scholarly journals Data-Driven Analysis of Stratified Flow Effect on Suspended Sediment Concentration in an Estuary

2020 ◽  
Vol 8 (8) ◽  
pp. 606
Author(s):  
Heui-Jung Seo ◽  
Minsang Cho ◽  
Hyun-Doug Yoon
Keyword(s):  
Flow Velocity ◽  
Suspended Sediment ◽  
River Discharge ◽  
Suspended Sediment Concentration ◽  
Stratified Flow ◽  
Sediment Concentration ◽  
Data Driven ◽  
Observation Data ◽  
Rainy Period ◽  
Port Area

An estuary is an area where a complex circulation pattern appears due to various hydrodynamic parameters such as tides, river discharge, salinity and water density. Especially during a flood, a large amount of freshwater discharge from a river can cause stratified flows due to the difference in density between freshwater and seawater. This makes it difficult to understand the mechanism of behavior of the suspended sediment concentration in an estuary. To elucidate this problem, we investigated field observation data in the Gyeongin Port area in South Korea during the rainy period. It was found that there were stratified flow features of flow velocity, salinity and temperature between the upper and lower layers due to the abruptly increased amount of freshwater from a river in the rainy period. An artificial neural network (ANN), one of the data-driven modeling techniques, was applied to inductively analyze the hydrodynamic factors affecting the suspended sediment concentration in the estuary. The ANN model showed the best performance when including river discharge, and flow velocity and salinity measured at the surface and bottom layer. This shows that stratified flow is important to understand the behavior of suspended sediment concentration in the estuary.

Dynamics of Suspended Sediments Related to Fine Particles in Lower Mekong River

2013 ◽  
Vol 446-447 ◽  
pp. 1528-1533
Author(s):  
Sarunya Promkotra
Keyword(s):  
Shear Stress ◽  
Flow Velocity ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Fine Particles ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Mekong River ◽  
Fall Velocity ◽  
Stream Discharge

Analytical results are considered the factors of suspended sediment concentration, fall velocity, dimensionless shear stress, transportation rate and stream discharge. As a result of suspended sediments of Loei, Huang and Mekong River, fine particles account for the applicability in sediment deposits. Floating suspended sediments explicit more clay minerals than suspended sediments. Suspended sediment concentration (SSC) in the estuarine of Loei River and Huang River are moderately less than Mekong River. Flow directions of the interconnected rivers to the mainstream-Mekong River lead to the quantity of SSC. Sediment concentrations attain to the dynamic response. Dimensionless shear stress relates to shear velocity, geometry and grain size of particles, and difference of flow velocity. This shear stress is directly comparative to flow velocity and clay mineral concentrations. The transport rate involves in the flow velocity, SSC and depth of the river. Moreover, stream discharge can be presumed by the geometry of the river and topography of sampling locations.

scholarly journals Suspended sediment fluxes in an Indonesian river draining a rainforested basin subject to land cover change

2011 ◽  
Vol 8 (4) ◽  
pp. 7137-7175 ◽  
Author(s):  
F. A. Buschman ◽  
A. J. F. Hoitink ◽  
S. M. de Jong ◽  
P. Hoekstra
Keyword(s):  
Land Cover ◽  
Suspended Sediment ◽  
River Discharge ◽  
Soil Loss ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Sediment Fluxes ◽  
Suspended Sediment Flux ◽  
The Impact

Abstract. Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in the tropics. The increasing sediment fluxes pose a threat to coastal marine ecosystems such as coral reefs. This study presents observations of suspended sediment fluxes in the Berau river (Indonesia), which debouches into a coastal ocean that can be considered the preeminent center of coral diversity. The Berau is an example of a small river draining a mountainous, relatively pristine basin that receives abundant rainfall. Flow velocity was measured over a large part of the river width at a station under the influence of tides, using a Horizontal Acoustic Doppler Current Profiler (HADCP). Surrogate measurements of suspended sediment concentration were taken with an Optical Backscatter Sensor (OBS). Tidally averaged suspended sediment concentration increases with river discharge, implying that the tidally averaged suspended sediment flux increases non-linearly with river discharge. Averaged over the 6.5 weeks observations covered by the benchmark survey, the tidally averaged suspended sediment flux was estimated at 2 Mt y−1. Considering the wet conditions during the observation period, this figure may be considered as an upper limit of the yearly averaged flux. This flux is significantly smaller than what could have been expected from the characteristics of the catchment. The consequences of ongoing clearing of rainforest were explored using a plot scale erosion model. When rainforest, which still covered 50–60 % of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment flux in the Berau river would impose a severe sediment stress on the global hotspot of coral reef diversity. The impact of land cover changes will largely depend on the degree in which the Berau estuary acts as a sediment trap.

