Journal of East China Normal University(Natural Science) ›› 2020, Vol. 2020 ›› Issue (3): 43-54.doi: 10.3969/j.issn.1000-5641.201941013

• Estuary and Coastal Research • Previous Articles     Next Articles

Numerical simulation of erosion and deposition at the water intake channel of the outer seawall sluice in the ecological restoration project area of Chongming Dongtan Bird Habitat

LU Peiyi, ZHU Jianrong, QIAN Weiwei, YUAN Lin   

  1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
  • Received:2019-04-25 Published:2020-05-22

Abstract: A three-dimensional numerical model for erosion and deposition at the water intake channel of the outer seawall of Chongming Dongtan Bird Sanctuary was established based on the hydrodynamic model of the estuary coupled with the sediment module and the bottom erosion and sedimentation equation. The model’s upstream boundary condition at the sluice was specified with water flux calculated by the Weir formula, where the inner water level was calculated by the hydrodynamic model of the Suitang River. The model’s downstream boundary condition of the water level, salinity and sediment concentration were calculated by the large domain numerical model of the Changjiang Estuary. We measured bottom elevations at the water intake channel before and after the sluice opening from July 28 to July 30, 2018 and found that the calculated model elevations were in general agreement with the measured values, indicating that the model can accurately simulate erosion and sedimentation changes. The calculation results for scouring and siltation show that under natural conditions, the water intake channel becomes level after 60 days of sluice closure because of sediment deposit. Siltation is largest near the sluice and gradually decreases with distance from the sluice to the sea. After the water intake channel was naturally silted for two months, the mean erosion thickness at the water intake channel was 96 mm in the case where Suitang River accumulated up to 3.0 m of water and discharged thereafter, 133 mm in the case where Suitang River accumulated up to 3.8 m of water and discharged thereafter, and 625 mm in the case where Suitang River accumulated up to 3.0 m of water and the sluice was opened to receive tidal water. Leaving the sluice open to receive tidal water is the most effective way for scouring sediment in the water intake channel. The research results provide scientific and technical guidance for the protection and management of the ecological restoration project area in Chongming Dongtan National Nature Reserve and the scouring sediment scheme of the water intake channel.

Key words: Chongming Dongtan, birds nature reserve, deposit downstream sluice, scouring sediment of the water intake channel, numerical simulation

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