scholarly journals SAND TRANSPORT AND COASTAL STABILITY, LANCASHIRE, U.K.

1974 ◽  
Vol 1 (14) ◽  
pp. 48
Author(s):  
William Reginald Parker
Keyword(s):  
Sediment Transport ◽  
Qualitative Description ◽  
Sand Transport ◽  
Residence Times ◽  
Coastal Evolution ◽  
Dune Erosion ◽  
Sediment Fluxes ◽  
Dune Stability ◽  
Transport Patterns ◽  
The Stability

The stability of an alluvial coast depends upon the local sediment budget. Along the shore, changes from erosion to accretion may reflect changing sediment fluxes, sediment residence times and patterns of sediment movement. Processes influencing these parameters, such as mud sedimentation or migration of intertidal channels will, through their influence on beach gradients and sediment transport patterns, affect the processes and rates of coastal dune erosion and the safety of the dune protected hinterland. A qualitative description of some of the various processes and phenomena linking foreshore and dune stability with sediment circulation and coastal evolution is presented.

scholarly journals From Ripples to Large-Scale Sand Transport: The Effects of Bedform-Related Roughness on Hydrodynamics and Sediment Transport Patterns in Delft3D

2020 ◽  
Vol 8 (11) ◽  
pp. 892
Author(s):  
Laura Brakenhoff ◽  
Reinier Schrijvershof ◽  
Jebbe van der Werf ◽  
Bart Grasmeijer ◽  
Gerben Ruessink ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Water Movement ◽  
Small Scale ◽  
Sand Transport ◽  
Influence Model ◽  
The North ◽  
Ebb Tidal Delta ◽  
Transport Patterns ◽  
Set Up

Bedform-related roughness affects both water movement and sediment transport, so it is important that it is represented correctly in numerical morphodynamic models. The main objective of the present study is to quantify for the first time the importance of ripple- and megaripple-related roughness for modelled hydrodynamics and sediment transport on the wave- and tide-dominated Ameland ebb-tidal delta in the north of the Netherlands. To do so, a sensitivity analysis was performed, in which several types of bedform-related roughness predictors were evaluated using a Delft3D model. Also, modelled ripple roughness was compared to data of ripple heights observed in a six-week field campaign on the Ameland ebb-tidal delta. The present study improves our understanding of how choices in model set-up influence model results. By comparing the results of the model scenarios, it was found that the ripple and megaripple-related roughness affect the depth-averaged current velocity, mainly over the shallow areas of the delta. The small-scale ripples are also important for the suspended load sediment transport, both indirectly through the affected flow and directly. While the current magnitude changes by 10–20% through changes in bedform roughness, the sediment transport magnitude changes by more than 100%.

Satellite Observations of Sediment Transport Patterns in the Lac Saint-Pierre Region of the St. Lawrence River

1988 ◽  
Vol 23 (2) ◽  
pp. 243-252 ◽  
Author(s):  
J.E. Bruton ◽  
J.H. Jerome ◽  
R.P. Bukata
Keyword(s):  
Sediment Transport ◽  
Close Relationships ◽  
Satellite Observations ◽  
Near Surface ◽  
Thermal Data ◽  
Digital Formats ◽  
Transport Patterns ◽  
Mutually Independent ◽  
River Corridor ◽  
St Lawrence River

Abstract Satellite data from Landsats 4 and 5 were utilized to delineate the seasonal variations of sediment transport zones in the Lac Saint-Pierre region of the St. Lawrence River corridor. A seasonally cyclic succession of patterns displaying persistent, mutually independent, and extensive (in both space and time) turbidity zones was clearly in evidence. Visible and thermal data in both imagery and digital formats were used to show the close relationships existing among the distinct zonal synoptic patterns, the bathymetry of lake and river, and the near surface aquatic temperatures.

Monitoring sediment transport patterns on an energetic ebb-tidal delta using dual-signature tracers

2018 ◽  
Author(s):  
Stuart Pearson ◽  
Bram van Prooijen ◽  
Jack Poleykett ◽  
Matthew Wright ◽  
Kevin Black ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Ebb Tidal Delta ◽  
Transport Patterns

Sediment transport patterns on the Estremadura Spur continental shelf: Insights from grain-size trend analysis

2014 ◽  
Vol 93 ◽  
pp. 28-32 ◽  
Author(s):  
Maria Balsinha ◽  
Carlos Fernandes ◽  
Anabela Oliveira ◽  
Aurora Rodrigues ◽  
Rui Taborda
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Continental Shelf ◽  
Trend Analysis ◽  
Transport Patterns ◽  
Grain Size Trend Analysis

scholarly journals Effects of Cascade Reservoir Systems on the Longitudinal Distribution of Sediment Characteristics: A Case Study of the Heihe River Basin

2021 ◽  
Author(s):  
Yu Wang ◽  
Bao-long Li ◽  
Juan-juan Liu ◽  
Qi Feng ◽  
Wei Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Longitudinal Distribution ◽  
Heihe River ◽  
Hydrodynamic Conditions ◽  
Sediment Grain Size ◽  
Cascade Reservoirs ◽  
Grain Size Distributions ◽  
Transport Patterns ◽  
The Impact

