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大阿尔玛京卡河流域的雪崩与治理 总被引：1，自引：0，他引：1
大阿尔玛京卡河流域危险主要出现在中山森林－草原带和高山雪冰带。受局地气候、地貌与环境的综合作用，流域雪崩规模小、路程短，多见全程雪崩；雪崩类型单调，以干、湿雪崩占统治地位，在９０％以上，雪崩发生地点集中，而且每年都有出现，只有数量上的差异性。在西风气流的控制下，冬季积雪层的变质过程具温度梯度变质特征。积雪层负温梯度大，雪层深霜的发育和生长迅速，呈出“干寒型”积雪的基本特征。雪崩对道路、居民点和建筑 相似文献
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雪崩危险指标是评价雪崩对公路危害程度的主要依据之一。利用已有资料对伊焉公路巩乃斯沟口至艾肯山隘段的雪崩危险指标进行了分段计算，结果表明，该路段雪崩危险指标在0．022－2．685范围内，与国外资料相比，用于小量级，其主要原因是车（人）流量小。同时，利用上述计算结果并结合该路段的雪崩危害史，进行了雪崩灾害评价，评价结果反映在该路段灾害程度划分图上。 相似文献
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中国天山积雪雪崩站区的地理环境 总被引：15，自引：0，他引：15
中国天山积雪雪崩站站区自然地理垂直地带完整。降水丰富，最大达１１４０．８ｍｍ。冬半年降雪量占年降水量的３０％左右。积雪深度多年平均８０ｃｍ。深厚的积雪使站区每年冬季都发生雪崩和风吹雪灾害，成为天山大陆性雪崩研究的天然场所。同时，站区生态与环境良好，植被、土壤种类集天山之大成。站区旅游资源引人入胜。北有“东方阿尔卑斯”之称的乔尔马；南有巴音布鲁克天鹅湖，均由天山公路与本站相连通。 相似文献
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根据山地生态特征，地形切割深度及河谷横剖面形成和雪崩重视率等，将天山山系雪崩危险区分为：１）低山草原或半荒漠雪崩危险区；２）中山森林－草原雪崩危险区；３）中山草地雪崩危险区；４）高山冰缘带（石质）雪崩危险区；５）高山；极高山冰川带雪崩危险区。 相似文献
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雪崩危险指标是评价雪崩对公路危害程度的主要依据之一。利用已有资料对伊焉公路巩乃斯沟口至艾肯山隘段的雪崩危险指标进行了分段计算，结果表明，该路段雪崩危险指标在０．０２２－２．６８５范围内，与国外资料相比，属于小量级，其主要原因是车（人）流量小。同时，利用上述计算结果并结合该路段的雪崩危害史，进行了雪崩灾害评价，评价结果反映在该路段灾害程度划分图上。 相似文献
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塔克拉玛干沙漠的起沙风速 总被引：53，自引：1，他引：53
起沙风速根据观测高度、风速时距以及流体或冲击起动性质分别确定。本文建立了塔克拉玛干沙漠腹地肖塘地区不同高度、不同时距的流体起动与冲击起动风速的相关方程。结果表明：该地天然沙的瞬时冲击起动风速（２ｍ高度）５．０ｍ／ｓ，流体起动风速６．０ｍ／ｓ；１分钟平均流体起动与冲击起动风速为５．２ｍ／ｓ和４．３ｍ／ｓ。气象站观测高度（１１．４ｍ）瞬时流体起动和冲击起动风速为７．８ｍ／ｓ和６．６ｍ／ｓ；１０分钟平均值为７．４ｍ／ｓ和５．９７（≈６．０）ｍ／ｓ。 相似文献
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中国天山是我国积雪丰富、雪崩频繁、灾害性雪崩又具明显周期性的山地。作者以雪崩制图的非变化因素(地形形态)为主,提出了中国天山积雪站区雪崩路径分布图与雪崩分带(区划)图,并作了概略说明。这为当地的土地合理利用、山区道路与矿山建设、雪崩治理提供了科学依据。 相似文献
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新疆精(河)-伊(宁)铁路沿线雪害形成机制及其防治工程措施 总被引：4，自引：0，他引：4
天山西部的降雪丰富,伊犁河流域年最大雪深普遍超过60crn,中国科学院天山积雪与雪崩研究站和伊犁的最大雪深分别高达152crn和89cm。因此,天山西部山区风吹雪和雪崩灾害较多,严重影响着当地的交通安全。新疆精(河)-伊(宁)铁路经过的缓坡丘陵区是风吹雪灾害多发区,崇山峻岭区是雪崩灾害多发区。通过对铁路沿线的气象要素进行分析与推算,结果表明,该地区的最大风速平均值14．0m／s,30a-遇的最大风速与最大积雪深度分别为20．3m／S和160cm;平均冬季降水量153．2mm,为风吹雪灾害的发生提供了物质与动力条件。在风吹雪多发区,风吹雪的主要危害类型是路堑型风吹雪沉积,其次为低路堤型风吹雪沉积等。经过野外考察和室内分析,基本上查清了精(河)一伊(宁)铁路沿线风吹雪的发生与分布规律,并且针对性地提出了铁路在雪害多发区的设计原则和雪害防治方法。认为路堤防风吹雪的适宜高度为200～1500cm,路堤若低于200cm,路面上易发生风吹雪沉积;若路堤的边坡较陡,则路面上不易发生风吹雪沉积;路堑边坡的角度越小,路堑越深,路堑走向与主导风向的夹角越小,风吹雪沉积越不易发生;风吹雪的防治应以防风吹雪走廊和下导风板为主,并辅以侧导板、挡雪墙等工程。精-伊铁路雪崩灾害主要发生在崇山峻岭区,主要类型为坡面雪崩和坡面沟槽雪崩。阳坡雪崩多发生在降雪季节,雪崩危害相对较少;阴坡积雪不易融化,雪崩危害大。阴坡雪崩在整个冬季从开始下雪直到次年春季积雪融化以前都可发生,危害时期长。在雪崩灾害的多发区,铁路选线时明线工程最好能选在阳坡,永久性建筑物或设施要尽量避开沟槽雪崩的运动区和堆积区;铁路线横穿河流处,桥梁的桥墩和铁路延伸线一定要避开沟槽雪崩的运动区和堆积区,尽量选在两雪崩之间的山梁或山脊处,隧道出入口也要选在突出的山嘴或山梁等正地貌部位。在其他条件允许的情况下,线路应尽量向坡面的上部抬升。精一伊铁路沿线雪崩灾害治理原则：在所有的隧道出入口,隧道再向外延伸3m,上方再修建导雪堤,可保隧道口的安全;在工程建设过程中,要求尽量少地破坏铁路两侧的植被,特别是树林和灌木。 相似文献
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柯林斯冰帽两支冰芯层位记录证实了该冰帽主冰穹顶部（海拔约７００ｍ）属暖渗浸带，小冰穹顶部（海拔约２５０ｍ）属渗浸带。雪、冰的层位分布和密度变化包含了一定的测年信息。主冰穹顶冰芯密度－深度曲线在表层呈现韵律性变化，与层位记录中的融化冻结现象相对应，据此粗略划分年层，断定当地年积累雪层厚度为３－３．５ｍ，折合水当量１６５０－１９２５ｋｇ／ｍ２ａ，年平均积累速率约为２．０ｍ／ａ（冰当量）。主冰穹顶成冰深度为３８－３９ｍ，此深度以上密度自上而下缓慢增加，但以下由于含水层的出现，密度迅速升高，在５－６ｍ区间达到９００ｋｇ／ｍ３。小冰穹冰芯除表层外，密度基本在８００－９００ｋｇ／ｍ３之间，冰芯中雪冰互层，存在污化面，４０ｍ以下发现很厚的火山灰沉积物。小冰穹平均年积累率约为０．７ｍ／ａ（冰当量），成冰深度７－８ｍ，成冰年限为１０年左右 相似文献
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David R. Butler 《自然地理学》2013,34(1):72-87
