Combining echo and hydrodynamic measurements for estimating non uniform sand transport under waves and currents

2017 ◽  
Vol 141 (5) ◽  
pp. 3716-3716
Author(s):  
Rodrigo Mosquera ◽  
Francisco Pedocchi
Keyword(s):  
Sand Transport ◽  
Waves And Currents

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 Practical sand transport formula for non-breaking waves and currents

2013 ◽  
Vol 76 ◽  
pp. 26-42 ◽  
Author(s):  
Dominic A. van der A ◽  
Jan S. Ribberink ◽  
Jebbe J. van der Werf ◽  
Tom O'Donoghue ◽  
René H. Buijsrogge ◽  
...  
Keyword(s):  
Breaking Waves ◽  
Sand Transport ◽  
Waves And Currents

scholarly journals FLUME EXPERIMENTS ON SAND TRANSPORT BY WAVES AND CURRENTS

2011 ◽  
Vol 1 (8) ◽  
pp. 11 ◽  
Author(s):  
Douglas L. Inman ◽  
Anthony J. Bowen
Keyword(s):  
Wave Height ◽  
Fold Increase ◽  
Total Power ◽  
Sand Transport ◽  
Flume Experiments ◽  
Wave Travel ◽  
Solid Discharge ◽  
Waves And Currents ◽  
The Waves

Measurements were made of the sand transport (solid discharge) caused by waves and currents traveling over a horizontal sand bed in water 50 cm deep. The waves had heights of 15 cm, and periods of 1.4 and 2.0 sec. The sand transport was measured first in the presence of waves only, then in the presence of waves superimposed on currents. The currents flowed in the direction of wave travel, with steady uniform velocities of 2, 4, and 6 cm/sec. Since sand moves to and fro under the influence of waves, sand traps were placed flush with the surface at either end of the bed. The net sand transport was determined by subtracting the amount of sand trapped at the upwave end of the bed, from that trapped at the downwave end. The total amount of sand caught in both traps was greatest with waves of 2.0 sec period, while the net sand transport was greatest with waves of 1.4 sec period. Super position of waves on currents of 2 cm/sec produced a two-fold increase in the sand transport for both wave types. Surprisingly, faster currents of 4 and 6 cm/sec caused the discharge to decrease somewhat. Estimates of the power expended by waves was obtained from the decrement in wave height as the wave traveled over the sand bed. The decrement in wave height was found to be about I0--5 per unit of distance traveled. Certain calculations show that about one tenth of the total power expended by the waves was used in transporting sediment.

scholarly journals Intertidal finger bars at El Puntal, Bay of Santander, Spain: observation and forcing analysis

2014 ◽  
Vol 2 (1) ◽  
pp. 349-361 ◽  
Author(s):  
E. Pellón ◽  
R. Garnier ◽  
R. Medina
Keyword(s):  
Surf Zone ◽  
High Tide ◽  
Small Scale ◽  
Sand Transport ◽  
Maximum Speed ◽  
Northern Coast ◽  
Astronomical Tide ◽  
Transport Direction ◽  
Waves And Currents ◽  
Main Candidate

Abstract. A system of 15 small-scale finger bars has been observed, by using video imagery, between 23 June 2008 and 2 June 2010. The bar system is located in the intertidal zone of the swell-protected beaches of El Puntal Spit, in the Bay of Santander (northern coast of Spain). The bars appear on a planar beach (slope = 0.015) with fine, uniform sand (D50 = 0.27 mm) and extend 600 m alongshore. The cross-shore span of the bars is determined by the tidal horizontal excursion (between 70 and 130 m). They have an oblique orientation with respect to the low-tide shoreline; specifically, they are down-current-oriented with respect to the dominant sand transport computed (mean angle of 26° from the shore normal). Their mean wavelength is 26 m and their amplitude varies between 10 and 20 cm. The full system slowly migrates to the east (sand transport direction) with a mean speed of 0.06 m day-1, a maximum speed in winter (up to 0.15 m day-1) and a minimum speed in summer. An episode of merging has been identified as bars with larger wavelength seem to migrate more slowly than shorter bars. The wind blows predominantly from the west, generating waves that transport sediment across the bars during high-tide periods. This is the main candidate to explain the eastward migration of the system. In particular, the wind can generate waves of up to 20 cm (root-mean-squared wave height) over a fetch that can reach 4.5 km at high tide. The astronomical tide seems to be important in the bar dynamics, as the tidal level changes the fetch and also determines the time of exposure of the bars to the surf-zone waves and currents. Furthermore, the river discharge could act as input of suspended sediment in the bar system and play a role in the bar dynamics.

scholarly journals NEW PRACTICAL MODEL FOR SAND TRANSPORT INDUCED BY NON-BREAKING WAVES AND CURRENTS

2011 ◽  
Vol 1 (32) ◽  
pp. 10
Author(s):  
Dominic Alexander Van der A ◽  
Jan S Ribberink ◽  
Jebbe J Van der Werf ◽  
Tom O'Donoghue
Keyword(s):  
Fine Sand ◽  
Breaking Waves ◽  
Sand Transport ◽  
Phase Lag ◽  
Flow Conditions ◽  
Large Wave ◽  
Lag Effects ◽  
Flow Acceleration ◽  
Wide Range ◽  
Waves And Currents

Many existing practical sand transport formulae for the coastal marine environment are restricted to limited ranges of hydrodynamic and sediment conditions. This paper presents a new practical formula for net sand transport induced by non-breaking waves and currents, and currents alone. The formula is based on the semi-unsteady, half wave-cycle concept, with bed shear stress as the main forcing parameter. Unsteady phase-lag effects between velocities and concentrations are accounted for, which are especially important for rippled bed and fine sand sheet-flow conditions. Recently recognized effects on the net transport related to flow acceleration skewness and progressive surface waves are also included. The formula is calibrated against a large dataset of net transport rate measurements from oscillatory flow tunnels and a large wave flume covering a wide range of flow and sand conditions. Good agreement is obtained between observations and predictions, and its validity is shown for bedload dominated steady flow conditions.

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