Introducing surface sampling threshold factor for suspended sediment transport: model development using Sri Lankan tropical highland river basins

2013 ◽  
Vol 46 (1) ◽  
pp. 136-155 ◽  
Author(s):  
Sandun Illangasinghe ◽  
Tilak Hewawasam
Keyword(s):  
Sri Lanka ◽  
Suspended Sediment ◽  
Transport Model ◽  
Low Cost ◽  
Model Development ◽  
Sediment Concentration ◽  
Generic Model ◽  
Suspended Sediment Transport ◽  
Surface Sampling ◽  
Threshold Factor

Estimation of suspended sediment concentration (SSC) in rivers is a prerequisite to address many issues related to hydrology. Therefore, we make an attempt in this study to introduce a low-cost technique to estimate the SSC. Both surface and depth-and-width-integrated water samples were collected and measured for SSC from eight tributaries in Sri Lanka over a complete hydrological year. A site-specific calibration curve was established between SSCs measured by two methods for each tributary where R2 varied from 0.72 to 0.99. The same relationship is developed in general for all tributaries studied in the hilly terrain of Sri Lanka. This generic model exhibits a strong correlation (R2 = 0.91), which will be useful to calculate an accurate SSC from a simply measured surface SSC. To select the appropriate gauging method, be it surface or depth-and-width-integrated sampling, a new concept of surface sampling threshold factor (SSTF) is introduced. The preliminarily analysis on SSTF using available data for the studied catchments reveals that surface sampling is only adequate for estimating a representative SSC if SSTF varies from 35 to 45. When SSTF deviates from this range, the SSC measured by surface sampling needs to be adjusted by depth-and-width-integrated sampling.

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 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 Comparative Assessment of Fluvial Suspended Sediment Concentration Analysis Methods

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 873 ◽  
Author(s):  
Flóra Pomázi ◽  
Sándor Baranya
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Acoustic Doppler Current Profiler ◽  
Sediment Concentration ◽  
Comparative Assessment ◽  
Danube River ◽  
Suspended Sediment Transport ◽  
Indirect Methods ◽  
Analysis Methods ◽  
Sediment Monitoring

The monitoring of fluvial suspended sediment transport plays an important role in the assessment of morphological processes, river habitats, or many social activities associated with river management. However, establishing and operating a well-functioning sediment monitoring system requires the involvement of advanced indirect methods. This study investigates the advantages and limitations of optical and acoustic devices, to quantify the uncertainties and provide a comprehensive comparative assessment of the investigated indirect methods. The novelty of this study, compared to previous ones, is that four different indirect techniques are parallel tested, i.e., the laser diffraction based LISST-Portable|XR, an infrared based optical instrument, the VELP TB1 turbidimeter, the acoustic based LISST-ABS (Acoustical Backscatter Sensor) sensor, and a 1200 kHz Teledyne RD Instruments Acoustic Doppler Current Profiler (ADCP). The calibration of all the indirect methods was performed based on more than 1000 samples taken from the Hungarian section of the Danube River within a wide suspended sediment concentration range. Implementing a comparative assessment of the different sediment analysis methods, a qualitative and quantitative characterisation of the applicability is provided. Furthermore, a proposal for an optimised sediment monitoring methodology is also suggested.

scholarly journals Experimental validation of a cohesive suspended sediment transport model for two Mexican rivers

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Juan Antonio García-Aragón ◽  
Klever Izquierdo-Ayala ◽  
María Mercedes Castillo-Uzcanga ◽  
Laura Carrillo-Bibriezca ◽  
Humberto Salinas-Tapia
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Experimental Validation ◽  
Transport Model ◽  
Suspended Sediment Transport ◽  
Sediment Transport Model

scholarly journals Large-scale suspended sediment transport and sediment deposition in the Mekong Delta

2014 ◽  
Vol 18 (8) ◽  
pp. 3033-3053 ◽  
Author(s):  
N. V. Manh ◽  
N. V. Dung ◽  
N. N. Hung ◽  
B. Merz ◽  
H. Apel
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Large Scale ◽  
Transport Model ◽  
Mekong Delta ◽  
Sediment Dynamics ◽  
Sediment Deposition ◽  
Mineral Fertilizers ◽  
Suspended Sediment Transport ◽  
Extreme Flood

Abstract. Sediment dynamics play a major role in the agricultural and fishery productivity of the Mekong Delta. However, the understanding of sediment dynamics in the delta, one of the most complex river deltas in the world, is very limited. This is a consequence of its large extent, the intricate system of rivers, channels and floodplains, and the scarcity of observations. This study quantifies, for the first time, the suspended sediment transport and sediment deposition in the whole Mekong Delta. To this end, a quasi-2D hydrodynamic model is combined with a cohesive sediment transport model. The combined model is calibrated using six objective functions to represent the different aspects of the hydraulic and sediment transport components. The model is calibrated for the extreme flood season in 2011 and shows good performance for 2 validation years with very different flood characteristics. It is shown how sediment transport and sediment deposition is differentiated from Kratie at the entrance of the delta on its way to the coast. The main factors influencing the spatial sediment dynamics are the river and channel system, dike rings, sluice gate operations, the magnitude of the floods, and tidal influences. The superposition of these factors leads to high spatial variability of sediment transport, in particular in the Vietnamese floodplains. Depending on the flood magnitude, annual sediment loads reaching the coast vary from 48 to 60% of the sediment load at Kratie. Deposited sediment varies from 19 to 23% of the annual load at Kratie in Cambodian floodplains, and from 1 to 6% in the compartmented and diked floodplains in Vietnam. Annual deposited nutrients (N, P, K), which are associated with the sediment deposition, provide on average more than 50% of mineral fertilizers typically applied for rice crops in non-flooded ring dike floodplains in Vietnam. Through the quantification of sediment and related nutrient input, the presented study provides a quantitative basis for estimating the benefits of annual Mekong floods for agriculture and fishery, and is an important piece of information with regard to the assessment of the impacts of deltaic subsidence and climate-change-related sea level rise on delta morphology.

