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fine sediment OF THE UPPER MISSISSIPPI ANDILLINOIS RIVERS AND THE DISASTROUS CONSEQUENCES

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International Journal of sediment Research 1999年第2期14卷 171-178页

作者： TaWei SOONG1 (l Watershed Science Section, Illinois State Water Survey. Department of natural Resources. 2204 Griffith Drive. Champaign, IL 61820)

Increased sediment loads and sedimentation rates in rivers and streams have produced major disturbances to the society. However, while discussing f sediment transport and sediment induced problems focuses have often been given to those related to coarse sediments; tine sediment induces problems have been primarily investigated in bays and estuaries. In the case of Upper Mississippi River System (UMRS), increased turbidity and suspended sediment solids in the water column; heavy sediment deposition in channel boarders, backwater lakes, and side channels have shown to be problematic. Besides their impacts on human activities, fine sediments have also adversely affected water quality and flora and fauna of the river System. The total areas that affected, their accessibility, the amount, not to mention the contaminants involved, are complex challenges to the e1Yorts to restore the rivers’ functions. Many resource managers consider heavy sediment deposition in backwaters and side channels to be one of the most severe environmental problems on the UMRS. Large rivers are priceless resources and sedimentation plays a vital role in their sustainability. The example and experience learned from the UMRS can provide valuable information for management practices of other river basins.

关键词： Mississippi River fine sediment sediment transport Water quality

Study of deposition of fine sediment within the pores of a coarse sediment bed stream

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International Journal of sediment Research 2013年第2期28卷 210-219页

作者： N.K.KHULLAR U.C.KOTHYARI K.G.Ranga RAJU Department of Civil Engineering PAU Ludhiana-India Prof.Dr. Department of Civil Engineering IIT Roorkee-India Prof.Dr. Department of Civil Engineering IIT Roorkee-India Formerly Prof.Dr.

Elaborate experiments were performed in a 30 m long,0.5 m deep and 0.2 m wide laboratory flume to study the process of infiltration of fine sediment into the pores of coarse sediment forming the channel bed *** concentrations of suspended load of fine sediment of size 0.064 mm were passed over the channel bed made up of three different types of coarse sediments;two uniform and one *** proportion of fine sediment infiltrated into the pores of bed material for each equilibrium concentration of suspended load of fine sediment in the flow was studied during several experimental *** proportion of fine sediment within the pores of bed material increased with an increase in the equilibrium concentration of suspended load of fine sediment in the *** process continued till the pores within the coarse sediment bed were filled up to the capacity with the fine sediment transported by the flow in *** theoretical value was identified for limit for maximum proportion of fine sediment that can be present within the pores of bed *** further increase in the concentration of suspended load of fine sediment in the flow,deposition of fine sediment occurs on the surface of the flume bed in the form of ripples of the fine *** condition is defined as ’depositional condition’.Experimental observations on these and related aspects are presented herein.

关键词： fine sediment Flume experiment Bed material Concentration of suspended sediment Deposition condition

Laboratory measurements of the fall velocity of fine sediment in an estuarine environment

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International Journal of sediment Research 2020年第2期35卷 217-226页

作者： Jiaqi Yang Limo Tang Yuntong She Jiao Sun State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Water Conservancy and Hydropower Engineering Hohai University Department of Civil and Environmental Engineering University of Alberta Zhejiang Qianjiang Science and Technology Development Company

The study of the fall velocity variation of fine sediment in estuarine areas plays an important role in determining how various factors affect the flocculation *** experimental studies have focused solely on the relation between the median fall velocity and influencing factors,while in the current study,the variation of the fall velocity in quiescent water also was *** experimental results showed that the vertical distribution of sediment concentration was more uneven,and larger variations occurred earlier during the settling process under higher salinity and/or sediment concentration *** fall velocity initially increased then decreased over time,peaking at～20 min after settling began,and stabilizing at a value similar to that in freshwater,regardless of the initial sediment concentration and salinity *** the water depth,the fall velocity increased monotonically with a gradually decreasing *** median fall velocity increased then decreased with increased *** salinity at which the peak fall velocity occurred depended on the initial sediment *** relation between the median fall velocity and initial sediment concentration displayed an obvious two-stage pattern(i.e.,accelerated flocculation and decelerated,hindered settling) at higher salinities;whereas the maximum median fall velocity was observed at two consecutive sediment concentration values under lower salinity ***,an empirical equation estimating the median fall velocity of cohesive fine sediment was formulated,incorporating the effects of both salinity and sediment concentration.

关键词： Laboratory experiments fine sediment Estuarine environment Fall velocity Salinity sediment concentration

An investigation into the effects of particle texture,water content and parallel plates' diameters on rheological behavior of fine sediment

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International Journal of sediment Research 2016年第2期31卷 120-130页

作者： Masoumeh Moayeri Kashani Lai Sai Hin Shaliza Binti Ibrahim Nik Meriam Binti Nik Sulaiman Fang Yenn Teo Department of Civil Engineering Faculty of EngineeringUniversity of Malaya Department of Chemical Engineering Faculty of EngineeringUniversity of Malaya Research Development and Innovation DivisionNational Water Services Commission

Siltation,a phenomenon resulted from the presence of fine particles in an aqueous environment,dominated by silt and clay,is a known and common environmental issue *** accumulation of fine sediments engenders murky water with low oxygen levels,which leads to the death of aquatic ***,investigating the physical and mechanical properties of fine sediment by rheological methods has *** is the science of deformation and flow of matter in *** survey investigates the rheological behavior of six samples of soil as the fine particles structure(D fine *** samples were examined in two rheological curve and amplitude sweep test methods to investigate the effect of water content ratio,texture,and structure of patticles on rheological *** was found that the content of fine sand,clay,and silt had an effect on the stiffness,structural stability,and shear ***,the pseudoplastic and viscoelastic behaviot are respectively ***,the amount of fine sediments present in water *** concentration of these particles,has a direct effect on the rheological curve.A reduction in viscosity of samples with higher concentrations of water has been *** a consequence,a considerable quantity of fine sediments are distributed within the water body and remain suspended over the *** a result,the sedimentation rate slows *** needs to be asserted that the stotage modulus G′,loss modulus G″,and yield point can vary depending on particle *** G′ and G″were instigated for samples(70%and 45%concentrations) that demonstrated viscoelastic characteristics using the same rotational rheometer with a parallel-plate measuring device.

