MATHEMATICAL MODEL FOR 2-D TIDAL FLOW AND WATER QUALITY WITH ORTHOGONAL CURVILINEAR COORDINATES

1 .　INTRODUCTIONThedischargeofpollutedwaterisbecominganincreasingthreattotheresourcesintidalareas.Thenumericalsimulatingthe 2 Dtidalflowandwaterqualityisthebasisofwaterresource plan ningandmanagement.Inrecentyears,althoughconsiderableattentionhasbeenfocusedonthisproblem ,thecomputationaldifficultiesinnaturaltidalriversremaintobeabigproblem ,suchasthecomplicatedboundaryconfigurations ,the greatdisparitybetweenlengthandwidth ,etc .Inthefollowing ,a 2 Dnumericalmodelbasedonthealternating…     

TARGET ANALYSIS OF SUZHOU CREEK REHABILITATION PROJECT STAGE II: BASED ON WATER QUALITY MODEL

1 .　INTRODUCTIONTheSuzhouCreekisamaintributaryoftheHuangpuRiver .ItislocatedinthedeltaoftheYangtseRiver,originatingfromGuajingkouoftheTaihuLake ,thenpassingSuzhouCityofJiang suProvince ,crossingthecentralareaofShanghaiCity ,andfinallypouringintotheHuangpuRiveratWaibaidu .Itis 12 5kmlong ,5 3.1kminShang haiCity .Theaveragewidthis 70m 80mathigh tidetime .Theaverageflowis 6 .0m3/s ,andabout4 0 % 6 0 %isthesewagefromriverside .Theflowiscontrolledbytide ,andthewatervelocityisverylow…     

A NUMERICAL MODEL OF FLOW FIELD AND WATER QUALITY FOR TIDAL REGIONS BASED ON TRIANGULAR MESHES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＵｐｔｏｎｏｗ ,ｔｈｅｒｅｐｏｒｔｓｆｏｒｓｏｌｖｉｎｇ 2Ｄｄｅｐｔｈ ｉｎｔｅｇｒａｔｅｄｅｑｕａｔｉｏｎｓｏｆｆｌｏｗａｎｄｍａｓｓｔｒａｎｓｐｏｒｔｉｎｔｉｄａｌｒｅｇｉｏｎｈａｖｅｂｅｅｎｉｎｔｒｏｄｕｃｅｄｉｎｌａｒｇｅｎｕｍ ｂｅｒｓ .ＦｒｏｍｔｈｅｂｅｇｉｎｎｉｎｇｏｆＹａｎｅｎｋｏ[1] .ＴｈｅＦｉ ｎｉｔｅＤｉｆｆｅｒｅｎｃｅＭｅｔｈｏｄ (ＦＤＭ )ｈａｓｂｅｅｎｗｉｄｅｌｙａｐｐｌｉｅｄｂｙＦａｌｃｏｎｅｒ[2 ] ,ＶｉｎｃｅｎｚＣａｓｕｌｌｉ[3,5] ,ＨｅＳｈ…     

DEVELOPMENT OF TWO-DIMENSIONAL HYDRODYNAMIC AND WATER QUALITY MODEL FOR HUANGPU RIVER

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＨｕａｎｇｐｕＲｉｖｅｒ,ｏｒｉｇｉｎａｔｉｎｇｆｒｏｍｔｈｅＴａｉｈｕ ,ｒｕｎｓａｃｒｏｓｓＳｈａｎｇｈａｉａｎｄｆｅｅｄｓｉｎｔｏＹａｎｇｔｚｅＲｉｖｅｒａｔＷｕｓｏｎｇｋｏｕ .Ｉｔｉｓａｔｉｄａｌｉｎｆｌｕｅｎｃｉｎｇｒｉｖｅｒｗｉｔｈｍｏｒｅｔｈａｎ 5 0ｔｒｉｂｕｔａｒｉｅｓａｍｏｎｇｗｈｉｃｈｓｏｍｅｍａｊｏｒｔｒｉｂｕ ｔａｒｉｅｓａｒｅｓｈｏｗｎｉｎＦｉｇ .1 .Ｆｉｇ .1　ＤｅｐｉｃｔｉｏｎｏｆＨｕａｎｇｐｕＲｉｖｅｒｗａｔｅｒｓｈｅｄＮｏｗａｄａｙｓｔｈ…     

MATHEMATICAL MODEL FOR ALLUVIAL TIDAL WATER COURSE

This paper presents a mathematical model to predict the bed deformation of Jiang-men water course,a tributary of Xijiang River in South China,affected by navigation regula-tion.This model has been verified by the field data.     

