浅析美国建坝与拆坝

分析了美国101座建坝(坝高100 m或库容30亿m3以上)和248座拆坝(1999~2005年)的特征。得出如下结论:①20世纪60年代为美国建坝高峰期,建坝集中于中西部偏远地区的小河或大河支流上,密西西比河干流未建坝;建坝开发目标依次为防洪、供水灌溉、发电、旅游生态、航运,坝型依次为土石坝、重力坝、堆石坝、拱坝、混合坝及其他;最大坝高234 m,最大库容348.5亿m3。②拆坝的建坝时间为1708~1970年,拆坝的坝高大多小于5 m,最大坝高18 m,拆除的主要是建在小支流或溪沟上的老、弃、废和"无名"坝;拆坝的原因依次为"生态环境"、"水坝安全"、"经济效益"和"泥沙淤积"。③美国建坝与拆坝具有"中西部河流建大坝、东部小河拆小坝"的总体特征。     

美国拆坝统计分析

对美国1921~2013年共计1 093座水坝拆除进行了信息统计,从拆坝数量、大坝规模、筑坝材料、坝龄等方面系统分析了美国拆坝现状,并从生态、经济、安全方面分析拆坝的主要原因。统计结果表明水坝拆除现象在美国一直存在,且至今为止美国所拆除的主要为小型水坝、旧坝、病险坝。对美国经济发展有重要影响的水坝不仅未被拆除,还不断得到维护,水坝在美国的经济和社会发展中仍贡献着重要力量。     

依法管坝 确保运行全过程安全

<正>水库尤其是高坝大库,可有效调蓄洪水、发电、利用和保护水资源等,为人类带来巨大的利益。20世纪90年代以来,我国大坝建设在世界各国中不仅数量上居首位,而在大坝高度上也明显增高。目前,我国已建、在建坝高100~200 m的大坝151座,坝高200~300 m的大坝12座,坝高大于300 m的大坝2座。这些大坝大多数属于电力行业,在发挥巨大的社会、经济效益的同时,也具有潜在的安全风险,大坝一旦出现严     

广东省水库工程分布特点分析

根据广东省第一次全国水利普查水利工程基本情况普查成果,分析了广东省水库工程总体分布、工程规模、建成年代、坝型等特点,由此得出：广东省水库工程主要分布在粤东西北地区;河源市水库总数量和总库容均位居全省之首;以小型水库为主,但大中型水库起决定性作用;水库多建成于20世纪50-70年代;主要为均质土坝。     

关于高土石坝接合面的若干问题

随着高土石坝坝高的加大和数量的增加,有关技术问题也不断增多,这是近几年来土石坝失事数量增加的重要原因。在世界上失事的坝中,最高的是土石坝,如美国的提堂(Teton)坝,坝高92米,1976年失事;鲍德温山(Ba-     

RCC在美国水利工程中的应用

自从美国陆军工程师团在20世纪80年代建造了RCC结构的柳溪坝后,RCC坝就在美国取得了一席之地。美国联邦政府机构近年来不断地在全国大坝和水工建筑物上推广使用RCC结构,使用RCC结构的大坝及水工建筑物的数量和规模也在不断增长和扩大。主要介绍了美国最近完工和一些在建的RCC大坝及水工建筑物的各项参数及状况。     

水电七局承建的成都锦江世纪湾闸坝一期工程通过阶段性验收

正由中国水利水电第七工程局有限公司承建的成都市锦江世纪湾闸坝工程位于成都市高新区会展中心背后,工程总宽度为126 m;其中泄流坝采用2孔布置,单孔净宽62 m,坝孔净宽124 m,中隔墩厚2 m;正常蓄水位高程479 m,坝顶设计高程479.2 m,设计坝高2.9 m,闸底板采用宽顶堰型式。按照成都市高新区政府建设规划,锦江世纪湾闸坝位于高新区会展中心东侧、锦江世纪湾主景区末端。工程建成后,将使府河常年具备更加宽阔的水面和亲水条件,是区域景观打造的重要配套工程。     

