澜沧江-湄公河流域温度和降水变化趋势分析

利用澜沧江-湄公河流域7个代表气象站1980—2009年的温度和降水观测资料,采用线性倾向估计、滑动平均和Mann-Kendall检验方法对流域年、季温度和降水变化趋势进行分析。结果表明:流域年平均温度呈明显上升趋势,线性倾向率为0.02℃/a;流域北部高海拔地区温度增加趋势比南部明显,而温度季节增加趋势不明显。流域年平均降水呈增加趋势,线性倾向率为10.49mm/a,不同地区降水增减趋势不同;雨季降水增加趋势明显,而旱季降水增加趋势不明显。     

青藏高原大通河流域气候要素时空演变特性分析

以青藏高原大通河流域为研究区域,将流域内及周边5个气象站1960-2012年的年降水、年均气温及年潜在蒸散发作为研究对象,利用气候倾向率法、Mann-Kendall法、滑动平均和小波分析法对各气候要素的演变特性进行了分析,以期为大通河流域水电站梯级调度运行、减轻旱涝灾害及其影响提供科学依据。结果表明:153a以来,大通河流域年降水以0.60 mm/a线性趋势不显著增加,年均气温以0.03℃/a的线性趋势显著增加,而多年潜在蒸散发却以0.94 mm/a线性趋势不显著减小;2流域年降水受祁连山及季风的影响,在东西方向自西南向东北逐渐增加,在流域的中游达到最大;受海拔的影响,年均温度的空间分布东高西低,南低北高,最高温度出现在流域中下游;而流域年潜在蒸散自西南向东北呈现带状相间的分布规律;3该流域年降水、年均气温均未出现突变,流域年潜在蒸散发在1970及2008年出现突变;4周期分析显示,流域年降水序列周期为17、28 a左右,年均气温周期为8、15 a左右,年潜在蒸散发序列周期为18、30a左右。     

1960－2014年淮河上中游流域年降水和主汛期降水的时空分布特征

基于淮河上中游流域19个站点1960-2014年的月降水数据,采用气候倾向率、Mann-Kendall趋势分析、变差系数、年内不均匀系数、小波分析、Kriging空间插值等方法,对年降水和主汛期降水的统计特征、趋势和周期性等时间特征及空间分布特征进行研究。结果表明:流域主汛期降水占到年降水的50%以上,地域分布上以东南部和西南部雨量较多。年降水和主汛期降水在年际上分别呈现21~32a、8~19a、3~7a和24~32a、8~21a、3~7a三个时间尺度的丰枯演变特征,同一时间尺度的丰枯变化基本相同。主汛期降水年际Cv普遍大于年降水,但空间分布不一致;年降水Cv较大值分布于流域西部和北部,较小值分布于流域东部和东南部;主汛期降水年际Cv较大值分布于流域西部,较小值分布于流域东北部及蚌埠一带;北部降水的年内分配不均性略大于南部。年降水和主汛期降水的变化趋势均不显著,没有通过95%的置信度检验,但主汛期降水略呈增加趋势而年降水呈微弱下降趋势;年降水在流域北、西和西南部表现为减少趋势,尤以西、西南部较为明显,而流域中、南和东南部主要表现为增加趋势;主汛期降水则从北向南以条带状表现为增加趋势。     

东江流域降水演变特征及其影响因素分析

利用东江流域河源、连平、惠阳、增城、深圳5个代表站1953—2012年的逐月降水、气温、日照和风速资料,运用线性趋势估计、Mann-Kendall非参数检验、R/S分析法以及相关、偏相关分析研究了东江流域的降水变化特征及其影响因素。研究结果表明,近60年来,东江流域降水呈不显著增加趋势,整体上有较明显的丰、枯变化。深圳站降水呈减少趋势,连平、惠阳和增城站呈增加趋势,其中增城站降水增加趋势最为明显(32.95 mm/10 a);R/S分析结果显示各站降水变化均呈不显著的持续性,M-K检验结果显示除深圳站外其他4站降水均有较明显突变。同时,研究发现东江流域降水与日照、风速呈不同程度的负相关,而气温对降水的影响相对较弱;海拔高度对降水也有较明显的影响。研究成果可为气候变化背景下的东江流域水资源管理提供参考依据。     

气候变化背景下山东省气温与降水时空变化特征分析

【目的】为了探讨气候变化背景下山东省气温与降水的时空变化特征,【方法】根据山东省25个国家级气象观测站1981年1月—2021年2月逐月气温和降水资料,通过线性趋势、Mann-Kendall检验、小波分析、重标极差分析法等方法研究山东省气温、降水的时空变化特征,并预测未来变化趋势。【结果】结果显示：(1)山东省年均气温呈显著上升趋势,倾向率为0.4℃·(10 a)^-1,年均气温在1986年发生较明显突变,鲁南东部和西部、鲁西北东部及半岛西部增温最快。山东省年降水量呈不显著增加趋势,倾向率为26.5 mm·(10 a)^-1,未发生明显突变,鲁西北东部和鲁南东部降水增加最明显。(2)山东省四季平均气温均呈显著上升趋势,倾向率分别为春季0.5℃·(10 a)^-1、夏季<0.3℃·(10 a)^-1、秋季0.3℃·(10 a)^-1和冬季0.4℃·(10 a)^-1;春季、夏季、冬季降水量呈不显著增加趋势,倾向率分别为5.5 mm·(10 a)^-1     