Hazardous snow avalanches in Glacier National Park, Montana, are associated with a variety of meteorologic conditions: heavy snow; heavy snows followed by a rise in air temperature to above freezing; a rise in air temperature to above freezing, without precipitation; and rain in association with above-freezing air temperatures. Years of major, widespread avalanching may be recognized by examination of historical information and tree-ring data. Avalanche types include slab avalanches, wet snow avalanches, and dry loose snow avalanches. February is the peak avalanche month. Intraannual seasonalities of avalanche trigger mechanisms and type of avalanche are related. The presence of sun crusts in some cases provides unstable stratigraphic planes in the snowpack over which freshly deposited snow may glide. Destructive windblasts also occur in association with some avalanches. Insufficient data from east of the Continental Divide precluded a comparison of avalanche type and trigger mechanisms from the western and eastern portions of Glacier National Park. The general avalanche climate is more similar to that reported from the southern Canadian cordillera than to continental locations such as the mountains of Colorado. [Key words: Snow avalanches; avalanche trigger mechanisms; avalanche types; avalanche seasonality; Glacier National Park, Montana; northern Rocky Mountains; hazard planning.] 相似文献
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Vincent Jomelli & Pascal Bertran 《Geografiska Annaler: Series A, Physical Geography》2001,83(1-2):15-28
We analyse the morphology and sedimentology of 25 dirty snow avalanche deposits in the French Alps. The deposits typically have either a snow-ball structure or a massive structure with sliding planes. The snow balls show a longitudinal and a vertical sorting that reflects a sieve effect, similar to that observed in other rapid inertial granular flows. The massive type results from snow compaction when the avalanche is channelled by a gully or when it reaches the distal part of the scree. Velocity decrease and compaction limit the deformation to a zone at the base of the snow mass and cause the formation of distinctive sliding planes. These appear as smooth recrystallised surfaces due to local melt from frictional heating. The flow can be assimilated to a frictional granular flow. No systematic variation of size and shape of the rock debris has been observed along the profiles in both types of deposit. The distribution of rock debris and its fabric suggest that the clasts are transported passively and do not undergo any sorting during displacement. Snow melt after avalanching causes a redistribution of rock debris particularly when the snow thickness is important. This redistribution does not generate new sedimentological characteristics such as enhanced sorting or fabric. 相似文献
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利用MODIS和Landsat TM/ETM+遥感数据,得出研究区的积雪面积,同时结合精伊公路规划图及地形图,分析了公路沿线可能存在风吹雪和雪崩的危险区,并提出相应的防治措施。结果表明:研究区近5年来11月到次年3月是积雪最丰富时期,9月、10月、4月和5月积雪较少。近5年来积雪呈增加趋势,最大积雪时间集中在2009—2010年积雪季。MODIS积雪数据精度在积雪面积越大时,精度越高;积雪面积越小时,精度越低。精伊公路东线走廊K60以上路段和西线走廊K100以上路段风吹雪对公路影响较大;精伊公路北段的雪崩的可能性很小;东线走廊K60～K77段和西线走廊K90～K110段有一定的雪崩灾害;西线走廊K58～K90段有较大的雪崩危害。并提出防治措施。 相似文献
