上海、浙江、福建三省市海堤现状调查

根据调研成果对上海、浙江和福建三省市的海堤情况进行介绍,主要包含:海堤的建设经验、损毁情况、主要破坏特点、建设标准以及目前设计的主要依据;风速计算方法;沿海潮位和台风暴潮特点;波浪计算方法;堤顶高程确定;生物消浪措施;海堤主要结构和断面形式;海堤地基情况、堤基处理方式及计算方法;堤身填筑材料、施工方法及安全控制措施等。总结了三省市海堤建设中遇到的问题,并对《海堤工程设计规范》编制提出建议。     

海堤工程设计中风速问题的探讨

风速是海堤设计的重要基础资料,由于海堤工程特殊的地理位置,使得其风的问题更加复杂。该文结合调研和《广东省海堤工程设计导则》编制的部分成果,对风速标准、风速换算及风速分析方法等问题进行了探讨,提出了海堤工程设计时风速选用的几点意见,可供设计参考。     

北海市城区北部海堤的风潮组合分析

广西海堤一般采用设计潮位与同频率主风向风速组合方案进行波浪计算,由于北海市城区所处的特殊地理位置,按这种组合计算不切合实际.为此,通过3场典型风暴潮组合分析,提出在满足防潮要求的前提下,北海市区北部海堤按设计潮位与同频率相应风速、设计风速与同频率相应潮位两种组合之外包值作为设计值.     

海堤防御标准商榷

针对广东省海堤堤高设计中存在选用设计风速偏低、波浪爬高计算偏低等存在问题,相应提出了堤高设计标准的建议,根据湛江市的实测资料,介绍了风速、有效吹程、风浪爬高,堤顶超高及暴潮水位选定等水文水利计算方法及成果,并按建议的海堤设计标准进行了经济分析。     

秦山核电厂海堤加高工程挡浪墙波浪力研究

为应对超标准风暴潮对秦山核电厂海堤的影响,对其海堤加高工程的挡浪墙受到的波浪作用力进行了水槽模型试验及经验公式计算.结果表明,计算的波浪力仅为模型试验成果的1/2,在类似工程设计中,可由经验公式计算成果的2倍作为挡浪墙上的设计波浪力.     

开敞海域海堤设计波浪波高数值研究

由于水下地形和陆域边界的影响,近岸波浪设计要素随之变化,从而影响海堤的设计。因而海堤堤前设计波浪波高的确定对于安全、可靠、经济的海堤设计意义重大。文章以平海石井海堤为例,通过确定海域风浪条件、设计潮位与计算组合,构建研究区域数值模型,计算开敞海域波浪波高,计算成果为海堤设计提供参考。     

大清河西海段河道风场要素的确定

本工程段位于盖州市北海新区北部,用盖州市气象站30年最大风速值统计资料,通过皮尔逊Ⅲ型和极值Ⅰ型曲线2种方法,计算不同频率的设计风速值,确定主、次风向。根据工程段的位置、特性及不同风向,分别计算各风浪要素,选取较大值作为工程设计值,以提高工程的安全性。     

高标准海堤潮位与波浪设计标准组合研究

针对高标准海堤设计波浪是否应采用与设计潮位相同重现期的问题,结合三门县洋市涂围垦工程实例分析不同潮位与波浪设计标准组合下海堤的经济性,并分析实测潮位与波浪遭遇情况,总结提出高海堤潮位与波浪设计标准组合的建议。     

阶梯式海堤波浪爬高试验研究

利用波浪模型试验分析阶梯式海堤的波浪爬高,研究在不同台阶尺寸、水文要素下阶梯式海堤的消浪效果,提出合理的设计应用方案,并得出阶梯式海堤的糙渗系数,可供河口或内河的相关堤防工程设计参考。     

大亚湾区海堤加固达标工程波浪越浪量优化试验研究

结合大亚湾区石化段A(海堤长1 436.28 m,迎浪面坡比1∶1.75)、B(海堤长5 638.31 m,迎浪面坡比1∶1.5)和C(海堤长955.28 m,迎浪面坡比1∶2.5)3种类型现状海堤断面的波浪越浪量研究成果,通过物理模型试验研究分析了B、C类海堤断面加固方案在不同潮位波浪作用下的波浪爬高及越浪量,验证了海堤迎浪面护面块体的稳定性,试验成果可为海堤设计提供相关的技术依据。     

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.     

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.     

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.     

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.     

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.