基于VIC模型的龙滩水库流域径流模拟研究

基于大尺度陆面水文模型VIC(Variable Infiltration Capacity)模型,采用纳什效率系数和相对误差作为评判标准,探讨VIC模型在龙滩水库流域上的适用性,并对径流的时空分布进行分析的结果表明,VIC模型在龙滩水库流域具有良好的适用性,率定期和验证期的月径流模拟Nash-Sutcliffe效率系数均在0.85以上,相对误差大部分在10%以内,满足流域水资源评价与规划的要求;VIC模型对径流变化过程具有较好的模拟效果,峰现时间模拟较准确,对峰值流量的模拟效果略有不足,且丰水年模拟效果优于枯水年模拟效果;流域径流在空间上呈现东多西少,北多南少的分布特性;与基准期相比,流域在2001年~2010年多年平均径流呈现出一定的减少。     

大尺度分布式水文模型VIC在嘉陵江流域径流模拟中的应用

大尺度分布式流域水文模型是目前评价流域环境变化的重要工具,以嘉陵江流域为研究对象,构建了嘉陵江流域大尺度分布式VIC模型(Variable Infiltration Capacity,VIC model),利用Maryland大学的全球1 km×1 km土地覆盖数据,同时参考LDAS(Land Data Assimilation System)成果,建立了嘉陵江流域VIC模型的参数库,通过4个水文站以上流域的水文模拟试验,结果表明建立的VIC模型能有效地模拟嘉陵江流域各典型站的日、月径流过程,模拟的水量平衡误差在5%以内,日径流过程模拟的确定性系数均在70%以上,月径流过程模拟的确定性系数超过90%。该模型可以用来分析环境变化对嘉陵江流域水资源及洪水过程的影响。     

基于VIC模型的修河干流径流模拟研究

为了更好地对修河流域水资源进行科学合理的规划与评价,以修河干流虬津站断面以上控制流域为研究区域,构建修河干流流域大尺度分布式VIC模型(Variable Infiltration Capacity,VIC model),利用普林斯顿气象同化数据集驱动模型进行流域的径流模拟研究,以纳什效率系数NSE和相对误差Er两个评价...     

基于VIC模型的老挝南乌河流域水资源量评估

老挝正在积极参与澜湄水资源合作研究工作,水文实测数据短缺是制约水资源规划工作的现实问题。以老挝南乌河流域为例,采用流域地形、土壤、植被以及气象驱动等数据资料,通过建立流域分布式水文模型——VIC模型对径流进行模拟,以分析水资源量的时空分布规律。模拟结果表明:模型在对南乌河流域日、月尺度的水文过程模拟中表现出了较好的适应性,南乌河流域内的水量主要靠降水补给,径流的地区分布基本上与降水的地区分布一致,总的趋势是由流域上游向流域下游递减,径流系数的趋势也是由流域上游向流域的下游递减。研究成果可为无资料地区的水资源规划方案的制定及水资源量分析提供参考与借鉴。     

两种水文模型在汤河流域水文模拟中的对比分析

本文分别引入分布式水文模型SWAT模型和VIC模型,以汤河流域为例,结合流域内二道河子水文站2000~2010年实测水文数据,对比分析不同分布式水文模型在汤河流域的适用性和模拟精度。基于分布式水文模型SWAT模型,通过设定2种气温变化情景模式,定量分析气温变化对流域径流影响。研究表明:SWAT模型模拟的径流深相对误差和确定性系数均好于分布式水文模型VIC模型,SWAT模型更适合于汤河流域水文模拟。研究成果对于汤河流域分布式水文模拟提供参考价值。     

黄河流域大尺度水文过程模拟研究

大尺度水文过程模拟是分析评价环境变化对流域水文影响的重要基础工作,首先介绍了土壤-植物-大气输移方案中具有国际可比性的可变下渗容量模型(Variable Infiltration Capacity Model,简称VIC模型).将黄河流域划分为432个50 km×50 km正交网格,由108个雨量站1960～1970年的逐日降水量资料插补到各个网格,根据土壤、植被分布资料,确定各网格的模型参数,进而模拟了黄河流域径流量的空间分布.对典型支流及区间径流量的模拟结果表明,VIC模型具有较好的径流模拟能力,可用于评价气候变化对流域河川径流影响.     

