阳澄西湖围堰施工中悬浮物输移扩散数值模拟

为了探究涉水工程建设对湖泊系统的影响,基于二维非稳态水动力模型,对阳澄西湖水动力进行数值模拟,并在水动力模拟正确的基础上建立悬浮物预测模型,模拟了不同风向、施工工况下阳澄西湖隧道围堰施工扰动水体所引起的阳澄西湖悬浮物输移扩散,分析了围堰施工对水域环境的影响.模拟结果表明:围堰抽排水引起的悬浮物浓度增加对水生态影响最为严...     

干旱区湖泊风生流特征研究

以新疆博斯腾湖为例,建立干旱地区湖泊三维水动力数学模型,通过对不同工况计算结果的比较分析,研究博斯腾湖风生流形成过程,环流结构和影响因素。结果可知,大湖区流场主要是由风场作用引起,而风向对大湖区环流结构有显著影响。风速大小的改变对博湖风生流形态的影响不大,风速越大,湖区水域流速越大,环流强度增加便于大湖区水体的交换。     

博斯腾湖湖流及矿化度分布研究

根据大型内陆湖泊水动力、气象、水环境特征，建立了博斯腾湖二维水动力、矿化度数学模型，预测分析了不同风场、水文条件、水资源调度方案对湖流、矿化度空间分布的影响。研究发现：风场是湖流、矿化度空间分布的主要影响因素：吞吐流对流场、矿化度分布的影响居次要地位，但在静风条件下，吞吐流对取(进)水口附近的局部水域水流流态及矿化度空间分布特征有较大影响；水资源开发利用将对湖泊环境产生一定影响，在进行水工建筑物布设时，应综合考虑风力、风向、吞吐流等各种因素，进行方案比选。     

扩散作用对静水湖泊水质浓度空间分布的影响

根据水域开阔的中小型浅水湖泊的水动力特征,建立了加入扩散项的湖泊移流模式,分析了污染物对流输移、降解作用、扩散作用对污染物浓度空间分布的影响。研究发现:在静风条件下,对流输移、降解作用是湖泊水质浓度空间分布的主要影响因素,扩散作用对湖泊水质浓度空间分布的影响居次要地位。但当排污流量较小且污染物浓度较高时,扩散作用对预测结果有一定的影响。在进行湖泊水质空间分布精确预测时,应综合考虑对流输移、降解及扩散作用等因素的综合影响。     

基于GPS的洪泽湖水流流场质点示踪及数值模拟

针对不同水文气象条件下湖泊真实流场描述的难题,通过在洪泽湖主要入口分别投放GPS示踪器,实现了对湖泊表层水流轨迹、方向的实时监测,形成洪泽湖初步流场图。野外示踪实验结果表明:流经湖泊中心区域的水流运动轨迹均为自西向东的曲线;入湖流量较小时水流难以进入湖泊中心流场,入湖流量较大时流速空间分布不均,流场较复杂;小流量入湖条件下水流运动受到湖泊表面风场的影响,流量较大时水流流动的主要影响因素为湖泊自身的流场。同时,构建了不同入湖流量条件下的洪泽湖二维水动力数值模型,水动力模型模拟的流场分布基本符合水流质点GPS示踪实验的结果,两者拟合较好。本次研究揭示了洪泽湖的真实流场,基于GPS的示踪方法可用于分析河流湖泊的水动力空间变化,为泥沙、污染物质的输移和扩散提供了重要参考依据。     

汾河水库水动力及水质数值模拟

汾河水库是万家寨引黄工程的调节水库和山西省最大的地表水饮用水源地,其上游河段的COD和TN有超标现象,故确定库区污染物的输移扩散规律并提出相应的保护措施对保证水库水质安全至关重要。以工程技术资料、DEM模型、遥感及GPS实测信息为基础,采用GIS技术将汾河水库边界和地形进行数字化处理;通过实测数据进行参数率定与模型验证,确定汾河水库的水动力模型和水质模型;将模型进行耦合联用,以汾河水库的水动力为基础,选取COD和TN进行数值模拟,计算污染物在不同进水浓度时库区污染物超标面积,以库区污染物超标面积百分比来表征水库受污染程度。模拟结果表明:风场是影响水库水动力的主要因素;在静风和主导风力作用下污染物分别沿地形和沿下风向堤岸扩散;污染物超标面积百分比与进水污染物浓度限值呈二次函数关系。     

中山河口近岸海域混合区敏感点访问几率研究

以黄海中山河口近岸海域水动力、污染物输移扩散规律及污染物排放量对附近海域影响为主要研究内容。建立二维水流、水质模型,利用有限体积法离散方程并对中山河口近岸海域的水动力状况及污染物输移扩散规律进行数值模拟;选用COD为主要的污染物指标,模拟计算污染物混合区,然后确定混合区内相对不利的3个敏感点,应用统计学原理,统计混合区近岸边缘污染物访问几率。     

