水资源价值流的运移传递过程

本文从环境经济学角度论述了水资源价值的构成,分析了水资源价值流逆向传递与连续传递等特性。依据水文循环及水资源价值规律,给出了水资源价值传递概念模型。该模型建立的前提是忽略水资源价值流传递过程中槽蓄价值量的变化及价值传递时发生的滞时,认为水资源价值传递规律为：水资源循环过程中入流处获得的价值与出流处传递上来的价值处于平衡状态,即出流的总价值等于入流的间接价值。并以我国北方一河段为例进行了模型应用研究。     

黄河小北干流漫滩洪水分析和预报方法探讨

在分析黄河小北干流河道特性、漫滩洪水水沙特点和演进规律以及平滩流量随来水来沙和河道冲淤变化情况的基础上,考虑小北干流宽浅河道的特点和漫滩洪水调蓄特征,用实测淤积断面资料和水位站资料建立了河道槽蓄关系,用"蓄率中线法"对漫滩洪水进行演算预报。对高含沙漫滩大洪水在滩地滞蓄淤积,洪量减小、洪峰曲线坦化的情况,建立了滞水滞沙处理模型。结果表明:1960年以来21场漫滩洪水的预报检验合格率为85.7%,对黄河"92·8"洪水和"96·8"洪水预报的确定性系数分别为0.87、0.93,洪峰流量预报精度分别为86.5%、96.3%。     

大凌河流域水资源变化规律及影响因素分析

根据大凌河流域社会经济状况和自然地理环境,将流域划分为Ⅰ区(成水与用水环境)、Ⅱ区(成水环境)、Ⅲ区(用水环境)3个水资源区。通过整理分析相关研究资料,运用近50a流域水文、气象数据探讨各分区的水资源演变规律,从内在机理的角度探析引起水资源变化的因素。结果表明:大凌河流域近50a水资源量呈下降趋势,各分区的变化幅度存在明显差异;受气候变化与人类活动影响,Ⅰ区、Ⅱ区的水资源变化影响程度与机理不同;人类活动直接决定了Ⅲ区的水资源变化程度,可不考虑自然因素作用。     

用槽蓄关系联解圣维南方程组模拟洪水演进的方法探讨

采用槽蓄关系联解圣维南方程组模拟洪水演进的水力学方法,首次发现了在Δt时段可将圣维南方程组简化后绘制两种不同形式的河段槽蓄增量图形:一是根据水流连续方程可绘制槽蓄增量1,二是根据水流运动方程也可绘制槽蓄增量2。由于河段槽蓄增量1、2应相等,因此,可以用槽蓄增量为纽带求解圣维南方程组。     

基于STELLA的安徽省水资源供需预测研究

利用系统动力学软件STELLA建立由水资源供给和居民、工业、农业、生态环境、公共需水等子系统组成的水资源供需系统模型,对安徽省2012-2030年水资源供需情势进行模拟分析,模拟效果较好。参数灵敏度分析表明,模型结果对工业增加值增长率、万元工业增加值用水量、农田有效灌溉系数的变化最为敏感。基于此提出应对水资源短缺问题的3种综合调控方案(方案I,方案Ⅱ和方案Ⅲ)。结果表明:与现有发展模式相比,方案I和方案Ⅱ延迟了水资源短缺的时间;以经济平稳增长、生态环境友好为目标的方案Ⅲ则会有效地解决未来水资源供需矛盾。最后在各种模式的基础上提出了应对水资源问题措施,为缓解安徽省水资源矛盾、优化水资源配置提供参考。     

考虑水流滞时影响的梯级水电站群短期优化调度研究

针对梯级水电站群短期统一优化调度中调度期水量不平衡问题,基于水量平衡原理提出了考虑水流滞时影响的梯级水电站群短期统一优化数学模型,将受水流滞时影响的调度期分为受前一调度期影响时段、本调度期影响时段和影响下一调度期时段3部分。在此基础上,采用基于POA的模型分块求解方法,选取大渡河瀑布沟及以下梯级水电站群开展实例研究。结果表明,采用的方法能够很好地克服水流滞时所带来的计算困难,较好的体现受水流滞时影响的调度期发电效益,简单实用,有较强的通用性。     

暗槽中悬移质泥沙与紊动传递作用

这篇论文是叙述关于在横断面为10.5×3时的矩形槽中输送混有不同成份的泥沙的浑水的试验,这里采用两种大小的泥沙——以泥沙的平均粒径来表示为0.1公厘和0.16公厘。试验资料是用以研究(a)水流内存在悬移质泥沙对水流特性的影响和(b)假定水流为二元水流,沿水槽中线纵断面的动量传递系数和含沙量传递系数。现在的试验表明紊流交换的通用常数 k 随悬移质的增加而减小。当平均含沙量重量比为4.3%时,k 值减小到0.2。k 的减小未曾达到极限。当水流流速高于某一速率时,泥沙的存在对摩擦系数λ几乎没有影响。此种流速与推移质有关;那就是河床上所有的沙丘均被携带为悬浮状的流速;并且它随着水槽的总沙量和所采用的泥沙的大小而增加。如低于该流速,λ比清水中的大。泥沙的传递系数 e_s 在泥沙粒径为0.1公厘时等于动量传递系数 e_m 的1.5倍,在泥沙粒径为0.16公厘时等于1.3e_(mo)。e_s 和 e_m 两者在槽两旁的2/3范围内依正规抛物线的形式变化而在中间1/3范围内为一常数。     

复式明槽的最小比能

由于应用能量原理分析明槽水流常常有助于弄清比能的概念,这个概念是1912年由Bakhmeteff提出来的。对于一元明槽水流来说,比能的定义为:高于槽底的能坡线的高度。分析断面比能的变化,可将明槽水流分成缓流和急流两类,它们由大于或小于比能是最小时的水深(即临界水深)来区别。最小比能的数学推导结果,在临界水深时佛汝德数的值为1。当佛汝德数大于1时为急流,小于1时为缓流。对于水力工程师来说,临界水深和它相应的最小比能的存在具有很大的实用意义。它为计算稳定渐变流水面线提供了流态分界的界线。水面线计算是水资源研究的组成部分,包括     

CES模型计算复式河槽过流能力及方法对比

复式河槽的洪水漫滩后,滩槽水流相互作用,在滩槽交界处形成动量交换,若直接采用曼宁公式进行水力计算将产生很大误差。应用CES(Conveyance Estimation System)模型首先计算了不同复式河槽的垂线平均流速,并结合英国科学工程研究理事会洪水水槽设备(SERC-FCF)的试验资料进行了验证,进而分析了不同形态复式河槽的水流特性;然后通过对比分析CES模型与经验方法(湿周修正法、断面分割法)和理论方法(谢汉祥法、刘沛清法、河槽协同度法)计算流量时的精度,论证了该模型在复式河槽水力计算中的优越性。结果表明,由CES模型计算的断面垂线平均流速分布符合复式河槽的水流特性且与实测资料吻合良好,较之其他模型方法,该模型能适用于任意形态复式河槽的流量计算且精度较高。     

漫滩水流的二维流速分布及水力学计算

漫滩水流的水流结构及水力学计算问题,前人已作了大量的工作,提出了一些水力学计算经验关系式,但由于其局限性较大,难以广泛应用.谢汉祥根据动量传递理论,考虑了漫滩水流剪应力沿横向的变化,导得了滩槽垂线平均流速沿横向分布的理论计算式,在理论上取得了较大的进展,但仍未解决点的时均流速二维分布问题.本文对此求得了二维分布的理论解,进而求得滩槽流量分配.     

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.