大型浅水湖泊三维水环境数值模拟及关键参数研究

浅水湖泊也存在水动力垂向分层结构及污染物垂向非均匀分布情况,水力结构对水环境变化有重要影响,需要采用更加精细化的数学模型模拟其过程。针对国内外大型浅水湖泊三维水环境数值模拟相关研究及水动力参数取值方案进行了综述,对现有成果进行了总结与分析。指出下一步亟需构建复杂边界条件下的生态动力学模型,探索多条件耦合的富营养化微观响应机制,加强数值模拟精细化及参数规范化研究,为探索浅水湖泊水动力及水环境提供理论依据和技术支撑。     

海上溢油数值模拟研究进展

为了更好地处置溢油事故对海洋环境造成的污染,运用数值模拟预测溢油流散规律对有效围控油品泄漏后的扩散范围意义重大。文章分析了溢油模拟研究面临的难题,分别从油膜扩展、动力漂移、油膜粒子化和风化作用4个方面综述了溢油基础模型的发展。结合最新研究成果阐明了溢油数值模拟发展现状,对比分析了当前国内外广泛应用的溢油模型及软件的原理、适用条件及优缺点。在此基础上,指出目前溢油数值模拟存在的问题及今后的研究重点,指出一种运用欧拉-欧拉法建立溢油模型的新思路。     

溢油对地表水体影响预测模型的搭建

以M原油管道在穿越N江处发生溢油事故为例,探讨了溢油对地表水体的影响、以及预测该影响所使用的预测模型。通过对石油类物质与水动力条件的作用分析,分析了一维水动力模型、污染物对流扩散模型的原理,探讨了两种模型的搭建。使用MIKE 11软件在河流水动力与污染物迁移两方面建立了预测模型,为后续模拟预测工作奠定了理论与模型基础。     

芬顿法和湿式过氧化氢氧化法处理醇酮模拟水的研究

以醇酮模拟水为研究对象,系统考察了芬顿法和湿式过氧化氢氧化法主要因素的影响规律,其中包括H2O2加量、pH值、Fe2+加量、反应时间等。通过单因素实验分别得到较优的反应条件。在较优条件下,芬顿法使醇酮模拟水的COD去除率达到73.40%,B/C由原来的0.15提高至0.30;湿式过氧化氢氧化法使醇酮模拟水的COD去除率达到73.12%,B/C提高到0.36。两种处理方法较大的提高了醇酮模拟水的可生化性,为后续的深度处理创造了条件。     

水动力模式在溢油研究中的应用

文章将对POM/ECOM、FVCOM、EFDC、DELFT3D、MIKE21等常用的水动力模式做简单介绍,将国内外学者近期关于这些模式在溢油中应用的研究进行总结,讨论了水动力模式在溢油研究中的重大作用。文章认为当前的水动力模式已经发展到了比较成熟的阶段,除了对于一些复杂地形其计算精度仍有待提高外,一般情况下均能取得较好的效果。     

三亚湾海岸动力演变的数值模拟研究

近年来,海岸侵蚀呈现不断加剧的趋势,给沿海地区经济社会的发展造成了极大危害。关于三亚湾海岸侵蚀过程及其动力学研究多停留在定性或半定量阶段。从海岸动力地貌学角度出发,基于沉积物迁移理论,利用数值模拟方法,定量研究了三亚湾海岸在波浪和潮流作用下的动力演变过程。计算结果重现了海水波浪的传播形态及动态特征:涨潮时,波高极值相对较大,水位随之升高,波动现象明显,波动形态复杂;落潮时,波高极值相对减小,水位也随之降低,海面相对较平静,波形态在离岸区域较单一,仅在近岸区域相对多样化。同时,数值模拟结果也很好地显示了三亚湾岸线附近的沉积或侵蚀过程特征:三亚湾西段海洋动力条件较强,沉积或侵蚀现象明显,沉积/侵蚀能力由三亚湾西段逐渐向东段减小。此外,以海洋动力学机制为基础,定量模拟了三亚湾海岸侵蚀与演变物理过程,为该地区海岸开发利用、海岸环境保护提供科学依据。     