波浪边界层中细颗粒粘性泥沙的再悬浮和扩散输移

本文用多尺度摄动方法从理论上推导了波浪边界中细颗粒粘性泥沙的再悬浮和扩散输移的规律，并用几个算例细致地分析了波浪对细颗粒经沙再悬浮和扩散输移的作用。指出：在近 岸及湖泊地位、波浪不仅是细颗粒粘性泥沙再悬浮的主要动力，而且其引起的泥沙扩散输称我工和风生流相当。     

大型浅水湖泊纳污能力核算的风场设计条件分析

分析了东南风、西北风及东北风3种不同主导风场下太湖的风生湖流形态特征、环流结构及湖流流速大小变化,研究了不同风生湖流特征条件下环湖入湖污染物的输移扩散规律和湖区水质空间分布特征差异,以及在不同主导风场和常年主导风向下风速变化对太湖各主要湖湾纳污能力的影响。同时,参照水情设计条件要求,选择相对不利的主导风向和保证率为90％时的风速,对太湖进行了纳污能力计算。计算结果表明：在平均风速1.0m/s的西北风和枯水年型设计来水条件下,太湖的CODMn、TP、TN指标纳污能力分别为29732t/年、393t/年和7550t/年,较常年主导风向及多年平均风速条件下的纳污能力分别减小13.5％、 11.3％、23.6％。     

潮滩围垦对近海潮流及污染物输移的影响研究

为研究潮滩围垦对潮流和污染物输移的影响,基于二维嵌套的水动力水质模型,以通州湾为例分别模拟了不同潮滩围垦工程前后的潮流场及污染物浓度场,并用实测资料对模型进行验证,据此分析潮滩围垦作用下的流速变化和以COD为污染指标的物质输运特征。研究结果表明:通州湾围垦工程具有一定的阻水作用,且在围垦一、围垦二的堤头出现了局部挑流现象,其余海域的流速流向基本没有变化;潮滩围垦阻碍了通州湾南侧海域高浓度污染物的输移扩散,改变了该海域的污染物浓度场,且随着围垦范围的扩大,局部污染物浓度有所增加。综上所述,潮滩围垦改变了潮滩地形、水动力环境特征和污染物输移扩散能力,进而影响到潮滩的水文状况和水质环境。     

Finite Element Circulation Model for Lake St. Clair

In the numerical modeling of a toxic chemical in a lake, it is necessary to solve the hydrodynamics of the transporting flow as well as the transformation processes of the pollutant in the lake. It is important to calibrate and verify the model before predictive applications. A simple numerical hydrodynamic model which includes wind stress, bottom friction, Coriolis force, inflow, outflow, and the bottom topography of the lake has been developed and verified with field data for Lake St. Clair. The overall root mean square differences between predicted and measured current magnitudes and directions were 1.30 cm s^-1 and 22.5°, respectively, while the correlation coefficients were 0.99 and 0.95, respectively. The hydrodynamic model was tested for stability, convergence, and sensitivity to parameters such as wind shear, wind direction, and vertical eddy viscosity effects. This model is used to generate the typical lake circulation patterns for different steady state wind and ice conditions that are required for the long-term pollutant simulation models such as the EPA (TOXIWASP) model. The depth average velocities were also used in a finite element pollutant transport model. An upwind finite element formulation was used to obtain a stable solution for the convective transport phenomena. The predicted pollutant (chloride ion) concentration pattern was compared with observed field data and fairly good agreement was obtained.     

Numerical study of hydrodynamic process in Chaohu Lake

In this paper, the hydrodynamic characteristics of water flow in Chaohu Lake are studied by using the finite volume coastal ocean model(FVCOM), which is verified by the observed data. The typical flow field and the 3-D flow structure are obtained for the lake. The flow fields under extreme conditions are analyzed to provide a prospective knowledge of the water exchange and the transport process.The influence of the wind on the flow is determined by the cross spectrum method. The results show that the wind-driven flow dominates most area of the lake. Under prevailing winds in summer and winter, the water flows towards the downwind side at the upper layer while towards the upwind side at the lower layer in most area except that around the Chaohu Sluice. The extreme wind speed is not favorable for the water exchange while the sluice's releasing water accelerates the process. The water velocity in the lake is closely related with the wind speed.     

