港口疏浚产生悬浮物三维数值模拟

为研究港口疏浚产生悬浮物的输运规律，建立了三维潮流及悬浮物数学模型，模型中主 要考虑了潮流等因素作用下悬浮物的三维输运以及悬浮物的扩散、沉降和再悬浮作用。将模型应用于大丰港拟建码头疏浚区疏浚产生悬浮物输运数值模拟预测，模拟了工程海域潮流场及悬浮物浓度场，并根据预测结果初步分析了其对水环境的影响。分析结果表明，疏浚对海水水质影响很小，且影响主要集中于施工期。     

典型城市型湖泊风生流的数值模拟

湖流是湖泊中污染物扩散、悬浮物沉降及输移等的主要水动力学要素。造成湖水运动的成因机制很复杂，其中风生流是重要形式。通过应用无结构网格有限体积法sher格式的二维水流数值模型，对不同风情下的典型城市型湖泊——南京市玄武湖湖流流态进行模拟研究，探讨其吞吐流较小，沿岸无人流的情况下的风生流特征。     

河道温度及浓度场的平面二维数值模拟

 立了河道水流、温度及浓度输运的水深平均平面二维数值模拟模型，由模拟水流、温度及浓度和紊流3个子模型组成。该模型在计算定解条件 模型参系数取值、河道岸边界和动边界模拟以及水流自动调整计算思想等方面进行了适用可行的处理。应用该模型进行了试验室空腔水槽温度和含沙量场以及长江口南支河段温排水及盐水入侵的数值模拟计算，证明了模型的可行性和适用性。     

长江口二维非均匀悬沙数值模拟

针对长江口水流泥沙运动的特点建立了非均匀悬沙的平面二维数值模型。在模型中考虑了波浪对流场的影响和对水流挟沙力的影响 ,在确定悬沙絮凝沉速时考虑了泥沙粒径、盐度、含沙量及水流紊动的影响。悬沙模型建立在曲线坐标下 ,悬沙输运方程采用破开算子的方法求解 ,平流项采用UltimateQuickest格式求解 ,提高了计算的精度。通过实测资料对数学模型计算的悬沙含量进行检验 ,表明它较好地反应了长江口地区泥沙的运动规律     

长江中游分汊型河道二维水沙数值模拟

针对长江分汊型河道边界复杂的特点,建立了基于多连通域贴体正交曲线坐标系下的二维水沙数学模型.模型采用有限差分法离散平面二维水流运动方程和泥沙输运方程,通过非恒定流多个时间步逼近模拟恒定流的方法,模拟了多分汊河段的水位、流速场及泥沙场.将所建模型初步应用于长江中游典型分汊河段--窑监河段的水沙过程模拟,结果表明模型能较好地模拟分汊河道的水沙运动规律.     

汕尾电厂进港航道疏浚悬浮物扩散数值模拟

利用交替方向隐格式(ADI法),首先对工程海域潮流场进行了数值模拟,进而建立了工程海域疏浚悬浮物的二维输运——扩散模型,并应用于汕尾电厂进港航道疏浚区的悬浮物输运扩散数值模拟预测,根据预测结果分析了进港航道疏浚区施工期间悬浮物对附近水环境的影响。     

高含沙水库泥沙运动数学模型的研究及应用

通过修正泥沙运动基本方程，并采用水流挟沙力、河床糙率、异重流计算等方面的最新研究成果，建立起高含沙水库泥沙数学模型。通过选择黄河三门峡水库及巴家嘴水库的泥沙观测资料进行仿真计算，证明了所建模型的可靠性。并应用该数学模型模拟泾河东庄水库泥沙淤积及排沙规律，取得了与泥沙模型试验结果相接近的计算成果，表明该模型具有模拟高含沙水流运动、溯源冲刷、泥沙级配变化、异重流运动等功能。     