WATER QUALITY MODELING OF SUZHOU CREEK

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮ1 .1　ＴｈｅｐｒｏｊｅｃｔｂａｃｋｇｒｏｕｎｄＴｈｅｒｉｖｅｒｓｉｎＳｈａｎｇｈａｉｗｅｒｅｓｅｒｉｏｕｓｌｙｐｏｌｌｕｔｅｄ ,ｓｏｔｈｅｍｕｎｉｃｉｐａｌｇｏｖｅｒｎｍｅｎｔｄｅｃｉｄｅｄｔｏｓｔａｒｔａｈｕｇｅｐｒｏｊｅｃ     

STOCHASTIC ANALYSIS MODEL FOR RIVER WATER QUALITY AND ITS APPLICATION

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｗａｔｅｒｅｎｖｉｒｏｎｍｅｎｔｉｍｐａｃｔｓｔａｔｅｍｅｎｔａｎｄｗａｔｅｒｑｕａｌｉｔｙｓｙｓｔｅｍａｎａｌｙｓｉｓａｎｄｐｌａｎｎｉｎｇ，ｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓａｒｅｗｉｄｅｌｙｕｓｅｄｔｏｓｉｍｕｌａｔｅｔｈｅｐｒｏｃｅｓｓｏｆｐｈｙｓｉｃａｌ，ｃｈｅｍｉｃａｌａｎｄｂｉｏｌｏｇｉｃａｌｃｈａｎｇｅｓｏｆｃｏｎｔａｍｉｎａｎｔｉｎｗａｔｅｒｂｏｄｙ．Ｇｅｎｅｒａｌｌｙｔｈｅｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓｃａｎｂｅｃｌａｓｓｉｆｉｅ…     

NUMERICAL SIMULATION OF 2-D TIDAL FLOW AND WATER QUALITY UNDER THE CURVILINEAR COORDINATES

This paper presents a numerical method to simulate the 2-D tidal flow and water quality under the curvilinear coordinates. In order to overcome the computational difficulties in natural rivers, such as the complicated boundary figures, the great disparity between length and width of computational domain, etc. , boundary-fitted grid is used, the irregular domain in physical plane is transformed into a rectangular domain in transformed plane, and the depth-averaged momentum equations and mass equation are rewritten and discretized based on the finite volume techniques in curvilinear coordinates. Practical application of the method is illustrated by an example for the Dachangzhen Section of the Yangtze River. A fair agreement between the values measured and computed demonstrates the validity of the method developed.     

THREE-DIMENSIONAL NUMERICAL MODEL FOR WINDING TIDAL RIVER WITH BRANCHES

Natural rivers are usually winding with branches and shoals,which are difficult to be simulated with rectangular grids. A 3-D current numerical model was established based on the orthogonal curvilinear coordinate system and vertical σ coordinate system. The equations were discretisized using a semi-implicit scheme. The “predictor” and “corrector” steps were applied for the horizontal momentum equations to meet the basic requirement that the depth-integrated currents obtained from the equations for 2-D and 3-D modes have identical values. And a modification of traditional method of dry/wet discriminance was proposed to determine accurately the boundary and ensure the continuity of variable boundary in the simulation. This model was verified with the data measured in a winding tidal river with branches in April,2004. The simulated data of water levels and velocities agree well with the measured ones,and the computed results reveal well the practical flow characteristics,including the vertical secondary flow in a winding reach.     

FUZZY MODEL FOR TWO-DIMENSIONAL RIVER WATER QUALITY SIMULATION UNDER SUDDEN POLLUTANTS DISCHARGED

Based on the fuzziness and impreciseness of water environmental system, the fuzzy arithmetic was used to simulate the fuzzy and imprecise relations in modeling river water quality. By defining the parameters of water quality model as symmetrical triangular fuzzy numbers, a two-dimensional fuzzy water quality model for sudden pollutant discharge is established. From the fuzzy model, the pollutant concentrations, corresponding to the specified confidence level of α, can be obtained by means of the α-cut technique and arithmetic operations of triangular fuzzy numbers. Study results reveal that it is feasible in theory and reliable on calculation applying triangular fuzzy numbers to the simulation of river water quality.     

