Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary
<p>Salt intrusion in estuaries has been exacerbated by climate change and human activities. Previous studies have primarily focused on salt intrusion in the mainstem of estuaries, whereas those in sub-estuaries (those that branch off their main estuaries) have received less attention. During a...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-02-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/20/181/2024/os-20-181-2024.pdf |
| _version_ | 1797302948776116224 |
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| author | Z. Lin Z. Lin Z. Lin G. Zhang G. Zhang H. Zou H. Zou W. Gong W. Gong |
| author_facet | Z. Lin Z. Lin Z. Lin G. Zhang G. Zhang H. Zou H. Zou W. Gong W. Gong |
| author_sort | Z. Lin |
| collection | DOAJ |
| description | <p>Salt intrusion in estuaries has been exacerbated by climate change and human activities. Previous studies have primarily focused on salt intrusion in the mainstem of estuaries, whereas those in sub-estuaries (those that branch off their main estuaries) have received less attention. During an extended La Niña event from 2021 to 2022, a sub-estuary (the East River estuary) alongside the Pearl River estuary, China, experienced severe salt intrusions, posing a threat to the freshwater supply in the surrounding area. Observations revealed that maximum salinities in the main estuary typically preceded spring tides, exhibiting significant asymmetry in salinity rise and fall over a fortnightly timescale. In contrast, in the upstream region of the sub-estuary, the variation in salinity was in phase with that of the tidal range, and the rise and fall of the salinity were more symmetrical.</p>
<p>Inspired by these observations, we employed idealized numerical models and analytical solutions to investigate the underlying physics behind these behaviors. It was discovered that under normal dry conditions (with a river discharge of 1500 <span class="inline-formula">m<sup>3</sup> s<sup>−1</sup></span> at the head of the main estuary), the river–tide interaction and change in horizontal dispersion accounted for the in-phase relationship between the salinity and tidal range in the upstream region of the sub-estuary. Under extremely dry conditions (i.e., a river discharge of 500 <span class="inline-formula">m<sup>3</sup> s<sup>−1</sup></span> at the head of the main estuary), salinity variations were in phase with those of the tidal range in the middle as well as the upstream region of the sub-estuary. The variation in salinity in the main estuary along with those in salt dispersion and freshwater influx inside the sub-estuary collectively influenced salinity variation in the well-mixed sub-estuary. These findings have important implications for water resource management and salt intrusion prevention in the catchment area.</p> |
| first_indexed | 2024-03-07T23:46:15Z |
| format | Article |
| id | doaj.art-8170063e73ba4205870d4536a73a19dc |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-03-07T23:46:15Z |
| publishDate | 2024-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-8170063e73ba4205870d4536a73a19dc2024-02-19T11:43:22ZengCopernicus PublicationsOcean Science1812-07841812-07922024-02-012018119910.5194/os-20-181-2024Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuaryZ. Lin0Z. Lin1Z. Lin2G. Zhang3G. Zhang4H. Zou5H. Zou6W. Gong7W. Gong8School of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, ChinaKey Laboratory of Pearl River Estuary Regulation and Protection of Ministry of Water Resource, Guangzhou 510611, ChinaPearl River Water Resource Research Institute, Guangzhou 510611, ChinaSchool of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, ChinaGuangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Zhuhai 519082, ChinaKey Laboratory of Pearl River Estuary Regulation and Protection of Ministry of Water Resource, Guangzhou 510611, ChinaPearl River Water Resource Research Institute, Guangzhou 510611, ChinaSchool of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, ChinaGuangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Zhuhai 519082, China<p>Salt intrusion in estuaries has been exacerbated by climate change and human activities. Previous studies have primarily focused on salt intrusion in the mainstem of estuaries, whereas those in sub-estuaries (those that branch off their main estuaries) have received less attention. During an extended La Niña event from 2021 to 2022, a sub-estuary (the East River estuary) alongside the Pearl River estuary, China, experienced severe salt intrusions, posing a threat to the freshwater supply in the surrounding area. Observations revealed that maximum salinities in the main estuary typically preceded spring tides, exhibiting significant asymmetry in salinity rise and fall over a fortnightly timescale. In contrast, in the upstream region of the sub-estuary, the variation in salinity was in phase with that of the tidal range, and the rise and fall of the salinity were more symmetrical.</p> <p>Inspired by these observations, we employed idealized numerical models and analytical solutions to investigate the underlying physics behind these behaviors. It was discovered that under normal dry conditions (with a river discharge of 1500 <span class="inline-formula">m<sup>3</sup> s<sup>−1</sup></span> at the head of the main estuary), the river–tide interaction and change in horizontal dispersion accounted for the in-phase relationship between the salinity and tidal range in the upstream region of the sub-estuary. Under extremely dry conditions (i.e., a river discharge of 500 <span class="inline-formula">m<sup>3</sup> s<sup>−1</sup></span> at the head of the main estuary), salinity variations were in phase with those of the tidal range in the middle as well as the upstream region of the sub-estuary. The variation in salinity in the main estuary along with those in salt dispersion and freshwater influx inside the sub-estuary collectively influenced salinity variation in the well-mixed sub-estuary. These findings have important implications for water resource management and salt intrusion prevention in the catchment area.</p>https://os.copernicus.org/articles/20/181/2024/os-20-181-2024.pdf |
| spellingShingle | Z. Lin Z. Lin Z. Lin G. Zhang G. Zhang H. Zou H. Zou W. Gong W. Gong Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary Ocean Science |
| title | Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary |
| title_full | Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary |
| title_fullStr | Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary |
| title_full_unstemmed | Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary |
| title_short | Salt intrusion dynamics in a well-mixed sub-estuary connected to a partially to well-mixed main estuary |
| title_sort | salt intrusion dynamics in a well mixed sub estuary connected to a partially to well mixed main estuary |
| url | https://os.copernicus.org/articles/20/181/2024/os-20-181-2024.pdf |
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