The bivariate landslide susceptibility index (LSI) was applied to calculate the spatial probability of landslides occurrence. The Landslide Susceptibility Index map was produced by numerically adding the weighted thematic maps for slope gradient and aspect, water table, soil texture, lithology, built environment and land use. Validation curves were obtained using the random-split strategy for two combinations of variables: (a) all seven variables and (b) three variables which showed highest individual success rates with respect to landslides occurrences (slope gradient, water table and land use). The principal pre-disposing factors were found to be slope steepness and groundwater table. Vulnerability was established as the degree of loss to individual buildings resulting from a potential damaging landslide with a given return period in an area. Risk was calculated by multiplying the spatial probability of landslides by the vulnerability for each building and summing up the losses for the selected return period. 相似文献
13.
We explore the challenges of avalanche and debris flow hazard assessment for urban areas exposed in the Sakhalin region. Avalanches are a threat to more than 60 settlements in the region and debris flows to more than 30. Data are provided for avalanche and debris flow events that occurred in the Sakhalin region between 1928 and 2015. In this paper, the method for the design of hazard maps for snow avalanches and debris flows is described, providing the starting point for any planning constraints in general settlement planning schemes. These maps further allow conducting an assessment of avalanche and debris flow risk within a short time period for a larger territory and at minimum cost. 相似文献
14.
Due to its geographical location, geology and topography, Turkey mainly undergoes three different types of natural disasters related to gravity flows. They are floods, landslides and snow avalanches.The heavy snow falls during winter pose the hazard of snow avalanches. According to statistics, 800 people were killed in snow avalanches during the period of 1960–1997. Within the program of the International Decade of Natural Disaster Reduction (1990–2000), an international cooperation has been initiated among SFISAR (Swiss Federal Institute for Snow and Avalanche Research), CEMAGREF (Centre National du Machinisme Agricole du Génie Rural des Eaux at des Forets) and AFET (Turkish Ministry of Public Works and Settlement, General Directorate of Disaster Affairs). This three-year project started in 1994 as a development project on avalanche forecasting, mapping, zoning and paravalanche construction technologies. For the pilot project area, the Soanli Mountains located in north-eastern Turkey were chosen, covering an area of approximately 40 by 30 km. After training the Turkish engineers, the basic technologies in avalanche forecasting and avalanche mapping were transferred from Switzerland and France to Turkey with the necessary infrastructure. The difficulties faced in meteorological data collection with the help of local observers and the limited data available caused some delay in avalanche forecasting. If automatic weather stations could take the place of manual work, the realization of a prognosis would be quicker. At present, avalanche-hit houses are rebuilt in new disaster-free zones by AFET. With this project, the idea of using paravalanche structures for protection is promoted. The physico-sociological impacts of avalanche disasters, avalanche mapping and zoning of disaster areas on local people are also studied. 相似文献
15.
Chris Stethem Bruce Jamieson Peter Schaerer David Liverman Daniel Germain Simon Walker 《Natural Hazards》2003,28(2-3):487-515
Snow avalanches affect recreation, transportation, resource industries and property. During the 1990s an average of 12.5 persons per year were killed in avalanches in Canada. The snow avalanche hazard has affected people and facilities in B.C, Alberta, Yukon, NWT, Nunavut, Ontario, Quebec and Newfoundland. Avalanche risk may be voluntary, for example skiing and snowmobiling, or involuntary, for example public transportation corridors. A worst-case avalanche scenario is most likely to occur in the Western Cordillera, resulting from a single large-scale weather pattern, where a cold period resulting in the development of a weak layer in the snowpack is followed by a series of major mid-winter storms. Emergency preparedness for avalanches is most advanced in western Canada. New education and information initiatives in Quebec and Newfoundland are aimed at improving preparedness there. Current research is focused on avalanche forecasting, weather forecasting for avalanche prediction, avalanche failure characteristics, forestry and avalanches and geomorphology and avalanches. An important area of future research is the impact of climate change on avalanches, particularly in northern Canada. 相似文献
16.
Avalanche hazard and risk mapping is of utmost importance in mountain areas in Europe and elsewhere. Advanced methods have been developed to describe several aspects of avalanche hazard assessment, such as the dynamics of snow avalanches or the intensity of snowfall to assume as a reference meteorological forcing. However, relatively little research has been conducted on the identification of potential avalanche release areas. In this paper, we present a probabilistic assessment of potential avalanche release areas in the Italian Autonomous Province of Bolzano, eastern Alps, using the Weights of Evidence and Logistic Regression methods with commonly available GIS datasets. We show that a data-driven statistical model performs better than simple, although widely adopted, screening criteria that were proposed in the past, although the complexity of observed release areas is only partly captured by the model. In the best case, the model enables predicting about 70 % of avalanches in the 20 % of area classified at highest hazard. Based on our results, we suggest that probabilistic identification of potential release areas could provide a useful aid in the screening of sites for subsequent, more detailed hazard assessment. 相似文献
17.
