scholarly journals Relevance of acoustic methods to quantify bedload transport and bedform dynamics in large sandy-gravel bed river

2020 ◽  
Author(s):  
Jules Le Guern ◽  
Stéphane Rodrigues ◽  
Thomas Geay ◽  
Sébastien Zanker ◽  
Alexandre Hauet ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Reference Method ◽  
Acoustic Doppler Current Profiler ◽  
Accurate Method ◽  
Bedload Transport ◽  
Fluvial Systems ◽  
Sandy Gravel ◽  
Gravel Bed ◽  
Current Profiler ◽  
Gravel Bed River

Abstract. Despite the inherent difficulties to quantify its value, bedload transport is essential to understand fluvial systems. In this study, we assessed different indirect bedload measurement techniques with a reference direct bedload measurement in a section of a large sandy-gravel bed river. Acoustic Doppler Current Profiler (aDcp), Dune Tracking Method (DTM) and hydrophone measurement techniques were used to determine bedload transport rates using calibration with the reference method or using empirical formula. Results show that the hydrophone is the most efficient and accurate method to determine bedload flux in the Loire River. Even though parameters controlling self-generated noise of sediments still need to better understood, the calibration determined in this study allows a good approximation of bedload transport rates. Moreover, aDcp and hydrophone measurement techniques are both able to continuously measure bedload transport associated to bedform migration.

scholarly journals Relevance of acoustic methods to quantify bedload transport and bedform dynamics in a large sandy-gravel-bed river

2021 ◽  
Vol 9 (3) ◽  
pp. 423-444
Author(s):  
Jules Le Guern ◽  
Stéphane Rodrigues ◽  
Thomas Geay ◽  
Sébastien Zanker ◽  
Alexandre Hauet ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Reference Method ◽  
Acoustic Doppler Current Profiler ◽  
Accurate Method ◽  
Calibration Procedure ◽  
Bedload Transport ◽  
Empirical Formulas ◽  
Sandy Gravel ◽  
Gravel Bed ◽  
Gravel Bed River

Abstract. Despite the inherent difficulties in quantifying its value, bedload transport is essential for understanding fluvial systems. In this study, we assessed different indirect bedload measurement techniques with a reference direct bedload measurement in a reach of a large sandy-gravel-bed river. An acoustic Doppler current profiler (aDcp), the dune tracking method (DTM) and hydrophone measurement techniques were used to determine bedload transport rates by using calibration with the reference method or by using empirical formulas. This study is the first work which attempted to use a hydrophone to quantify bedload rates in a large sandy-gravel-bed river. Results show that the hydrophone is the most efficient and accurate method for determining bedload fluxes in the Loire River. Although further work is needed to identify the parameters controlling self-generated sediment noise, the calibration procedure adopted in this study allows a satisfactory estimation of bedload transport rates. Moreover, aDcp and hydrophone measurement techniques are accurate enough to quantify bedload variations associated with dune migration.

scholarly journals Entrainment and deposition of boulders in a gravel bed river

2021 ◽  
Author(s):  
Pascal Allemand ◽  
Eric Lajeunesse ◽  
Olivier Devauchelle ◽  
Vincent Langlois
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
West Indies ◽  
River Discharge ◽  
Bedload Transport ◽  
Transport Time ◽  
Gravel Bed ◽  
River Bed ◽  
Effective Transport ◽  
Gravel Bed River

Abstract. Rivers transports coarse sediment (gravel, cobbles, or boulder) as bedload. During a flood, when the discharge is high enough, the sediment grains move by rolling and bouncing on the river bed. Measuring bedload transport in the field is notoriously difficult. Here, we propose a new method to characterize bedload transport by floods. Using a drone equipped with a high resolution camera, we recorded yearly images of a bar of the Vieux-Habitants river, a gravel-bed river located on Basse-Terre Island (Guadeloupe, French West Indies). These images, combined with high frequency measurements of the river discharge, allow us to monitor the evolution of the population of boulders on the river bed. Based on this dataset, we estimate the smallest discharge that can move the boulders, and calculate the effective transport time of the river. We find that transport occurs about 10 hours per year. When plotted as a function of this effective transport time, likelihood of a given boulder remaining at the same location decreases exponentially, with an effective residence time of 17 hours. We then propose a rough estimate of the average number of boulders that the river carries every year.