内陆河流水体跨越管道溢油模拟及应急对策

介绍了内陆河流水体跨越管道溢油模拟技术与基本流程,以西北地区某河段油品跨越管道为研究对象,分析发生管道泄漏突发溢油事故的风险,考虑丰/枯水期、强/静风、泄漏位置等影响因素,设计构建了12种溢油突发事件情景,应用MIKE21模拟软件建立水动力模型,并分析不同情景下的溢油漂移扩散规律。根据模拟计算结果并考虑河流自身特点,确定了高风险水域多个应急处置关键断面,给出了不同应急处置关键断面的有效应急时间,为溢油突发事件应急准备工作提供了技术支持。     

国内关于旅游发展动力机制研究述评

旅游发展是一项系统工程,涉及到经济、社会、文化以及发展政策、旅游资源、消费趋势、旅游产品等方面的因素而不断发展.从旅游发展动力机制的角度,着重对我国旅游发展动力机制研究的理论框架、动力机制类型、区域旅游发展动力机制以及相关的案例进行述评,并结合当前我国旅游发展动力机制研究的趋势和重点,对旅游发展动力机制研究进行展望.     

京沪高速铁路跨阳澄湖特大桥不同施工方案SS浓度场模拟研究

为了对比京沪高铁双排筑坝围堰施工和钢栈桥施工两种施工方案对阳澄湖西湖湖区SS浓度场的影响程度,探讨阳澄湖大桥施工方式对阳澄湖SS浓度场的影响规律,开展阳澄湖现状水质监测,采用Delft-3D可视水动力-水质联合模拟软件系统对SS浓度场进行模拟研究。结果表明,相对于栈桥施工,双排筑坝围堰施工对水体SS浓度影响较小,对阳澄湖水环境保护作用明显。     

新沟河排水对太湖水环境影响研究

太湖西北部尤其是梅梁湖水质较差,新沟河延伸拓浚工程实施后,可通过外排梅梁湖水改变太湖的水动力水质环境.利用Mike21建立太湖二维水动力水质数学模型,研究该工程实施后对太湖水动力水质的影响.研究得到:新沟河工程实施后,可有效改善梅梁湖的水动力条件,梅梁湖换水周期缩短13.3％;同时,梅梁湖CODMn、 TP、TN等主要...     

Indicators for hydraulic and pollution retention assessment of stormwater infiltration basins

Infiltration basins are frequently used for stormwater management even though their long-term evolution is not well understood nor controlled. The two main problems encountered are clogging which compromises the hydraulic capacity of the basin and possible contamination of underlying soil and groundwater. This paper defines a framework for evaluating the hydraulic and pollution retention performance of infiltration basins in the long-term. Sets of context and performance indicators are proposed, along with two complementary modes of evaluation. Context indicators are identified in order to define the clogging and contamination states of the basins. Performance indicators are developed to assess several aspects of basin performance: drainage duration, overflow frequency, predictive life period, particle filtration and pollution trapping. Modes of evaluation include field investigation and long-term simulation modeling. Indicators are tested on five infiltration basins in suburban Lyon (France). Both context indicators and hydraulic performance indicators are reliable and their evaluation is representative of basin behavior. This is not the case for pollution retention performance indicators. Their assessment is difficult because of data quality. Field data has high uncertainties. The model is satisfactory for the hydraulic simulation and the evolution of clogging. Improvements are necessary for pollution flow simulation and the acquisition of better quality data is required.     

