基于流溪河模型的中小河流洪水预报方法

针对中小河流缺乏河道断面资料而无法实际应用分布式水文模型的问题,以流溪河模型为原型,假定河道断面为矩形,采用卫星遥感影像估算河道断面尺寸,通过实测洪水资料优选模型参数,提出了中小河流洪水预报的流溪河改进模型。应用于江西省典型中小河流——太平江流域的结果表明:河道分级越多,模型模拟的洪水的洪峰流量越大、次洪径流系数越大;洪峰出现时间越提前,模拟的洪水过程的效果越好,精度越高;改进的流溪河模型对50场洪水模拟的相关系数达0.92,洪峰误差均值为5.54%,最大不超过20%,平均峰现时间差为0 h;洪水过程的预报结果可评定为甲等。该模型可应用于中小河流实时洪水预报中。     

河道数据对流溪河模型预报中小河流洪水的影响

针对琴江流域构建了中小河流洪水预报流溪河模型,分别从河道断面形状、断面尺寸和河道分级的角度定量评估了河道特征数据对应用流溪河模型开展中小河流洪水预报的影响。结果表明:河道分级越多,模型模拟洪水的洪峰流量峰值越大、次洪径流系数越大、洪峰出现时间越早,模拟的洪水过程效果越好;在构建流溪河模型时,假定河道断面为矩形,采用卫星遥感影像估算河道断面尺寸的方法是可行的,模型模拟的洪水过程精度可以满足实际洪水预报的精度要求;利用改进的流溪河模型进行中小河流洪水预报时,以3级河道构建的模型洪水模拟精度最好,可很好地模拟中小河流洪水过程。     

论泥沙数学模型中断面简化对输沙能力确定的影响

在河道泥沙数学模型中，河道断面水流的挟沙能力确定是关键内容之一，其确定准确与否，直接关系到数学模型的准确性和可用性。将不规则断面形态简化为矩形断面是目前河流泥沙一堆数学模型中所广泛采用的方法，本文结合黄河实测资料，分析了这一简化对确定水流挟沙能力的影响，得出了将不规则断面概化为矩形断面将使计算得的断面挟沙能力比实际断面的挟沙能力为小，在许多情况下偏小的幅度较大。对黄河下游的河床演变的数学模拟的有问     

HEC⁃HMS模型在黄河中游大理河流域适用性研究

水文预报对流域防洪减灾、水资源利用与管理具有重要意义。为探究HEC-HMS分布式水文模型在黄河中游地区的适用性,以大理河流域为研究区,根据流域DEM、土地利用和土壤等数据,基于GIS技术划分流域单元、提取流域信息,采用SCS曲线法、Snyder单位线法、退水曲线法和马斯京根法进行流域产汇流计算和河道洪水演进模拟。选取流域内13场实测雨洪资料,进行模型参数率定和验证。结果表明:13场洪水的洪峰流量模拟误差均小于20%、峰现时刻误差均小于3 h;率定期8场洪水模拟合格率为87.5%,平均Nash系数为0.816;验证期5场洪水模拟合格率为80.0%,平均Nash系数为0.710,预报精度达到乙级,模型可以应用于大理河流域洪水模拟。     

游荡型河流的洪水演算

本文依据黄河下游河道的河相关系和简化圣维南方程组，建立了游荡型河流洪水演进的对流一扩散模型，该模型将随机性和确定性相结合，用河相关系定义了洪水波的平移与衰减特性，只要在进口输入上游流域的来水来沙条件，可同步输出全河段所有断面的流量过程。经历史洪水验证表明，预报成果的精度和可靠性是比较满意的。     

珠江流域跨省河流管理基础空间数据库建设

从珠江流域跨省河流管理需求出发,阐述珠江流域跨省河流管理基础空间数据库建设的原则、依据、内容,设计其空间数据库的结构关系,建立了跨省河流管理基础空间数据库的一个原型。该原型以珠江流域1：250000基础地理信息、TM遥感数据及相关法律法规为基本依据,实现了基础水系、跨省河流、管理河段及相关管理河段的水事巡查、遥感动态监测、审批管理成果等的可视化、对象化、规范化整编和统一管理,不仅可以直接服务于珠江流域跨省河流的水行政管理,也为扩展以水系为核心的数字流域基础空间数据库建设奠定基础。     

青藏高原山区河流广义河相关系与多频率沿程河相关系

山区河流地貌由流域来水来沙和地质地貌等下垫面背景因素决定,基岩限制性河段与冲积河段相间分布,这些河流是否存在稳定的河相关系,是山区河流地貌演变研究亟待回答的重要问题.本研究以发源于青藏高原的六大水系共129个水文测验断面的实测流量和实测大断面数据为主要数据源,以青藏高原六大水系的沿程河相关系为研究对象,探讨了同一河段与...     

干旱与极端干旱白杨河流域生态需水分析

本文根据流域各河流水系形成的自然生态环境属性及河道取水工程设施节点,采用Penman-Monteith生态需水定额和卫星遥感面积识别及水文年内展布综合方法,分析评估白杨河流域现状敏感区生态环境需水量和河流生态基流及其调控断面。分析结果可为流域生态环境保护提供参考依据。     

V型断面河流推移质输沙率的探讨

在假定河道顺直，水流流向与河道平行且不产生的环流的情况下，本文分配了Ｖ型断面河流泥沙的起动条件，导出了Ｖ型断面河流岸坡与矩形断面河流床面泥沙起动拖曳力关系，根据Ｐ．Ｄｕｂｏｙｓ的推移质运动拖曳力理论，以通用性较好的Ｍｅｙｅｒ－Ｐｅｔｅｒ－Ｍｕｌｌｅｒ公式为基础，得到了适用于山区流域Ｖ型断面河流的推移质输沙率公式，该公式以物理机理为基础，能弥补许多学者用矩形水槽率定的推移质公式应用的局限性。     

无资料或少资料区河流流量监测与定量反演

河流流量是流域水循环和水文计算的关键因素,受复杂地形、恶劣气候或经济、政治等因素的影响,无资料或少资料区水文站点的建设、维护和流量测量极为困难。为解决上述问题,将常见的河道过流断面概化为三角形断面和幂函数型断面两种形态,通过水力分析建立水面宽与流量函数关系的一般表达式,结合实时、高效、观测范围广和数据量大的遥测技术,提出了一种适用于无资料或少资料区的、水力学与遥感相耦合的径流反演方法,并基于模型实验和野外实测资料对提出的方法进行了校验。根据模型实验水面宽反演的56组流量,相对误差平均值为18.77%;其中,40组数据与实测流量的相对误差小于20%,占比为71.43%。根据野外实测水面宽反演的流量,相对误差平均值为20.71%;其中,64.66%的数据与实测流量的相对误差小于20%,86.03%的相对误差小于30%。本文提出的方法能够较为准确地反演河流流量,为无资料或少资料区径流的实时高效监测提供了一种解决方案。     

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.