1951年-2010年贵阳市气温变化特征分析

利用贵阳站1951年-2010年的逐月、年气温时间序列,运用滑动平均法、累积距平法和Mann-Kendall趋势检验法,分析了贵阳市的年、季气温变化特征。结果表明:贵阳60a来,年平均气温呈微弱下降趋势;年平均最高气温下降趋势较明显,其下降倾向率为0.14℃/10a,年平均最低气温无明显变化;极端最高气温呈微弱下降趋势,极端最低气温显著上升,上升倾向率为0.28℃/10a;对于不同季节,春、夏季的年平均气温下降幅度比秋、冬季明显;春、夏季的年平均最高气温下降幅度也比秋、冬季明显;各个季节年平均最低气温变化均不明显;春、冬季的极端最高气温比夏、秋季的下降显著;秋、冬季的极端最低气温增加最为突出,对年极端最低气温的上升贡献最大,春季的极端最低气温增加的最微弱。各季及年的极端最低气温的显著上升和极端最高气温的缓慢下降,表明贵阳的极端气温变化正趋于缓和。     

1954—2013年漳河上游流域降水演变规律分析

降水是径流主要来源,直接影响水资源时空分布。为探索漳河上游流域降水演变规律,根据流域内77个雨量站资料,采用线性回归法、滑动平均法和Mann-Kendall秩次相关检验法分析流域1954—2013年降水量变化。结果表明,漳河上游流域降水量年际变化大,极值比约为2.5,总体呈微弱减少趋势,变化倾向率约为11.1mm/10a;20世纪70年代以前及21世纪以后高于多年平均值,20世纪80—90年代低于多年平均值;空间分布不均,存在区域性降水集中明显现象;年内分配不均匀,降水主要集中在汛期,汛期降水量约占全年降水总量的72%。     

大渡河流域降水时空分布特征

利用1961～2010年大渡河流域14个地面气象观测站逐日降水资料,运用气候倾向率、Mann-Kendall非参数检验法、小波变换法,对大渡河流域降水时空分布特征进行了研究。结果表明:①流域平均年降水量介于596～1 748 mm,9个站点集中在650～850 mm,最大值出现在峨眉山,最小值在丹巴,下游年降水量多于上游和中游;峨眉山和峨边年降水量呈减少趋势,气候倾向率分别为-84.7 mm/10 a和-20.1 mm/10 a,小金、丹巴、康定、泸定、甘洛呈增加趋势,气候倾向率区间为12.6～39.5 mm/10 a;小金、甘洛突变发生在1976年,峨眉山发生在1991年,多数站点存在4～6 a和10～14 a变化周期。②峨眉山是各等级降雨日数的大值区,"丹巴—小金"一带为小值区;小雨、中雨、年降雨日数在中游地区偏少,中雨、大雨、年降雨日数在下游地区偏多。③小雨日数和年降雨日数通过检验的站点均为减少趋势,峨眉山最为显著,倾向率分别为-7.7 d/10 a和-9.9 d/10 a;中雨日数仅康定、泸定、峨眉山变化趋势显著,气候倾向率分别为1.0 d/10 a,0.6 d/10 a,-1.4 d/10 a;大雨日数在壤塘、马尔康减少趋势为-0.3 d/10 a左右,小金、康定、甘洛增加趋势超过0.3 d/10 a。小雨日数和年降雨日数突变集中在1987～1993年,中雨日数和大雨日数在1962～1973年。④整个流域小雨、中雨、大雨、年降雨日数既存在4～8a的共有短周期,又分别存在10～14,9～13,10～11,10～15 a的中长周期。     

金沙江流域近55a降水时空分布特征及变化趋势

利用金沙江流域内44个气象站点的逐月降水数据资料,采用5 a滑动平均法、Mann-Kendall法、克里金插值法以及空间分布格局法,研究了该流域近55 a降水时空分布特征及变化趋势。结果表明:流域年降水量和非汛期降水量均呈不显著的增加趋势,汛期则呈不显著的减少趋势;流域年内降水分布不均匀,主要集中在汛期5~10月,降水量约占全年的89%;流域降水空间分布特征主要表现为由上游向下游呈逐渐增加的趋势;流域降水的空间格局具有较大差异,主要呈现出流域河源及其中游地区降水量增加,下游地区降水量减少的变化特征。     

金沙江流域降水空间分布特征及变化趋势分析

依据金沙江流域25个气象站点1961~2010年的降水观测数据,采用Mann-Kendall非参数检验及经验模态(EMD)趋势拟合等方法,分析了流域降水时空分布特征及其近期变化趋势。结果表明,金沙江流域年季降水量存在明显的区域差异。高程4 000 m以上的区域降水总体呈显著增加趋势,面平均年降水量变幅达1.68 mm/a;高程4 000~3 000 m的区域降水量总体呈不显著增加趋势,面平均年降水量变幅为0.8 mm/a;高程3 000 m以下的区域降水量总体表现为不显著下降趋势,面平均年降水量降幅为-0.59 mm/a。年降水量变化主要体现在夏秋季降水量变化上;高程4 000 m以上和3 000 m以下两个区域降水集中性和降水强度存在增加趋势,其干旱现象也愈发严重;近期流域极端降水可能存在增加趋势。     

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.