基于物理基础的分布式水文模型应用研究

为了探讨基于物理基础的分布式水文模型在国内半干旱半湿润流域的应用,研究模型径流模拟在中小尺度流域的合理性与适用性,采用基于连续栅格单元演算的分布式水文模型CASC2D,对县北沟流域1983年～2007年8场洪水和栾川流域1961年～1998年8场洪水进行了径流模拟.对模拟精度、特征值等方面进行的比较分析结果表明,模型在县北沟流域和栾川流域均取得较好的模拟效果,且县北沟流域的模拟效果比栾川流域好;模型适用于中小尺度的半干旱半湿润流域,在超渗产流与混合产流流域均能取得较高的精度.     

黄河流域典型流域水文气象变化与径流过程模拟

典型流域水文气象分析及水文过程模拟是合理评价黄河流域水资源变化的重要基础。利用Mann-Kendall秩次相关检验法和均值差异T检验法分析了黄河流域7个典型流域的年降水量、年径流量和年均气温序列的变化特征,并采用VIC模型、新安江模型、WBM模型和GR4J模型模拟站点的径流过程。结果表明:各典型流域年均气温显著升高;年降水量变化趋势和突变情况均不明显;而年径流量呈显著下降趋势,且突变多发生在1980s。模型模拟结果表明4种水文模型在黄河流域应用效果较好。就Nash效率系数而言,VIC和新安江模型因为考虑产汇流过程较为详细,模拟径流过程与实测过程更贴近;就径流相对误差而言,WBM模型在水量模拟计算中表现较优,其结构简单,适用于流域水资源的模拟与评价。     

不同水文模型在滦河流域对比运用研究

为对比研究不同水文模型在滦河流域的模拟精度,分别选取垂向混合产流模型和VIC模型,以滦河滦县水文站以上流域为研究流域,基于滦县水文站1980—1989年水文资料,对比分析不同水文模型的模拟精度,并在此基础上,定量分析不同蒸发输入和不同计算时段对水文模型模拟的影响。研究结果表明:垂向混合产流模型相比于VIC模型,在滦河流域具有更好的适用性,日模拟相对误差均小于VIC模拟的相对误差,且确定性系数均高于VIC模型;时段步长为0.5 h的次洪模拟,不论是在洪峰峰值模拟还是整个洪峰过程的拟合程度方面模拟精度都要优于计算步长为1 h的次洪模拟;运用Penman-Monteith公式计算的潜在蒸散发作为垂向混合产流模型蒸发输入,模拟的日径流过程总体上优于运用实测蒸发皿蒸发作为蒸发输入的模拟精度。模型的研究成果可以为滦河流域水文模拟和模型研究提供参考价值。     

基于人工神经网络的雅砻江流域 水文过程多模型集合模拟

为降低水文模型的不确定性对流域水文过程模拟的影响,优化模型的实际应用效果,选取四种常见的水文模型:SWAT模型、BTOPMC模型、VIC模型和DTVG模型在中国西南的雅砻江流域分别建模,采用一套统一的模型输入数据与模拟时间范围,再次运用四个水文模型进行径流计算,并运用北京师范大学水科学研究院自主开发的基于人工神经网络方法的多模型输出集合系统对四个模型的模拟结果进行集合计算,得到集合计算的流量过程线及误差水平,与各水文模型计算结果相比较。研究结果表明,多模型集合计算的确定性系数和纳什效率系数均达到了0.90,相比单一水文模型的计算精度有大幅提高,且计算结果较稳定,与实际径流过程具有很好的一致性,说明多模型集合模拟在该流域具有很好的适用性。     

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.