灌溉田块中污染物流失规律的数值模拟及其验证

本文将土壤中水流运动和溶质迁移结合,考虑降雨、扩散和对流作用对溶质地表径流损失的影响,对溶质的地表损失规律进行研究,建立了新的水流和溶质迁移模型。通过室内土壤实验对该模型进行了验证,实验数据和模拟结果吻合良好。此模型可用来分析灌溉田块中溶质地表及地下流失,为农业面源污染分析提供参考。     

受潮汐影响的镇江内湖水沙通量研究

内湖与长江直接相通,在径流与潮流双重作用下,其水量、悬沙交换规律复杂多变.本文建立了内湖二维水流-悬沙耦合数学模型,在有限体积法框架下应用通量差分裂(FDS)格式计算模型中各跨单元边界的数值通量,基于内湖野外同步监测数据对模型进行了率定验证;选择典型年及典型潮汐过程,对不同时间尺度下内湖与长江水沙交换过程进行数值计算,结果表明:内湖水流通量、悬沙沉积量年际、年内分布较不均匀,丰水年内湖水流通量及悬沙沉积量明显高于平水年、枯水年;各典型年内,水沙交换量主要集中在洪季5月至10月,洪季水流通量与悬沙沉积量分别约占全年总量的90%与95%;内湖洪季全日潮水流通量约8 292.3万m3,悬沙沉积量约1 344.1t,明显高于枯季;潮汐作用对内湖水沙交换影响较大,在全潮最低水位时刻,内湖水流通量最小但悬沙沉积量却达到最大.     

流域洪水模拟

通过对流域水流运动规律的分析，将流域的水流概化为调蓄单元的零维模拟、河道水流的一维模拟、行洪区水流的二维模拟、联系的处理及无资料径流的处理，对各部分的特点，采用相应的数值方法，统一进行求解，即构成了流域洪水模型，最后以淮河中下游段为试验区，进行了洪水还原计算，结果令人满意。     

基于GOCI影像反演湖泊悬浮物和叶绿素a含量的研究述评

悬浮颗粒物和叶绿素a是两个重要的湖泊水质参数,常用来衡量湖泊的富营养化程度。阐述了基于GOCI数据的湖泊悬浮颗粒物和叶绿素a浓度反演的研究现状,分析了几种大气校正方法对于GOCI数据的适宜性,发现基于6S模型的大气校正取得的效果最好。对比了GOCI的几种用于叶绿素a和悬浮颗粒物反演的模型,发现基于经验方法的反演虽然简单易行,但缺乏物理依据;基于分析方法的反演机制明确,但较难实现;基于半分析方法的反演是统计水质参数的光谱特征,建立遥感数据的波段组合与水质参数值之间的定量关系,进而估算水质参数含量,此方法较易实现且有一定物理意义。最后,通过总结现状,对利用GOCI反演水体指标的发展提出了一些自己的见解。     

A 12‐month sediment and nutrient budget in a floodplain reach of the River Adour,southwest France

The sediment and nutrient budget in the floodplain reach of the River Adour in southwest France has been examined over a 1‐year period (1991–1992). Outputs of total suspended matter, dissolved inorganic nitrogen (i.e. nitrate+ammonium ions) and dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) have been compared with inputs. Alternating phases of mobilization and retention are observed for all the elements considered. Low water periods in summer allowed retention of both soluble material (24–26% for inorganic nitrogen) and suspended matter (9–19%). However, mobilization of PP associated with suspended matter transport during these periods. Elevated discharges associated with increased rainfall during the autumn period induced significant mobilization for all elements. In contrast, the winter flood event gave rise to a retention of particulate material (i.e. suspended matter and PP, 11% and 26%, respectively), but a loss of soluble materials (5% for inorganic nitrogen and 186% for DIP). The spring flood event produced retention for particulate materials (26%) while inducing losses of inorganic nitrogen (9%) and gains of DIP (7.4%). These results are related to riparian vegetation and the dynamics of nutrient cycling within the floodplain. Copyright © 2000 John Wiley & Sons, Ltd.     