scholarly journals Investigation of Ship-Induced Hydrodynamics and Sediment Suspension in a Heavy Shipping Traffic Waterway

2020 ◽  
Vol 8 (6) ◽  
pp. 424
Author(s):  
Lilei Mao ◽  
Yimei Chen
Keyword(s):  
Shear Stress ◽  
Flow Velocity ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Wave Structure ◽  
Sediment Concentration ◽  
Secondary Wave ◽  
Sediment Suspension ◽  
Bottom Shear Stress ◽  
Shipping Traffic

In order to investigate the complex hydrodynamics and associated sediment movement resulting from the ship passages in heavy shipping traffic waterways, field measurements were performed in a heavy shipping traffic waterway. Based on the collected waves, flow velocity and water turbidity data, the analyses of the ship-induced hydrodynamics and associated sediment suspension phenomena were conducted. The low-frequency primary wave and high-frequency secondary wave were more pronounced for a barge and yacht in the wave structure, respectively, and contributed more to the flow velocity fluctuations and the bottom shear stress. The ship-induced bottom shear stress can cause significant suspended sediment concentration increase, and there is a correlation between the maximum suspended sediment concentration and maximum ship-induced drawdown height, which can provide a reference for the waterway management.

SUSPENDED SEDIMENT CONCENTRATION ASSESSMENT AS A PRECURSOR TO RIVER CHANNEL SHIFTING IN THE BENGAWAN SOLO RIVER, INDONESIA

2018 ◽  
Vol 80 (5) ◽  
Author(s):  
Mahendra Andiek Maulana ◽  
Ria Asih Aryani Soemitro ◽  
Toshifumi Mukunoki ◽  
Nadjadji Anwar
Keyword(s):  
Flow Velocity ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Field Investigation ◽  
Outer Side ◽  
River Morphology ◽  
Curved Channel ◽  
Channel Shifting ◽  
Curved Section

This study attempts to recognize the fundamental issues in river morphology by examining suspended sediment concentration (SSC) and flow velocity at the curved channel in an alluvial river. To capture the entire set of the afore mentioned conditions, a field investigation was conducted at the inner and outer banks of the flow path of a curved channel, which is considered as the critical section in river change development. The field observations were conducted over a 1-year period, from January to December 2014, in which both dry and rainy seasons occurred. Because the curved channel is subject to severe erosion, especially around the outer bank, lateral migration of the channel might regularly occur. The field investigation showed that the outer side of the curved section migrated approximately 0.0625 m/month during the study period. The SSC, which peaked at 25% and 43% of the maximal flow velocity in the upstream and downstream sections, respectively, showed the rapid erosion of the curved section leading to lateral channel shifting. A channel resistance evaluation confirmed the potential capability of the riverbed material at the curved section was 20% lower than that in the upstream and downstream sections. According to the SSC and flow features, a new understanding of changing river morphology with respect to a curved channel of the Bengawan Solo River was developed.

Distribusi Kecepatan dan Konsentrasi Sedimen Suspensi pada Aliran Menikung (Studi Kasus pada Saluran Irigasi Mataram Yogyakarta)

2016 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Chairul Muharis
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Suspended Sediment ◽  
Centrifugal Force ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Low Velocity ◽  
Distribution Profile ◽  
Bend Flow ◽  
Distribution Of Flow

The flow velocity and suspended sediment concentration are important parameters of sediment transport mechanisms, especially for agradation and degradation problems. The centrifugal force at the bend channels will increased flow velocity at the outer bank of the bend. It is of course also affects the distribution of flow velocity toward the outside and the inside of the bend channels. The change of the velocity distribution  it is very possible also changes the distribution of suspended sediment concentration. In this paper will discuss the velocity distribution profile and distribution of sediment concentration in the bend flow. This research was conducted at Mataram Irrigation Channel Yogyakarta. The channel rectangular in shape and made of masonry with angle bend 580. Measuring the flow velocity used Propeller currentmeter and  sediment concentration used Opcon Probe. Measuring flow velocity and sediment concentration conducted simultaneously for each measurement point.The results showed that due to the centrifugal force in bend flow, flow velocity distribution and sediment concentration distribution undergoing significant change the outside and the inside of the bend. In general, the distribution of flow velocity toward the outerbank of the bend has increased and the distribution suspended  sediment concentration has decrease  and the opposite occurs innerbank of the bend. A low velocity on the inner bank of the channel bend causes larger grains of sediment that settles and potentially silting.