A COUPLED MODEL OF HYDRODYNAMICS AND WATER QUALITY FOR YUQIAO RESERVOIR IN HAIHE RIVER BASIN

In order to simulate the characteristics of hydrodynamic field and mass transport processes in the Yuqiao Reservoir （YQR）, a 2-D coupled model of hydrodynamics and water quality was developed, and the water-quality related state variables in this model included CODMn, TN and TP. The hydrodynamic model was driven by employing observed winds and daily measured flow data to simulate the seasonal water cycle of the reservoir. The simulation of the mass transport and transformation processes of CODMn, TN and TP was based on the unsteady diffusion equations, driven by observed meteorological forcing and external loadings, with the fluxes form the bottom of reservoir and the plant photosynthesis and respiration as internal sources and sinks. A finite volume method and Alternating Direction Implicit （ADI） scheme were used to solve these equations. The model was calibrated and verified by using the data observed from YQR in two different years. The results showed that in YQR, the wind-driven current was an important style of lake current, while the concentration of water quality item was decreasing from east to west because of the external pollutant loadings. There was a good agreement between the simulated and measured values, with the minimal calculation error percent of 0.1% and 2.6% and the mean error percent of 44.0% and 51.2% for TN and TP separately. The simulation also showed that, in YQR, the convection was the main process in estuaries of inflow river, and diffusion and biochemical processes dominate in center of reservoir. So it was necessary to build a pre-pond to reduce the external loadings into the reservoir.     

APPLICATION OF LARGE SCALE TURBULENT SIMULATION FOR WATER QUALITY MODELLING OF THE YANGTZE RIVER

Large scale turbulent structures play an important role in mass transport of natu-ral river turbulence diffusion,After adopting the theory of Large Scale Turbulent Simulation tonatural rivers,some 1-D stream quality models,such as QUAL-Ⅱ,have been widely applied tolarge,middle and small rivers in China with reasonable success.Moreover,on this basis,2-Dand 3-D river quality models have also been developed.Both 2-D and 3-D models used upwindscheme plus Peaceman-Rachford's alternating scheme in the first one and Douglas'scheme inthe second one.These models have also been successfully applied to the Yangtze River as well assome middle and small rivers in China.     

INVERSE PROBLEM METHOD FOR WATER ENVIRONMENT TOTAL CAPACITY CONTROL OF A TIDAL RIVER

In this paper, an improved method for water environment total capacity control of tidal rivers was presented. The maximal capacity of point pollution sources for the Huangpu River was computed by this method, and the result was compared with the practically observed data. The numerical result shows that the method is effective and efficient.     

AN OPTIMIZATION METHOD OF AQUATIC ENVIRONMENTAL CAPACITY FOR TIDAL RIVER NETWORK

1. INTRODUCTION Aquatic environmental capacity is the ability to hold pollution under given water range, water quality standard and design conditions[1]. In the region of outfall, the problem of aquatic environment becomes more and more important because …     

AN ANALYSIS OF THE OXYGEN BALANCE IN AN ANOXIC TIDAL RIVER

ＡＮＡＮＡＬＹＳＩＳＯＦＴＨＥＯＸＹＧＥＮＢＡＬＡＮＣＥＩＮＡＮＡＮＯＸＩＣＴＩＤＡＬＲＩＶＥＲＪｏｓｅｐｈＨ．Ｗ．Ｌｅｅ，Ｋ．Ｗ．Ｃｈｏｉ（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌａｎｄＳｔｒｕｃｔｕｒａｌＥｎｇｉｎｅｅｒｉｎｇ，Ｕｎｉｖｅｒｓｉｔｙｏｆ...     

