Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary
Over the past few decades, the topography and river-tide-salt dynamic characteristics of the Pearl River Delta (PRD) have undergone a myriad of changes due to the unnatural evolution process induced by diverse human activities, such as dam construction, land reclamation, sand excavation, and dredgin...
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MDPI AG
2021-11-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/9/12/1327 |
| _version_ | 1797503337796468736 |
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| author | Changjie Liu Ziyue Zhong Yiqing Xiao Xiaoqi Chen Minghui Yu |
| author_facet | Changjie Liu Ziyue Zhong Yiqing Xiao Xiaoqi Chen Minghui Yu |
| author_sort | Changjie Liu |
| collection | DOAJ |
| description | Over the past few decades, the topography and river-tide-salt dynamic characteristics of the Pearl River Delta (PRD) have undergone a myriad of changes due to the unnatural evolution process induced by diverse human activities, such as dam construction, land reclamation, sand excavation, and dredging for navigation. To investigate the impact of human activities on hydrodynamic structures in the PRD of the Modaomen Estuary (ME) during the dry season, a three-dimensional river-tide-salt dynamic model was used to simulate the hydrodynamic characteristics of the ME for different historical periods. The model results indicate that large-scale land reclamation weakened the tidal dynamics and mixing effects in the ME, promoting gravity circulation with opposite velocity directions at the surface and bottom within 15 km downstream of the estuary. Additionally, riverbed downcutting enhanced the tidal dynamics, which intensified saltwater intrusion, leading to the spatial scale-of-gravity circulation expanding 1–2 times. The enhancement of riverbed downcutting on the tidal dynamics in the ME was significantly greater than the weakening effect of land reclamation. Hence, due to the comprehensive influence of human activities between the 1970s and 2010, the hydrodynamic structures in the ME changed from a state of atypical gravity circulation, with nonobvious stratification, to a state of highly stratified and large-scale gravity circulation. The pollutant diffusion in the ME under different scenarios is also discussed in this paper. The results show that reclamation results in weakening of tidal dynamics, which is not conducive to the mixing and diffusion of pollutants in the estuary. However, the narrowed estuary due to land reclamation is conducive to the rapid entry of pollutants into the open sea. |
| first_indexed | 2024-03-10T03:49:10Z |
| format | Article |
| id | doaj.art-d76e228600644f4f8ea3dbae2da3e64a |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-10T03:49:10Z |
| publishDate | 2021-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-d76e228600644f4f8ea3dbae2da3e64a2023-11-23T09:02:08ZengMDPI AGJournal of Marine Science and Engineering2077-13122021-11-01912132710.3390/jmse9121327Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen EstuaryChangjie Liu0Ziyue Zhong1Yiqing Xiao2Xiaoqi Chen3Minghui Yu4School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518000, ChinaState Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, ChinaSchool of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518000, ChinaState Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, ChinaState Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, ChinaOver the past few decades, the topography and river-tide-salt dynamic characteristics of the Pearl River Delta (PRD) have undergone a myriad of changes due to the unnatural evolution process induced by diverse human activities, such as dam construction, land reclamation, sand excavation, and dredging for navigation. To investigate the impact of human activities on hydrodynamic structures in the PRD of the Modaomen Estuary (ME) during the dry season, a three-dimensional river-tide-salt dynamic model was used to simulate the hydrodynamic characteristics of the ME for different historical periods. The model results indicate that large-scale land reclamation weakened the tidal dynamics and mixing effects in the ME, promoting gravity circulation with opposite velocity directions at the surface and bottom within 15 km downstream of the estuary. Additionally, riverbed downcutting enhanced the tidal dynamics, which intensified saltwater intrusion, leading to the spatial scale-of-gravity circulation expanding 1–2 times. The enhancement of riverbed downcutting on the tidal dynamics in the ME was significantly greater than the weakening effect of land reclamation. Hence, due to the comprehensive influence of human activities between the 1970s and 2010, the hydrodynamic structures in the ME changed from a state of atypical gravity circulation, with nonobvious stratification, to a state of highly stratified and large-scale gravity circulation. The pollutant diffusion in the ME under different scenarios is also discussed in this paper. The results show that reclamation results in weakening of tidal dynamics, which is not conducive to the mixing and diffusion of pollutants in the estuary. However, the narrowed estuary due to land reclamation is conducive to the rapid entry of pollutants into the open sea.https://www.mdpi.com/2077-1312/9/12/1327Pearl River DeltaModaomen Estuaryhuman activitiesgravity circulation |
| spellingShingle | Changjie Liu Ziyue Zhong Yiqing Xiao Xiaoqi Chen Minghui Yu Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary Journal of Marine Science and Engineering Pearl River Delta Modaomen Estuary human activities gravity circulation |
| title | Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary |
| title_full | Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary |
| title_fullStr | Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary |
| title_full_unstemmed | Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary |
| title_short | Impacts of Human Activities on Hydrodynamic Structures during the Dry Season in the Modaomen Estuary |
| title_sort | impacts of human activities on hydrodynamic structures during the dry season in the modaomen estuary |
| topic | Pearl River Delta Modaomen Estuary human activities gravity circulation |
| url | https://www.mdpi.com/2077-1312/9/12/1327 |
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