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NUMERICAL MODELING OF Suspended sediment transport IN CHANNEL BENDS

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Journal of Hydrodynamics 2006年第4期18卷 411-417页

作者： HUANG Sui-liang JIAY．F,WANG Sam S. Y. College of Environmental Science and Engineering Nankai University Tianjin 300071 China National Center for Computational Hydroscience and Engineering The University of Mississippi Oxford USA

An algorithm to compute three-dimensional sediment transport effect was proposed in this paper to enhance the capability of depth-averaged numerical models. This algorithm took into account of non-uniform distributions of flow velocities and suspended sediment concentrations along water depth, it significantly enhanced the applicability of 2D models in simulating open channel flows, especially in channel bends. Preliminary numerical experiments in a U-shaped and a sine-generated experimental channel indicate that the proposed method performs quite well in predicting the change of bed-deformation in channel bends due to Suspended sediment transport. This method provides an effective alternative for the simulations of channel morphodynamic changes.

关键词： algorithm dispersion terms bends Suspended sediment transport 2D numerical model

STREAM-SUBSURFACE EXCHANGE, Suspended sediment transport, AND THE COUPLED transport OF COLLOIDS AND CONTAMINANTS IN sediment BEDS

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International Journal of sediment Research 2003年第2期 199-207页

作者： Jianhong REN Aaron I. PACKMAN Department of Civil and Environmental Engineering Northwestern University Evanston IL USA

Recent interest in the role of sediments in contaminant transport and stream ecology has motivated additional study of both stream-subsurface exchange flows and Suspended sediment transport, deposition, and resuspension. Detailed consideration of the hydrodynamic coupling of stream and pore water flows indicates that there will often be a considerable exchange flux between streams and porous stream beds. As a result, suspended sediments are readily carried from the stream into the subsurface where they can deposit due to physico-chemical interactions with the bed sediments. These processes can greatly influence the transport of fine sediments in streams, and also have important implications for the transport and fate of contaminants. Stream-subsurface exchange allows contaminants to interact with streambed sediments, and contaminants such as metals can sorb to colloidal phases, so that contaminant fate also depends to a large extent on the fate of the suspended sediments. Various degrees of interaction between colloids, contaminants, and stream bed sediments can result in a wide range of transport behavior. In addition, contaminant-particle and particle-particle interactions both depend on the background water chemistry (e.g., pH and ionic strength). Fundamental understanding of the underlying processes allows prediction of the coupled transport of suspended sediments and contaminants. These problems have been analyzed by combining fundamental fluid mechanics with appropriate chemical or physico-chemical interactions between contaminants, colloids, and bed sediments. Long-term modeling of fine sediment and contaminant transport in streams will require consideration of dynamic interactions between stream-subsurface exchange hydrodynamics and fine particle transport.

关键词： Stream hydraulics Suspended sediment transport Contaminant transport Hyporheic exchange

Numerical simulation on seasonal transport variations and mechanisms of suspended sediment discharged from the Yellow River to the Bohai Sea

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Journal of Geographical Sciences 2010年第6期20卷 923-937页

作者： LI Guosheng WANG Hailong LIAO Heping School of Geographic Science Southwest University Chongqing 400715 China Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Guangdong Electric Power Design Institute Guangzhou 510663 China

Based on sediment and discharge flux data for the Yellow River, realistic forcing fields and bathymetry of the Bohai Sea, a Suspended sediment transport module is driven by a wave-current coupled model to research seasonal variations and mechanisms of sus- pended load transport to the Bohai Sea. It could be concluded that surface sediment concentration indicates a distinct spatial distribution characteristic that varies seasonally in the Bohai Sea. sediment concentration is rather high near the Yellow River estuary, seasonal variations of which are controlled by quantity of sediment from the YeUow River, suspended sediment concentration reaches its maximum during summer and fall. Furthermore, sediment concentration decreases rapidly in other seas far from the Yellow River estuary and maintains a very low level in the center of the Bohai Sea, and is dominated by seasonal variations of climatology wind field in the Bohai Sea. Only a small amount of sediments imported from the Yellow River are delivered northwestward to the southern coast of the Bohai Bay. Majority of sediments are transported southeastward to the Laizhou Bay, where sediments are con- tinuously delivered into the center of the Bohai Sea in a northeastward direction, and part of them are transported eastward alongshore through the Bohai Strait. 69% of sediments from the Yellow River are deposited near the river delta, 31% conveyed seaward, within which, 4% exported to the northern Yellow Sea through the Bohai Strait. Wind wave is the most essential contributor to seasonal variations of sediment concentration in the Bohai Sea, and the contribution of tidal currents is also significant in shallow waters when wind speed is low.