博斯腾湖矿化度影响因子的敏感度分析

水位,吞吐流,风场从不同机理不同程度影响着博斯腾湖的矿化度分布。本文在定性分析博斯腾湖矿化度分布的影响因子的基础上,建立水流-盐度数学模型,通过采用单因子影响的分析的方法,进行矿化度分布对各影响因子的敏感度分析。研究表明:风场对博湖矿化度分布的影响最为明显,水位和吞吐流对博湖矿化度分布的影响均不明显。该研究对博湖的水环境综合治理有一定的指导意义。     

Current variability in a wide and open lacustrine embayment in Lake Geneva (Switzerland)

Field measurements and numerical simulations were used to determine the effects of dominant meteorological conditions on the hydrodynamics of a wide (aspect ratio ~ 2), relatively deep (seasonally stratified) and open lake embayment (Vidy Bay, Lake Geneva). A three-dimensional hydrodynamic model (Delft3D-FLOW) was employed to simulate flow in the lake. High-resolution maps of wind, temperature and humidity (over the lake) were applied as input to drive the model. Because wind was the main force driving flow in the lake, currents in the embayment were investigated systematically for different wind conditions and seasonal stratification. Satisfactory model validation was achieved using drifter and moored measurements within the embayment. Markedly different circulation patterns were measured within the embayment, with the transition from one pattern to another occurring abruptly for small changes in wind direction. These distinct patterns resulted from relatively small changes in the large gyre of Lake Geneva's main basin, especially the angle between the current in front of the embayment and the embayment shoreline. The boundary between the embayment and the pelagic zone was defined by the largest gyre within the embayment. This study shows that, (i) in a large lake, complex current patterns can occur even within a minor embayment, and (ii) that these patterns can transition rapidly over a small range of wind directions. Near-shore gyre can occur for lengthy periods, which has implications for flushing of discharges within the embayment.     

大型浅水湖泊水动力特性数值分析

准确模拟太湖水流动态变化特性及水动力特征对模拟、预测污染物迁移转化规律以及理解水流运动与污染物相互作用机制具有重要的实用价值。以环境流体力学(EFDC)模型为基础,收集2009年-2010年水文、气象数据及湖区地形数据,并考虑引江济太工程对湖区的影响,建立符合太湖湖区水流特性的水动力模型。模型模拟结果表明最大风向、最大风速的组合方式模拟出来的流场情况最接近真实湖体流场,引江济太工程对湖流的影响微小,模型的水动力模拟效果良好。     

洪泽湖换水能力的时空分布特征EI北大核心CSCD

为研究洪泽湖换水能力的时空分布特征,基于MIKE21建立洪泽湖二维水动力模型,模拟分析了洪泽湖不同湖区的换水周期;考虑洪泽湖的流场呈现风生流和吞吐流双重特点,分析了不同季节和不同风场条件下换水周期的空间变化特征。结果表明:洪泽湖换水周期空间异质性明显,从南到北梯度递增,冬季和春季全湖平均换水周期较长,分别为75 d和60 d,秋季和夏季的全湖平均换水周期较短,分别为49 d和31 d;实际风场对洪泽湖的换水能力起到正向作用,东南风对洪泽湖的换水能力起正向作用,东北风对洪泽湖的换水能力起到抑制作用。     

Wind Fields over the Great Lakes Measured by the SeaWinds Scatterometer on the QuikSCAT Satellite

This paper demonstrates the utility of satellite scatterometer measurements for wind retrieval over the Great Lakes on a daily basis. We use data acquired by the SeaWinds Scatterometer on the QuikSCAT (QSCAT) satellite launched in June 1999 to derive wind speeds and directions over the lakes at a resolution of 12.5 km, which is two times finer than the QSCAT standard ocean wind product at a resolution of 25 km. To evaluate QSCAT performance for high-resolution measurements of lake wind vectors, we compare QSCAT results with Great Lakes Coastal Forecasting System (GLCFS) nowcast wind fields and with standard QSCAT measurements of ocean wind vectors. Although the satellite results over the Great Lakes are obtained with an ocean model function, QSCAT and GLCFS wind fields compare well together for low to moderate wind conditions (4–32 knots). For wind speed, the analysis shows a correlation coefficient of 0.71, a bias of 2.6 knots in mean wind speed difference (nowcast wind is lower) with a root-mean-square (rms) deviation of 3.8 knots. For wind direction, the correlation coefficient is 0.94 with a very small value of 1.3° in mean wind direction bias and an rms deviation of 38° for all wind conditions. When excluding the low wind range of 4–12 knots, the rms deviation in wind direction reduces to 22°. Considering QSCAT requirements designed for ocean wind measurements and actual evaluations of QSCAT performance over ocean, results for high-resolution lake wind vectors indicate that QSCAT performs well over the Great Lakes. Moreover, we show that wind fields derived from satellite scatterometer data before, during, and after a large storm in October 1999, with winds stronger than 50 knots, can monitor the storm development over large scales. The satellite results for storm monitoring are consistent with GLCFS nowcast winds and lake buoy measurements. A geophysical model function can be developed specifically for the Great Lakes using long-term data from satellite scatterometers, to derive more accurate wind fields for operational applications as well as scientific studies.