岛群海域环境下泥沙运动及地形冲淤变化数值模拟研究

建立波浪、潮流共同作用下泥沙运动及地形冲淤积变化数学模型,并根据2007年4月份实测水文泥沙资料对模型进行了验证,验证表明,潮位、垂线流速、流向及含沙量过程的计算值与实测值吻合良好;波浪、潮流共同作用下悬沙引起的冲淤变化与实测冲淤分布趋势基本一致,较好地复演了洋山港工程建设后海域流场、含沙量场和地形变化.运用该模型对洋山深水港西港区工程方案进行了数学模型研究,研究表明,汊道方案实施后,由于颗珠山汉道的存在,使得通道内水流向北偏移,使得通道北侧西部流速较工程前流速有所增加,使西港区地形基本保持冲淤平衡略有冲刷;颗珠山汊道的存在,能够继续保持目前通道南侧淤积,北部刷深的格局,对西部港区的建设是有利的.     

呼图壁河渠首工程水库泄空冲沙研究

对于多沙河流上水库的排沙方法,前人已有较多研究,但通过模型试验来模拟水库高淤积后的排沙研究较少。通过水工动床模型试验,对呼图壁河渠首拟建水库高淤积状态下的泄空冲沙进行了研究,根据冲淤前后的断面变化情况,对泄空冲沙过程中的溯源冲刷和沿程冲刷进行了分析,找出了泄空冲沙的规律及运用原则。通过对泥沙冲淤的数值分析,建立了溯源冲沙的概化图形,推导出了一套适合该水库的泄空冲沙公式。经验证,建立的泄空冲沙公式可以用于呼图壁河渠首工程水库排沙形态预测及排沙量的估算。     

长江口深水航道整治工程影响下北槽河床冲淤变化分析

根据长江口深水航道整治工程前后(1998年1月与2008年2月)的地形测图,定量分析工程影响下的北槽河床冲淤变化,结果表明:1)10年间,研究区域内泥沙淤积总量高达3.37亿方,平均淤积厚度1.03m,其中入口段、上段、中段及下段的淤积量分别占淤积总量的16.5％、32.1％、29.6％与21.8％,淤积厚度分别为1.23m、1.12m、1.39m与0.65m;2)坝田泥沙淤积总量3.50亿方,其中航道北侧淤积量占58.3％,淤积分布特征为上段淤积厚度最大,下段次之,中段最小,分别为3.94m、2.44m和0.92m,航道南侧从上游向下淤积厚度逐渐减小,分别为3.32m、3.10m与1.87m;3)主槽整体净冲刷,泥沙冲刷总量0.68亿方,其中航道北侧冲刷量占87.9％,主槽上段冲刷深度最大,平均1.40m,下段次之(南侧0.10m北侧0.79m),中段淤积(南侧1.28m北侧0.59m).此外,还发现北槽河床冲淤分布,主要受整治工程影响,疏浚抛泥仅影响贮泥坑和抛泥区附近的局部区域,流域来沙量变化对北槽淤积量变化影响很小.     

大丰港一期工程码头区典型冲淤形态及形成原因分析

大丰港一期工程建成后,码头区出现码头北侧冲刷、南侧淤积的不对称冲淤形态,这种典型的冲淤形态对开敞海域强潮海区大型泊位码头的平面布置具有极大的启示作用。本文总结了一期工程码头区的冲淤形态特点并初步分析了这种冲淤形态形成的原因。     

分流淤积的理论分析及其计算

本文以输沙能力关系为基础,考虑不同的分流比和分沙比,对分流河道的悬移质淤积的机理进行了分析;导出淤积率、增淤率、淤积比和增淤比的估算公式.同时还给出了冲淤和增减淤的临界条件.根据不同的分流化和分步比及原河道冲淤判别数把分流淤积划分为四个区域,即冲刷减冲区、冲刷转淤积区、淤积增淤区和淤积减淤区,本文结论和实际资料的分析结果是一致的     

水库泥沙冲淤计算的数学模型

本文根据三门峡等水库的冲淤资料,建立水库冲淤计算经验关系式及描绘其相应冲淤部位,并利用微型计算机进行了计算。 对水库滞洪壅水运用时的出库输沙率采用排沙比法,其淤积形态由当时库容与进库水量建立的判别式来确定,并按当时库水位进行铺沙。建立出库挟沙率与进库来沙系数和库区比降的关系式,根据库区地形及沙量平衡计算库区冲刷量。     

长江中下游水沙与河床冲淤变化特性研究

利用长江干、支流水文和河道地形实测资料,研究了三峡工程运用前后坝下游水沙输移特性与河湖泥沙冲淤的时空格局和变化特征。结果表明：① 三峡工程建成运行后,长江中游洪峰流量减小,中水时间延长,汛后退水时间缩短,干流输沙量大幅减少,泥沙来源发生新变化,荆江三口分流分沙量继续减少;② 长江中游干流河势总体稳定,但河床沿程纵向冲刷强度与三峡水库运用前相比明显增大,且冲刷强度和发展速度均大于原预测值;③ 荆江三口洪道由蓄水前的淤积转为冲刷;④ 洞庭湖淤积速度大为减缓,鄱阳湖受河道采砂等影响,总体由淤积转为冲刷;⑤ 长江中游河、湖泥沙冲淤格局发生调整,三峡水库蓄水前长江中游河、湖呈淤积状态,蓄水后则呈冲刷状态。      

新水沙环境下青草沙水库外侧滩地形态调整特征及保护措施

采用青草沙水库周边2014—2019年实测水下地形数据，定量分析了各堤段滩地形态调整特征，基于MIKE21数值模型对护滩措施的效果进行了模拟。结果表明：2014年后青草沙水库外侧滩地基本未出现明显的淤积外延发展，且局部沙体逐渐萎缩，其中北堤中段外侧滩地头部大幅度冲退，最大距离近900 m(-5 m及-10 m等深线),沙体形态呈扁平化调整，须适时进行保护；新桥通道进、出口落潮主流略有偏转，向水库大堤侧靠近，影响滩地的冲淤过程；在青草沙外侧滩地头部沙体实施潜堤护滩措施后，北堤中段外沙体滩面流速整体明显减小，且对周边区域的水动力过程影响较小。     

汉江雅口枢纽坝下河道冲淤及水面线变化数值模拟

丹江口水库大坝加高完成、南水北调中线工程通水后,改变了汉江中下游水沙条件,梯级水库建设亦将改变河道边界条件。以汉江中游雅口至碾盘山河段为研究对象,采用一维水沙数学模型,研究了梯级水库运行后的河床冲淤变化及其对水面线的影响。研究结果表明:碾盘山枢纽未建时,雅口枢纽坝下河道呈整体冲刷态势,坝下河道水面线受河床冲刷下切而降低;碾盘山枢纽建成后,雅口枢纽坝下河道冲淤变化表现为近坝段微冲,其余河段淤积,总体呈淤积态势,河段水面线受河床淤积而抬升。研究成果可为枢纽工程、航道整治、防洪工程等设计和论证提供科学依据。     

水道地形观测误差分析及改进措施

水库建成后,水库淤积及坝下游冲刷是重点研究的内容。水道地形资料是分析研究水库淤积及坝下游河床冲淤演变的重要依据。通过水道地形观测误差来源及实测数据分析,提出了测深仪选型、等精度观测等改进措施,并在三峡水库淤积及坝下游荆江河段河床冲刷演变观测中得到成功应用。     

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.     

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.     

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。     

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.