MODELING PERCOLATION LOSSES FROM A PONDED FIELD UNDER VARIABLE WATER-TABLE CONDITIONS1

ABSTRACT: A numerical simulation model was developed to predict the vertical and lateral percolation losses from a ponded agricultural field. The two-dimensional steady-state unsaturated/ saturated flow equation was solved using the finite-difference technique. A constant ponding depth was maintained at the soil surface with different water table conditions in an application of the model for rice fields bordered by bunds. Field experiments were conducted for two different water table depths to collect data on the spatial distribution of volumetric soil-moisture content for model verification. The measured soil-moisture content values were found to be in close agreement with those predicted by the model. The sensitivity analysis of the model with selected hydrologic conditions shows that the model is most sensitive to the values of saturated hydraulic conductivity, but relatively less sensitive to water table depth, ponding depth, and evaporation rate from the soil surface. It implies that, in a ponded rice field condition, the lateral and vertical percolation losses are mostly governed by the hydraulic conductivity of the soil. The vertical percolation losses were almost equal to the saturated hydraulic conductivity values and, in most cases, these losses increased with deeper water table depths. The lateral percolation losses also increased with deeper water table depths; however, these losses were relatively small in comparison to the vertical percolation losses. The vertical and lateral percolation losses increased with the increase in ponding depths. The lateral percolation losses through the bund decreased when the evaporation losses increased from the soil surface. The results of this study indicate that the percolation losses from a ponded field may be predicted accurately for a wide range of soil and hydrological conditions when the values of hydraulic conductivity, evaporation rate, depth of ponding, and water table depth are accurately known.     

流域非点源分布式模型AnnAGNPS参数的不确定性研究

流域非点源分布式模型的不确定性研究成为目前的热点问题之一。本研究以宁波市章溪河流域为研究区，通过GIS软件AreView和AnnAGNPS模型，集成利用莫里斯分类筛选法，选取临界源面积、SCS曲线系数、水土保持因子、饱和导水率、氮磷吸收率、施肥量等6个因子进行敏感性分析。模拟结果表明，土壤饱和导水率、水土保持因子和径流曲线CN值对模型输出结果影响较大；水土保持因子对泥沙、总磷和总有机碳负荷的模拟结果影响最大，均呈显著负效应；径流曲线CN值对总氮负荷计算结果影响最大，呈显著正效应。     

UNSATURATED FLOW THROUGH SOLID WASTE LANDFILLS: MODEL AND SENSITIVITY ANALYSIS1

ABSTRACT: The movement of precipitation water infiltrating through the material (refuse) of solid waste landfills is examined via numerical solution of the equations of continuity, and motion (Darcy's Law). The solution of the equations is obtained by a fully implicit, finite-difference scheme. Both unsaturated and saturated surface conditions are considered, making the scheme suitable for real-time simulation of net precipitation and moisture redistribution events. A sensitivity analysis showed that for unsaturated surface conditions the solution is primarily affected by hydraulic conductivity and capillary diffusivity, and is relatively independent of the space and time steps. In addition, the precipitation averaging process is shown to be critical in the correct computation of moisture transport during the time period where the transition from unsaturated to saturated conditions occurs. The model presented herein is suitable for analysis of water movement through landfills, and the design of bottom collection systems.     

ESTIMATING THE PROBABILITY OF EXCEEDING GROUNDWATER QUALITY STANDARDS1

ABSTRACT: A model for estimating the probability of exceeding groundwater quality standards at environmental receptors based on a simple contaminant transport model is described. The model is intended for locations where knowledge about site-specific hydrogeologic conditions is limited. An efficient implementation methodology using numerical Monte Carlo simulation is presented. The uncertainty in the contaminant transport system due to uncertainty in the hydraulic conductivity is directly calculated in the Monte Carlo simulations. Numerous variations of the deterministic parameters of the model provide an indication of the change in exceedance probability with change in parameter value. The results of these variations for a generic example are presented in a concise graphical form which provides insight into the topology of the exceedance probability surface. This surface can be used to assess the impact of the various parameters on exceedance probability.     

