scholarly journals Investigating Suspended-Sediment Transport in a Shallow Lake Using a Three-Dimensional Model

2017 ◽  
Author(s):  
Hong-Ming Liu ◽  
Wen-cheng Liu ◽  
Chih-Yu Chiu
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Shallow Lake ◽  
Suspended Sediment Concentration ◽  
Transport Model ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
Sediment Distribution ◽  
Mean Current

A three-dimensional, unstructured grid, hydrodynamic and suspended-sediment transport model (i.e., SELFE-SED) was developed to simulate temporal and spatial variations of suspended sediment and was applied to the subtropical subalpine Tsuei-Feng Lake (TFL) of Taiwan. The model was validated with measured water level and suspended‑sediment concentration in 2009, 2010, and 2011. The overall model simulation results are in quantitative agreement with the observational data. The validated model was then applied to explore the most important parameter that affects the suspended-sediment concentration and to investigate the effect of wind stress on the mean current and suspended‑sediment distribution in this shallow lake. Modeling results of sensitivity analysis reveal that the settling velocity is a crucial parameter and erosion rate is less important in the suspended-sediment transport model. Remarkable lake circulation was found based on the strength of wind speed and wind direction. Strong wind would result in higher mean current in the top layer and suspended-sediment distribution in the top and bottom layers. This study demonstrated that the wind stress played a significant influence on mean circulation and suspended-sediment transport in a shallow lake.

scholarly journals Numerical Simulation of Flow and Suspended Sediment Transport in the Distributary Channel Networks

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Wei Zhang ◽  
Qiong Jia ◽  
Xiaowen Chen
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Transport Model ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
Governing Equations ◽  
Channel Networks ◽  
Distributary Channel

Flow and suspended sediment transport in distributary channel networks play an important role in the evolution of deltas and estuaries, as well as the coastal environment. In this study, a 1D flow and suspended sediment transport model is presented to simulate the hydrodynamics and suspended sediment transport in the distributary channel networks. The governing equations for river flow are the Saint-Venant equations and for suspended sediment transport are the nonequilibrium transport equations. The procedure of solving the governing equations is firstly to get the matrix form of the water level and suspended sediment concentration at all connected junctions by utilizing the transformation of the governing equations of the single channel. Secondly, the water level and suspended sediment concentration at all junctions can be obtained by solving these irregular spare matrix equations. Finally, the water level, discharge, and suspended sediment concentration at each river section can be calculated. The presented 1D flow and suspended sediment transport model has been applied to the Pearl River networks and can reproduce water levels, discharges, and suspended sediment concentration with good accuracy, indicating this that model can be used to simulate the hydrodynamics and suspended sediment concentration in the distributary channel networks.

scholarly journals Surf Zone Turbulence and Suspended Sediment Dynamics—A Review

2021 ◽  
Vol 9 (11) ◽  
pp. 1300
Author(s):  
Troels Aagaard ◽  
Joost Brinkkemper ◽  
Drude F. Christensen ◽  
Michael G. Hughes ◽  
Gerben Ruessink
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Surf Zone ◽  
Sediment Concentration ◽  
Sandy Beaches ◽  
Suspended Sediment Transport ◽  
Velocity Signal ◽  
Wave Phase ◽  
Turbulence Production

The existence of sandy beaches relies on the onshore transport of sand by waves during post-storm conditions. Most operational sediment transport models employ wave-averaged terms, and/or the instantaneous cross-shore velocity signal, but the models often fail in predictions of the onshore-directed transport rates. An important reason is that they rarely consider the phase relationships between wave orbital velocity and the suspended sediment concentration. This relationship depends on the intra-wave structure of the bed shear stress and hence on the timing and magnitude of turbulence production in the water column. This paper provides an up-to-date review of recent experimental advances on intra-wave turbulence characteristics, sediment mobilization, and suspended sediment transport in laboratory and natural surf zones. Experimental results generally show that peaks in the suspended sediment concentration are shifted forward on the wave phase with increasing turbulence levels and instantaneous near-bed sediment concentration scales with instantaneous turbulent kinetic energy. The magnitude and intra-wave phase of turbulence production and sediment concentration are shown to depend on wave (breaker) type, seabed configuration, and relative wave height, which opens up the possibility of more robust predictions of transport rates for different wave and beach conditions.

scholarly journals A Three-Dimensional Flow and Sediment Transport Model for Free-Surface Open Channel Flows on Unstructured Flexible Meshes

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 18 ◽  
Author(s):  
Yong Lai ◽  
Kuowei Wu
Keyword(s):  
Free Surface ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
Open Channel ◽  
Transport Model ◽  
Three Dimensional ◽  
Suspended Sediment Transport ◽  
Open Channel Flows ◽  
Sediment Transport Model ◽  
Flow And Sediment Transport

Three-dimensional (3D) hydrostatic-pressure-assumption numerical models are widely used for environmental flows with free surfaces and phase interfaces. In this study, a new flow and sediment transport model is developed, aiming to be general and more flexible than existing models. A general set of governing equations are used for the flow and suspended sediment transport, an improved solution algorithm is proposed, and a new mesh type is developed based on the unstructured polygonal mesh in the horizontal plane and a terrain-following sigma mesh in the vertical direction. The new flow model is verified first with the experimental cases, to ensure the validity of flow and free surface predictions. The model is then validated with cases having the suspended sediment transport. In particular, turbidity current flows are simulated to examine how the model predicts the interface between the fluid and sediments. The predicted results agree well with the available experimental data for all test cases. The model is generally applicable to all open-channel flows, such as rivers and reservoirs, with both flow and suspended sediment transport issues.

