Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries

<p>An efficient recognition and extraction of the estuarine turbidity maximum zone (TMZ) is important for studying terrestrial hydrological processes. Although many studies relevant to the TMZ have been conducted worldwide, the extraction methods and criteria used to describe the TMZ vary sign...

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Autores principales: C. Wang, L. Wang, D. Wang, D. Li, C. Zhou, H. Jiang, Q. Zheng, S. Chen, K. Jia, Y. Liu, J. Yang, X. Zhou, Y. Li
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Publicado: Copernicus Publications 2021
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spelling oai:doaj.org-article:563ba4fb68a0437bbcb130757311010a2021-11-11T08:59:31ZTurbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries10.5194/gmd-14-6833-20211991-959X1991-9603https://doaj.org/article/563ba4fb68a0437bbcb130757311010a2021-11-01T00:00:00Zhttps://gmd.copernicus.org/articles/14/6833/2021/gmd-14-6833-2021.pdfhttps://doaj.org/toc/1991-959Xhttps://doaj.org/toc/1991-9603<p>An efficient recognition and extraction of the estuarine turbidity maximum zone (TMZ) is important for studying terrestrial hydrological processes. Although many studies relevant to the TMZ have been conducted worldwide, the extraction methods and criteria used to describe the TMZ vary significantly both spatially and temporally. To improve the applicability of the methods adopted in previous studies and to develop a novel model to accurately extract the TMZ in multiple estuaries and different seasons from remote-sensing imageries, this study estimated the total suspended solid (TSS) and chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) concentrations in three estuaries. These were the Pearl River estuary (PRE), the Hanjiang River estuary (HRE), and the Moyangjiang River estuary (MRE) of Guangdong Province, China. The spatial distribution characteristics of the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations were analyzed. A nearly opposite association was found between the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations in the three estuaries, particularly in the PRE. The regions with high (low) TSS concentrations had relatively low (high) Chl <span class="inline-formula"><i>a</i></span> concentrations and, therefore, a turbidity maximum zone index (TMZI), defined as the ratio of the difference and sum of the logarithmic transformation of the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations, was firstly proposed. By calculating the TMZI values in the PRE on 20 November 2004 (low-flow season), it was found that the criterion <span class="inline-formula">TMZI&gt;0.2</span> could be used to identify the TMZs of the PRE effectively. The TMZ extraction results were generally consistent with the visual-interpretation results. The area-based accuracy measures showed that the quality (<span class="inline-formula"><i>Q</i></span>) of the extraction reached 0.8429. The same criterion was applied in the PRE on 18 October 2015 (high-flow season), and high accuracy and consistency across seasons were observed (<span class="inline-formula"><i>Q</i>=0.8171</span>). The western shoal of the PRE was the main distribution area of TMZs. Extracting TMZs by the newly proposed index performed well in different estuaries and on different dates (HRE on 13 August 2008 in the high-flow season and MRE on 6 December 2013 in the low-flow season). Compared to the previous fixed threshold of TSS or turbidity methods, extracting the TMZ using the TMZI had higher accuracy and better applicability (<span class="inline-formula"><i>Q</i></span>: 0.1046–0.4770 vs. 0.8171–0.8429). Evidently, this unified TMZI is potentially an optimized method for the global monitoring and extraction of TMZs of estuaries from different satellite remote-sensing imageries. It can be used to help the understanding of the spatial and temporal variation in TMZs and estuarine processes at regional and global scales as well as improve the<span id="page6834"/> management and sustainable development of regional society and the natural environment.</p>C. WangC. WangL. WangD. WangD. LiC. ZhouC. ZhouC. ZhouH. JiangQ. ZhengQ. ZhengS. ChenK. JiaY. LiuJ. YangJ. YangX. ZhouY. LiY. LiCopernicus PublicationsarticleGeologyQE1-996.5ENGeoscientific Model Development, Vol 14, Pp 6833-6846 (2021)