污水海洋处置等截面扩散器水力特性的研究

本文就污水海洋处置中等截面扩散器的水力分配问题,结合上海市污水排海工程实际进行了模型试验,并在建立的水力特性模式基础上对排放口局部阻力系数进行了分析率定,经检验与试验其他结果相吻合,说明采用的模式是可行的,对同类研究具有一定的参考价值。     

OPTIMIZATION OF TRANSPORTATION NETWORKS DURING URBAN FLOODING1

ABSTRACT: In this paper a numerical model for flood propagation in urban areas is proposed. It has been applied to evaluate flooding hydraulic characteristics in terms of potential flood elevations, depths, and inundated areas. Furthermore, the algorithm efficiency and the consequent reduced computation time allow the use of the hydraulic model as a part of a more complex system for civil protection actions, planning, and management. During flood events, the transportation network plays a main role both in rescuing people when they are more vulnerable and in moving people and materials from and toward affected areas. The reduced efficiency of this transportation network is evaluated based on a least‐flood‐risk path‐finding algorithm. The results of a case study concerning the northern part of the city of Rome, show that the numerical model for unsteady flow in open channel networks achieves the proposed aims. It has proven to be able to describe the flood hydraulic characteristics and to be suitable for real‐time flood emergency management in urban areas.     

碟形越浪式波能发电装置的三维数值模拟

基于计算流体力学软件的三维数值模拟技术,分析了碟形越浪式波能发电装置的越浪性能,通过构建基于水气两相VOF(Volume of Fluid)模型的三维数值波浪水槽对该装置进行三维数值模拟研究,数值计算结果与物理试验结果相互对比验证较为吻合,验证了所构建的三维数值波浪水槽的可靠性,通过考察装置的坡度、导流叶片个数、干舷高度对越浪性能的影响确定装置的最优结构参数。结果表明,在装置的斜坡面边缘增加回流板可减少波浪的反射,提高装置的越浪性能。在数值模拟中将装置的斜坡面边缘处安装回流板对碟形越浪式波能发电装置参数进行优化,通过分析回流板的长度对装置越浪性能的影响来探索最优回流板长度。     

Tailoring dam structures to water quality predictions in new reservoir projects: Assisting decision-making using numerical modeling

Selection of reservoir location, the floodable basin forest handling, and the design of dam structures devoted to water supply (e.g. water outlets) constitute relevant features which strongly determine water quality and frequently demand management strategies to be adopted. Although these crucial aspects should be carefully examined during dam design before construction, currently the development of ad hoc limnological studies tailoring dam location and dam structures to the water quality characteristics expected in the future reservoir is not typical practice. In this study, we use numerical simulation to assist on the design of a new dam project in Spain with the aim of maximizing the quality of the water supplied by the future reservoir. First, we ran a well-known coupled hydrodynamic and biogeochemical dynamic numerical model (DYRESM–CAEDYM) to simulate the potential development of anoxic layers in the future reservoir. Then, we generated several scenarios corresponding to different potential hydraulic conditions and outlet configurations. Second, we built a simplified numerical model to simulate the development of the hypolimnetic oxygen content during the maturation stage after the first reservoir filling, taking into consideration the degradation of the terrestrial organic matter flooded and the adoption of different forest handling scenarios. Results are discussed in terms of reservoir design and water quality management. The combination of hypolimnetic withdrawal from two deep outlets and the removal of all the valuable terrestrial vegetal biomass before flooding resulted in the best water quality scenario.     

EVALUATION OF AN INDUCED INFILTRATION MODEL AS APPLIED TO GLACIAL AQUIFER SYSTEMS1

ABSTRACT: Numerical models were used to examine the limitations of the assumptions used in an analytical induced infiltration model. The assumptions tested included negligible streambed effects, negligible areal recharge, two-dimensional ground water flow, fully penetrating rivers and wells, and constant surface water stage. For situations that deviate from the underlying assumptions, the analytical model becomes a less reliable predictor of induced infiltration. The numerical experiments show that streambed effects cannot be neglected if the streambed conductivity is more than one order of magnitude lower than the aquifer hydraulic conductivity. Areal recharge cannot be neglected if the ground water basin receives more than 5 in/yr of areal recharge. Three-dimensional flow effects due to well partial penetration cannot be neglected if the ratio of horizontal hydraulic conductivity to vertical hydraulic conductivity (K_h/K_u) is greater than 10. Surface water elevation fluctuations can significantly influence the induced infiltration rate, depending on the degree of fluctuations and the ground water hydraulic gradient.