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对甘肃舟曲特大泥石流灾害的初步认识 总被引：13，自引：3，他引：10
2010-08-07T23:00左右,甘肃省甘南藏族自治州舟曲县县城北面的罗家峪、三眼峪流域突降强暴雨,引发了特大泥石流灾害.泥石流将沿途村庄和城区夷为平地,摧毁了沿途的楼房民居,毁坏了大量的农田.泥石流还冲进白龙江形成堰塞湖,将半个舟曲县城淹在水中.此次泥石流流速快、流量大、规模超大,发生于半夜,且表现为山洪-泥石流-堰塞湖灾害链形式,因而造成重大人员伤亡和财产损失.截止08-15,共造成4 496户、20 227人受灾,水毁农田约95 hm2、房屋5 508间,1 248人遇难,496人失踪,是建国以来我国损失最严重的泥石流灾害.现场调查与遥感图像分析表明,舟曲泥石流是局部强降雨作用下发生的百年一遇的水力型特大泥石流灾害.三眼峪、罗家峪泥石流总方量约220×104 m3.沟内储存的大量的崩塌、滑坡体及坡积物、残积物为泥石流提供了丰富的固体物质.形成区陡峭的地形以及沟道内堆石坝、拦沙坝形成的陡坎级联堵溃效应,加大了泥石流的流速、流量与破坏力.在分析本次泥石流的背景条件、灾害成因、特征以及发展趋势的基础上,提出了相应的减灾对策. 相似文献
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《山地学报》2017,(1)
合理的降雨阈值是确定区域暴雨泥石流减灾防灾的关键。为了探求诱发舟曲地区泥石流的降雨阈值,本研究以舟曲三眼峪、罗家峪为例,研究了在前期含水量一般(湿润)和干旱两种条件下,触发不同预警级别泥石流的降雨雨强与历时函数关系,采用水文学方法计算了不同频率下洪峰流量以及对应的不同规模泥石流启动降雨量阈值。结果表明:在前期含水量干旱和一般条件下,三眼峪、罗家峪泥石流红色Ⅰ级降雨预警值为56.10 mm/h和50.86 mm/h、橙色Ⅱ级预警值为40.70 mm/h和37.87 mm/h、黄色Ⅲ级预警值为31.74 mm/h和29.88 mm/h、蓝色Ⅳ级预警值为23.83 mm/h和21.69 mm/h,预备Ⅴ级预警值为7.31 mm/h和15.69 mm/h、预备Ⅵ级预警值为10.16 mm/h和9.48 mm/h;不同预警级别条件下的降雨雨强与降雨历时成I=α×D~β幂函数关系,和数值在不同预警级别下成规律性变化;能够诱发舟曲地质灾害的降雨特征可分为两种:一是降雨雨强大的单峰型短历时强降雨("点雨");二是降雨雨强小、持续时间较长的"绵绵细雨"。研究成果可作为舟曲区域暴雨泥石流监测预警研究提供科学依据。 相似文献
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甘肃省舟曲县城2010年“8·8”特大泥石流灾害损失惨重,造成1675人死亡失踪,损毁房屋200余栋,世界震惊.通过现场对舟曲三眼峪泥石流调查和研究,认为“8·8”特大泥石流灾害既是天灾(自然条件),又是人祸(人为因素).换言之,自然条件和人为因素是导致“8·8”特大泥石流的主要致灾因素.自然因素调查结果表明:1.三眼峪流域在25 km2范围内高差达2500m,且大眼峪和小眼峪沟谷纵坡降分别达到33％和36％,地形较为陡峻;2.三眼峪流域内松散固体物质总量约为26.4×106 m3,被“8·8”特大泥石流冲出的固体物质仅为1.52×106m3,松散物源丰富;3.小时降雨量为77.3 mm,属极端强降雨.人为因素分析表明:1.城镇建设(建筑物和农田)挤占泥石流排泄通道,导致行洪能力每秒不足300 m3;2.按50 a一遇的防洪标准进行设计,以往防治工程设计标准显然不足. 相似文献
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潼关金矿区矿渣型泥石流灾害及防治对策 总被引：4，自引：0，他引：4
在潼关金矿区206.8 km2范围内,采矿坑口达2 500处,矿渣堆944处,占压林地土地面积255.3×104m2,矿渣量达1 100×104m3,年增加30×104m3。矿渣占到了泥石流物源的90%。74.97%矿渣堆没有拦渣稳渣工程措施,86.37%废石堆占据河道,71%废石堆稳定性差、极差。7条峪道18条沟谷均是泥石流隐患沟。针对日益严重的矿渣型泥石流灾害隐患,提出了在加大防治泥石流灾害宣传、制定泥石流灾害防治规划、建立降雨预警预报制度的基础上,采取各种工程治理措施,避免和减轻群死群伤的重大泥石流灾害发生的对策建议。 相似文献
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冕宁县盐井沟受泸沽铁矿的开采所影响,流域内留存有大量矿山弃渣,在历史上曾造成严重的泥石流灾害。原有的防灾方式主要依靠沟道内修建的导流堤、拦砂坝等工程措施,但需要政府每年投入大量资金进行沟道清淤,无法根治灾害。新的防灾模式则通过综合利用泸沽铁矿的弃渣,在生产建筑砂石料的同时回收其中的铁矿粉,并利用弃土回填实现复垦和生态改良。上述措施不仅能有效减少盐井沟内松散物源的堆积,降低地质灾害风险,同时也能为企业创造利润、增加政府财政收入及促进地居民的就业,还间接地减少了河道砂石的开采、减轻了对河道生态环境的破坏,起到了减灾、增收、环保的多重效果。这种循环经济理念下的防灾新模式可试推广至其他受矿渣堆积地质灾害影响的地区。 相似文献
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汶川地震引发的次生山地灾害链及人工断链效果——以小岗剑泥石流沟为例 总被引：1，自引：0，他引：1
汶川地震后,小岗剑沟由于滑坡、崩塌产生了大量松散物质,其地势陡峻,暴雨频率高,2009—2011年连续暴发10场泥石流,损毁公路,规模大时会堰塞绵远河,形成以频发性泥石流为主的典型地震次生山地灾害链。2012年完成泥石流治理工程,同年8月小岗剑沟再次发生泥石流,破坏了部分工程。以小岗剑沟为例,通过整理现场采集的图片和数据,并对比以往资料,研究次生山地灾害链链式反应过程以及经过工程治理后的灾害链人工断链效果。研究表明:小岗剑沟频发型次生灾害链的衰减不仅体现在引起下一级次生灾害的土石方量逐级减小上,而且体现在随时间变化的灾害激发条件提高上;虽然泥石流发生条件提高,但由于泥石流沟沟床不断被切深,小岗剑沟危险性随着可动势能增大而逐年增大,人工断链失败后,沟床再次下切,建议使用阶梯-深潭结构增加沟道阻力,保护沟道底部,避免可动势能继续增大;对比小岗剑沟、文家沟和红椿沟泥石流治理工程,发现灾害链总能量与投资正相关,要根据灾害能量进行合理投资,当能量到达一定量时,单位能量所需要的投资大幅度降低。 相似文献
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低频率泥石流灾害及工程防治 总被引：5，自引：0，他引：5