关键词： The Yellow River Suspended sediment transport seasonal variation dynamic mechanism numerical simulation

Study on the sediment transport Flux and Mechanism in the Bohai Strait at the Tidal and Monthly Scales in Summer

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Journal of Ocean University of China 2023年第1期22卷 75-87页

作者： YUAN Xiaodong FENG Xiuli HU Rijun JIANG Shenghui ZHONG Wei College of Marine Geoscience Ocean University of ChinaQingdao 266100China Key Laboratory of Submarine Geosciences and Prospecting Techniques MOEOcean University of ChinaQingdao 266100China

Based on the data of tidal currents and suspended sediment concentrations observed synchronously at 11 stations in the Bohai Strait lasting for 25 hours,the temporal and spatial variations of currents and suspended sediment concentrations in the Bohai Strait in summer were analyzed.The Study preliminarily discussed the transport mechanism,transport trend and transport flux of suspended sediments in summer,using flux-mechanism decomposition method and numerical simulation.The Suspended sediment transport was mainly controlled by advection and next influenced by vertical net circulation,while resuspension is relatively weak in Bohai Strait.The single-width fluxes of investigation stations varied from 3.8 to 89.1 gm^(−1) s^(−1),with the maximum value in Miaodao Strait.The Suspended sediment transport trends in Laotieshan channel along the vertical section are obviously distinct.The waters mainly flow out of the Bohai Sea in surface layer,while into the Bohai Sea in bottom layer.However,the transport trends of other channels in the centre and south are consistent vertically.The sediments in the Bohai Strait follows the transport pattern of moving outward from the south and inward from the north in summer,i.e.,the sediments are carried out of the Bohai Sea through the Laotieshan channel,while into the Bohai Sea through other channels.And the outflow flux exceeds the inflow flux in August with the net water flux of 1.4×10^(10)m^(3),basically same as the deliveries of the rivers into the Bohai Sea.Moreover,the suspended sediment flux is 0.33 Mt under the action of tidal residual currents in the Yellow Sea in August.

关键词： Bohai Strait Suspended sediment transport numerical simulation summer

Numerical modeling of bedload and suspended load contributions to morphological evolution of the Seine Estuary(France)

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International Journal of sediment Research 2021年第6期36卷 723-735页

作者： Baptiste Mengual Pierre Le Hir Aurélie Rivier Matthieu Caillaud Florent Grasso IFREMER DYNECO/DHYSED Laboratory Centre de Bretagne UMR 7266 LIENSs CNRS-La Rochelle University IRSN (Institut de Radioprotection et de S?reté Nucléaire) PRP-ENV/SERIS/LRC Laboratory

This numerical modeling study(i) assesses the influence of the sediment erosion process on the sediment dynamics and subsequent morphological changes of a mixed-sediment environment, the macrotidal Seine estuary, when non-cohesive particles are dominant within bed mixtures(non-cohesive regime), and(ii) investigates respective contributions of bedload and suspended load in these dynamics.A three dimensional(3 D) process-based morphodynamic model was set up and run under realistic forcings(including tide, waves, wind, and river discharge) during a 1-year period. Applying erosion homogeneously to bed sediment in the non-cohesive regime, i.e., average erosion parameters in the erosion law(especially the erodibility parameter, E0), leads to higher resuspension of fine sediment due to the presence of coarser fractions within mixtures, compared to the case of an independent treatment of erosion for each sediment class. This results in more pronounced horizontal sediment flux(two-fold increase for sand, +30% for mud) and erosion/deposition patterns(up to a two-fold increase in erosion over shoals, generally associated with some coarsening of bed sediment). Compared to observed bathymetric changes, more relevant erosion/deposition patterns are derived from the model when independent resuspension fluxes are considered in the non-cohesive regime. These results suggest that this kind of approach may be more relevant when local grain-size distributions become heterogeneous and multimodal for non-cohesive particles. Bedload transport appears to be a non-dominant but significant contributor to the sediment dynamics of the Seine Estuary mouth. The residual bedload flux represents, on average, between 17 and 38% of the suspended sand flux, its contribution generally increasing when bed sediment becomes coarser(can become dominant at specific locations). The average orientation of residual fluxes and erosion/deposition patterns caused by bedload generally follow those resulting from suspended sediment dynamics. sediment mass budge

