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131.
Landslides generate enormous volumes of sediment in mountainous watersheds; however, quantifying the downstream transport of landslide‐derived sediment remains a challenge. Landslide erosion and sediment delivery to the Shihmen Reservoir watershed in Taiwan was estimated using empirical landslide frequency–area and volume–area relationships, empirical landslide runout models, and the Hydrological Simulation Program‐ FORTRAN (HSPF). Landslide erosion rates ranged from 0.4 mm yr‐1 to 2.2 mm yr‐1 during the period 1986–2003, but increased to 7.9 mm yr‐1 following Typhoon Aere in 2004. The percentage of landslide sediment delivered to streams decreased from 78% during the period 1986–1997 to 55% in 2004. Although the delivery ratio was lower, the volume of landslide sediment delivered to streams was 2.81 × 106 Mg yr‐1 in 1986–1997 and 8.60 × 106 Mg yr‐1 in 2004. Model simulations indicate that only a small proportion of the landslide material was delivered downstream. An average of 13% of the landslide material delivered to rivers was moved downstream during the period 1986–1997. In 2004, the period including Typhoon Aere, the annual fluvial sediment yield accounted for approximately 23% of the landslide material delivered to streams. In general, the transfer of sediment in the fluvial system in the Shihmen Reservoir watershed is dominantly transport limited. The imbalance between sediment supply and transport capacity has resulted in a considerable quantity of landslide material remaining in the upper‐stream regions of the watershed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
132.
Based on raw data from dams damaged in the Wenchuan earthquake, including many that were severely damaged, characteristics and factors that influenced the damage are discussed in this paper. Findings from this study include: severely damaged dams were densely distributed along the seismologic fault; small dams, especially small earth-rock dams, had the most serious damage that was caused by a variety of factors; the most serious damage was caused by seismic waves; damage was aggregated by aftershocks; and the extent of the damage patterns increased with the seismic intensity. Damage patterns varied in different intensity zones and cracking was the most common type of damage. Most of the dams had a good base with relatively high bearing capacity, and the walls of the earth-rock dams were mostly of clay soil. This type of base and body material mitigated some of the damage to dams. Reservoir maintenance and other factors also have a significant impact on the seismic safety of the dam. Finally, some recommendations to reduce seismic damage to dams are proposed. 相似文献
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石油地质学是国家石油战略的组成部分,是国家石油安全的组成部分,必须予以高度重视。石油地质学来源于实践。但随着石油勘探开发实践的不断深入,仅仅依靠归纳和总结来自实践的认识已经无法满足人们对石油地质学在科学层面的理解和掌握。从沉积层获得的有关构造、生油、储层方面的知识无法全面解释在结晶基底和火山岩中发育油气藏的事实,而最新揭示出金属、非金属矿床、油气藏与深部构造和深部流体存在密切关系,为我们发展石油地质学提供了崭新的思路。欧洲惠更斯号探测器发现土卫六上存在甲烷湖的事实告诉我们,石油地质学的不仅仅是地质学问题,更是天文学问题。所以,及时吸收消化各学科最新成果,创新发展中国石油地质学,已是保障国家石油安全的当务之急。 相似文献
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Combined with quantitative determination of concentration and isotopic composition of petroleum hydrocarbons, weathering simulation experiments on artificially mixed oils and their two end-member oils are performed for identification and quantification of mixed sources. The >C18n-alkanes show no appreciable losses during a short-term weathering process. An approach based on distribution of long-chain n-alkanes (>C18) is suggested for estimating the contribution proportion of each source in mixed oils. Stable carbon isotope profile of individual n-alkanes is a powerful tool to differentiate sources of oil spills, but unavailable to accurately allocate each contribution due to a relatively large analytical error. 相似文献
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汶川8.0级地震水坝震害调查 总被引:11,自引:1,他引:10
“5.12”汶川地震中水坝损毁严重,造成了巨大的经济损失。震后对69座溃坝险情和310座高危险情水库水坝进行了系统的调查,典型震害现象包括坝体裂缝、塌陷、滑坡、渗漏、启闭设施损坏和其他附属设施的损毁等。文中给出了不同烈度区的水坝震害分布,并对地震中水坝的震害现象做了初步总结和分析。 相似文献
139.
以大量的实际观测资料及多次震例 ,深入研究了地下水中Rn和Hg的震兆特征。结果表明 :Hg对地壳岩石应力应变的反应程度比Rn更灵敏 ,更有利于地震预报。通过研究得出以下几点认识 :(1)大震前 ,Hg有 1年左右的中期趋势异常且都出现在距震中较近的有利部位 ,Rn有 1— 2年的趋势异常出现在距震中 5 0 0km范围内 ;(2 )大震前 ,大多数观测台站能观测到Hg突出的短临异常 ,而Rn出现短临异常的台站数只有Hg的1/ 2 ,且异常幅度小 ;(3)中强地震前 ,在距震中较近的观测台站 ,能观测到Hg异常 ,相同条件下的Rn异常则不明显。地下水中Rn和Hg的这些异常特征对未来地震三要素的预报有一定帮助。 相似文献
140.
柴达木盆地干柴沟地区油气成藏条件及其勘探意义 总被引:5,自引:0,他引:5
干柴沟地区烃源岩发育良好 ,具有较为有利的油气储、盖层 ,特别是在其东南部和南北向古构造带中油气勘探前景良好 ,但构造圈闭和有利的岩相带的相匹配 ,才是形成干柴沟地区油气藏的关键 相似文献