scholarly journals AIRBORNE LIDAR BATHYMETRY APPLIED TO COASTAL HYDRODYNAMIC PROCESSES

2011 ◽  
Vol 1 (32) ◽  
pp. 26
Author(s):  
Bernard Long ◽  
Françis Aucoin ◽  
Stéphane Montreuil ◽  
Valérie Robitaille ◽  
Régis Xhardé
Keyword(s):  
Suspended Sediment ◽  
Sediment Concentration ◽  
Airborne Lidar ◽  
Ct Scanner ◽  
Laser Reflectance ◽  
Lab Experiments ◽  
Sediment Compaction ◽  
Airborne Lidar Bathymetry ◽  
Hydrodynamic Processes ◽  
The Waves

In this study, the possibility to get sedimentological (density, compaction) and hydrodynamical (suspended sediment concentration, turbulence) information from ALB surveys is demonstrated. ALB laser reflectance was found to be higher on the lee-side and on the crest of the ripple bedform than in the trough and on the stoss-side. Moreover, laser reflectance was also found to be higher on “active” subtidal dunes, located within the depth of action of the waves, than on deeper “passive” bedforms. Based on lab experiments conducted in a hydraulic flume under X-ray CT-Scanner, these observations were related to sediment compaction and suspended sediment.

scholarly journals Instability of flow with suspended sediment in an inclined channel

1991 ◽  
Vol 13 (1) ◽  
pp. 1-8
Author(s):  
Nguyen Van Diep ◽  
Dang Huu Chung
Keyword(s):  
Nonlinear Analysis ◽  
Steady Flow ◽  
Suspended Sediment ◽  
Nonlinear Evolution ◽  
Sediment Concentration ◽  
Linear Analysis ◽  
Inclined Channel ◽  
Inclined Angle ◽  
The Waves ◽  
Unchanged Form

In this work the authors had studied the instability and nonlinear evolution of steady flow suspended sediment in inclined channel with fixed and plane bed. With the linear analysis- it has been shown that at the critical inclined angle, an arbitrary disturbance will be splinted in three modes 3F0/2, F0/2, F0, in which F0/2 and F0 propagate downstream and deaden while mode 3F0/2 propagates downstream and its form is unchanged. In particular the waves of sediment concentration always propagate downstream with velocity F0 and unchanged form. The nonlinear analysis has shown that the concentration waves propagate downstream with velocity F and deaden when the time t is large.

Neural networks approached for modelling river suspended sediment concentration due to tropical storms

2013 ◽  
Vol 11 (4) ◽  
pp. 457-466
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Time Series Data ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Series Data ◽  
Generalized Regression Neural Network ◽  
Event Based

Artificial neural networks are one of the advanced technologies employed in hydrology modelling. This paper investigates the potential of two algorithm networks, the feed forward backpropagation (BP) and generalized regression neural network (GRNN) in comparison with the classical regression for modelling the event-based suspended sediment concentration at Jiasian diversion weir in Southern Taiwan. For this study, the hourly time series data comprised of water discharge, turbidity and suspended sediment concentration during the storm events in the year of 2002 are taken into account in the models. The statistical performances comparison showed that both BP and GRNN are superior to the classical regression in the weir sediment modelling. Additionally, the turbidity was found to be a dominant input variable over the water discharge for suspended sediment concentration estimation. Statistically, both neural network models can be successfully applied for the event-based suspended sediment concentration modelling in the weir studied herein when few data are available.

APPLICATION OF ACOUSTIC METHODS IN RESEARCHES OF THE BOTTOM SEDIMENT DYNAMICS

2018 ◽  
Author(s):  
Б. Дивинский ◽  
B. Divinskiy ◽  
И. Грюне ◽  
I. Gryune ◽  
Р. Косьян ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Sediment Concentration ◽  
Irregular Waves ◽  
Single Frequency ◽  
Contactless Measurement ◽  
Measurement Means ◽  
Uniform Field ◽  
Wave Flume ◽  
Acoustic Methods ◽  
Back Scattering

Acoustic methods belong to contactless measurement means, possess high spatial and time resolution. Thus, the use of multifrequency allows directly profile both concentration and granulometric structure of the suspended substances. In 2008 in the Big Wave Flume (Hanover, Germany) by efforts of the Russian and German scientists there have been carried out the experiment on studying the bottom material suspension laws under the influence of irregular waves. The Aquascat 1000 acoustic back scattering sensor (ABS) manufactured by British company Aquatec (www.aquatecsubsea.com), equipped by a three-frequency transmitter with frequencies 1,0, 2,0 and 3,84 MHz, has been set on distance of 0,75 m from the bottom and 111 m from wave generator at the total depth of 3,2 m. Several dozen series of measurements at various parameters of surface waves have been carried out. The general picture of suspension is so that the external dynamic influence (currents, wave movements, turbulence, gravitation forces) creates a non-uniform field (gradient) of the suspended particles and in most cases due to this the average size of particles undergoes to the spatial-time variations. For this reason while defining the mass concentration of suspended sediment, using the single frequency transmitter there is necessity for numerous definition of the suspension granulometric structure what by isn’t always possible. If two and more frequencies are used the observed results comparison can give the information on average diameters of particles and on that basis the calculation of suspended sediment concentration is possibleLet's emphasize the basic advantages of back scattering acoustic gauges usage: – Obtaining the particles sizes and concentration distribution profiles is possible; – The initial granulometric structure of bottom sediments can be unknown (at use of several frequencies). The following can be referred to some lacks of the device: – The system should be calibrated in laboratory conditions; – In a positive feedback conditions the iterative computing process can converge to zero or to infinity. In this case experiments with a variation of carrier frequencies chosen for the analysis allow partially solve the problem (say experiments with different frequencies pairs, as 2/1 of MHz or 4/2 MHz).

AIRBORNE LIDAR BATHYMETRY ON RUMOI COAST IN HOKKAIDO

2019 ◽  
Vol 75 (2) ◽  
pp. I_115-I_120
Author(s):  
Shinji IKI ◽  
Tatsuo FUJIYAMA ◽  
Kiwamu KADOWAKI ◽  
Tomoaki YOKOTA ◽  
Tomoharu WATANABE ◽  
...  
Keyword(s):  
Airborne Lidar ◽  
Airborne Lidar Bathymetry
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