世界混凝土面板堆石坝的发展与回顾

面板坝于 19世纪中叶起源于美国 ,起初采用抛填堆石加木面板防渗 ,以后采用混凝土面板 .到 2 0世纪 60年代末引入振动碾压 ,进行薄层碾压堆石施工 ,使坝体密实而变形较小 ,由此这种坝型才得以迅速发展 .在 1899年 ,世界上仅有几座铺设面板的不透水堆石坝 ,坝高为 15～ 2 0ｍ .随着设计和施工技术的日益成熟 ,分别制定了设计导则和施工规范 ,指导和规范面板坝建设的发展 .到 1999年 ,混凝土面板堆石坝(ＣＦＲＤ)的数量已接近 30 0座 ,坝高近 2 0 0ｍ .ＣＦＲＤ已从一种新坝型成为经常被采用的主要坝型 .1　抛填堆石的ＣＦＲＤ(1 899～ 1 96 0…     

“阿斯旺”一座成功的高坝

20世纪60年代中期,埃及修建了一座高坝——阿斯旺水坝。此坝1964年动工,1968年建成。这是建在世界第一大河尼罗河上的一座“土心墙沙石坝”,坝高111米,长3 830米,形成总库容1680亿立方米的特大水库,这个人工大湖被命名为纳赛尔湖,面积达6500平方公里。湖容量之大足以装下尼罗河两年中的全部水量,属多年全面调节型水库。阿斯旺水坝在防洪、抗旱、灌溉     

复合土工膜或土工膜堤坝实例述评(续)

2 土石坝和混凝土坝用复合土工膜防渗加固 2.1 Paradela混凝土面板堆石坝 葡萄牙Paradela混凝土面板堆石坝是1958年建成的。坝高110m,上下游边坡都是1:1.3,坝顶宽7.75m。堆石是抛投法施工。美国在20世纪30年代以前用抛投法堆石建成了几座高50～80m的混凝土面板堆石坝,如Dix坝、Cogswell坝等,因坝不高故混凝土面板没有很严重裂缝。1931年建成了100m高的Salt Springs混凝土面板堆石坝,发生了严重裂缝,有些缝宽2.5cm,漏水很大。此后美国     

Downstream benthic responses to small dam removal in a coldwater stream

Increased awareness of the negative effects of dams combined with an aging dam infrastructure has led to an increase in dam removals. However, ecological responses of downstream biota to such actions are poorly understood. We examined the influence of a pair of small dam removals on downstream periphyton and macroinvertebrates in Boulder Creek, WI (USA). The dams were 180 m apart and both were removed on 9 July 2003. We monitored algae and macroinvertebrates as well as habitat characteristics for approximately 2 months before and after the removals upstream and downstream from the two dams, and continued our observations over a similar period (mid‐May to mid‐July) the following summer. After the removals, an initial release of sediment significantly increased the proportion of fine sediments in the downstream reach and buried benthic substrate. This burial led to a 60% reduction in chlorophyll in the downstream reach the week following removal, while concentrations increased in the upstream reference reach. Similarly, macroinvertebrate densities 2 weeks post‐removal were lower relative to pre‐removal densities and were associated with declines of ephemeropterans, trichopterans and dipterans. Examination of Trichoptera genera demonstrated substantial changes in this assemblage associated with diminished densities of the formerly dominant genus Brachycentrus. Algal and invertebrate populations increased in the weeks after the dam removal, but did not reach densities similar to the upstream reference reach. In the following year, both periphyton and invertebrate densities were lower in the downstream reach, suggesting a long‐term effect of the removal. Thus, effects of the dam removal were alternatively positive or negative over time, and indicate that the time scale of consideration has a strong effect on the interpretation of the consequences of this management activity. Copyright © 2008 John Wiley & Sons, Ltd.     

中国碾压混凝土坝技术的进展与运行经验

中国碾压混凝土坝建设始于８０年代中期，１９８６年从第１座坑口碾压土坝完成后，１０多年来已竣工２８座，在建的有１５座，合计４３座，居世界之首，还有２１座正在设计中，在设计、科研、施工实践中，碾压混凝土筑坝技术有所发展，有所进步。通过运行证实，这些成熟的经验将对下一世纪继续发展碾压混凝土坝有指导和推动作用。即将开工兴建的友滩水电站一期工程大坝高１９２ｍ，将是世界上最高的碾压混凝土重力坝。     

淤地坝对流域水沙影响模拟研究

使用SWAT模型,结合淤地坝特点对模型自带的水库模型进行修正来设置淤地坝模块,研究淤地坝对流域径流和输沙的影响,并在内蒙古十大孔兑之一的西柳沟流域进行模拟和验证.以1980-1990年为率定期、2006-2015年为验证期,龙头拐水文站模拟径流量和输沙量与实测值拟合较好,线性拟合系数R2和纳什效率系数ENS均超过0.6...     