重现期＞50 a的泥石流被定义为低频率泥石流。低频率泥石流灾害可能发生在生态环境良好的地区,并造成重大的财产损失和人员伤亡。低频率泥石流灾害具有需要大暴雨、特大暴雨、冰湖或水库(尾矿坝)溃决、火山爆发、冰雪融化、冰崩、雪崩、滑坡、地震等特殊因素激发,危害严重,难于预测预报等特点。低频率泥石流灾害应采取土木工程进行预防性治理,工程设计的要点是,在沟谷中布置坚固的大中型骨干拦挡工程,并保证有充足的拦淤库容。新型拦砂坝设计采用重力式结构,低坝群布置,浆砌石建造,在坝体上设置大孔口,具有工程投资小,就地取材,施工简单,有选择性地拦截泥沙,拦淤库容可以反复使用等优点,适合我国国情。 相似文献
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关家沟是一条活动频繁、危害较大的泥石流沟 .对其需采用工程措施稳沟、拦挡泥沙、排导和封山育林、植树造林等生物措施相结合的综合治理方案 相似文献
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《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):290-302
Two-years of ground temperatures (10 cm and 50 cm depths) from the foreland of Storbreen in the Jotunheimen Mountains of Norway demonstrate that seasonal and annual ground temperature differences induced by microtopographic position at a constant elevation are comparable to differences stemming from ～ 100 m to ～ 300 m in elevation. Between ～ 1460 m a.s.l. and ～ 1150 m a.s.l., mean annual lapse rates calculated for soil depths of 10 cm were≤0.8°C per100m beneath tundra, moraine crests, and moraine proximal base positions, each of which was calculated independently. Seasonal lapse rates were often larger,≥1.0°C per 100m in both summer and winter. The calculated ground temperature lapse rates compare favorably with those already reported in the literature for the region. Categorical data in the form of Thawed, Freeze-Thaw, Isothermal, and Frozen Days also showed considerable variability by elevation and microtopographic position. Variability in growing conditions was examined by calculating Thawing Degree Days and Growing Degree Days. These values sometimes, but not always, mimic ground temperature patterns. Although no wintertime field observations are available, the depth and duration of seasonal snow cover appears to be the primary source of variability. 相似文献
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A survey of the regional snow accumulation variability on Spitsbergen, Svalbard, was carried out during three field campaigns in May 1997. The survey was carried out along three transects from west-to-east approcimately at the following latitudes: 77°30', 78° and 78°50'degrees north. The altitudes span from sea level to 1000 metres elevation. Snow depth was measured with two different ground-penetrating radar systems, PulsEKKO (450 MHz) and GSSI SIR System-2 (500 MHz), pulled behind snow machines. Snow characteristics such as snow temperature, snow density and stratigraphy were measured in snow pits in nine areas, three along each transect. Our data suggest the following: (1)the accumulation-elevation gradients vary from 3 mm/100 m in the northeast to 237 mm/100 min the central-south with an average value of 104 mm/100m for all measurements: (2)snow accumulation was 38 to 49% higher at the eastern coast than at the western coast; (3) a clear minimum in accumulation (or continental climate) is seen for the central (inland) locations in the middle and northern transects while no such minimum exists along the southern transect; (4) a south-to-north gradient produces 55% and 40% less snow accumulation at the northern locations compared to the southern locations at the western and eastern coasts, respectively. These drops in winter snow accumulation occur over a distance of less than 200 km. 相似文献