Evaluation of data driven models for river suspended sediment concentration modeling

2016 ◽  
Vol 535 ◽  
pp. 457-472 ◽  
Author(s):  
Mohammad Zounemat-Kermani ◽  
Özgür Kişi ◽  
Jan Adamowski ◽  
Abdollah Ramezani-Charmahineh
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Data Driven ◽  
Evaluation Of Data

Investigation of Sand Ripple Dynamics with Combined Particle Image and Tracking Velocimetry

2018 ◽  
Vol 35 (10) ◽  
pp. 2019-2036
Author(s):  
Donya P. Frank-Gilchrist ◽  
Allison Penko ◽  
Joseph Calantoni
Keyword(s):  
Flow Velocity ◽  
Suspended Sediment ◽  
Particle Image ◽  
Suspended Sediment Concentration ◽  
Fluid Velocity ◽  
Maximum Flow ◽  
Sediment Concentration ◽  
Flow Measurements ◽  
Oscillatory Flows ◽  
Maximum Flow Velocity

AbstractAccurately assessing the response of sediments to oscillatory flows requires high-resolution fluid velocity and sediment transport measurements at the fluid–sediment interface. Fluid and sediment grain velocities were measured simultaneously with combined particle image and tracking velocimetry under oscillatory flows over movable sand ripples. Three high-speed cameras equipped with varying optical filters were used to distinguish between fluorescent fluid tracers and the grains, from which the fluid and grain velocities were determined, respectively. Individual grains were tracked during transport to determine velocities and trajectories. Sediment grains were first mobilized by a vortex impacting the bed during flow reversal and suspended into the water column just prior to vortex ejection from the ripple crest, similar to previous observations. During phases of maximum flow velocity, additional grains were mobilized by the shear stress and were subsequently suspended. The flow reversed and similar observations were made in the opposite direction. Consequently, four peaks in suspended sediment concentration were observed throughout the flow cycle, consistent with previous observations. However, some previous researchers attributed peaks in suspended sediment concentration occurring during phases of maximum flow velocity to sediment-laden vortices that were shed from adjacent ripples. The measured sediment grain velocities were of similar magnitude and phase to the near-bed fluid velocities when the grains were being advected with the flow. Measurements of suspended sediment concentration agreed well with semiempirical formulations having an average root-mean-square deviation of approximately 4 × 10−5 m3 m−3. Predictions of settling velocity also compared well with the laboratory estimates, agreeing to within 90%.

Assessment of several nonlinear methods in forecasting suspended sediment concentration in streams

2016 ◽  
Vol 48 (5) ◽  
pp. 1240-1252 ◽  
Author(s):  
Mohammad Zounemat-Kermani
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Proper Time ◽  
Gene Expression Programming ◽  
Sediment Concentration ◽  
Data Driven ◽  
Inference System ◽  
Nonlinear Methods ◽  
Significance Level ◽  
Correlation Exponent

In this paper, the use of nonlinear nearest trajectory based on phase space reconstruction along with several data-driven methods, including two types of perceptron artificial neural networks with Levenberg–Marquardt (ANN-LM) and particle swarm optimization learning algorithms (ANN-PSO), adaptive neuro-fuzzy inference system (ANFIS) and gene expression programming for forecasting suspended sediment concentration (SSC) dynamics in streamflow is studied. The nonlinearity of the series was tested using the method of surrogate data at 0.01 significance level as well as correlation exponent method. The proper time delay is calculated using the average mutual information function. Obtained results of different models are compared using root mean square error (RMSE), Pearson's correlation coefficient (PCC) and Nash–Sutcliffe efficiency with logarithmic values (Eln). Of the applied nonlinear methods, ANFIS generates a slightly better fit under whole daily SSC values (the least amount of RMSE = 10.5 mg/l), whereas ANN-PSO shows superiority based on the Eln criterion (the highest amount of Eln = 0.885). According to the non-parametric Mann–Whitney test, all data-driven models represent the same forecasted results and are significantly superior to the nearest trajectory-based model at the 99% confidence level.

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