Snow avalanches,which are widely and frequently developed at high elevations,seriously threatens the built traffic corridors in the Tibetan Plateau. Susceptibility evaluation of snow avalanche via machine learning model with a high forecast accuracy can be appled to quickly and effectively assess the regional avalanche risk. This paper took the central Shaluli Mountain region as the study area,in which the snow avalanche inventory was established through remote sensing interpretation and field investigation verification. We quantitatively extracted 17 evaluation factors via GIS-based analysis,and these factors were selected through the variance expansion factor（VIF）. Four machine learning models containing SVM,DT,MLP and KNN were used to compile the susceptibility index map of snow avalanches,and kappa coefficient and ROC curve were used to verify the accuracy. The results suggested that the susceptibility indexes obtained from SVM,DT,MLP and KNN were in the range of［0,0. 964］,［0,815］,［0,0. 995］and［0,1］,respectively. The accuracy test results show that these four models all have good prediction accuracy. Among them,the SVM model is the best. The results also indicated that the areas with the high snow avalanche susceptibility mainly distributed in Genie Mountain and Rigong Mountain,most of which were above the planation surface of the Tibetan Plateau. The average altitude of the extremely high snow-avalanche-prone areas is 4 939 m,while the average altitude of the high snow avalanche-prone areas is 4 859 m. The snow avalanche has low perniciousness on the Sichuan-Tibet Highway and the Sichuan-Tibet Railway in the study area. This study can provide theoretical basis and method reference for disaster prevention and mitigation of snow avalanche along Sichuan-Tibet Railway and other major projects across Shaluli Mountains region. © 2022 Science Press (China). 相似文献
18.
We explore the challenges of avalanche and debris flow hazard assessment for urban areas exposed in the Sakhalin region. Avalanches are a threat to more than 60 settlements in the region and debris flows to more than 30. Data are provided for avalanche and debris flow events that occurred in the Sakhalin region between 1928 and 2015. In this paper, the method for the design of hazard maps for snow avalanches and debris flows is described, providing the starting point for any planning constraints in general settlement planning schemes. These maps further allow conducting an assessment of avalanche and debris flow risk within a short time period for a larger territory and at minimum cost.
相似文献19.
Peter Höller 《Natural Hazards》2009,48(3):399-424
During the last 50 years, an average of 30 persons per year was killed by avalanches in Austria. About one-third of all avalanche
fatalities occurred as a result of so-called ‘catastrophic avalanches’. ‘Catastrophic avalanches’ are spontaneously released
avalanches that affect villages and cause damage to property (buildings, roads and other infrastructure). The biggest avalanche
events in Austria were in 1950/1951 (135 fatalities), in 1953/1954 (143 fatalities) and in February 1999, when 38 persons
were killed in Galtür and Valzur. This article deals with an analysis of nine major avalanche cycles in the last 55 years.
An avalanche cycle in this article is defined as 50 recorded avalanches of at least size 3 in two days and/or 5 persons killed
in villages within two days. The basis of this study are the well-documented records from Fliri (1998), who analysed natural
disasters in the western part of Austria and the Trentino, including floods, mudflows, earthquakes and avalanches. The meteorological
data were taken from two relevant observation sites in the northern part of the Austrian Alps, from two sites in an intermediate
and continental region, respectively and from one site in the southern part of the Austrian Alps. Atmospheric patterns were
analysed by using weather charts for the relevant periods. Both the meteorological data and the weather charts were provided
by the Central Institute for Meteorology and Geodynamics (ZAMG). It was found that there was a major cycle every 6 years (on
average). Two-thirds of all investigated cycles were characterised by a continuous increase of snow depth over a period of
at least three days. In only three periods (1975, 1986, 1988), daily extreme values could be observed. More than 40% of all
the cycles occurred in January. In two-thirds, a north-westerly oriented frontal zone was responsible for the formation of
a major cycle. The remaining cycles were released by low-pressure areas over Central Europe and the Mediterranean Sea, respectively. 相似文献
20.
梅里雪山雪崩多发,但缺乏系统监测和研究。1991年1月3日梅里雪山发生了造成中日联合登山队17名队员遇难的巨大雪崩事件。2019年安装在明永冰川末端附近的物候相机拍摄到临近梅里雪山明永冰川的一次雪崩事件。两次事件类型不同,这对我们进行雪崩预测预警有良好的指示作用。本研究以RAMMS(Rapid Mass Movement System)模型为手段,利用经验值和经验公式确定影响模拟结果的主要模型参数和积雪可能断裂深度,在优化分析的基础上,对两次雪崩事件进行重建,定量分析雪崩堆积量、堆积范围等。结果显示:1991年雪崩共持续了192s,雪崩体从海拔5730m处断裂,沿坡面崩塌而下最终堆积在海拔约5000m的冰川粒雪盆地区,形成面积为0.6km^(2),体积约67×10^(4)m^(3)的堆积体。2019年雪崩共持续了158s,雪崩流最大高度35.91m,最大速度79.34m·s,堆积量76.2×10^(4)m^(3),雪崩堆积范围与野外观测到的一致。两次雪崩事件发生地位于雪崩极高危险区和高危险区,在一定程度上验证了风险评估的准确性。研究结果可为梅里雪山地区未来潜在雪崩灾害的风险评估提供依据,为雪崩预测预警提供良好的参考。 相似文献