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The Qinghai-Tibet Plateau has developed into a vast fortress-like structure that has recently presented a barrier limiting the egress of moisture-bearing air masses. Lower sea levels also affected the climate. This paper examines their effects on the current evidence for the timing of past glaciations, and the development and evolution of permafrost. There are two theories regarding glaciation on the Qinghai-Tibet Plateau(QTP). Kuhle suggested that there was a major, unified ice-cap during the Last Glacial Maximum(LGM), whereas major Chinese glaciologists and others have not found or verified reliable evidence for this per se. There have been limited glaciations during the last 1.1 Ma B.P. but with increasing dominance of permafrost including both primary and secondary tessellons infilled with rock, sand or loess. The East Asia Monsoon was absent in this area during the main LGM, starting at 30 ka B.P. on the plateau, with sufficient precipitation reappearing about 19 ka B.P. to produce ice-wedges. A weak Megathermal event took place between 8.5 and 6.0 ka B.P., followed by Neoglacial events exhibiting peak cold at 5.3–4.7 ka, 3.1–1.5 ka, and the Little Ice Age(LIA) after 0.7 ka. Subsequently,mean annual air temperature has increased by 4 °C. 相似文献
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The recognition of ice-marginal deltas constructed during the formation of the Nakina II moraine and a previously unrecognized
spillway, in the vicinity of Longlac, northern Ontario, indicates that existing concepts of ancestral lake level history and
drainage systems in the Lake Superior–Lake Nipigon region is inadequate. Based on isostatically corrected digital elevation
maps, ice-marginal deltas of the Nakina II moraine probably formed at the level of glacial Lake Minong, most likely Minong
III, and not glacial Lake Nakina as has been commonly suggested. In addition, the presence of a spillway near Longlac indicates
that lake water drained southward through the Mullet Outlet–Pic River system immediately following ice-marginal retreat from
the Nakina II moraine and not eastward as previously proposed. Architectural-element analysis of exposures within the spillway
indicates hyperconcentrated outbursts of meltwater produced thick channel-fill elements during flood conditions with peak-velocities
exceeding 3 m/s. Subsequent retreat of ice from the Pic River valley to the east, may have allowed waters of Lake Agassiz,
Lake Barlow–Ojibway, or both, to drain into post-Minong lake levels in the Lake Superior basin. These findings place major