scholarly journals Modeling Hydro-Dynamics in a Harbor Area in the Daishan Island, China

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 192 ◽  
Author(s):  
Yuting Li ◽  
Zhiyao Song ◽  
Guoqiang Peng ◽  
Xuwen Fang ◽  
Ruijie Li ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Suspended Sediment ◽  
Hydrodynamic Model ◽  
Transport Model ◽  
Measurement Data ◽  
Cross Flow ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
The Impact

This study presents an incorporation and application of a two-dimensional, unstructured-grid hydrodynamic model with a suspended sediment transport module in Daishan, China. The model is verified with field measurement data from 2017: water level, flow velocities and suspended sediment concentration (SSC). In the application on the Daishan, the performance of the hydrodynamic model has been satisfactorily validated against observed variations of available measurement stations. Coupled with the hydrodynamic model, a sediment transport model has been developed and tested. The simulations agreed quantitatively with the observations. The validated model was applied to the construction of breakwaters and docks under a different plan. The model can calculate the flow field and siltation situation under different breakwater settings. After we have analyzed the impact of existing breakwater layout schemes and sediment transport, a reasonable plan will be selected. The results show that the sea area near the north of Yanwo Shan and Dongken Shan has a large flow velocity exceeding 2.0 m/s and the flow velocity within the isobath of 5 m is small, within 0.6 m/s. According to the sediment calculation, the dock project is feasible. However, the designed width of the fairway should be increased to ensure the navigation safety of the ship according to variation characteristics of cross flow velocity in channel.

scholarly journals FIELD INVESTIGATIONS OF SUSPENDED SEDIMENT TRANSPORT IN THE NEARSHORE ZONE

1984 ◽  
Vol 1 (19) ◽  
pp. 120 ◽  
Author(s):  
R.W. Sternberg ◽  
N.C. Shi ◽  
John P. Downing
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Surf Zone ◽  
Pressure Sensors ◽  
Sediment Concentration ◽  
Daily Basis ◽  
Transport Rate ◽  
Suspended Sediment Transport ◽  
Sediment Distribution ◽  
Longshore Transport

The suspended sediment distribution and longshore sediment transport characteristics at Leadbetter Beach, Santa Barbara, California were investigated using a series of miniature optical backseatter sensors which can measure particle concentrations as high as 180 gm/£ and have 10 Hz frequency response. Vertical arrays of sensors were maintained at up to four positions across the surf zone during 7-25 February 1980 and were operated concurrently with pressure sensors and current meters. Data were collected on a daily basis over 2-4 hour periods. The data were analyzed to reveal concentration profiles of suspended sediment, the average suspended sediment loads, and the longshore particle flux in relation to varying wave conditions. Results show that sediment transport occurs as individual suspension events related to incident wave motions and infragravity motion oscillations within the surf zone; suspended sediment concentration decreases approximately logarithimically away from the seabed; the maximum values of longshore transport rates occur in the mid-surf zone; and the measured suspended sediment longshore transport rate is equal to the total longshore transport rate as predicted by existing transport equations.

scholarly journals Transport Mechanism of Suspended Sediments and Migration Trends of Sediments in the Central Hangzhou Bay

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2189
Author(s):  
Zekun Song ◽  
Weiyong Shi ◽  
Junbiao Zhang ◽  
Hao Hu ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Hangzhou Bay ◽  
The South ◽  
Transport Mode ◽  
Tidal Pumping ◽  
The North

Based on the 2013 field survey data of hydrology, suspended sediments and bottom sediments in the Central Hangzhou Bay, this paper explores the dynamic mechanism of suspended sediments in Hangzhou Bay by employing material flux decomposition. Meanwhile, the migration trends of bed sediments are also investigated by analyzing grain size trends. The results show that during an ebb or flood tide, the hydrograph of suspended sediment concentration of Hangzhou Bay is dominated by an M shape (bimodal), which is attributed primarily to the generation of a soft mud layer and a separate fluid mud layer. Laterally, the distribution of suspended sediment concentration is high in the south and low in the north. From a macroscopic perspective, the net sediment transport in the study area displays a “north-landward and south-seaward” trend, presenting a “C”-shaped transport mode. That is, the sediments are transported from the bay mouth to the bay head on the north side and from the bay head to the bay mouth on the south side. The sediment transports by advection and tidal pumping are predominant, while the sediment transport by vertical circulation makes little contribution to the total sediment transport. Moreover, the sediment transport in the center of the reach area is dominated by advection, whereas that near both sides of the banks is controlled by tidal pumping. The asymmetry of the tides, i.e., flood-dominance in the north and ebb-dominance in the south, is the primary cause of the dynamic mechanism for the overall “C”-shaped transport mode in Hangzhou Bay. Additionally, coupled with the narrow-head wide-mouth geomorphology, Hangzhou Bay remains evolving by south shore silting and north shore scouring.

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