关键词： Non-cohesive sand-mud mixtures Erosion Suspended sediment transport Bedload transport Morphodynamics Seine Estuary

The Dynamics of suspended Particulate Matter in the Oued Nachef(Tafna Basin,Algeria):Typology of Flood Events and Contribution to sediment transport

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Journal of Geological Resource and Engineering 2020年第5期8卷 145-160页

作者： Kazi Tani Hycham Abdesslam Bouanani Abderrazak Baba-Hamed Kamila Probst Jean-Luc Laboratory N°25 Dpt.HydraulicInstitute of Science and TechnologyMaghnia University Center13300MaghniaAlgeria Laboratory N°25 Dpt.HydraulicFaculty of TechnologyUniversity Abou Bakr Belkaid13300TlemcenAlgeria Laboratory of Functional Ecology and Environment University of ToulouseCNRSToulouse INPUniversity Toulouse 3-Paul Sabatier(UPS)Toulouse 31062France

This article focuses on the study of sediment transport during flood events in the Oued Nachef watershed that feeds the Mefrouche dam.To understand the sediment dynamics in this watershed,ANRH data on instantaneous water discharges and the respective concentrations of suspended particulate matter were used.This enabled the selection of some of the largest flood events over a 24-year period in order to establish the log-log relationships between sediment load(concentration and flux)and water discharge.However,the discharge-concentration relationships revealed hysteresis phenomena that enabled a flood typology to be established and classified into seven categories,thus showing very different transfer dynamics in relation to flood events.The results showed that Category 6 floods presenting hysteresis in the form of a figure of eight exported almost 44%of the suspended particulate matter load while representing just 29%of the flow discharge.

关键词： Algeria Oued Nachef Suspended sediment transport flood hysteresis typology

Comparative study of multilayer perceptron-stochastic gradient descent and gradient boosted trees for predicting daily suspended sediment load: The case study of the Mississippi River, U.S.

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International Journal of sediment Research 2021年第4期36卷 512-523页

作者： Sadra Shadkani Akram Abbaspour Saeed Samadianfard Sajjad Hashemi Amirhosein Mosavi Shahab S.Band Department of Water Engineering Faculty of Agriculture University of Tabriz Environmental Quality Atmospheric Science and Climate Change Research Group Ton Duc Thang University Faculty of Environment and Labour Safety Ton Duc Thang University Institute of Research and Development Duy Tan University Future Technology Research Center College of Future National Yunlin University of Science and Technology

Monitoring sediment transport is essential for managing and maintaining rivers.Estimation of the sediment load in rivers is fundamental for the study of sediment movement,erosion,and flood control.In the current study,three machine learning models-multi-layer perceptron(MLP),multi-layer perceptron-stochastic gradient descent(MLP-SGD),and gradient boosted tree(GBT)-were utilized to estimate the suspended sediment load(SSL) at the St.Louis(SL) and Chester(CH) stations on the Mississippi River,U.S.Four evaluation criteria including the Correlation Coefficient(CC),Nash Sutcliffe Efficiency(NSE),Scatter Index(SI),and Willmott’s Index(WI) were utilized to evaluate the performance of the used models.A sensitivity analysis of the models to the input variables revealed that the current day discharge variable had the most effect on the SSL at both stations,but in the absence of current-day discharge data(Qt),a combination of input parameters including SSLt-3,SSLt-2,SSLt-1,Qt-3,Qt-2,Qt-1can be used to estimate the SSL.The comparative outcomes indicated the high accuracy of MLP-SGD-5 model with a CC of 0.983,SI of 0.254,WI of 0.991,and NSE of 0.967 at station CH and the MLP-SGD-6 model with a CC of 0.933,SI of 0.576,WI of 0.961,and NSE of 0.867,respectively,at station SL.The results of MLP models were improved by SGD optimization.Therefore,the MLP-SGD method is recommended as the most accurate model for SSL estimation.

