正挑丁坝区鱼类栖息地水力生境指标分布特征数值模拟

丁坝区鱼类栖息地研究对河流生态保护具有重要意义,基于三维水流数学模型,探讨了正挑丁坝区鱼类栖息地水力生境指标的分布特征,结果表明：（1）水流流速随弗劳德数Fr的增大而增大,坝后回流区宽度逐渐减小,主流区沿程从急变流变为渐变流,并逐渐恢复为均匀流;（2）主流区和回流区流速梯度G较小,G>2的区域主要集中在水槽左右两岸和丁坝坝头附近,横断面上G随弗劳德数Fr的增大而减小;（3）丁坝上游至下游剖面动能梯度M的分布特征与G相似,M高值区出现在水槽右岸及坝头附近相对槽宽B⁺=0.25～0.40区段,但水槽左岸的M值较小且沿程变化不大;（4）丁坝上游流速适宜度S_u随Fr的增大而减小,丁坝和丁坝下游断面S_u随Fr的增大而增大;丁坝下游回流区的S_u较小,一般不超过0.3,而主流区的S_u可能超过0.8,表明该区域鱼类产卵栖息条件较好。研究结果可为丁坝区鱼类资源保护和生态航道工程建设提供参考。     

透水丁坝纵向流速分布试验研究

通过水槽概化模型试验研究不同淹没程度、不同空隙率和不同空隙尺寸条件下,对丁坝上游回流区、下游回流区和主流区纵向流速的影响规律。结果表明:淹没程度、空隙率、空隙尺寸和纵向流速具有较强的相关性,回流区纵向流速随淹没程度的增大而增大,主流区随淹没程度增大而减小;空隙率和空隙尺寸具有相似的变化规律。可为长江上游散抛石丁坝的维修加固提供参考。     

插板透水丁坝透水孔优化方案数值模拟

针对插板透水丁坝透水孔孔数和布置方式对丁坝作用区水流特性和冲淤变化影响的问题,采用CCHE2D水沙数学模型对塔里木河干流其满河段实体模型水槽插板透水丁坝区进行二维水流数值模拟,分析不同透水孔数和不同布置方式对河槽断面流速分布、水位及河床切应力的影响规律,寻求插板透水丁坝透水孔优化方案。结果表明:在来流量、透空率等因素不变条件下,插板透水丁坝透水孔数越多,流速均匀性越好,丁坝下游河床切应力呈减小趋势。当透水孔数达到4孔时,丁坝上游、下游水位、流速和河床切应力变化趋势均趋于稳定,为最佳的透水孔优化方案。研究成果为进一步研究插板透水丁坝区水流特性与缓流促淤效果奠定理论基础。     

护岸式铅丝笼丁坝挑角的选择

通过室内模型试验,研究了不同挑角时丁坝附近的水流结构、坝后回流区及自由水面的变化情况,以及不同挑角丁坝附近局部冲淤变化的规律。结果表明:随着丁坝挑角的增大,坝上游流速减小区范围扩大,坝头流速变幅增大,坝后回流区长度和宽度均有所增大,坝头水面比降也增大;结合实际工程经验,建议护岸式铅丝笼丁坝的挑角宜设计为下挑45°。     

含淹没植被明渠水位及糙率变化试验研究

采用概化水槽试验研究了在不同植物间距、水流条件下,含淹没植被明渠水位、曼宁糙率系数的变化特征,给出了含淹没植被明渠的糙率经验公式.试验结果表明:相同的流量、水深条件下,明渠的水位壅高值和水面比降均随植物间距的减小而逐渐增大,当植物枝叶相互间贴近或交叉时,植物对明渠水位、比降的影响程度相对较大;水深基本相同、植物排列方式相同的情况下,随着流量的增加,水面比降基本呈线性增大趋势;水深相同的条件下,含淹没植被明渠糙率受水流流速的影响较小.     

单排井柱桩透水丁坝的阻水缓流作用分析

井柱桩透水丁坝为挡水和透水建筑物,推求了单排井柱桩透水丁坝上游及下游流速公式,通过计算塔里木河其满水库三号口断面单排井柱桩透水丁坝上、下游平均流速,并进行比较表明,水流通过井柱桩透水丁坝后下游平均流速较上游明显降低,从而证明了井柱桩透水丁坝具有阻水缓流作用,但仍大于不冲流速。     

潮汐双向流条件下丁坝水流特性研究

以长江口南支河段为原型,概化并建立水槽数学模型,研究径潮双向流条件下丁坝附近的水流结构。研究表明:丁坝一侧河岸,丁坝下游潮差远大于上游,在丁坝上游潮差小于对岸侧,下游潮差大于对岸侧;落潮时,丁坝回流区与壅水区长度大于涨潮,转流时刻,丁坝坝头附近流速相对较大;河床底部剪切应力变化在涨落急时刻最大,且落潮大于涨潮,转流时刻坝头及坝身迎水侧剪切应力增加明显。     

丁坝对弯道水流水力特性影响的研究

针对丁坝对弯道水流水力特性影响的问题,建立了相应的概化模型,通过数值模拟的方法,利用RNG k-湍流模型封闭Reynods方程,VOF法追踪自由表面,通过有限体积法离散求解,模拟研究了不同弯道中心角情况下,丁坝对弯道水流横向水面超高和流速场的影响。结果表明:在丁坝影响下,弯道水流水面横比降计算公式需要进行修正,应当考虑丁坝对河道的束窄、丁坝尺寸和弯道角度等综合因素的影响。     

长江乌江交汇口水力特征数值模拟分析

采用SMS水动力学软件构建二维数值模型,对长江乌江交汇口水域在不同汇流比下的水面形态、流速分布及交汇口处分离区、滞留区等位置进行分析可知,计算河段水面存在横比降,弯道处凹岸水位壅高,凸岸水位跌落,且在上游交 汇角处形成滞留区;交汇口下游水文断面支流侧形成分离区,分离区外侧水流流速明显增大,形成最大流速区.其成果可 ...     

非淹没复式断面丁坝区的流速分布规律

复式断面丁坝是常见的航道整治建筑物。通过室内水槽试验开展非淹没复式断面丁坝流速分布规律研究。结果表明①表层合流速高速区主要出现在一级丁坝坝头下游外侧,二级丁坝长度b₂对高速区流速大小及平面分布形态具有明显影响,而弗劳德数Fr只影响高速区流速大小,表层横向流速平面分布接近扇形,最大横流可达试验流速的0.45倍;②横断面上纵向流速高速区位于一级丁坝坝头附近,强横流区位于二级丁坝前缘,均呈带状分布,b₂越大,带宽越小,高速区分布更为集中;③纵剖面上纵向流速最大值出现在丁坝下游靠近水面附近,其沿程位置随b₂的增大而上移,横向流速呈先增大后减小的变化,最大值出现在丁坝附近靠近槽底的部位,强横流区呈枫叶型分布。研究结果可为航道整治工程设计和丁坝水毁保护等提供参考。     

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.     

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.     

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.     

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.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．