Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Study on asymmetric extension of river boundary and regulation in the lower section of North Channel inYangtze Estuary
Yuzhong Li 1,2,3 , Yongxin Ji 1,2,3
1. Shanghai Water Engineering Design & Research Institute Co., Ltd
2. Shanghai beach Coastal Engineering Technology Research Center
3. Estuarine Coastal & Offshore Engineering Research Center of Shanghai Municipal Oceanic Bureau
Shanghai, China

There are many research results on the riverbed evolution andregulation scheme of North Channel. Liu (2011), Li (2012), Wu (2016)
and others pay attention to the riverbed evolution characteristics andengineering impact of the upstream entrance and the middle and upper
section of North Channel, Mo (2015), Xu (2017) and others believe thatthe reclamation of Hengsha Eastern Beach on the South Bank of North
Channel is one of the reasons for the scour between North shoal of North
Channel and Chongming Island. Lou (2012) believes that the key tochannel development is to open up the mouth bar, and suggests that theregulation project be implemented by stages. Xu (2015) believes that thedevelopment of North Channel is constrained by the nature reserve. Yuan
(2020) suggested the implementation of projects such as guide dike andspur dike to deepen North Channel, which is arranged outside the naturereserve. As for the impact of Hengsha Eastern Beach reclamation on
North Channel evolution, the existing research is not deep enough. It israre to pay attention to the asymmetric extend of the river boundary inNorth Channel and its impact on the riverbed evolution in the entrance
to sea. Therefore, It is helpful to study from this perspective.

ABSTRACT
According to the underwater topographic map of Yangtze Estuaryover the years, the impact of Hengsha Eastern Beach reclamation projecton the river evolution of the lower section of North Channel is analyzed.
With the continuous reclamation in Hengsha Eastern Beach, the south
boundary of the lower section of North Channel continues to extend tothe sea. For the north boundary is open and the pressure of northward
increases, the ebb tidal current in the lower section of the north port
shows signs of northward deviation and the main trough near theentrance to the sea is silted. It is suggested to build the north boundary
project to make the river boundary develop symmetrically, andappropriately reduce the intersection angle between the trend of thelower section of North Channel and the main direction of the open sea
tidal current. The calculation of hydrodynamic mathematical modelshows that the project is helpful to improve the river pattern. The
engineering scheme integrating river control, waterway improvement
and ecological protection will help to promote the implementation of theregulation engineering in the lower section of North Channel.

REGIONAL OVERVIEW

KEY WORDS: Yangtze Estuary, North Channel, Hengsha EasternYangtze Estuary presents a river pattern of three-class branching
and four entrances to the sea. Below Xuliujing, Yangtze River is divided
into South Branch and North Branch by Chongming Island. South
Branch is divided into South Channel and North Channel by Changxing
Island and Hengsha Island. South Channel is divided into South Passage
and North Passage by Jiuduansha Shoal (Fig.1). Yangtze Estuary is atidal estuary with irregular semi diurnal tide. The tidal intensity ismedium. The annual average tidal range is 2.66 m at Zhongqun Station.
The annual average wave height is 0.9~1.0 m at Yinshuichuan Station.
The average annual runoff and sediment discharge of Yangtze River into
the sea are 87.81 million m3 and 134 million tons respectively (20032020). Runoff and tidal current are very important for shaping theriverbed of Yangtze Estuary.
North Channel is the second-class branch river of Yangtze Estuary.
It is connected to the South Branch on the upper side and the open seaon the lower side. It is about 75km long and 4.0~ 8.1km wide. Hengsha
Island divides North Channel into upper and lower sections. The upper
section is about 35km long and the water depth of the main trough isabout 13~19m. The lower section is about 40km long and the water depthof the main trough is about 5~ 3m.

Beach, River Evolution, Regulation Project.

INTRODUCTION
Since the beginning of North Passage Deepwater Channel
Regulation Project in 1998, Yangtze Estuary has entered a period ofhigh-intensity regulation and development. A number of major projects
have been implemented, such as Baimaosha regulation project,
Xinliuhesha regulation project, Qingcaosha Reservoir, Nanhui Eastern
Shoal reclamation, Hengsha Eastern Beach reclamation and so on. Now,
the river pattern and the diversion of each branch in Yangtze Estuary are
more stable. The waterway, freshwater and soil resources have beeneffectively utilized. The remarkable achievements have been made in
ecological protection.
There are also some key problems that need to be paid more
attention to, such as the inflow discharge of North Branch is still small,
Biandansha shoal in South Branch has not been effectively controlled,
Ruifengsha Shoal in South Channel has been seriously scoured, and thenorth boundary of the lower section of North Channel is still open. Theseproblems need to be further studied to find appropriate countermeasures.

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