关键词： Suspended sediment transport Ensemble learning Multilayer perceptron Stochastic gradient descent Machine learning

Hydrometeorological assessments and suspended sediment delivery from a central Himalayan glacier in the upper Ganga basin

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International Journal of sediment Research 2018年第4期33卷 493-509页

作者： Amit Kumar Akshaya Verma Anupam Anand Gokhale Rakesh Bhambri Anshuman Misra Shipika Sundriyal Dwarika Prasad Dobhal Naval Kishore Centre for Glaciology Wadia Institute of Himalayan Geology Centre of Advanced Study in Geology Department of Geology Panjab University

Integrated hydrometeorological investigations are not frequently available at a regional scale over a longer time period, especially near the terminus of Indian Himalayan glaciers. An integrated approach to the collection of hydrological data has major advantages for understanding the runoff generation mechanisms at basin scale, particularly when coupled with meteorological observations. The current study involves time series analysis of hydrometeorological records collected near the terminus of the Chorabari Glacier, for four consecutive ablation seasons(June-Sept.) 2009-2012. The analysis shows that variation in rainfall was higher(c= 0.9) at the same elevation over proximal sites, while the intensity of extreme rainfall events was 121-160 mm/d. The diurnal temperature range(DTR) has a tendency to reduce over the ablation season because of the onset of the Indian Summer Monsoon(ISM) and then further increases during the ISM withdrawal indicating humid-temperate conditions. The peak discharge(Qpeak) was found to be higher during July and August. Snow and glacier melt contributed 76% of the total Suspended sediment transport during peak ISM months(July and August) reflecting seasonal evolution of the hydrologic conduits. The results indicate that Karakoram and western Himalayan glaciers produce comparatively low sediment yield compared to central Himalayan glaciers. The hydrological variations are depicted through flow duration curves(FDC) for meltwater discharge and sediment load. The flow corresponding to Q, Q, and Q(where Qx is the discharge that is exceeded x percent of the time referred to as % dependability) are 4.2, 3.7, and 2.8 m~3/s; and the corresponding dependability for suspended sediment loads(SSLs) are 409.0, 266.0, and 157.2 t/d, respectively. The daily SSL and discharge(Q) from 2009 to 2012 were used to develop a sediment rating curve(SSL = 39.55 × Q. R~2 = 0.8).Multiple regressions are used to determine the impacts of meteorological parameters on glacier melt.The meteorological conditions, hydrol

关键词： High elevation meteorology Suspended sediment transport Flow duration curves Multivariate regression Indian summer monsoon

Measuring and modeling suspended sediment concentration profiles in the surf zone

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Journal of Palaeogeography 2012年第2期1卷 172-192页

作者： Ping Wang Department of Geology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620, USA Department of Geology University of South Florida

Time-averaged suspended sediment concentration profiles across the surf zone were measured in a large-scale three-dimensional movable bed laboratory facility (LSTF:Large-scale sediment transport Facility). sediment suspension under two different types of breaking waves, spilling and plunging breakers, was investigated. The magnitudes and shapes of the concentration profiles varied substantially at different locations across the surf zone, reflecting the different intensities of breaking-induced turbulence. sediment sus- pension at the energetic plunging breaker-line was much more active, resulting in nearly homogeneous concentration profiles throughout most of the water column, as compared to the reminder of the surf zone and at the spilling breaker-line. Four suspended sediment concentration models were examined based on the LSTF data, including the mixing turbulence length approach, segment eddy viscosity model, breaking-induced wave-energy dissipation approach, and a combined breaking and turbulence length model developed by this study. Neglecting the breaking-induced turbulence and subsequent sediment mixing, suspended sediment concentration models failed to predict the across-shore variations of the sediment suspension, especially at the plunging breaker-line. Wave-energy dissipation rate provided an accurate method for estimating the intensity of turbulence generated by wave breaking. By incorporating the breaking-induced turbulence, the combined breaking and turbulence length model reproduced the across-shore variation of sediment suspension in the surf zone. The combined model reproduced the measured time-averaged suspended sediment concentration profiles reasonably well across the surf zone.

关键词： sediment transport Suspended sediment transport wave breaking coastal morphodynamics coastal processes beach processes surf zone physical modeling