排序方式： 共有38条查询结果，搜索用时 187 毫秒
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<正>雅鲁藏布江像一条银色的巨龙,从海拔5300米以上的喜马拉雅山脉中段北坡冰雪山岭发源,自西向东奔流于号称撌澜缥菁箶的青藏高原南部,最后于巴昔卡 相似文献
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雅鲁藏布江,全长3848千米,被藏族人民视为"摇篮"和"母亲河",为中国第5大河(仅次于长江、黄河、黑龙江和珠江)、西藏地区第一大河。它的上游是世界海拔最高的大河,也是中国坡降最陡的大河。在藏语中雅鲁藏布江意为"高山 相似文献
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<正>印度喜马拉雅山区流域17%的面积被永久性积雪和冰川覆盖,大约有32000km2,其中,冰川共计在9000条以上,储存了大约12000km3的淡水资源.这些冰川对维持区域生态的稳定和调节河流径流供水具有重要意义.各流域的冰川分 相似文献
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Effects of topography and land use on woody plant species composition and beta diversity in an arid Trans-Himalayan landscape,Nepal 总被引：1，自引：1，他引：0
Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only（Pisang site） while the other pair has clear differences in land use in addition to slope exposure（Braka site）. In each site, we sampled 72 plots（36 on each slope） in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis（CA） results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables（e.g., radiation index） affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Br 相似文献
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MONA Lisa 《《地质学报》英文版》2014,88(4):1157-1168
The site of Mansehra is located seismically in an active regime, known as the Crystalline Nappe Zone and Hazara-Kashmir Syntaxis in NW Himalayas, Pakistan. Seismic Hazard Assessment （SHA） for the site has been carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation. The Mansehra Thrust, Oghi Fault, Banna Thrust, Balakot Shear Zone, Main Boundary Thrust, Panjal Thrust, Jhelum Fault and Muzaffarabad Fault and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Mansehra. Using the available instrumental seismological data from 1904 to 2007, SHA has been carried out. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 7.8 has been assigned to the Balakot-Bagh fault using four regression relations. The peak ground acceleration value of 0.25 g （10% probability of exceedance for 50 years） and 0.5 g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches. 相似文献
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本文根据近年来对青藏高原广泛开展的考察所积累起来的实际材料,以板块构造观点,简要讨论了青藏高原主要构造特征。文章以地质历史、沉积特征、冈瓦纳相沉积、蛇绿岩套、混杂岩和外来岩块的分布、变形特征、岩浆活动的规律以及雅鲁藏布江两侧变质带的特点,论证了喜马拉雅地区板块活动的方式和特征,对喜马拉雅运动进行了分期并对各期运动的性质作了分析。文章提出了冈瓦纳大陆的北界可能是班公湖—东巧构造带以及雅鲁藏布江构造带在中生代拉开、早第三纪闭合机制的新设想 相似文献
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我国东部中低山区第四纪冰川的存在与否一直存在争议,但冰川必然对山体进行冰蚀作用形成冰蚀地貌。为了分析我国东部中低山区的山体地貌是否具有冰蚀特征,该文选取了现代冰川集中发育区—喜马拉雅山脉作为冰蚀地貌的研究对象,通过宏观分析,除了由缩口、三角脊、残弧组成的冰斗系统外,还发现冰蚀作用过程存在避谷、吞脊、切壁、穿梁等特殊习性。分析认为冰蚀过程主要受制于雪线高程、积雪高程与坡向坡角三方面因素的控制。以此为基础,对我国东部的江西庐山、山东蒙山、大兴安岭主峰黄岗梁三个地区的山体地貌进行对比分析,发现这些山区的山体地貌与喜马拉雅山脉的冰蚀地貌具有一致性。文章从冰蚀过程的角度确认了我国东部中低山区存在第四纪冰川的事实。 相似文献