scholarly journals Grain‐size distribution and propagation effects on seismic signals generated by bedload transport

2021 ◽  
Author(s):  
Sophie Lagarde ◽  
Michael Dietze ◽  
Florent Gimbert ◽  
Jonathan B. Laronne ◽  
Jens M. Turowski ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Bedload Transport ◽  
Seismic Signals ◽  
Propagation Effects

scholarly journals Passive acoustic measurement of bedload grain size distribution using self-generated noise

2018 ◽  
Vol 22 (1) ◽  
pp. 767-787 ◽  
Author(s):  
Teodor Petrut ◽  
Thomas Geay ◽  
Cédric Gervaise ◽  
Philippe Belleudy ◽  
Sebastien Zanker
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Measurement Techniques ◽  
Bedload Transport ◽  
Transport Processes ◽  
Signal Spectrum ◽  
Inversion Method ◽  
Passive Acoustic

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

scholarly journals Estimation of Bed Load Transport in River Osun, South-Western of Nigeria Using Grain Size Distribution Data

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
O.S. Olaniyan
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Bedload Transport ◽  
Cross Sectional Area ◽  
Sediment Supply ◽  
Distribution Data ◽  
Sectional Area ◽  
Cross Sectional ◽  
Standard Methods

Sediment transport rate depends on bed composition, flow hydraulics and sediment supply. There is a paucity of information on bedload transport in River Osun. In this study, bedload in River Osun was estimated using grain size distribution data to predict channel migration and mitigate flooding. Grab sampler was used to collect sediment samples at the sampling point across the river designated as T1-T4. Sieve analysis was carried out in triplicate on sediment from sampling points using standard methods. Discharge and cross-sectional area were measured between December 2017 and December 2018 at sampling stations using standard methods. The seasonal and bedload were estimated using standards equations. The percentage of bed material particles above 5mm and less than or equal to 2mm were 50 and 22.49%, respectively. The average median grain (d50) size was 2.4mm. The discharge and cross-sectional area across River Osun ranged (0.53-17.46) m3/s and (3.83-47.46) m2. The seasonal suspended and bedload across the river were (206.43×103 kg/annum) and 2,538.77×103(kg/annum), respectively. The estimated sediment load of River Osun could be useful in determining the dredging period at any point across the river where deposition of sediment could be monitored.

scholarly journals Temporal variations of bed load transport rate and the grain size distribution of non-uniform size sediment during a constant flow rates

2018 ◽  
Vol 195 ◽  
pp. 05001
Author(s):  
Yusron Saadi ◽  
Ida Bagus Giri Putra ◽  
Agus Suroso
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sampling Period ◽  
Degradation Process ◽  
Temporal Variations ◽  
Bedload Transport ◽  
Transport Rate ◽  
Uniform Size ◽  
Short Period

Bedload transport rates at a point using both laboratory and field measurement vary with time, from almost zero to several folds of the mean rate. The need to carry out point measurements over a sufficiently long sampling period is very important to cover inconsistency in the transport rate during a short period of observation. In this experiment the bedload was collected at a slot type sediment trap with ten-minute intervals throughout the tests. The aim was to examine the behaviour of mixed grain size sediment transportation during constant flowrates. Two hydrographs were applied to quantify the transport mode changes caused by an increase in time length as the mixtures were continuously exposed to the flow. It shows that intense bed degradation process occurred within three hours of the tests as indicated by almost identical rates of bedload transport during this period and the diminishing rate in the remaining hours. This reflects that a stable bed was achieved after three hours in which the armouring process was believed to take place. The grain size distribution suggests that the proportion of fine mode was relatively stable and the modal grain size of this mode experienced a similar pattern throughout the tests whilst the coarse mode was inconsistent and varied periodically.

scholarly journals Comparison between experimental and numerical stratigraphy emplaced by a prograding delta

2014 ◽  
Vol 2 (1) ◽  
pp. 323-338 ◽  
Author(s):  
E. Viparelli ◽  
A. Blom ◽  
C. Ferrer-Boix ◽  
R. Kuprenas
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Mass Conservation ◽  
Bedload Transport ◽  
Experimental Results ◽  
Delta Front ◽  
One Dimensional ◽  
Future Studies ◽  
Base Level

Abstract. A one-dimensional model that is able to store the stratigraphy emplaced by a prograding delta is validated against experimental results. The laboratory experiment describes the migration of a Gilbert delta on a sloping basement into standing water, i.e., a condition in which the stratigraphy emplaced by the delta front is entirely stored in the deposit. The migration of the delta front and the deposition on the delta top are modeled with total and grain-size-based mass conservation models. The vertical sorting on the delta front is modeled with a lee-face-sorting model as a function of the grain size distribution of the sediment deposited at the brinkpoint, i.e., at the downstream end of the delta top. Notwithstanding the errors associated with the grain-size-specific bedload transport formulation, the comparison between numerical and experimental results shows that the model is able to reasonably describe the progradation of the delta front, the frictional resistances on the delta top, and the overall grain size distribution of the delta top and delta front deposits. Further validation of the model in the case of variable base level is currently in progress to allow for future studies, at field and laboratory scale, on how the delta stratigraphy is affected by different changes of relative base level.

scholarly journals Passive Acoustic Measurement of Bedload Grain Size Distribution using the Self-Generated Noise

2017 ◽  
Author(s):  
Teodor I. Petrut ◽  
Thomas Geay ◽  
Cédric Gervaise ◽  
Philippe Belleudy ◽  
Sebastien Zanker
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Power Spectrum ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Bedload Transport ◽  
Transport Processes ◽  
Signal Spectrum ◽  
Inversion Method ◽  
Passive Acoustic

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport processes description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload-grain sizes involved in elastic impacts with the bed river treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model which predicts the acoustic field generated by the collision between rigid bodies. Here it is proposed an analytic model of the acoustic power spectrum generated by the impacts between a sphere and a slab. The proposed model is written as linear system of analytic power spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied on real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensures high spatial and temporal resolution measurements for sediment transport in rivers.

scholarly journals Comparison between experimental and numerical stratigraphy emplaced by prograding bedforms with a downstream slip face

2013 ◽  
Vol 1 (1) ◽  
pp. 1151-1186 ◽  
Author(s):  
E. Viparelli ◽  
A. Blom ◽  
C. Ferrer-Boix ◽  
R. Kuprenas
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Mass Conservation ◽  
Bedload Transport ◽  
Experimental Results ◽  
Delta Front ◽  
One Dimensional ◽  
Base Level ◽  
Delta Progradation

Abstract. A one-dimensional model that is able to store the stratigraphy emplaced by prograding bedforms with a downstream slip face is validated against experimental results. The laboratory experiment describes the migration of a Gilbert delta on a sloping basement into standing water, i.e. a condition in which the stratigraphy emplaced by the delta front (the lee face) is entirely stored in the deposit. The migration of the delta front and the deposition on the delta top are modeled with a total and a grain size based mass conservation models. The vertical sorting on the delta front is modeled with a lee face sorting model, as a function of the grain size distribution of the sediment deposited at the brinkpoint, i.e. at the downstream end of the delta top. Notwithstanding the errors associated with the grain size specific bedload transport formulation, the comparison between numerical and experimental results shows that the model is able to reasonably describe the progradation of the delta front, the frictional resistances on the delta top, and the overall grain size distribution of the delta top and delta front deposits. Further validation of the model under the case of variable base level is currently in progress to allow for future studies on Gilbert delta progradation at field scale.

Sign in / Sign up

Export Citation Format

Share Document