Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022
Estuarine regions heavily rely on the supply of freshwater from rivers, which could suffer saltwater intrusion. In the late summer and autumn of 2022, the Changjiang basin experienced prolonged severe drought, resulting in the river discharge decreasing to its lowest level according to historical re...
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Frontiers Media S.A.
2025-04-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2025.1573883/full |
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| author | Rui Ma Cheng Qiu Jianrong Zhu Zhilin Zhang Yiping Zhu Lingting Kong Lei Ding Wei Qiu Hui Wu |
| author_facet | Rui Ma Cheng Qiu Jianrong Zhu Zhilin Zhang Yiping Zhu Lingting Kong Lei Ding Wei Qiu Hui Wu |
| author_sort | Rui Ma |
| collection | DOAJ |
| description | Estuarine regions heavily rely on the supply of freshwater from rivers, which could suffer saltwater intrusion. In the late summer and autumn of 2022, the Changjiang basin experienced prolonged severe drought, resulting in the river discharge decreasing to its lowest level according to historical records. Furthermore, the Changjiang Estuary was affected successively by three typhoons in September. Saltwater intrusion extremes have occurred since early September, resulting in the Qingcaosha Reservoir, the largest estuarine reservoir in the world, being unsuitable for water intake for 98 days. This has seriously threatened the safety of the water supply in Shanghai. No such extremely severe event has occurred since salinity has been recorded in the estuary, even in the dry season. Our findings show that saltwater intrusion extremes were caused by the combined effect of extremely low river discharge and typhoons, which drove substantial landward water transport to form a horizontal estuarine circulation flowing into the North Channel and out of the South Channel. This landward net water transport overcame seaward runoff and brought highly saline water into the estuary. The extremely low river discharge is the fundamental cause for the severe saltwater intrusion, and the typhoons greatly amplified it. The surface and bottom salinities at the water intake of the Qingcaosha Reservoir were amplified 9.6 and 23.4 times by Typhoon Hinnamonr and 10.1 and 15.1 times by Typhoon Nanmadol, respectively. We reveal the dynamic cause of saltwater intrusion extremes, which is conducive for developing effective response measures for estuarine freshwater resources safety. |
| format | Article |
| id | doaj-art-5f2f19c7717142b8a60c838aeb2410ab |
| institution | OA Journals |
| issn | 2296-7745 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Marine Science |
| spelling | doaj-art-5f2f19c7717142b8a60c838aeb2410ab2025-08-20T02:19:19ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452025-04-011210.3389/fmars.2025.15738831573883Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022Rui Ma0Cheng Qiu1Jianrong Zhu2Zhilin Zhang3Yiping Zhu4Lingting Kong5Lei Ding6Wei Qiu7Hui Wu8State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, ChinaShanghai Marine Monitoring and Forecasting Centre, Shanghai, Shanghai, ChinaState Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, ChinaSurvey Bureau of the Hydrology and Water Resources of Changjiang Estuary, Shanghai, ChinaShanghai Chengtou Raw Water Limited Company, Shanghai, ChinaShanghai Water (Ocean) Planning and Design Research Institute, Shanghai, ChinaNanjing Hydraulic Research Institute, Nanjing, ChinaRiver Research Department, Changjiang River Scientific Research Institute, Wuhan, ChinaState Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, ChinaEstuarine regions heavily rely on the supply of freshwater from rivers, which could suffer saltwater intrusion. In the late summer and autumn of 2022, the Changjiang basin experienced prolonged severe drought, resulting in the river discharge decreasing to its lowest level according to historical records. Furthermore, the Changjiang Estuary was affected successively by three typhoons in September. Saltwater intrusion extremes have occurred since early September, resulting in the Qingcaosha Reservoir, the largest estuarine reservoir in the world, being unsuitable for water intake for 98 days. This has seriously threatened the safety of the water supply in Shanghai. No such extremely severe event has occurred since salinity has been recorded in the estuary, even in the dry season. Our findings show that saltwater intrusion extremes were caused by the combined effect of extremely low river discharge and typhoons, which drove substantial landward water transport to form a horizontal estuarine circulation flowing into the North Channel and out of the South Channel. This landward net water transport overcame seaward runoff and brought highly saline water into the estuary. The extremely low river discharge is the fundamental cause for the severe saltwater intrusion, and the typhoons greatly amplified it. The surface and bottom salinities at the water intake of the Qingcaosha Reservoir were amplified 9.6 and 23.4 times by Typhoon Hinnamonr and 10.1 and 15.1 times by Typhoon Nanmadol, respectively. We reveal the dynamic cause of saltwater intrusion extremes, which is conducive for developing effective response measures for estuarine freshwater resources safety.https://www.frontiersin.org/articles/10.3389/fmars.2025.1573883/fullsaltwater intrusion extremesnumerical simulationlow river dischargetyphoondynamic mechanism |
| spellingShingle | Rui Ma Cheng Qiu Jianrong Zhu Zhilin Zhang Yiping Zhu Lingting Kong Lei Ding Wei Qiu Hui Wu Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 Frontiers in Marine Science saltwater intrusion extremes numerical simulation low river discharge typhoon dynamic mechanism |
| title | Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 |
| title_full | Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 |
| title_fullStr | Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 |
| title_full_unstemmed | Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 |
| title_short | Dynamic cause of saltwater intrusion extremes and freshwater challenges in the Changjiang Estuary in flood season of 2022 |
| title_sort | dynamic cause of saltwater intrusion extremes and freshwater challenges in the changjiang estuary in flood season of 2022 |
| topic | saltwater intrusion extremes numerical simulation low river discharge typhoon dynamic mechanism |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2025.1573883/full |
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