Fracturing dams,fractured data: Empirical trends and characteristics of existing and removed dams in the United States

Dam removals in the United States continue to accelerate in pace and scope, but no national analyses have examined how removed dams compare with existing dam stock. Here, we review and analyse the best available national data on dams from the National Inventory of Dams (NID), dam removals from American Rivers, the U.S. Geological Survey, and the National River Restoration Science Synthesis databases to compare trends and characteristics of removed versus existing dams in the United States. If historical trends continue, by 2050 the United States can expect between 4,000 and 36,000 total removals, including 2,000–10,000 removals of NID dams. Best‐fit regression models estimate total costs between $50.5 million and $25.1 billion (mean $10.5 billion, median $416.5 million) for all removals and $29.6 million to $18.9 billion (mean $7.2 billion, median $285 million) for NID removals, a significant cost savings over present stated dam rehabilitation needs. Structural characteristics and ages of documented removals are not representative of existing dams, with privately owned hydroelectric dams subject to public oversight and water supply dams the most disproportionately removed. We conclude that dam removal science would benefit from the creation of an interdisciplinary framework for studying dams as environmental, social, and technological interventions, facilitated by transparent datasets around dams and removals and reflexive research approaches that combine statistical approaches with place‐based analyses.     

Occupancy Patterns of Mammals and Lentic Amphibians in the Elwha River Riparian Zone Before Dam Removal

The downstream transport of sediments and organics and upstream migration of anadromous fishes are key ecological processes in unregulated riverine ecosystems of the North Pacific coast, but their influence on wildlife habitats and populations is poorly documented. Removal of two large hydroelectric dams in Washington's Elwha Valley provides an unprecedented opportunity to study long‐term responses of wildlife populations to dam removal and restoration of these key ecological processes. We compared pre‐dam removal patterns in the relative abundance and occupancy of mesocarnivores, small mammals and lentic amphibians of the Elwha River riparian zone above, between and below the dams. Occupancy of riparian habitats by three mesocarnivore species diminished upriver but did not appear to be closely linked with the absence of salmon in the upper river. Although the importance of salmon in the lower river cannot be discounted, other gradients in food resources also likely contributed to observed distribution patterns of mesocarnivores. Abundance and occupancy patterns within congeneric pairs of new world mice (Peromyscus spp.) and shrews (Sorex spp.) indicated that closely related species were negatively associated with each other and responded to habitat gradients in the riparian zone. The availability of lentic habitats of amphibians was highly variable, and occupancy was low as a result of rapidly changing flows during the larval development period. We speculate that long‐term changes in habitat conditions and salmon availability following dam removal will elicit long‐term changes in distribution of mesocarnivores, small mammals and amphibians. Long‐term monitoring will enhance understanding of the role of fish and restored ecosystem processes on wildlife communities along salmon‐bearing rivers in the region. Copyright © 2013 John Wiley & Sons, Ltd.     

Prioritizing removal of dams for passage of diadromous fishes on a major river system

Native diadromous fishes have been extirpated from much of the Susquehanna River system for nearly a century. Recent restoration efforts have focused on removal of dams, but there are hundreds of dams and presently there is no biologically based system to assist in prioritizing their removal. We present a new method that uses existing habitat suitability index models (HSI) for American shad Alosa sapidissima, alewife A. pseudoharengus, blueback herring A. aestivalis, and American eel Anguilla rostrata to prioritize the removal of non‐hydropower dams within the Susquehanna River system. We ranked HSI scores for each of the four species, association between a landscape‐scale factor and HSIs, length of river opened by removing a dam, and distance from the mouth at Chesapeake Bay for each dam and then calculated a mean rank prioritization for dam removal by averaging the ranks for the seven criteria. This prioritization method is resistant to outliers, is not strongly affected by somewhat arbitrary decisions on metrics included in the analysis, and provides a biologically based prioritization for dam removal that can be easily amended to include other metrics or adapted to other river systems and that complements other social and economic considerations that must be included in decisions to remove dams. Published in 2008 by John Wiley & Sons, Ltd.     