关键词： fine sediment Rheology Siltation Soil texture Stiffness degradation

Predictability of sediment transport in the Yellow River using selected transport formulas

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International Journal of sediment Research 2008年第4期23卷 283-298页

作者： D.S.van MAREN Postdoctoral Fellow Delft University of Technology Faculty of Civil Engineering and Geosciences the Netherlands and WL | Delft HydraulicsPO Box 177 2600 MH Delft The Netherlands.

This paper evaluates the applicability of the sediment transport methods developed by Engelund and Hansen, Ackers and White, Yang et al., and van Rijn, together with the Wuhan methods developed in China, to the Yellow River, which has highly concentrated and fine-grained sediment. The sediment data includes over 1000 observations from the Yellow River, 32 sets of data from a canal, and 266 sets of data from laboratory flumes. The best predictions were obtained by the Yang 1996 method, the Wuhan method, and the modified Wuhan method by Wu and Long, while reasonably good predictions were also provided by the van Rijn 2004 method. The Engelund and Hansen, the Ackers and White, and the van Rijn 1984 methods in their original forms are not applicable to the Yellow River. The predicted results for total load concentrations were as good as for bed-material concentrations, even though the total load includes a large portion of wash load.

关键词： Yellow River sediment transport High concentration fine sediment

A three-dimensional modeling of the morphological change in the Liaodong Bay

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Frontiers of Earth Science 2015年第3期9卷 509-520页

作者： Qiushun WANG Haigui KANG State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China

The morphology in the Liaodong Bay has undergone a marked change over the past decades due to the cutoff of nearby rivers. The fine sediment of the bay consists of both non-cohesive and cohesive fractions with relatively small particles over the seabed. Thus, a three- dimensional morphodynamic model accounting for non- cohesive and cohesive fractions is established to investi- gate the morphological change without sediment input from nearby rivers. A representative wave is chosen to compute the wave distribution in the Liaodong Bay and depth-dependent wave radiation stresses are employed by the hydrodynamic model. The advection-diffusion equa- tion is used to simulate the fine sediment transport under the representative wave and tidal currents. The erosion flux of non-cohesive and cohesive sediment is taken into account. The simulated results of tidal level, velocities, directions, and sediment concentrations are in agreement with the measured data. The results demonstrate that the present model, which takes the erosion flux of both non- cohesive and cohesive fractions into account, gives more reasonable values than when accounting for cohesive sediment alone. When the three-dimensional morphody- namic model is applied to predict morphological change over the course of a year, the deposition is shown to be relatively small and the range of the erosion is increased compared to previous results of sediment input from the river. It can be concluded that the erosion in the Liaodong Bay is increasing due to the cutoff of the river, and that morphological evolution must be taken into account if any type of coastal construction plans are to be carried out over the seabed.

关键词： fine sediment three-dimensional model morphological change representative wave

Numerical investigation of the factors influencing the vertical profiles of current,salinity,and SSC within a turbidity maximum zone

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International Journal of sediment Research 2017年第1期32卷 20-33页

作者： Yuanyang Wan Li Wang Shanghai Estuarine and Coastal Science Research Center International Marine and Dredging Consultants

The flow-sediment interaction plays a considerable role on the vertical(internal) profiles of current,salinity and suspended sediment concentration(SSC) within a turbidity maximum zone(TMZ).Numerical modeling provides valuable insights into the complex estuarine physical *** combining numerical modeling with field observations,the influencing factors of fine sediment dynamics within the TMZ of Yangtze Estuary have been explored in this ***,during the neap tide,the measured data present that the current is too weak to break the density stratification,and the vertical flow structure is effectively ***,a three-dimensional numerical model based on the Delft3 D has been developed and a range of numerical sensitivity analyses were carried out to distinguish the dominant mechanisms and physical processes responsible for the phenomena observed from the measurement *** numerical investigation highlights the following findings.(1) The vertical profile of currents within the TMZ is largely affected by saltwater intrusion,especially during lower currents when the baroclinic pressure gradient can significantly reshape the local vertical profiles of velocity.(2) The baroclinic effects are primarily determined by the stratification of salinity.(3) In addition to salinity,SSC also influences the local density stratification when its contribution to fluid density is comparable to that of salinity.(4) The settling velocity determines the overall sediment distribution and vertical profiles of the SSC in the water *** SSC-dependent settling velocity(including the flocculation-induced acceleration and hindered settling deceleration phases) affects the longitudinal movement of the sediments.(5) The vertical profiles of current,salinity and SSC within the TMZ are highly associated with the turbulence determined by the *** approach to modulate the vertical eddy viscosity in the model,based on the empirical dependency between Rigand Prt,may

关键词： Turbidity maximum zone(TMZ) fine sediment Residual circulation Yangtze Estuary Modelling Tidal asymmetry Stratification Turbulence Salinity