A 2-D HYDRODYNAMIC MODEL FOR THE RIVER, LAKE AND NETWORK SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

The main river,the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system,for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems,based on the latest developments of computer technologies and numerical methods.To better handle irregular boundaries and keep the computation cost well in a reasonable limit,unstructured grids of moderate scale are used. In addition,a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods,especially,when the moderate scale gird can not describe flows in narrow river-network channels at low water levels.Theθsemi-implicit method and the Eulerian-Lagrangian Method(ELM)are adopted,which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions.Properties and efficiency of the model are discussed,and it is concluded that the new model is robust and efficient enough for the simulation of a big,complex water system.Validation tests show that the simulation results agree well with field data.It takes about 0.96 h to complete the computation of a 76 d flood,which indicates that the model is efficient enough for engineering applications.     

A REAL-TIME MATHEMATICAL MODEL FOR TWO DIMENSIONAL TIDAL FLOW AND WATER QUALITY

A real-time mathematical model for two dimensional tidal flow and water quality is presented in this paper.The control-volume-based-finite-difference method and the "power interpolation distribution" advocated byPatankar [4] have been employed, and new boundary condition for tidal flow is recommended. The model is un-conditionally stable and convergent, and able to deal with irregular estuarine topography and movable boundaryproblems. Practical application of the model is illustrated by an example for the Swatou Bay. A fair agreement be-tween the values measured and computed demonstrates the validity of the model developed.     

DEVELOPMENT OF COUPLED 1D-2D MATHEMATICAL MODELS FOR TIDAL RIVERS

Some coupled 1D-2D hydrodynamic and water quality models depicting tidal water bodies with complex topography were presented. For the coupled models, finite element method was used to solve the governing equations so as to study tidal rivers with complex topography. Since the 1D and 2D models were coupled, the principle of model coupling was proposed to account appropriately for the factors of water level, flow and pollutant flux and the related dynamical behavior was simulated. Specifically the models were used to probe quantitative pollution contribution of receiving water from neighboring Jiangsu and Zhejiang Provinces to the pollution in the Huangpu River passing through Shanghai City. Numerical examples indicated that the developed coupled 1D-2D models are applicable in tidal river network region of Shanghai.     

EFFECTS OF ARTIFICIAL FLOODING ON WATER QUALITY OF A FLOODPLAIN BACKWATER

Seasonal flooding of riverine backwaters is important in maintaining diverse aquatic habitats, but anthropogenic impacts have reduced the frequency and duration of such flooding. This study, conducted in a 2.5‐km‐long shallow floodplain severed meander backwater adjacent to the Coldwater River in Tunica County, Mississippi, USA, compared water quality during a late summer 30‐day artificial flooding period with 28‐day pre‐flood and 26‐day post‐flood periods. Flooding was simulated by pumping 0.22 to 0.35 m³ s^?1 from the river into the upstream portion of the backwater. In situ parameters (temperature, pH, dissolved oxygen, conductivity and fluorescent chlorophyll) were measured every 30 min at one site within the backwater. Solids (dissolved and suspended) and nutrients (phosphorus and nitrogen) were measured at three sites in the backwater and in the river every 3 to 5 days. Decreases in the amplitude of temperature, dissolved oxygen and pH diel cycles within the backwater were observed during flooding. Changes in patterns of solids and nutrients were also associated with flooding. Complex patterns in phosphorus and nitrogen emerged as a result of utilization by autotrophs (measured as chlorophyll) and seasonal changes. Artificial flooding in a shallow floodplain water body stabilized and improved water quality for aquatic biota and is a viable method for habitat rehabilitation in these systems. Copyright © 2011 John Wiley & Sons, Ltd.     

STUDY AND APPLICATION OF STEADY FLOW AND UNSTEADY FLOW MATHEMATICAL MODEL FOR CHANNEL NETWORKS

Based on the Preissmann implicit scheme for the one-dimensional Saint-Venant equation, the mathematical model for one-dimensional river networks and canal networks was developed and the key issues on the model were expatiated particularly in this article. This model applies the method of three-steps solution for channel-junction-channel to simulate the river networks, and the Gauss elimination method was used to calculate the sparse matrix. This model was applied to simulate the tree-type irrigation canal networks, complex looped channel networks and the Lower Columbia Slough networks. The results of water level and discharge agree with the data from the Adlul and field data. The model is proved to be robust for simulating unsteady flows in river networks with various degrees of complex structure. The calculated results show that this model is useful for engineering applications in complicated river networks. Future research was recommended to focus on setting up ecological numerical model of water quality in river networks and canal networks.