Rapid Response of a Sand‐Dominated River to Installation and Removal of a Temporary Run‐of‐the‐River Dam

Run‐of‐the‐river dams (RORDs) comprise the vast majority of dams on river systems and are commonly removed as a part of stream restoration strategies. Although these dams are routinely removed, few studies have documented the geomorphological responses of sand‐bed rivers to the removal of RORDs. We examined the response of a large sand‐bed river located in South‐Central Kansas, USA, to the installation and removal of a dam that is installed annually for seasonal recreational purposes. Channel adjustments were tracked using cross‐sections sampled over the course of 7 months as the dam was installed and subsequently removed. Multivariate spatiotemporal analysis revealed emergence of channel stability when the dam was in place for most cross‐sections, except for those immediately adjacent to or at great distances from the dam. Our results provide an approximation for how sand‐bed rivers respond to RORD construction and removal and are useful for guiding management decisions involving preservation or restoration of connectivity. Results of this study suggest that sand‐bed rivers are resilient and recover quickly when transient RORDs are removed. Copyright © 2014 John Wiley & Sons, Ltd.     

面板坝软岩料的工程特性

 面板坝是当今国内外大坝建设中的主要坝型。以往面板坝要求用硬岩填筑,但是近十余年来,软岩料的利用已成为一个重要的趋势。有的高坝也以软岩料作为主堆石料,今后超100 m级的软岩坝也是可能的。为此,有必要加强对软岩工程特性的研究。基于大坳、鱼跳、盘石头、寺坪、十三陵上池、云南茄子山、水布垭等面板堆石坝软岩料的试验结果及工程应用情况,对软岩的物理、力学特性进行评价和总结。     

Sedimentology of New Fluvial Deposits on the Elwha River,Washington, USA,Formed During Large‐Scale Dam Removal

Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river‐restoration efforts have included dam removal, large dam removals have been rare enough that their physical and ecological effects remain poorly understood. New sedimentary deposits that formed during this multi‐stage dam removal result from a unique, artificially created imbalance between fluvial sediment supply and transport capacity. River flows during dam removal were essentially natural and included no large floods in the first two years, while draining of the two reservoirs greatly increased the sediment supply available for fluvial transport. The resulting sedimentary deposits exhibited substantial spatial heterogeneity in thickness, stratal‐formation patterns, grain size and organic content. Initial mud deposition in the first year of dam removal filled pore spaces in the pre‐dam‐removal cobble bed, potentially causing ecological disturbance but not aggrading the bed substantially at first. During the second winter of dam removal, thicker and in some cases coarser deposits replaced the early mud deposits. By 18 months into dam removal, channel‐margin and floodplain deposits were commonly >0.5 m thick and, contrary to pre‐dam‐removal predictions that silt and clay would bypass the river system, included average mud content around 20%. Large wood and lenses of smaller organic particles were common in the new deposits, presumably contributing additional carbon and nutrients to the ecosystem downstream of the dam sites. Understanding initial sedimentary response to the Elwha River dam removals will inform subsequent analyses of longer‐term sedimentary, geomorphic and ecosystem changes in this fluvial and coastal system, and will provide important lessons for other river‐restoration efforts where large dam removal is planned or proposed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

特高坝及梯级水库群设计安全标准研究Ⅲ:梯级土石坝连溃风险分析

为承应本系列论文提出的建立在梯级水库群连续溃决风险分析基础上的特级土石坝分级标准,本文阐述了溃坝计算、洪水演进和连溃分析模型的基本原理,通过对冲刷模型、泄流渠水深计算方法等方面的改进,提出了一个数值分析稳定、对输入参数敏感性低的溃坝分析方法。通过实际工程算例分析表明,本文方法不仅适用于单坝溃决洪水分析,计算成果符合工程实际,而且对连溃分析也具有很好的操作性。溃坝风险分析可作为土石坝风险等级确定的重要手段,也为实施本系列论文建议的等级标准提供了基础支撑条件。