珠江三角洲河网与河口夏季水沙通量的模拟

本文利用一、三维水动力与泥沙耦合模型,计算珠江三角洲河网与河口夏季水沙通量,构建其收支模式,并分析水沙迁移路径与泥沙沉积特征。研究表明,西江为最主要的水沙输入源,磨刀门为最主要的水沙输出口门,蕉门次之。夏季泥沙以淤积为主,上游汇入的泥沙,有39.4％沉积于河网区,其余60.6％经八大口门输入珠江口后,有59.5％发生沉积,另外1.1％输入外海。河网区的水沙输送由径流控制,而河口区则由径流、潮汐、季风等因素控制。河网区各区域的沉积特点因动力条件的差异而呈现不同的规律,大量泥沙在西江干流、虎门水道淤积。珠江口中以内伶仃洋与磨刀门海域的沉积量最大,泥沙在西滩周边和磨刀门海域快速沉积,其中磨刀门海域淤积最为强烈。     

SEASONAL VARIATIONS OF CIRCULATION AND SUSPENDED MATTER TRANSPORT IN THE YELLOW AND EAST CHINA SEAS

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内外源共同作用对太湖营养盐贡献量研究

本文根据环太湖25条主要入湖河流的监测结果对入湖水量及污染物输入量进行分析,计算了不同季节外源对太湖营养物质的贡献量。分别于春、夏、秋、冬4个季节对太湖梅梁湾水体开展5次野外试验,利用沉积物捕获器收集沉积物,采用Gansith公式法计算沉积物的再悬浮通量,并建立其与风速的关系;对代表不同风浪作用下的太湖悬浮物进行7次静沉降试验,计算悬浮物的静沉降通量,并建立其与风速关系。以3.7m/s为界对底泥悬浮沉降过程进行分解和概化,并利用近10年的风速资料估算太湖年均内源释放量。计算结果表明,全年外源负荷和内源释放对太湖营养盐的贡献总量COD为24.23万t、总氮为3.80万t、总磷为2 045.20t,其中内源所占比例分别为20.47%,20.44%和13.47%外源、内源对太湖的贡献量在不同季节有较大差异,夏季贡献量最大,春季次之。风浪作用下的COD、TN释放量只相当于外源输入量的25.7%,而TP释放量仅相当于外源输入量的15.6%。外源输入量对营养盐的贡献占据相当高的比重,太湖河道入湖污染负荷的增加是太湖水质恶化的根本原因。     

水动力作用下太湖底泥的再悬浮通量

对太湖梅梁湾水体开展了两次野外实验,利用沉积物捕获器收集沉积物,研究了太湖悬浮物的沉降特征,计算了悬浮物的沉降通量和再悬浮通量,并建立了其与风速的关系。结果表明：太湖无机颗粒沉降是悬浮物沉降的主要形式。太湖平均风速在8m/s以内时,总悬浮物、有机物颗粒和无机物颗粒的沉降通量和再悬浮通量均呈现随风速增大而增大的特性,风速大小直接影响悬浮物在垂向的分布及垂向的沉降通量分布,并且相关性较好。该结论说明Gansith公式法适合于计算太湖再悬浮通量。     

Internal loading: A new solution to an old problem in aquatic sciences

Internal loading has long been regarded as an ‘Achilles heel’ in aquatic science and management. Internal loading is of fundamental importance in large and shallow lakes, where even low wind velocities can cause a considerable resuspension of matter deposited on the lake bed. The resuspended matter, and the chemical substances bound to the resuspended matter, will influence almost all processes in the aquatic ecosystem, such as water clarity and depth of the photic zone, and hence, primary and secondary production. If the sediments are contaminated, it will increase the concentrations of harmful substances in water and sediments and the potential ecosystem effects related to such concentrations. This paper presents an overview of the processes regulating bottom dynamic conditions in lakes (erosion, transport, accumulation), provides examples on the role of internal loading within the context of limnology and water management, and presents a new, general approach to quantify internal loading from sediments in lakes. The new approach has been critically tested, being a key factor behind the increase in predictive power of a new generation of lake models meant to be used for practical water management. Internal loading of any water pollutant depends on sedimentation. Sedimentation in this approach is presented as a function of two substance‐specific variables, including the fall velocity of the carrier‐particles and the particulate fraction (which, by definition, is the only fraction of a water pollutant that can settle out on the lake bed), and three generic variables, including mean depth, suspended particulate matter and ET‐areas (areas of erosion and transport). On ET‐areas there is, by definition, a discontinuous sedimentation of materials that settles according to Stokes' law. Basically, internal loading is the sum of advective (resuspension) and diffusive transport from the sediments. Resuspension from ET‐areas is given as a function of the lake form (a new algorithm based on the volume development) and the age of ET‐sediments.     

