Optimization of passive acoustic bedload monitoring in rivers by signal inversion
<p>Recent studies have shown that hydrophone sensors can monitor bedload flux in rivers by measuring the self-generated noise (SGN) emitted by bedload particles when they impact the riverbed. However, experimental and theoretical studies have shown that the measured SGN depends not only on bed...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-01-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/12/117/2024/esurf-12-117-2024.pdf |
| _version_ | 1827383770773192704 |
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| author | M. Nasr A. Johannot T. Geay T. Geay S. Zanker J. Le Guern A. Recking |
| author_facet | M. Nasr A. Johannot T. Geay T. Geay S. Zanker J. Le Guern A. Recking |
| author_sort | M. Nasr |
| collection | DOAJ |
| description | <p>Recent studies have shown that hydrophone sensors can monitor bedload flux in rivers by measuring the self-generated noise (SGN) emitted by bedload particles when they impact the riverbed. However, experimental and theoretical studies have shown that the measured SGN depends not only on bedload flux intensity but also the propagation environment, which differs between rivers. Moreover, the SGN can propagate far from the acoustic source and be well measured at distant river positions without bedload transport. It has been shown that this dependency of the measured SGN data on the propagation environment can significantly affect the performance of monitoring bedload flux by hydrophone techniques. In this article, we propose an inversion model to solve the problem of the SGN propagation and integration effect. In this model, we assume that the riverbed acts as SGN source areas with intensity proportional to the local bedload flux. The inversion model locates the SGN sources and calculates their corresponding acoustic power by solving a system of linear algebraic equations, accounting for the actual measured cross-sectional acoustic power (acoustic mapping) and attenuation properties. We tested the model using data from measured bedload SGN profiles (acoustic mapping with a drift boat) and bedload flux profiles (direct sampling with an Elwha sampler) acquired during two field campaigns conducted in 2018 and 2021 on the Giffre river in the French Alps. Results confirm that the bedload flux measured at different verticals on the river cross-section correlates more with the inversed acoustic power than measured acoustic power. Moreover, it was possible to fit data from the two field campaigns with a common curve after inversion, which was not possible with the measured acoustic data. The results of the inversion model, compared to measured data, show the importance of considering the propagation effect when using the hydrophone technique and offer new perspectives for the calibration of bedload flux with SGN in rivers.</p> |
| first_indexed | 2024-03-08T14:46:08Z |
| format | Article |
| id | doaj.art-902ddc69916947f6b4063df0a89c3315 |
| institution | Directory Open Access Journal |
| issn | 2196-6311 2196-632X |
| language | English |
| last_indexed | 2024-03-08T14:46:08Z |
| publishDate | 2024-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj.art-902ddc69916947f6b4063df0a89c33152024-01-11T10:13:12ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2024-01-011211713410.5194/esurf-12-117-2024Optimization of passive acoustic bedload monitoring in rivers by signal inversionM. Nasr0A. Johannot1T. Geay2T. Geay3S. Zanker4J. Le Guern5A. Recking6Université Grenoble Alpes, INRAE, ETNA, 38000 Grenoble, FranceUniversité Grenoble Alpes, INRAE, ETNA, 38000 Grenoble, FranceOffice National des Forêts, Service Restauration Terrain Montagne, 38000 Grenoble, FranceGINGER BURGEAP, R&D, 38000 Grenoble, FranceEDF Hydro, DTG, 38950 Saint-Martin-le-Vinoux, FranceGINGER BURGEAP, R&D, 38000 Grenoble, FranceUniversité Grenoble Alpes, INRAE, ETNA, 38000 Grenoble, France<p>Recent studies have shown that hydrophone sensors can monitor bedload flux in rivers by measuring the self-generated noise (SGN) emitted by bedload particles when they impact the riverbed. However, experimental and theoretical studies have shown that the measured SGN depends not only on bedload flux intensity but also the propagation environment, which differs between rivers. Moreover, the SGN can propagate far from the acoustic source and be well measured at distant river positions without bedload transport. It has been shown that this dependency of the measured SGN data on the propagation environment can significantly affect the performance of monitoring bedload flux by hydrophone techniques. In this article, we propose an inversion model to solve the problem of the SGN propagation and integration effect. In this model, we assume that the riverbed acts as SGN source areas with intensity proportional to the local bedload flux. The inversion model locates the SGN sources and calculates their corresponding acoustic power by solving a system of linear algebraic equations, accounting for the actual measured cross-sectional acoustic power (acoustic mapping) and attenuation properties. We tested the model using data from measured bedload SGN profiles (acoustic mapping with a drift boat) and bedload flux profiles (direct sampling with an Elwha sampler) acquired during two field campaigns conducted in 2018 and 2021 on the Giffre river in the French Alps. Results confirm that the bedload flux measured at different verticals on the river cross-section correlates more with the inversed acoustic power than measured acoustic power. Moreover, it was possible to fit data from the two field campaigns with a common curve after inversion, which was not possible with the measured acoustic data. The results of the inversion model, compared to measured data, show the importance of considering the propagation effect when using the hydrophone technique and offer new perspectives for the calibration of bedload flux with SGN in rivers.</p>https://esurf.copernicus.org/articles/12/117/2024/esurf-12-117-2024.pdf |
| spellingShingle | M. Nasr A. Johannot T. Geay T. Geay S. Zanker J. Le Guern A. Recking Optimization of passive acoustic bedload monitoring in rivers by signal inversion Earth Surface Dynamics |
| title | Optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| title_full | Optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| title_fullStr | Optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| title_full_unstemmed | Optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| title_short | Optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| title_sort | optimization of passive acoustic bedload monitoring in rivers by signal inversion |
| url | https://esurf.copernicus.org/articles/12/117/2024/esurf-12-117-2024.pdf |
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