Spatiotemporal Variations in Biophysical Water Quality Parameters

This study aims to develop and implement a methodology for retrieving bio-optical parameters in a lagoon located in the Biobío region, South-Central Chile, by analyzing time series of Landsat-8 OLI satellite images. The bio-optical parameters, i.e., chlorophyll-a (Chl-a, in mg·m) and turbidity (in N...

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Autores: Yépez, Santiago|||0000-0002-7879-7094, Velásquez, Germán, Torres, Daniel, Saavedra-Passache, Rodrigo, Pincheira, Martin, Cid, Hayleen, Rodríguez-López, Lien|||0000-0002-0550-0253, Contreras, Angela, Frappart, Frédéric|||0000-0002-4661-8274, Cristóbal, Jordi|||0000-0001-6244-4289, Pons, Xavier|||0000-0002-6924-1641, Flores, Neftali, Bourrel, Luc
Formato: artículo
Fecha de publicación:2024
País:España
Recursos:Universitat Autònoma de Barcelona
Repositorio:Dipòsit Digital de Documents de la UAB
Idioma:inglés
OAI Identifier:oai:ddd.uab.cat:289100
Acesso em linha:https://ddd.uab.cat/record/289100
https://dx.doi.org/urn:doi:10.3390/rs16020427
Access Level:acceso abierto
Palavra-chave:Eutrophication
Landsat
Chl-a
Turbidity
Spectral signatures
OLI
Chile
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spelling Spatiotemporal Variations in Biophysical Water Quality ParametersAn Integrated In Situ and Remote Sensing Analysis of an Urban Lake in ChileYépez, Santiago|||0000-0002-7879-7094Velásquez, GermánTorres, DanielSaavedra-Passache, RodrigoPincheira, MartinCid, HayleenRodríguez-López, Lien|||0000-0002-0550-0253Contreras, AngelaFrappart, Frédéric|||0000-0002-4661-8274Cristóbal, Jordi|||0000-0001-6244-4289Pons, Xavier|||0000-0002-6924-1641Flores, NeftaliBourrel, LucEutrophicationLandsatChl-aTurbiditySpectral signaturesOLIChileThis study aims to develop and implement a methodology for retrieving bio-optical parameters in a lagoon located in the Biobío region, South-Central Chile, by analyzing time series of Landsat-8 OLI satellite images. The bio-optical parameters, i.e., chlorophyll-a (Chl-a, in mg·m) and turbidity (in NTU) were measured in situ during a satellite overpass to minimize the impact of atmospheric distortions. To calibrate the satellite images, various atmospheric correction methods (including ACOLITE, C2RCC, iCOR, and LaSRC) were evaluated during the image preprocessing phase. Spectral signatures obtained from the scenes for each atmospheric correction method were then compared with spectral signatures acquired in situ on the water surface. In short, the ACOLITE model emerged as the best fit for the calibration process, reaching R values of 0.88 and 0.79 for Chl-a and turbidity, respectively. This underlies the importance of using inversion models, when processing water surfaces, to mitigate errors due to aerosols and the sun-glint effect. Subsequently, reflectance data derived from the ACOLITE model were used to establish correlations between various spectral indices and the in situ data. The empirical retrieval models (based on band combinations) yielding superior performance, with higher R values, were subjected to a rigorous statistical validation and optimization by applying a bootstrapping approach. From this process the green chlorophyll index (GCI) was selected as the optimal choice for constructing the Chl-a retrieval model, reaching an R of 0.88, while the red + NIR spectral index achieved the highest R value (0.79) for turbidity analysis, although in the last case, it was necessary to incorporate data from several seasons for an adequate model training. Our analysis covered a broad spectrum of dates, seasons, and years, which allowed us to search deeper into the evolution of the trophic state associated with the lake. We identified a striking eight-year period (2014-2022) characterized by a decline in Chl-a concentration in the lake, possibly attributable to governmental measures in the region for the protection and conservation of the lake. Additionally, the OLI imagery showed a spatial pattern varying from higher Chl-a values in the northern zone compared to the southern zone, probably due to the heat island effect of the northern urban areas. The results of this study suggest a positive effect of recent local regulations and serve as the basis for the creation of a modern monitoring system that enhances traditional point-based methods, offering a holistic view of the ongoing processes within the lake. 22024-01-0120242024-01-01Articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://ddd.uab.cat/record/289100https://dx.doi.org/urn:doi:10.3390/rs16020427reponame:Dipòsit Digital de Documents de la UABinstname:Universitat Autònoma de BarcelonaInglésengopen accesshttp://purl.org/coar/access_right/c_abf2Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.https://creativecommons.org/licenses/by/4.0/info:eu-repo/semantics/openAccessoai:ddd.uab.cat:2891002026-06-06T12:50:31Z
dc.title.none.fl_str_mv Spatiotemporal Variations in Biophysical Water Quality Parameters
An Integrated In Situ and Remote Sensing Analysis of an Urban Lake in Chile
title Spatiotemporal Variations in Biophysical Water Quality Parameters
spellingShingle Spatiotemporal Variations in Biophysical Water Quality Parameters
Yépez, Santiago|||0000-0002-7879-7094
Eutrophication
Landsat
Chl-a
Turbidity
