芦苇类典型挺水植物对水流的影响模拟研究

水生植物对河道水流的水力学特性及物质输运有着重要的影响。基于FLOW-3D流体计算模型,建立了芦苇类挺水植物RNG k-ε三维湍流模型,研究了两种典型密度条件下非淹没植物水流的时均流和湍流特性。模型验证表明该模型可以较好地模拟芦苇类挺水植物对水流结构的影响问题,模型计算结果表明植被区上游流态比较均匀,水流流速分布符合对数分布,植被区尾部流速达到最大。含不同密度植被水流的湍流动能和湍流动能耗散率空间分布规律一致,并表现为植株尾流区的湍流动能耗散率较大。     

航道整治工程泥沙数学模型的构造及计算方法

建立了正交曲线坐标系下二维紊流全沙数学模型，水流模型采用紊动动能和紊动耗散率闭合雷诺方程，把悬移质输沙概化为单纯淤积、单纯冲刷和淤粗冲细三种情况，依据悬沙与床沙交换机理建立了挟沙能力和非均匀沙分组挟沙能力的表达式．在水流输运及分组含沙量输运方程的离散过程中，采用守衡性较好的控制体积法和SIMPLEC计算程式，以提高计算稳定性和加快收敛．本模型对复杂条件的河床适应性较强，为平面二维长河段的河床变形计算进一步创造了条件．     

沉湖特大桥对河道防洪影响的数值模拟

为了分析沉湖特大桥对汉江沉湖河段的防洪影响情况,建立了非正交曲线坐标下平面二维水流数学模型,并应用该模型对汉江沉湖特大桥修建前后的水流运动情况进行了模拟。模型计算结果表明,桥梁修建后对工程附近河段水位和流速影响均较小,基本上不会对沉湖河段防洪产生不利影响。     

正交曲线坐标下三维代数应力通量模型

针对弯曲及不规则明渠的水动力及物质输运特性，本文建立了曲线坐标系下的三维代数应力通量数学模型，对平面上弯曲及不规则复杂边界情形，采用Poisson方程进行正交曲线坐标变换，各向异性的湍流代数应力通量模型被引用于本文的模拟计算中，以体现复杂边界条件引起的水动力及物质输运特性的变化。通过180度强弯曲明渠水槽及贵溪电厂不规则边界河段物理模型试验两个实例计算表明，实测值与计算吻合良好，效果令人满意。     

东风船舶公司船台滑道改造数学模型研究

由于工程修建后必然对河道水位和流态产生影响,为评价拟建工程对河道行洪、通航等方面影响大小,优化工程结构设计,采用非正交曲线坐标下的平面二维水流数学模型,对船台滑道改造前后河段水流情况进行了数值模拟。计算结果表明,工程修建后对附近河段水位和流速影响均很小,不会对河道河势、通航、行洪等方面带来不利影响。     

受植被影响的弯曲渠道水流平面二维湍流数值模拟

针对受植被影响的渠道水流流动特征,建立了有植被作用下的曲线坐标平面二维肛κ-ε双方程湍流数学模型.模型采用两种方法处理植被对水流的影响:拖曳力法和等效阻力系数法.并通过对实验室局部带有刚性植被的弯曲水槽进行模拟研究,得到了水位等值线图、速度矢量场图及测量断面速度,并与实测值进行对比,结果表明:计算结果和实测值符合较好.表明分别采用拖曳力法和等效阻力系数法建立的植被作用下的平面二维数学模型均可对河滩湿地及有植被作用的河道流动进行数值模拟.     

基于惯性耗散法的峡口岬角地形能耗分析

珠江河口峡口岬角地形(或者称"门")是珠江河口典型的高能耗区,研究其消能机制,对于解释珠江河口宏观动力现象,提高对河口动力过程的认识有重要意义。本文设计了峡口岬角局部突变地形的湍流能耗特性物理模型试验,采用Son Tek 16MHz ADV采集了高频流速数据,统计了时均流速及湍流特征量。利用"惯性耗散法"计算了峡口岬角突变地形与明渠水流的湍流动能耗率。峡口岬角地形的突变特征产生明显的形态阻力,本文试验工况引起的紊动强度量值是明渠的2倍到10多倍,湍流剪切应力较明渠水流大近2个数量级,湍流动能是明渠水流的40多倍,湍流动能耗散率比明渠水流湍流动能耗散率大2~3个数量级。从湍流局部平衡及能量传递理论看,峡口局部形态阻力导致时均流速的空间梯度、切应力增大及形成大量更小尺度的涡是湍流能耗率增加2~3个量级的重要原因。     

非正交曲线坐标系平面二维电厂温排水模拟

结合河道水流及温排水的运动特性，从非正交曲线坐标系下温排水基本方程出发，采用有限体积法及SIMPLE算法离散求解方程，建立了基于非正交曲线坐标系下非交错网格的平面二维温排水数学模型．用该模型模拟天然河流电厂温排水运动的计算结果表明，该数学模型能合理反映河段电厂温排水运动。     