scholarly journals Application of an Entropic Method Coupled with STIV for Discharge Measurement in Actual Rivers

2021 ◽  
Vol 945 (1) ◽  
pp. 012036
Author(s):  
Yoshiro Omori ◽  
Ichiro Fujita ◽  
Ken Watanabe
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
River Flow ◽  
Measurement Techniques ◽  
Vertical Direction ◽  
Acoustic Doppler Current Profiler ◽  
Surface Flow ◽  
Surface Velocity ◽  
Cross Sectional ◽  
Current Profiler

Abstract In recent years, due to the frequent occurrence of floods that exceed the facility maintenance level due to climate change, non-contact flood flow measurement techniques have been paid attention and actually some measurements have been conducted by applying them instead of the conventional float method. The space-time image velocimetry (STIV) which can measure the surface flow velocity distribution from video images is one of such techniques. In order to calculate the river flow from the surface velocity distribution, it is necessary to determine an appropriate surface velocity coefficient, which is the ratio of the average depth velocity to the surface velocity. However, at present, empirical default value has been still used in practice. In this study, the cross-sectional velocity distribution was calculated using an entropic method by utilizing the surface velocity distribution measured by STIV and compared with Acoustic Doppler Current Profiler (ADCP) observation. It was confirmed that the introduction of the velocity dip system express the flow velocity distribution in the vertical direction, where the velocity dip occurs due to the influence of vegetation.

Insights into bedload transport processes of a large regulated gravel-bed river

2017 ◽  
Vol 43 (2) ◽  
pp. 514-523 ◽  
Author(s):  
Marcel Liedermann ◽  
Philipp Gmeiner ◽  
Andrea Kreisler ◽  
Michael Tritthart ◽  
Helmut Habersack
Keyword(s):  
Bedload Transport ◽  
Transport Processes ◽  
Gravel Bed ◽  
Gravel Bed River

Thresholds of particle entrainment in a poorly sorted sandy gravel-bed river

CATENA ◽  
2001 ◽  
Vol 44 (3) ◽  
pp. 223-243 ◽  
Author(s):  
Ramon J Batalla ◽  
Juan P Martı́n-Vide
Keyword(s):  
Sandy Gravel ◽  
Gravel Bed ◽  
Particle Entrainment ◽  
Gravel Bed River

scholarly journals Calculated Potential Bedload Versus Real Transported Sands along the Guadiana River Estuary (Spain–Portugal)

2019 ◽  
Vol 7 (11) ◽  
pp. 393
Author(s):  
Juan A. Morales ◽  
Claudio Lozano ◽  
Mouncef Sedrati
Keyword(s):  
Bottom Water ◽  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Bedload Transport ◽  
Cohesive Sediments ◽  
Coastal System ◽  
Deep Channel ◽  
Current Profiler ◽  
Comparison Of The Results ◽  
Guadiana Estuary

The Guadiana estuary is a coastal system located in the southwest of the Iberian Peninsula and is the natural border between Portugal and Spain. It is a rock-bounded estuary which extends along more than 40 km and is characterized by a semidiurnal mesotidal regime. This paper represents an approach to the bedload transport across two flow sections located in the fluvial and marine domains. In the fluvial profile, the most frequent bedform is the plane bed. In the marine area the bed of the deep channel is composed of well-sorted sand, while a lateral bar displays partially cohesive sediments with dominant fine sands in a matrix of clayey silts. Data were acquired during spring and neap tides. Near-bottom water velocities were registered by an acoustic Doppler current profiler (ADCP). Density and bed rugosity were determined in sediment samples. These data were employed using Bagnold’s equation (1963) to quantify the potential bedload (Qb). Further, real bedload values (Sb) were obtained by using Poliakoff traps. The comparison of the results of Qb under both ebb and flood conditions demonstrated a clear river-to-sea net transport in both sectors. The values of Sb were lower than those of Qb in every condition. The sand input across the fluvial estuary cannot supply the potential bedload in the lower domain of the channel, thereby causing a deficit that explains this lack of agreement between potential and real transport.

Sign in / Sign up

Export Citation Format

Share Document