河西走廊水利工程风沙危害防治措施体系研究

河西走廊地处西北内陆河流域,由于气候干旱、风大沙多,风沙对水利工程的填埋淤积非常严重。在对河西走廊水利工程风沙危害现状全面调查的基础上,按风沙危害成因,将危害类型划分为以风沙流为主、以河道水力输沙为主和以沙丘前移为主的三种形式,并分别以榆林河水库及干渠、双塔水库和解放村水库为例,研究建立了不同危害类型的防治措施配置体系,以期延缓风沙对当地水利工程的填淤过程。     

永定河(北京段)水利工程建设与管理发展历程研究

永定河是首都重要的防洪安全屏障,同时又是北京市重要供水河道、水源保护区和补给区。为除害兴利,永定河上修建了各类水利工程,以控制水流并防治洪涝灾害。水利工程利国利民,综合利用水利枢纽工程除承担防洪、生态治理保护等社会公益性职能,又有供水、发电等经营性任务。从永定河水利工程建设与运行发展历程可以看出,水利工程正从传统的单一工程效益向工程效益与生态效益相结合的模式转变,工程结构设计的多样化发展也与时俱进。     

永定河综合治理与生态修复管理实践

永定河历史上是一条排洪河道,治理多以防洪减灾为主。自20世纪80年代起,永定河水量逐年减少直到下游出现断流,生态环境恶化,因此对河道的治理理念发生了转变,由单一防洪治理逐渐转变为综合治理、生态修复。河道经过多年运行,且随着经济社会的发展,跨河建筑物的不断增多,加之近年来综合治理和生态修复的实施,自2019年起连续五年大规模的生态补水,实现了全线通水,初步实现了打造“流动的河”的目标。本文阐述了永定河实施综合治理前后的河道现状,并对新时期永定河生态修复存在的问题进行了分析,并据此提出了相应对策建议,研究成果可为永定河新时期的综合治理与生态修复提供参考。     

湖光潋滟好秋色 生态补水显成效——北京市官厅水库管理处生态补水工作持续开展

<正>清风飒爽,洪波泛舟。红叶层峦叠嶂,群山巍峨竞苍,候鸟急急南归,空谷嘤嘤回响…。这是时下永定河官厅水库的一幅秋色画卷。永定河是京津冀地区重要的水源涵养区及生态屏障,更是首都北京的“母亲河”,受气候变化及流域上游工农业生产等因素影响,地下水位持续下降、生态系统严重退化。因此,恢复永定河生态系统已迫在眉睫！官厅水库作为永定河综合治理与生态修复的重要节点,贯彻落实习近平生态文明思想,统筹做好水灾害防治、水资源节约、水生态保护修复、水环境治理工作,将恢复永定河生态系统、确保河道有水作为首要工作,从2017年向下游永定河生态小流量放水以来,官厅水库持续开展生态补水工作,打造贯穿京津冀晋的绿色生态廊道,助力永定河865 km河道全线贯通,水库蓄水量稳步增加,生态系统修复成效日益显现。     

泥沙淤积对黄河下游中小洪水风险影响评价

泥沙淤积导致黄河下游中小洪水灾害发生次数及损失大小发生了变化。利用90系列洪水资料,分析了小浪底水库和黄河下游河道系统不同组合条件下滩区中小洪水风险变化特点。水库和下游河道淤积都导致了黄河下游中小洪水漫滩淹没损失发生的次数增多、损失值变大。在维持黄河下游平滩流量4 000m3/s条件下,泥沙淤积导致滩区中小洪水漫滩次数由小浪底水库拦沙运用初期的年均0.10次增大到拦沙运用后期的年均2.18次,相应的洪水灾害损失值也由年均0.220亿元增大到年均2.400亿元。     

内蒙古十大孔兑水沙特性及治理措施研究

分析了内蒙古十大孔兑来水来沙特点、洪水特性以及昭君坟河段沙坝淤堵黄河情况和由此带来的洪水灾害。根据孔兑流域特性及产水产沙特点提出了治理要坚持上、中、下游统筹兼顾,综合治理的原则。上游丘陵区以沟道坝系建设、退耕还林还草恢复植被为主;中游以防风固沙和引洪放淤为主;下游以防洪为主,结合引洪放淤改造滩地。     

深化科技赋能 保障地下水超采综合治理达效——北京市水科学技术研究院

<正>北京地处华北平原的西北端,平原区除山前一带为坡积、洪积堆积物外,主要由永定河、潮白河及拒马河等河流作用形成的冲洪积扇地相互连接而成,其中永定河和潮白河冲洪积扇最大两扇相临,几乎控制了整个平原地区。第四系厚度变化的总体规律是从山前至平原逐渐增厚。沿每条河流从上游到下游,含水层由单一含水层逐渐演变为多层,含水层颗粒由粗变细。     

回澜塔:锦江边上一支“箭”

<正>成都人引以为豪多年的锦江,其实是都江堰水利工程的副产品。制造灾害的水,李冰没有一排了事,而是把它变成了环绕成都的两条河——郫江和捡江,即后来所称府河与南河,合称锦江。锦江来自岷江,它环绕成都,整合了江安河、柏条河、走马河、三道堰等无数支渠,又生发出解玉溪、金河、御河等众多人工内河,最终在下游归入岷江。锦江,不仅奠定了成都的水系走向,也为这个城市注入了新的基因,它排     

广东旱灾成因与灾害链研究

旱灾是广东省主要的自然灾害之一,发生频率高,以春旱和秋旱为主,灾害损失严重且呈上升趋势。大气环流异常、厄尔尼诺影响、自然地理环境复杂、社会经济环境多变、水资源分布不均、人类活动不合理、水利工程欠完善都是广东旱灾的致灾因子。旱灾的危害主要表现为灾害链效应;诱发地质灾害、成潮、森林火灾、病虫害、瘟疫、人畜饮水困难,导致了粮食减产,从而恶化生态环境,阻滞经济发展,最终影响人类生活。     

北京开工建设防沙治沙绿色屏障

北京近郊一处最大的“绿色平台” ,永定河滞洪水库库区和堤防两边绿化工程全面开工 ,2 0 0 2年春完成绿化面积 3 98.4ｈｍ2 ,植树 3 6.7万株。永定河行洪河道是北京五大风沙危害区之一 ,每年冬春季节 ,西北风顺河谷而下 ,沿岸风沙弥漫 ,危害非常严重。加固河道两岸大堤 ,搞好河道两侧的绿化 ,既是确保永定河行洪安全的需要 ,也是绿化首都、构建防风固沙绿色生态屏障工程的需要。永定河绿化规划范围北起门头沟黑水河口 ,南至大兴崔指挥营 ,全长 78.2ｋｍ。横向范围为永定河两岸大堤的堤顶、内外堤坡及堤防两侧各 3 0ｍ管理范围内的区域。在此…     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。