Ambient noise in large rivers (L)

Vračar, Miodrag S.; Mijic, Miomir

doi:10.1121/1.3628666

Cited by 21 publications

(12 citation statements)

References 7 publications

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“…One of the more common difficulties in the application of SGN to the measurement of coarse sediment bedload transport is the level of the background aquatic soundscape (Wenz, 1972;Thorne, 1986b;Vracar and Mijic, 2011). Contributions from biophony (sounds from aquatic animals), geophony (sounds from natural abiotic phenomenon) and anthrophony (sounds from manmade activities) can make interpretation and assessment of the SGN problematic.…”

Section: Discussionmentioning

confidence: 99%

An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport

Thorne

2014

Earth Surf. Dynam.

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Abstract. Over the past 2 to 3 decades the concept of using sound generated by the interparticle collisions of mobile bed material has been investigated to assess if underwater sound can be utilised as a proxy for the estimation of bedload transport. In principle the acoustic approach is deemed to have the potential to provide non-intrusive, continuous, high-temporal-resolution measurements of bedload transport. It has been considered that the intensity of the sound radiated should be related to the amount of mobile material and the frequency spectrum to the size of the material. To be able to fully realise this use of acoustics requires an understanding of the parameters which control the generation of sound as particles impact. In the present work the aim is to provide scientists developing acoustics to measure bedload transport with a description of how sound is generated when particles undergo collision underwater. To investigate the properties of the sound generated, examples are provided under different conditions of impact. It is considered that providing an overview of the origins of the sound generation will provide a basis for the interpretation of acoustic data, collected in the marine environment for the study of bedload sediment transport processes.

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Section: Discussionmentioning

confidence: 99%

An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport

Thorne

2014

Earth Surf. Dynam.

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“…For example, hydrodynamic noises are generated by surface waves or pressure fluctuations induced by turbulence [Tonolla et al, 2009]. In large rivers, human activities such as boat traffic are also suspected of impacting the acoustic signals [Vračar and Mijić, 2011].…”

Section: Field Experiments With Hydrophonesmentioning

confidence: 99%

“…Origins of ambient noise can be attributed to a variety of processes occurring in a river. In particular, flowing water can generate high acoustic pressure in turbulent environments [Tonolla et al, 2009;Vračar and Mijić, 2011;Lorang and Tonolla, 2014]. Human activities, such as boat traffic or nearby road traffic, are also suspected of generating high acoustic pressure above 1000 Hz [Vračar and Mijić, 2011].…”

Section: The Drau Soundscapementioning

confidence: 99%

Passive acoustic monitoring of bed load discharge in a large gravel bed river

et al. 2017

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Surrogate technologies to monitor bed load discharge have been developed to supplement and ultimately take over traditional direct methods. Our research deals with passive acoustic monitoring of bed load flux using a hydrophone continuously deployed near a river bed. This passive acoustic technology senses any acoustic waves propagated in the river environment and particularly the sound due to interparticle collisions emitted during bed load movement. A data set has been acquired in the large Alpine gravel‐bedded Drau River. Analysis of the short‐term frequency response of acoustic signals allows us to determine the origin of recorded noises and to consider their frequency variations. Results are compared with ancillary field data of water depth and bed load transport inferred from the signals of a geophone array. Hydrophone and geophone signals are well correlated. Thanks to the large network of deployed geophones, analysis of the spatial resolution of hydrophone measurements shows that the sensor is sensitive to bed load motion not only locally but over distances of 5–10 m (10–20% of river width). Our results are promising in terms of the potential use of hydrophones for monitoring bed load transport in large gravel bed rivers: acoustic signals represent a large river bed area, rather than being local; hydrophones can be installed in large floods; they can be deployed at a low cost and provide continuous monitoring at high temporal resolution.

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“…Physical processes involving monitoring techniques of SGN are illustrated in Figure 1. SGN measurements are signals composed of bedload noises that can be mixed with extraneous noise sources, such as rain impacts (Roth et al, 2016), turbulence-induced noises (Gimbert et al, 2014), sounds generated by surface waves (Tonolla et al, 2009), road traffic (Barrière, Oth, et al, 2015b) or fluvial traffic (Vračar and Mijić, 2011). When bedload noises are isolated by signal processing tools (Barrière, Oth, et al, 2015b;Geay et al, 2017), SGN signals can be used to infer information on bedload transport.…”

Section: Introductionmentioning

confidence: 99%

Spectral variations of underwater river sounds

Geay

Belleudy

Laronne

et al. 2017

Earth Surf Processes Landf

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International audiencePassive acoustic monitoring of the self-generated noise of particle impacts has been shown to be correlated to bedload flux and bedload size. However, few studies have concentrated on the role of acoustic wave propagation in a river. For the first time, the river environment is modeled as a Pekeris waveguide, where a wave number integration technique is used to predict the transformation of sounds through their propagation paths. Focusing on the distance of a hydrophone from the channel bed and cutting off the low frequencies produced by impacts between gravel particles, we demonstrate that acoustic propagation modifies the spectral content of bedload-generated sound. Acoustic signals analyzed with the proposed model are interpreted by comparison to Helley–Smith bedload data obtained during flood conditions on the large gravel-bedded Arc-en-Maurienne River, France.This study shows that careful attention to acoustic propagation effects is required when estimating bedload grain size distribution with hydrophones in rivers, especially for rivers with slopes higher than 1%. Bedload monitoring with a hydrophone is particularly appropriate for large gravel-bed rivers – especially so during large floods, when in situ sampling is difficult or impractical and the impact of acoustic propagation is weaker relative to the self-generated noise of bedload impacts

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Ambient noise in large rivers (L)

Cited by 21 publications

References 7 publications

An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport

An overview of underwater sound generated by interparticle collisions and its application to the measurements of coarse sediment bedload transport

Passive acoustic monitoring of bed load discharge in a large gravel bed river

Spectral variations of underwater river sounds

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