On the Suspended Sediment Concentration Profile

2012 ◽  
Vol 212-213 ◽  
pp. 20-24 ◽  
Author(s):  
Chen Cheng ◽  
Zhi Yao Song ◽  
Yi Gang Wang ◽  
Jin Shan Zhang
Keyword(s):  
Boundary Condition ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Order Approximation ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
Surface Boundary ◽  
Sediment Diffusion Coefficient ◽  
Surface Boundary Condition ◽  
First Order Approximation

After analyzing the surface-boundary condition of suspended sediment concentration (SSC), Cheng et al.[7] further improved the sediment diffusion coefficient which was proposed by Bose and Dey[6]. Then an improved Rouse law (IRL) was developed. This equation, which has a similar form as Rouse law, not only overcomes the zero concentration at the free surface, but also behaves generally better than Rouse law and van Rijn equation over the whole water depth in the verification analysis. In this paper, the surface-boundary condition of SSC is further analyzed. It is elucidated that IRL satisfies the surface-boundary condition more reasonably than Rouse law. In addition, a first-order approximation of IRL is developed. From this approximation, we can easily get the explicit expression of the depth-averaged SSC without any implicit integrals to be solved numerically or by the help of a chart. This is very useful in the further study of non-equilibrium suspended sediment transport (SST).

Revised sediment transport model for estimation of suspended sediment flux and chemical composition of the Irrawaddy and Salween rivers

2020 ◽  
Author(s):  
J. Jotautas Baronas ◽  
Edward T. Tipper ◽  
Michael J. Bickle ◽  
Robert G. Hilton ◽  
Emily I. Stevenson ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Organic Carbon ◽  
Suspended Sediment ◽  
Transport Model ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Sediment Discharge ◽  
Anthropogenic Pressures ◽  
Modeling Framework ◽  
Sediment Delivery

<p>A large portion of freshwater and sediment is exported to the ocean by just several of the world's major rivers. Many of these mega-rivers are under significant anthropogenic pressures, such as damming and sand mining, which are having a significant impact on water and sediment delivery to deltaic ecosystems. However, accurately measuring the total sediment flux and its mean physicochemical composition is difficult in large rivers due to hydrodynamic sorting of sediments. To account for this, we developed an updated semi-empirical Rouse modeling framework, which synoptically predicts sediment concentration, grain size distribution, and mean chemical composition (organic carbon wt%, Al/Si ratio) with depth and across the river channel.</p><p>We applied this model to derive new sediment flux estimates for the Irrawaddy and the Salween, the last two free-flowing mega-rivers in Southeast Asia, using a newly collected set of suspended sediment depth samples, coupled to ADCP-measured flow velocity data. Constructing sediment-discharge rating curves, we calculated an annual sediment flux of 326 (68% confidence interval of 256-417) Mt/yr for the Irrawaddy and 159 (109-237) Mt/yr for the Salween, together accounting for 2-3% of total global riverine sediment discharge. The mean flux-weighted sediment exported by the Irrawaddy is significantly coarser (D<sub>84</sub> = 193 ± 13 µm) and OC-poorer (0.29 ± 0.08 wt%) compared to the Salween (112 ± 27 µm and 0.59 ± 0.16 wt%, respectively). Both rivers export similar amounts of particulate organic carbon, with a total of 1.9 (1.0-3.3) Mt C/yr, contributing ~1% of the total riverine POC export to the ocean. These results underline the global significance of the Irrawaddy and Salween rivers and warrant continued monitoring of their sediment fluxes, given the increasing anthropogenic pressures on these river basins.</p>

Landscape and river self-organization limit the flux of fine particles

2020 ◽  
Author(s):  
Colin Phillips ◽  
Carlos Rogéliz ◽  
Daniel Horton ◽  
Jonathan Higgins ◽  
Aaron Packman
Keyword(s):  
Suspended Sediment ◽  
Fine Particle ◽  
River Flow ◽  
Fine Particles ◽  
Strong Support ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Suspended Sediment Transport ◽  
Erosion Rates ◽  
Suspended Sediment Flux

<p>Fine particles in rivers comprise a substantial fraction (>50%) of the mass leaving a landscape, while at shorter timescales they represent significant carriers of nutrients and contaminants with the potential to both degrade and enhance aquatic habitats. Predicting fine particle dynamics within rivers remains challenging due to a complex relationship between sediment and water availability from the landscape. This inherent complexity results in watershed-specific understandings of suspended sediment dynamics, typically parameterized as empirical functions of catchment land use, geology, and climate. However, observations of significant fine particle storage within river corridors may indicate that the flux of suspended sediment depends on reach-scale hydraulics. To better understand these dynamics, we synthesized over 40 years of suspended sediment concentration (SSC), hydraulic geometry, river flow, and grainsize data collected by the US Geological Survey from hundreds of rivers spanning a large variety of environments across the continental United States. This data synthesis reveals a strong nonlinear trend between reach-scale hydraulics and the suspended sediment flux, with a secondary dependence on particle properties. The multi-site synthesis reveals that by normalizing the suspended sediment flux by the bankfull shear stress and flux results in a collapse of the observed data onto a single function that describes a self-organizing structure for suspended sediment transport in watersheds. This general relationship indicates strong support for the role of autogenic processes in setting the flux of fine particles and erosion rates of watersheds.</p>

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