Spectral signatures
OLI
Chile
title_short Spatiotemporal Variations in Biophysical Water Quality Parameters
title_full Spatiotemporal Variations in Biophysical Water Quality Parameters
title_fullStr Spatiotemporal Variations in Biophysical Water Quality Parameters
title_full_unstemmed Spatiotemporal Variations in Biophysical Water Quality Parameters
title_sort Spatiotemporal Variations in Biophysical Water Quality Parameters
dc.creator.none.fl_str_mv Yépez, Santiago|||0000-0002-7879-7094
Velásquez, Germán
Torres, Daniel
Saavedra-Passache, Rodrigo
Pincheira, Martin
Cid, Hayleen
Rodríguez-López, Lien|||0000-0002-0550-0253
Contreras, Angela
Frappart, Frédéric|||0000-0002-4661-8274
Cristóbal, Jordi|||0000-0001-6244-4289
Pons, Xavier|||0000-0002-6924-1641
Flores, Neftali
Bourrel, Luc
author Yépez, Santiago|||0000-0002-7879-7094
author_facet Yépez, Santiago|||0000-0002-7879-7094
Velásquez, Germán
Torres, Daniel
Saavedra-Passache, Rodrigo
Pincheira, Martin
Cid, Hayleen
Rodríguez-López, Lien|||0000-0002-0550-0253
Contreras, Angela
Frappart, Frédéric|||0000-0002-4661-8274
Cristóbal, Jordi|||0000-0001-6244-4289
Pons, Xavier|||0000-0002-6924-1641
Flores, Neftali
Bourrel, Luc
author_role author
author2 Velásquez, Germán
Torres, Daniel
Saavedra-Passache, Rodrigo
Pincheira, Martin
Cid, Hayleen
Rodríguez-López, Lien|||0000-0002-0550-0253
Contreras, Angela
Frappart, Frédéric|||0000-0002-4661-8274
Cristóbal, Jordi|||0000-0001-6244-4289
Pons, Xavier|||0000-0002-6924-1641
Flores, Neftali
Bourrel, Luc
author2_role author
author
author
author
author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Eutrophication
Landsat
Chl-a
Turbidity
Spectral signatures
OLI
Chile
topic Eutrophication
Landsat
Chl-a
Turbidity
Spectral signatures
OLI
Chile
description This study aims to develop and implement a methodology for retrieving bio-optical parameters in a lagoon located in the Biobío region, South-Central Chile, by analyzing time series of Landsat-8 OLI satellite images. The bio-optical parameters, i.e., chlorophyll-a (Chl-a, in mg·m) and turbidity (in NTU) were measured in situ during a satellite overpass to minimize the impact of atmospheric distortions. To calibrate the satellite images, various atmospheric correction methods (including ACOLITE, C2RCC, iCOR, and LaSRC) were evaluated during the image preprocessing phase. Spectral signatures obtained from the scenes for each atmospheric correction method were then compared with spectral signatures acquired in situ on the water surface. In short, the ACOLITE model emerged as the best fit for the calibration process, reaching R values of 0.88 and 0.79 for Chl-a and turbidity, respectively. This underlies the importance of using inversion models, when processing water surfaces, to mitigate errors due to aerosols and the sun-glint effect. Subsequently, reflectance data derived from the ACOLITE model were used to establish correlations between various spectral indices and the in situ data. The empirical retrieval models (based on band combinations) yielding superior performance, with higher R values, were subjected to a rigorous statistical validation and optimization by applying a bootstrapping approach. From this process the green chlorophyll index (GCI) was selected as the optimal choice for constructing the Chl-a retrieval model, reaching an R of 0.88, while the red + NIR spectral index achieved the highest R value (0.79) for turbidity analysis, although in the last case, it was necessary to incorporate data from several seasons for an adequate model training. Our analysis covered a broad spectrum of dates, seasons, and years, which allowed us to search deeper into the evolution of the trophic state associated with the lake. We identified a striking eight-year period (2014-2022) characterized by a decline in Chl-a concentration in the lake, possibly attributable to governmental measures in the region for the protection and conservation of the lake. Additionally, the OLI imagery showed a spatial pattern varying from higher Chl-a values in the northern zone compared to the southern zone, probably due to the heat island effect of the northern urban areas. The results of this study suggest a positive effect of recent local regulations and serve as the basis for the creation of a modern monitoring system that enhances traditional point-based methods, offering a holistic view of the ongoing processes within the lake.
publishDate 2024
dc.date.none.fl_str_mv 2
2024-01-01
2024
2024-01-01
dc.type.none.fl_str_mv Article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://ddd.uab.cat/record/289100
https://dx.doi.org/urn:doi:10.3390/rs16020427
url https://ddd.uab.cat/record/289100
https://dx.doi.org/urn:doi:10.3390/rs16020427
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
https://creativecommons.org/licenses/by/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
https://creativecommons.org/licenses/by/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Dipòsit Digital de Documents de la UAB
instname:Universitat Autònoma de Barcelona
instname_str Universitat Autònoma de Barcelona
reponame_str Dipòsit Digital de Documents de la UAB
collection Dipòsit Digital de Documents de la UAB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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