Abstract Spatial variations in grain-size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The grain size of the reservoir sediments within the cascade reservoir system was much lower than that of sediments in the natural river section, and the sediments in the natural river were well sorted, exhibiting leptokurtosis and positive or very positive skew. The lower reaches of the dammed river experienced strong erosion, and the grains of the bed sediments were coarse and poorly sorted; the grain-size distributions were more positively skewed and exhibited leptokurtosis. The backwater zone of the reservoir was influenced by both backwater and released water, and the sediment grain size was between the grain size of the natural river and that of the lower reaches of the dam; these sediments were moderately well sorted and had a positively skewed, leptokurtic grain-size distribution. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain-size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions.

scholarly journals SHEETFLOW SEDIMENT TRANSPORT UNDER SKEWED - ASYMMETRIC WAVES AND CURRENTS

2012 ◽  
Vol 1 (33) ◽  
pp. 50 ◽  
Author(s):  
Le Phuong Dong ◽  
Shinji Sato
Keyword(s):  
Sediment Transport ◽  
Laboratory Experiments ◽  
Fine Sand ◽  
Sand Transport ◽  
Phase Lag ◽  
Half Cycle ◽  
Experimental Conditions ◽  
Wide Range ◽  
Waves And Currents ◽  
Asymmetric Flows

Prototype scale laboratory experiments have been conducted to investigate the sheetflow sediment transport of uniform sands under different skewed-asymmetric oscillatory flows. Experimental results reveal that in most of the case with fine sand, the “cancelling effect”, which balances the on-/off-shore net transport under pure asymmetric/skewed flows and results a moderate net transport, was developed for combined skewed-asymmetric flow. However, under some certain conditions (T > 5s) with coarse sands, the onshore sediment transport was enhanced by 50% under combined skewed-asymmetric flows. Sand transport mechanism under oscillatory sheetflow conditions is also studied by comparing the maximum bed shear stress and the phase lag parameter at each half cycle. A comparison of measurements including the new experimental data with a number of practical sand transport formulations shows that the Dong et al. (2013) formulation performs the best in predicting the measured net transport rates over a wide range of experimental conditions

scholarly journals Coastal Flooding and Erosion under a Changing Climate: Implications at a Low-Lying Coast (Ebro Delta)

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 346 ◽  
Author(s):  
Albert Grases ◽  
Vicente Gracia ◽  
Manuel García-León ◽  
Jue Lin-Ye ◽  
Joan Pau Sierra
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Sea Level ◽  
Anthropogenic Activities ◽  
Management Strategies ◽  
Wave Model ◽  
Ebro Delta ◽  
Coastal Hazards ◽  
Sand Transport ◽  
Storm Waves

Episodic coastal hazards associated to sea storms are responsible for sudden and intense changes in coastal morphology. Climate change and local anthropogenic activities such as river regulation and urban growth are raising risk levels in coastal hotspots, like low-lying areas of river deltas. This urges to revise present management strategies to guarantee their future sustainability, demanding a detailed diagnostic of the hazard evolution. In this paper, flooding and erosion under current and future conditions have been assessed at local scale at the urban area of Riumar, a touristic enclave placed at the Ebro Delta (Spain). Process-based models have been used to address the interaction between beach morphology and storm waves, as well as the influence of coastal environment complexity. Storm waves have been propagated with SWAN wave model and have provided the forcings for XBeach, a 2DH hydro-morphodynamic model. Results show that future trends in sea level rise and wave forcing produce non-linear variations of the flooded area and the volume of mobilized sediment resulting from marine storms. In particular, the balance between flooding and sediment transport will shift depending on the relative sea level. Wave induced flooding and long-shore sand transport seem to be diminished in the future, whereas static sea level flooding and cross-shore sediment transport are exacerbated. Therefore, the characterization of tipping points in the coastal response can help to develop robust and adaptive plans to manage climate change impact in sandy wave dominated coasts with a low-lying hinterland and a complex shoreline morphology.

scholarly journals Tidal current power effects on nearby sandbanks: a case study in the Race of Alderney

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190503 ◽  
Author(s):  
Luke S. Blunden ◽  
Stephen G. Haynes ◽  
AbuBakr S. Bahaj
Keyword(s):  
Sediment Transport ◽  
Tidal Energy ◽  
Sand Wave ◽  
Sand Transport ◽  
Tidal Dynamics ◽  
Tidal Flows ◽  
Tidal Turbine ◽  
Turbine Arrays ◽  
Sediment Model

A validated numerical model of tidal flows and sediment transport around the Alderney South Banks was used to investigate the potential effects of large (300 MW) tidal turbine arrays at different locations in Alderney territorial waters. Two methods were used, firstly looking at hydrodynamic changes only and secondly modelling sediment transport over a non-erodible bed. The baseline hydrodynamic model was validated relative to ADCP velocity data collected in the immediate vicinity of the sandbank. Real-world sand transport rates were inferred from sand-wave migrations and agree favourably with sediment transport residuals calculated from model outputs. Outputs from the sediment model reproduced realistic morphological behaviours over the bank. Seventeen different locations were considered; most did not result in significant hydrodynamic changes over the South Banks; however, three array locations were singled out as requiring extra caution if development were to occur. The results provide a case for optimizing the array locations for twin objectives of maximizing array power and minimizing impacts on the sandbanks. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

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