挑流消能水气二相流数值模拟

采用VOF法对挑流消能从库区到下游水垫塘进行了全程水气二相流二维数值模拟。模拟了射流的空中轨迹线和水垫塘的自由水面，得到了计算域的流线、压力、流场、紊动能k及紊动能耗散率ε分布，并用物理模型对模拟结果进行了验证，二者吻合良好。说明利用湍流二相流模型及VOF法对空中射流水舌及水垫塘流态模拟是可行的。     

黄河下游平面二维非恒定输沙数学模型：Ⅰ—模型方程与数值方法

黄河下游冲淤变形剧烈，其平面二维泥沙数学模型的研究与开发是一个极其复杂的难题，在学术与工程实践上都具有重要意义。本文构建起具有通用性的黄河下游平面二维非恒定输沙数学模型。在该模型中：采用修正的河床变形方程；克服了以往数学模型计算中取饱和恢复系数小于1的缺陷；引入了符合黄河下游河道水沙特点的水流挟沙力和河床糙率计算等公式。在数值方法上：采用边界拟合坐标，对水流连续性方程与动量方程采用交错网格上的ADI方法进行离散求解，对泥沙连续性方程则采用控制容积法进行离散。     

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.     

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.     

The Impact of Economic Development on Water Pollution: Trends and Policy Actions in Malaysia

The paper examines the impact of development activities on water pollution in Malaysia. Hence, the main objective of this paper is not just to examine the trends of development-induced water pollution around the region of the country but to know where the problems are and the policy measures taken by the government. It evaluates the probable causative relationship between problems introduced due to technology employed in water pollution control and governmental policy measures. It examines the relationship between development indicators as sources of pollution and polluted rivers over a period of 12 years. The findings of the paper have shown that despite the policy enforcement actions against the identified sources of water pollution, all the three development indicators (chosen based on those identified sources) still accounted for high percentage of river pollution in Malaysia. The findings of the paper were used to identify the central fact of the location of the problem. Some crucial conclusions of where the problems likely to be, as reflected in the findings, are: (a) the issue of interactive-effects between pollutants that many policy-makers are not aware of. This is when policy measures concentrate only on one source of water pollution; (b) the enforcement strength and/or effectiveness of policy measures themselves; (c) financial constraints to invest in appropriate technology especially sewerage systems for controlling human source of water pollution in the country; as well as those confronting small polluting industries (d) finally, lack of cooperation between government and private business firms to comply with regulatory policies for water pollution control.     

Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.     

Seasonal variation in nutrient retention during inundation of a short‐hydroperiod floodplain

Floodplains are generally considered to be important locations for nutrient retention or inorganic‐to‐organic nutrient conversions in riverine ecosystems. However, little is known about nutrient processing in short‐hydroperiod floodplains or seasonal variation in floodplain nutrient retention. Therefore, we quantified the net uptake, release or transformation of nitrogen (N), phosphorus (P) and suspended sediment species during brief periods (1–2 days) of overbank flooding through a 250‐m floodplain flowpath on the fourth‐order Mattawoman Creek, Maryland U.S.A. Sampling occurred during a winter, two spring and a summer flood in this largely forested watershed with low nutrient and sediment loading. Concentrations of NO increased significantly in surface water flowing over the floodplain in three of the four floods, suggesting the floodplain was a source of NO. The upper portion of the floodplain flowpath consistently exported NH, most likely due to the hyporheic flushing of floodplain soil NH, which was then likely nitrified to NO in floodwaters. The floodplain was a sink for particulate organic P (POP) during two floods and particulate organic N and inorganic suspended sediment (ISS) during one flood. Large releases of all dissolved inorganic N and P species occurred following a snowmelt and subsequent cold winter flood. Although there was little consistency in most patterns of nutrient processing among the different floods, this floodplain, characterized by brief inundation, low residence time and low nutrient loading, behaved oppositely from the conceptual model for most floodplains in that it generally exported inorganic nutrients and imported organic nutrients. Published in 2007 by John Wiley & Sons, Ltd.     

浅淡溢洪道改扩建方案与选择

溢洪道改扩建和进行溢洪道方案布置，要择优选取溢洪道进口型式、防冲消能工，以使其工程量省、施工快、运行管理方便     

Experience in the Introduction of Steam-Water-Oxygen Cleaning, Passivation, and Preservation at the TÉTs-23 Cogeneration Plant of the Mosénergo Company

Conditions of the process of steam-water-oxygen cleaning, passivation, and conservation (SWOC, P, and C) of internal heating surfaces of the boiler and the high-pressure feed heater (HPFH) piping over the steam side are presented. The process produces partial cleaning of the internal heating surfaces from scale and yields a corrosion-resistant protective film that hinders corrosion processes both in the operation of the boiler and in the idle period.     

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。