STUDY ON SORPTION OF HEAVY METAL POLLUTANTS BY SEDIMENT PARTICLES

Sorption of heavy metal on sediment particles is studied theoretically am experimentally. Sorption processes of heavy metal pollutants on sediment particles can b well described by Langmuir model. Parameters in the model b,,k and k1 depend on proper ties of sediment and water, and have nothing to do with sediment concentration. By com bining the sorption dynamic equation and the mass conservation equation, the variation c N(sorption content of heavy metal pollutant by specific weight of sediment) and c (con centration of heavy metal pollutant in water phase) with time can be deduced. Further more, formulas for calculating the equilibrium sorption content N and the equilibriur concentration of heavy metal pollutant in water phase c are established too. Experimenta data well coincide with theoretical formulas. These can be treated as the basis for furthe quantitative study of sediment sorption-desorption characteristics.     

EXPERIMENTS ON SELF-PURIFICATION OF HEAVY METALPOLLUTANTS IN NATURAL RIVERS

1.INTRODUCTIONThemovementofwater,sedimentandpollutantsandtheinteractionamongtheminnaturalriversareverycomplicated.Movementofwater,sedimentandPOllutantsarerandom.ButfromastatisticalviewPOint,theirmovementfollowssomerules.Twokindsoftypicalcases,thatis,atributarywithheavymetalpollutantsjoiningamainstream,andanunPOllutedtributarywithmuchsedimententeringamainstreamcontaminatedbyheavymetals,arestudiedinthispaper.Besides,flowscenesinnaturalriversaredifferentindifferentseasons.InthenabPeriod,g…     

A VERTICAL 2-D NUMERICAL SIMULATION OF SUSPENDED SEDIMENT TRANSPORT

Numerical simulation of sediment transport and bed evolution has become an important technique in the sediment research. In this article,a numerical model of suspended sediment transport was proposed,which was established in the vertical σ coordinate for fitting the free surface and bottom. In the research of the sediment transport,the predominant factors were found to be the eddy diffusion,the settling velocity,the bed condition and so on. By the aid of the model in the article,the contribution of the Rouse parameter to the vertical profile of sediment concentration was clarified,which was identical to the theoretical results. In the comparison of the numerical results with laboratory data,the agreement between experimental data and numerical results was reached except for some data. And the possible reasons for the disagreement were discussed.     

FLOW STRUCTURE AND SEDIMENT TRANSPORT WITH IMPACTS OF AQUATIC VEGETATION

Aquatic vegetation plays an important role in the flow structure of open channels and thus changes the fate and the transport of sediment. This article proposes a three-dimensional turbulence model by introducing vegetation density and drag force into the control equations of water flow in the presence of vegetation. The model was used to calculate the impacts of submerged vegetation on the vertical profiles of longitudinal flow velocities, the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain, the removal of suspended sediment from the channels by emergent vegetation, and the bed changes around and in a vegetated island. Numerical investigations show that aquatic vegetation retards flow in the vegetation zone, reduces the sediment transport capacity, and contributes to erosion on both sides of the vegetated island. Calculated results agree well with experimental results.     

A MATHEMATICAL MODEL FOR UNSTEADY SEDIMENT TRANSPORT IN NINGXIA REACH OF THE YELLOW RIVER

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＮｉｎｇｘｉａｉｓｌｏｃａｔｅｄｉｎｔｈｅｗｅｓｔｅｒｎｐａｒｔｏｆＣｈｉｎａ .ＴｈｅＹｅｌｌｏｗＲｉｖｅｒｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｄｅｖｅｌ ｏｐｍｅｎｔｏｆＮｉｎｇｘｉａ’ｓｅｃｏｎｏｍｙａｎｄｐｏｌｉｔｉｃｓ,ｂｕｔｉｔａｌｓｏｂｒｉｎｇｓｇｒｅａｔｓｏｒｒｏｗｔｏｔｈｅｐｅｏｐｌｅｉｎｔｈｉｓｒｅｇｉｏｎｂｅｃａｕｓｅｔｈｅｒａｐｉｄｓｉｌｔａｔｉｏｎｏｆｔｈｅｃｈａｎｎｅｌｂｒｉｎｇｓａｂｏｕｔｓｅｒｉｏｕｓｐｒｏｂｌｅｍｓｆｏｒｆ…     

NUMERICAL MODELING OF SUSPENDED SEDIMENT TRANSPORT IN CHANNEL BENDS

1. INTRODUCTION Due to the fact that three-dimensional (3D) numerical models are quite expensive to simulate flow and sediment transport processes, vertically-integrated two-dimensional (2D) models are extensively applied at present, even to the predictio…     

黎河河道演变的数学模型——天然河道用作输水通道后的演变

天然条件下的山前性河流黎河被用作引滦入津的输水河道，来水条件的巨变和大量工程引起的河床调整，为研究这一调整我们建立了具有如下特点的数学模型：1、考虑了自上而下床沙粒径的巨大变化；2、反映了卵石夹沙河床宽级配的输沙特点以及清水冲刷时的粗化过程；3、模拟了粘性土河床的冲刷特性；4、考虑了跌水坎的不规则断面宽顶堰的过流特点以及有工程措施和人为干扰下的河床演变特点。本文介绍了上述数学模型的主要内容，这对于其它跨流域引水工程和河道治理工程有参考价值。     

NUMERICAL SIMULATION OF THE TIDAL MOTION AND SUSPEND EDSEDIMENT TRANSPORT IN THE RADIAL SANDBANK AREA OF THE SOUTHERN YELLOW SEA

A coupled 2-D numerical model for hydrodynamic-sediment transport was established and applied to simulate the tides, tidal currents and sediment movement in the submarine Radial Sandbank area of the southern Yellow Sea.With a high-resolution topography dataset used in the model,the simulation reproduced a fine-structured current field and erosion-siltation distribution. The modeled results show that,in the area of Radial Sandbanks, reversing tidal current and seabed erosion occurs within troughs while tidal current with more rotary feature and deposition occurs above sandbanks,which indicates the tidal-induced formation of the Radial Sandbanks. During a tidal period, associating with the variation of current speed, erosion alternates with siltation. The seabed deformation depends on the relative strength of erosion and siltation in a tidal period.