Estimating Sediment Budget at a River Basin Scale Using a Process-Based Distributed Modelling Approach

The paper presents a process-based distributed modelling approach for estimating sediment budget at a river basin scale with partitions of suspended and bed loads by simulating sediment loads and their interactions. In this approach, a river basin is represented by hillslopes and a network of channels. Hillslopes are divided into an array of homogeneous grid cells for modelling surface runoff and suspended sediments. Channels are defined by incorporating flow hydraulic properties into the respective hillslope grids as sub-grid attributes for modelling both suspended and bed loads. Suspended sediment transport is modelled using one dimensional kinematic wave approximation of Saint-Venant’s principles of conservation of mass and momentum. Transport capacity of runoff or streamflow is used to set the limit of suspended sediment transport rate. Bed load in channels is estimated based on the instantaneous water and hydraulic parameters. Fractional interchange between suspended load and bed load is then back calculated. The performance of the model was evaluated through a case study application in a large river basin in Japan. The model satisfactorily calculated the sediment transport and total sediment budget in the basin. The simulated bed load was found to be reasonable and consistent with the water flow and suspended sediment flux. The results showed the bed load can be expressed as a linear function of the suspended load. The fractions of different sediment loads also exhibit linear relationships with water discharge for the rising and recession limbs of the flood hydrographs. The case study has demonstrated that the process-based distributed modelling approach can efficiently describe the basin-scale sediment budgets with due consideration of the suspended and bed loads and their interactions in the hillslopes and channels.     

2-D NUMERICAL SIMULATION OF RADIONUCLIDE TRANSPORT IN THE LOWER YANGTZE RIVER

The assessment of the radiological impact of the liquid discharges from nuclear power plants is a major issue for the environmental protection. In this study, a numerical model for the radionuclide transport in the aquatic environment is built, based on the hydrodynamic equations, including the complete set of Saint-Venant equations, the sediment transport equations, with consideration of several different particle sizes and the deposition and erosion of the suspended sediments, and the radionuclide transport equations. The exchanges of radionuclides between water, suspended matter and bed sediments are described in terms of kinetic transfer coefficients. The model is used to simulate the transport of the radionuclides discharged from a planned nuclear power plant project to be sited along the lower Yangtze River. From the model results, one may see the detailed temporal-spatial evolution of the radionuclide contamination in the solution, in the suspended matter and in the bed sediments. The model can be used as a basic tool for studying the environmental impacts of the liquid discharges from nuclear facilities on a river system.     

引滦输水过程中悬浮物的沉降迁移特征

受黎河河道两岸铁矿砂影响,引滦输水黎河段水体中悬浮物含量远远高于引滦入津隧洞出口水的悬浮物含量。本文对引滦输水过程中悬浮物的沉降迁移特征进行了研究。结果表明:影响水体中悬浮物沉降速率的主要因素为悬浮颗粒粒径,影响悬浮物迁移量的主要因素为悬浮物的初始浓度。结合引滦输水过程中的悬浮物实际迁移情况,得出悬浮物主要影响引滦输水黎河河道,而汇入于桥水库的悬浮物含量较少且主要为粒径10μm的颗粒。应用研究成果,针对引滦输水工程的悬浮物污染特征,提出降低输水过程流速、增加入库前河道深度及种植水生植物等建议,以减少引滦输水过程中悬浮物含量。