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Richard A. Shakesby John A. Matthews Mark S. Berrisford & Lindsey J. McEwen 《Geografiska Annaler: Series A, Physical Geography》1999,81(1):31-45
It is demonstrated that pronival (protalus) ramparts can be formed by a snow-push mechanism and need not accumulate in the conventional manner as a result of supranival processes. Ridges in pronival positions up to 1.2 m high and of unequivocal snow-push origin are described from two sites in Smørbotn cirque, Romsdalsalpane, southern Norway. The seven lines of evidence are: (1) parallel abrasion tracks on large boulders embedded in the substrate; (2) displaced surface and embedded clasts with proximal furrows; (3) corrugated (flute-like) substrate surfaces; (4) the sickle-shaped plan-form of the ridges; (5) generally asymmetrical ridge cross-profiles (shallow, concave proximal; steep, convex distal); (6) strong preferred orientations and dips of surface-embedded clasts on ridge proximal slopes; and (7) a subnival/pronival ridge comprising loosely packed diamicton forming along the contact zone between the snowbed and substrate. This evidence indicates ridge formation by snow sliding involving bulldozing of the substrate. Factors considered important in favouring snow push producing distinct pronival ramparts at the sites include: a maritime periglacial climate with heavy winter snowfall and rapid snow-firn conversion producing snow densities of up to 900 kg m–3 ; a deformable substrate with relatively small inputs of rockfall or avalanche debris; and a steep headwall susceptible to snow avalanching and hence enhanced snow supply. Consideration is given to the prospect that larger pronival ramparts can form incrementally by a snow-push mechanism. 相似文献
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ABSTRACTStatistical relationships between weather conditions and the release of snow avalanches in the low-elevation coastal valleys of the northern Gaspé Peninsula are still poorly validated. As such, we explored climate–avalanche relationships through classification tree algorithms applied to tree-ring reconstructions of avalanche events. In order to assess the contribution of local factors on avalanche activity, avalanche regimes on east- and west-facing slopes were analyzed and compared. The results showed that avalanches on east-facing slopes appear to be primarily related to large cumulative snowfall in January, February, and March. On west-facing slopes, avalanches are mainly due to episodic snowfall and warming temperatures. However, both sides of the valleys showed the potential for the release of large avalanches in November and December, which is earlier than expected by the literature. Indeed, the weather variability at that time of the year (temperature oscillation around 0ºC) appears to favor the formation of an early, unstable snowpack and subsequent triggering of avalanches, such as the wet slab avalanche recorded by a time-lapse camera in November 2014. This camera provided a useful insight on the capacities of classification-tree models to link the yearly resolution of tree-ring data with weather triggers at different timescales. 相似文献