Spectral variations of underwater river sounds

Geay, Thomas; Belleudy, Philippe; Laronne, Jonathan B.; Camenen, B.; Gervaise, Cédric

doi:10.1002/esp.4208

Cited by 18 publications

(30 citation statements)

References 42 publications

(98 reference statements)

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“…Another propagation effect concerns the frequency cutoff phenomena, due to acoustic propagation in waveguides (Geay, 2013;Geay et al, 2017b;Jensen et al, 2011;Rigby et al, 2016). In our case, the Isère River has enough large depth that the bandwidth of bedload is not being impacted.…”

Section: Discussion On Real Data Resultsmentioning

confidence: 86%

“…However, the cross-sectional variability of sampled diameters is higher than the estimated one. This is explained by the fact that the hydrophone has the spatial integrative characteristic (Geay et al, 2017b). The phenomenon of signal integration is typical for rivers like the Isère, where high fluxes of bedload transport are concentrated only in a small portion across the section, i.e., in its center.…”

Section: Discussion On Real Data Resultsmentioning

confidence: 99%

“…Bedload SGN spectra monitored by a hydrophone are not only dependent on bedload sizes, but are also affected by propagation effects. For example, an alpine river has been modeled as a Pekeris waveguide (Geay et al, 2017b). Consequently, it has been shown Table 1 and U imp = 1 m s −1 .…”

Section: Discussion On Real Data Resultsmentioning

confidence: 99%

“…Bedload impacts can clearly be heard in the higher frequency band, sounding like the crackling of flames. Sounds occurring below 400 Hz are non-propagating sounds as they are localized below the cutoff frequency of the river waveguide (Geay et al, 2017b;Rigby et al, 2016). They are related to turbulence-induced noise around the sensor and to mechanical movements of the structure sharing the hydrophone.…”

Section: Definition Of the Sgn Spectrummentioning

confidence: 99%

See 3 more Smart Citations

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

Petrut¹,

Geay²,

Gervaise³

et al. 2018

Hydrol. Earth Syst. Sci.

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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.

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Section: Discussion On Real Data Resultsmentioning

confidence: 86%

Section: Discussion On Real Data Resultsmentioning

confidence: 99%

Section: Discussion On Real Data Resultsmentioning

confidence: 99%

Section: Definition Of the Sgn Spectrummentioning

confidence: 99%

See 2 more Smart Citations

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

Petrut¹,

Geay²,

Gervaise³

et al. 2018

Hydrol. Earth Syst. Sci.

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“…The role of acoustic wave propagation in a river was the focus of passive acoustic monitoring of the self-generated noise of particle impacts correlated with bedload flux and bedload size (Geay et al, 2017). Acoustic propagation modifies the spectral content of bedload-generated sound.…”

Section: Sediment Transport By Monitoring Approachesmentioning

confidence: 99%

Special Issue: Gravel Bed Rivers 8

Laronne

Tsutsumi

2018

Earth Surf Processes Landf

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Theoretical, modeling, experimental and monitoring of sediment transport in gravel bed rivers are introduced. The key findings of 27 papers on this theme were published in Earth Surface Processes and Landforms during the past year. Among these, 18 papers were published by attendants of the 8th Gravel Bed River Workshop held in Japan in 2015. This Commentary introduces the main themes associated with these papers including innovations in sediment transport conceptualization and modeling and monitoring, and also three wider themes: the importance of sediment supply; relationships between gravel bed river science and restoration; and the growing recognition of the critical role played by wood in gravel bed rivers. Copyright © 2018 John Wiley & Sons, Ltd.

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Strengths and weaknesses of acoustic pipe microphone systems in ephemeral, sandy, gravel‐bed rivers

Stark,

Cadol,

Varyu

et al. 2024

Earth Surf Processes Landf

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We calibrated an acoustic pipe microphone system to monitor bedload flux in a sandy, gravel‐bed ephemeral channel. Ours is a first attempt to test the limit of an acoustic surrogate bedload system in a channel with a high content of sand. Calibrations varied in quality; significant data subsetting was required to achieve R2 values >0.75. Several data quality issues had to be addressed: (1) apparent pulses, which occur when a sensor records an impulse from sediment impacting the surrounding substrate rather than directly impacting the sensor, were frequent, especially at higher signal amplifications. (2) The impact sensors were frequently covered by gravel sheets. This prompted the development of a cover detection protocol that rejected part of the impact sensor record when at least one sensor was partially or fully covered. (3) Because of the lack of sensor sensitivity to impacts of sand‐sized particles, which was anticipated, and the considerable sand component of bedload in this channel, a grain size‐limited bedload flux was estimated. This was accomplished by sampling the bedload captured by slot samplers and evaluating the variation of grain size with increasing flow strength. This considerably improved the results when compared to attempts at estimating the flux of the entire distribution of grain sizes. This calibration is a successful first attempt, though the impact sensors required several site‐specific calibration steps. A universal set of equations using impact sensors to estimate bedload transport of fine‐gravel with a large content of sand remains elusive. Notwithstanding, our study demonstrates the utility of impact sensor data, producing relatively low root mean square errors that are independent of measurements of flow strength (i.e. discharge). These tools will be particularly useful in settings that would benefit from new methodologies for estimating bedload transport in sand‐rich gravel‐bed rivers, such as the American desert Southwest.

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Spectral variations of underwater river sounds

Cited by 18 publications

References 42 publications

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

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

Special Issue: Gravel Bed Rivers 8

Strengths and weaknesses of acoustic pipe microphone systems in ephemeral, sandy, gravel‐bed rivers

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