小浪底水利枢纽对黄河下游生态的影响分析

为了准确量化小浪底水利枢纽对径流状态的影响,提出了水库生态影响与贡献率定量分析方法,对比分析了不同时段有无水库两种情景下的径流状态,揭示了水库对径流状态的影响,并通过与实测径流状态变化对比来量化水库的贡献率。结果显示:2000—2019年,小浪底水利枢纽年均减少下游利津断面断流81.15 d,减少生态基流、关键期最小生态流量和关键期适宜生态流量的不达标天数75.25 d、31.35 d和27.10 d,增加关键期入海水量23.71亿m³;与1980—1999年相比,2000—2019年黄河天然径流量减少10.59%,三门峡断面实测来水量减少22.15%,同时下游用水量增加,不利于河流生态流量保障;小浪底水利枢纽扭转了来水和取水的不利影响,保障了黄河下游径流和生态状态持续好转,对利津断面防断流、生态基流保障和关键期入海水量增加的贡献率分别为187.85%、137.32%和125.83%。     

丰满水库运行对局地气候的影响回顾

以我国最早建成的位于松花江上游大型水电站丰满水电站为例,统计了水库周边代表性气象站1961—2009年间的温度、降水量和相对湿度等数据,分析了建库后近50年来气候要素变化趋势和特征,并与建库前8年历史文献记录进行对比,以期揭示大型水库建设对局地气候变化的影响。结果表明:丰满水库年均和季均气温呈持续上升趋势,与吉林气象站年平均气温的差值也呈明显上升趋势,冬季的平均温度升高显著;丰满水库库区内年均降水量略有减少,近库区和远库区的年降水量比值呈明显上升趋势;丰满水库运行可能对局地气候中年均最低气温产生影响,并在一定程度上促进近库区降水量增加;年均相对湿度略有减小,总体呈暖干趋势;总云量变化不明显,且水库运行对雾凇景观的影响也不明显。     

三峡库区蓄水前后区域气象要素变化研究

对三峡库区及其周边12个气象站点1951—2010年的气象要素特征值进行了线性回归分析、阶段性分析和趋势分析,结果表明:①三峡库区气温呈上升趋势,年均气温、年均最高气温和年均最低气温的增速分别为0.12、0.12、0.16℃/10 a,年均相对湿度以-0.03%/10 a的速率呈下降趋势;②库区蓄水后,绝大多数站点不仅年均相对湿度低于多年均值,而且蓄水后多年均值也低于蓄水前的;③蓄水后,平均相对湿度的变化与潜在蒸散量、降水量的变化并不一致。     

黄河生态保护对郑州邙山局地小气候的影响

郑州西北部沿黄邙山2008年完成了黄河水土保持生态建设与保护工程,2010年建立生态观测基站并开始对其气象要素进行连续定位观测。利用郑州邙山2010—2020年生态实测数据,运用一元线性拟合、距平法分析黄河生态保护对郑州邙山局地小气候的影响,结果表明：郑州邙山局地小气候变化明显,年均气温、年最高气温、年最低气温、年均空气湿度、年降水量均值分别为15.7℃、40.35℃、-9.15℃、54.53%、406.35 mm,除降水外其他气象要素变化均呈上升趋势;年降水量减小、温度升高、空气湿度增大,说明土壤及地表植被持水、保水功能增强,黄河生态保护改善了郑州邙山局地小气候。     

三峡水库蓄水后库区气候要素变化趋势分析

为获取三峡水库建成蓄水后各种水循环要素的变化情况,基于2004～2016年库区12个沿江代表站的气象数据,采用趋势分析法和相关分析法研究了三峡库区相关气候要素的变化情况,并与前人的相关研究成果对比,探讨其变化趋势及变化原因。结果表明:水库蓄水后,由于下垫面的改变,水库年均气温呈弱的下降趋势,年均降水量与降水日数增加,年均相对湿度减小,风速增加,蒸发量下降;影响蒸发量的主要因素是年均气温、年均相对湿度与日照时数。研究成果可为气候变化背景下三峡库区水分、能量循环研究提供理论依据和参考。     

白龟山水库金属结构物防腐蚀方法

1概况白龟山水库是一座以防洪为主、兼顾农业灌溉、工业和城市用水综合利用的大二型年调节半平原水库,主要有泄洪闸、南北干渠渠道闸3座泄水建筑物。库区属大陆性气候,气象变化受季风影响,年均相对湿度为70％,年均降水量850～900mm,年均气温14℃,年最高温度42℃,年最低温度- 18℃,年均日照2300h。三闸水工建筑物中的闸门、门机和门槽埋件的金属结构物长期裸露在水中或暴露在大气环境下,     

小浪底水利枢纽对周边经济带动作用研究

小浪底水利枢纽是国内具有代表性的大型水利枢纽,为研究大型水利枢纽如何带动周边经济,围绕小浪底的发电、旅游、衍生经济对周边经济的影响进行了讨论,使用对比的方法分析小浪底兴建前后的防洪、灌溉等功能产生的经济效益,发现小浪底建成后带动了周边经济的发展,增加了周边财政收入,带动了当地就业,提高了周边居民生活水平。小浪底水力发电、旅游也会因为收入不稳定对周边经济产生不利影响。提出加大协调力度、加强小浪底旅游开发力度等政策建议。     

基于GAM模型的气候因素下水库悬浮物对水质的动态影响分析

文章采用GAM模型,结合辽宁北部某水库2000—2017年实测气象数据和水质监测数据,对气候因素下水库悬浮物对水质动态变化进行分析。结果表明:相对湿度、太阳辐射、风速以及降水量对水库悬浮物均具有不同程度的影响。     

三峡水库蓄水前后气候变化分析

利用1962年 ～2017年三峡水库及其周边区域24个站点的气温和降水数据,结合Mann-Kendall非参数检验法和累积距平法分析三峡水库蓄水前后局地气候变化趋势与突变情况.结果表明,气温和降水均受影响,且影响程度具有明显的地理分布规律.蓄水对气温趋势具有稳定作用.蓄水后,气温增长幅度增大的站点主要分布在四川盆地,幅...     

气候变化对大海波水库来水及用水影响

为分析在未来气候变化情景下大海波水库来水及用水的变化情况,选取楚雄站蒸发(1953年-2001年)、降水(1953年-2009年)、气温等气象资料,以及大海波水库(1990年-2009年)来水量资料,采用线性回归法、Mann-Kendall及Spearman趋势检测法对楚雄站点的气象要素进行趋势检测,并计算了水库下游参考作物需水量。结果表明:大海波水库的来水量呈减少趋势,下游参考作物需水量呈下降趋势;在未来气候情景下,楚雄年平均气温将升高2.56℃,年降水变化率为5.9%,气温升高时,下游参考作物需水量增加,对大海波水库的供水带来一定的不利影响。     

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。     

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。     

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.