关于黄河下游断流的思考

黄河下游断流是非正常现象，值得进一步深化入研究，对断流情况的详细了解分析是研究的基础。在实施黄河全流域治理开发规划的同时，抓紧缓解下游断流现象，主要对策有：进一步提高黄河上中游水库的调蓄能力；节约用水，按供水量定用水量、严格控制取水；在小浪底水库建成前、断流地区可增加临时性调蓄设施。黄河下游断流问题，涉及全流域长远治理问题，甚至若干自然和社会科学领域问题，因此，必须加强开展水利科学、水问题的不同空     

关于黄河下游断流的几点看法

在分析黄河下游频繁发生断流现象及其影响的基础上，结合断流产生的原因，指出断流是发展的必然趋势。并通过对黄河流域的需水量、节水措施、近期工程措施调控状况及水资源合理调度运用等方面的详细分析，进一步指出在当前没有十分有效措施的情况下，黄河下游断流将长期存在。基于这一认识，提出解决黄河下游河道断流的对策，最主要的还是开源、节流、加强管理。黄河下游用水必须有两手准备。     

强化黄河水资源优化配置和管理的几点建议

分析认为，黄河断流的原因有三：一是流域内水资源不足，供需矛盾日趋突出；二是黄河水的管理和统一调配不够有力；三是水资源短缺与浪费并存。黄河断流对下游沿黄地区经济和当地人民的生活对河道整治和防洪以及对下游地区及河口的生态环境都产生了严重的影响。为此，提出缓解黄河水资源不足、减少断流出现的对策和建议；强化黄河水资源的法制管理；进一步明确赋予黄河水利委员会代表国家水行政主管部门对黄河全流域水资源开发利用的     

黄河下游断流造成的影响

从黄河下游断流造成的经济损失、断流对河道冲淤及防洪的影响、断流对下游生态环境的影响几个方面进行了分析研究。认为黄河下游频繁断流，严重影响着下游涡黄地区工农业生产和人民生活对黄河防汛及河口三角洲生态环境也有不利的影响。     

黄河断流问题分析

自1987年起，黄河下游几乎年年断流，且断流时间不断提前，历时不断增加.断流使下游工农业生产、油田开发、城乡人民生活生态环境等很多方面受到严重影响，经济损失巨大.本文分析断流形成的原因认为一是天然径流不足，二是人为影响.防止黄河断流，重点在于解决下游枯水灌溉季节来水少，用水多的矛盾，主要对策有：增加来水量，减少用水量，调整用水时间，加强水环境保护。     

黄河下游断流分析及对策

对黄河下游断流的变化特点、成因及趋势进行了分析，结果表明，花园口站下泄流量在关键用水月份小于９００ｍ３／ｓ时，下游容易造成断流。从７０年代至９０年代，黄河下游断流形势越来越严重，而且有进一步加剧的可能。人类用水量的大幅度增加是造成下游断流加剧的主要原因，而黄河水资源缺乏、浪费严重、缺乏统一管理和调度也是造成断流的重要原因。文中最后提出了防止断流继续发生的几条对策     

黄河下游断流初步分析及缓解对策

进入９０年代以来，黄河下游河道连续发生断流，且有初始时间提前、时段延长、河段向上延伸的趋势。黄河断流给下游及沿黄地区带来不利影响，对黄河下游防洪和生态环境也造成威胁。要避免和缓解断流发生，必须大力开展节约用水，实现国务院批准的分水方案以法管水；在枯水年、枯水季节对水资源实行统一调度；积极兴建干流调蓄工程，提高黄河水资源利用的整体效益。     

黄河下游河道断流情况及特点

1黄河下游断流情况1．1断流历史回顾根据水文年鉴整编规定，河流在某一断面的日平均流量等于零，称为全日断流；日平均流量不为零，但一日内某些时段流量等于零，则称为间歇断流。断流天数系指全日断流与间歇断流天数之和。黄河从1855年到新中国成立前的近100年间，除1938年国民党在花园口扒口造成下游改道外，并未发生断流现象。即使在1875～1878年连续4年和1922～1932年连续11年发生的大旱年份，下游河道仍有水流。新中国成立后，黄河下游河道第一次发生断流是1960年，该年花园口水文站断流25天，夹河滩站断流16天，高村站断流7天，利津站…     

黄河下游断流及对策研究

黄河下游断流日趋严重，已引起人们的关注。本文从分析黄河下游断流的现状和特点入手，重点研究了黄河断流的成因、造成的影响以及缓解断流的对策。经分析认为，天然水资源贫乏、人类用水日益增多和缺乏科学的管理是造成断流的主要原因。为此，提出了加强黄河水资源统一管理与调度、中游尽快兴建有调蓄能力的枢纽工程，切实搞好节约用水，按市场经济规律调整水价，大力发展井渠双灌，以及逐步实现南水北调工程等一系列缓解断流的对策     

黄河下游断流成因典型年分析

1972～1996年黄河下游累计有19年发生断流，其中给人们印象较深、影响较大的是1992和1995年的断流。现将这两个典型年的断流成因及影响作简要分析。11992年典型分析1．三断流情况1992年，利津站自3月16日起共断流5次，累计83天，其中5月22日至7月22日连续断流62天，济南际口站从6月3日开始，断流2次累计31天；断流上首在陈日以上，长度303ktho该年黄河下游断流，造成黄河下游沿岸一批引黄涵闸无水可引，灌区停灌，给沿黄地区人民的生活用水带来不便，给河口地区工农业生产带来很大损失。地处黄河最下游的东营市，由于黄河水是其唯一的淡水资…     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

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.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

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。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

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.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.