constraints on previously proposed concepts of northeastern or eastern outlets of Lake Agassiz. 相似文献
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The Nanga Parbat Himalaya presents some of the greatest relief on Earth, yet sediment production and denudation rates have only been sporadically addressed. We utilized field measurements and computer models to estimate bank full discharge, sediment transport, and denudation rates for the Raikot and Buldar drainage basins (north slope of Nanga Parbat) and the upper reach of the Rupal drainage basin (south slope).The overall tasks of determining stream flow conditions in such a dynamic geomorphic setting is challenging. No gage data exist for these drainage basins, and the overall character of the drainage basins (high relief, steep flow gradients, and turbulent flow conditions) does not lend itself to either ready access or complete profiling.Cross-sectional profiles were surveyed through selected reaches of these drainage basins. These data were then incorporated into software (WinXSPRO) that aids in the characterization (stage, discharge, velocity, and shear stress) of high altitude, steep mountain stream conditions.Complete field measurements of channel depths were rarely possible (except at several bridges where the middle of the channel could actually be straddled and probed) and, when coupled with velocity measurements, provided discrete points of field-measured discharge calculations. These points were then used to calibrate WinXSPRO results for the same reach and provided a confidence level for computer-generated results.Flow calculations suggest that under near bank full conditions, the upper Raikot drainage basin produces discharges of 61 cm and moves about 11,000 tons day−1 (9980 tons day−1) of sediment through its channel. Bank full conditions on the upper portion of the Rupal drainage basin generate discharges of 84 cm and moves only about 3800 tons day−1 (3450 tons day−1) of sediment. Although the upper Rupal drainage basin moves more water, the lower slope of the drainage basin (0.03) generates a much smaller shear stress (461 Pa) than does the higher slope (0.12) of the upper Raikot drainage basin (1925 Pa).Dissolved and suspended sediment loads were measured from water/sediment samples collected throughout the day and night over a period of 10 days at the height of the summer melt season but proved to be a minor variable in transport flux. Channel bed loads were measured using a pebble count method of bank material and then used to generate ratings curves of bed loads relative to discharge volumes. When coupled with discharge data and basin area, mean annual sediment yield and denudation rates for Nanga Parbat are produced. Denudation rates calculated in this fashion range from 0.2 mm year−1 in the slower, more sluggish Rupal drainage basin to almost 6 mm year−1 in the steeper, faster flowing Raikot and Buldar drainage basins. 相似文献
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