institution DOAJ
collection DOAJ
language EN
topic Geology
QE1-996.5
spellingShingle Geology
QE1-996.5
C. Wang
C. Wang
L. Wang
D. Wang
D. Li
C. Zhou
C. Zhou
C. Zhou
H. Jiang
Q. Zheng
Q. Zheng
S. Chen
K. Jia
Y. Liu
J. Yang
J. Yang
X. Zhou
Y. Li
Y. Li
Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
description <p>An efficient recognition and extraction of the estuarine turbidity maximum zone (TMZ) is important for studying terrestrial hydrological processes. Although many studies relevant to the TMZ have been conducted worldwide, the extraction methods and criteria used to describe the TMZ vary significantly both spatially and temporally. To improve the applicability of the methods adopted in previous studies and to develop a novel model to accurately extract the TMZ in multiple estuaries and different seasons from remote-sensing imageries, this study estimated the total suspended solid (TSS) and chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) concentrations in three estuaries. These were the Pearl River estuary (PRE), the Hanjiang River estuary (HRE), and the Moyangjiang River estuary (MRE) of Guangdong Province, China. The spatial distribution characteristics of the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations were analyzed. A nearly opposite association was found between the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations in the three estuaries, particularly in the PRE. The regions with high (low) TSS concentrations had relatively low (high) Chl <span class="inline-formula"><i>a</i></span> concentrations and, therefore, a turbidity maximum zone index (TMZI), defined as the ratio of the difference and sum of the logarithmic transformation of the TSS and Chl <span class="inline-formula"><i>a</i></span> concentrations, was firstly proposed. By calculating the TMZI values in the PRE on 20 November 2004 (low-flow season), it was found that the criterion <span class="inline-formula">TMZI&gt;0.2</span> could be used to identify the TMZs of the PRE effectively. The TMZ extraction results were generally consistent with the visual-interpretation results. The area-based accuracy measures showed that the quality (<span class="inline-formula"><i>Q</i></span>) of the extraction reached 0.8429. The same criterion was applied in the PRE on 18 October 2015 (high-flow season), and high accuracy and consistency across seasons were observed (<span class="inline-formula"><i>Q</i>=0.8171</span>). The western shoal of the PRE was the main distribution area of TMZs. Extracting TMZs by the newly proposed index performed well in different estuaries and on different dates (HRE on 13 August 2008 in the high-flow season and MRE on 6 December 2013 in the low-flow season). Compared to the previous fixed threshold of TSS or turbidity methods, extracting the TMZ using the TMZI had higher accuracy and better applicability (<span class="inline-formula"><i>Q</i></span>: 0.1046–0.4770 vs. 0.8171–0.8429). Evidently, this unified TMZI is potentially an optimized method for the global monitoring and extraction of TMZs of estuaries from different satellite remote-sensing imageries. It can be used to help the understanding of the spatial and temporal variation in TMZs and estuarine processes at regional and global scales as well as improve the<span id="page6834"/> management and sustainable development of regional society and the natural environment.</p>
format article
author C. Wang
C. Wang
L. Wang
D. Wang
D. Li
C. Zhou
C. Zhou
C. Zhou
H. Jiang
Q. Zheng
Q. Zheng
S. Chen
K. Jia
Y. Liu
J. Yang
J. Yang
X. Zhou
Y. Li
Y. Li
author_facet C. Wang
C. Wang
L. Wang
D. Wang
D. Li
C. Zhou
C. Zhou
C. Zhou
H. Jiang
Q. Zheng
Q. Zheng
S. Chen
K. Jia
Y. Liu
J. Yang
J. Yang
X. Zhou
Y. Li
Y. Li
author_sort C. Wang
title Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
title_short Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
title_full Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
title_fullStr Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
title_full_unstemmed Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
title_sort turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries
publisher Copernicus Publications
publishDate 2021
url https://doaj.org/article/563ba4fb68a0437bbcb130757311010a
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