| WANG Chenglong,ZHAO Yifei,ZOU Xinqing,XU Xinwanghao,GE Chendong. 2017. Recent changing patterns of the Changjiang (Yangtze River) Estuary caused by human activities. Acta Oceanologica Sinica, 36(4):87－96 |
| Recent changing patterns of the Changjiang (Yangtze River) Estuary caused by human activities |
| 近年来人类活动影响下长江河口的变化模式 |
| Received:December 19, 2015 Revised:May 05, 2016 |
| DOI：10.1007/s13131-017-1017-z |
| Key words:remote sensing coastline change sediment load coastal engineering Changjiang (Yangtze River) Estuary |
| 中文关键词: 遥感 岸线变化 输沙量 海岸工程 长江口 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | WANG Chenglong | School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | ZHAO Yifei | School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | ZOU Xinqing | School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China
Collaborative Innovation Center of South China Sea Studies, Nanjing 210023, China | zouxq@nju.edu.cn | | XU Xinwanghao | School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China | | | GE Chendong | School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210023, China
Collaborative Innovation Center of South China Sea Studies, Nanjing 210023, China | |
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| Abstract: |
| To evaluate the controlling factors for coastline change of the Changjiang (Yangtze River) Estuary since 1974, we extracted the mean high tide line from multi-temporal remote sensing images that span from 1974 to 2014 at 2-year intervals. We chose 42 scenes to constrain the changing pattern of the Changjiang Estuary coastline, and implemented GIS technology to analyze the area change of the Changjiang (Yangtze) Subaerial Delta. Runoff, sediment discharge and coastal engineering were withal considered in the analysis of the coastline changes. The coastline has transgressed seaward since 1974, and a part of it presents inter-annual variations. The area of the Changjiang Subaerial Delta increased by 871 km2, with a net accretion rate of 21.8 km2/a. Based on the change of sediment discharge due to the major projects in the Changjiang River Basin, we divided the changing pattern of the coastline into three stages:the slow accretion stage (1974-1986), the moderate accretion stage (1987-2002), and the rapid accretion stage (2003-2014). Liner regression analysis illustrated that there is a significantly positive correlation between the area changes and sediment discharge in the Chongming Eastern Shoal and Jiuduansha. This suggested that sediment load has a fundamental effect on the evolution of the Changjiang Estuary. Construction of Deep Waterway in the North Passage of the Changjiang River (1998-2010) led to a rapid accretion in the Hengsha Eastern Shoal and Jiuduansha by influencing the hydrodynamics in North Passage. Coastal engineering such as reclamation and harbor construction can also change the morphology of the Changjiang Estuary. We defined a contribution rate of area change to assess the impact of reclamation on the evolution of Changjiang Estuary. It turned out that more than 45.3% of area increment of the Changjiang Estuary was attributed to reclamation. |
| 中文摘要: |
| 为了评估1974年以来长江河口岸线变迁的控制因素，我们选取该区域1974-2014年每两年间隔共计42景遥感影像，并提取了平均高潮线，结合GIS分析技术分析长江水上三角洲的变化情况。研究结果认为径流量、输沙量和海岸工程是该区域岸线变迁的主要影响因素。该区域海岸线自1974年以来总体呈现向海趋势，部分区域出现年际的侵蚀和淤积波动变化。研究时段内，长江水上三角洲增加土地面积约871km2，平均每年增长21.8km2。依据长江流域大型工程的建设时段导致的流域输沙变化，我们将长江河口的岸线变化分为三个阶段：缓慢增长阶段（1974-1986年），较快速增长阶段（1987-2002年）和快速增长阶段（2003-2014年）。崇明东滩和九段沙的面积增长与流域输沙之间的线性回归结果具有很好的相关性，说明流域输沙可能是控制这一区域岸线变化的主要因素。北港的深水航道建设，影响了该区域水动力条件，进而使得横沙东滩和九段沙得到了较快的增长。此外，海岸工程，如围垦、港口建设等也使得长江河口的岸线发生了改变。我们定义了一个变量——面积变化率来评估围垦对于河口演变的影响。结果表明，长江河口45.3%的土地增长是由围垦贡献的。 |
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