STUDY ON MECHANISM OF BACK-SILTATION IN THE DEEP-DRAFT WATERWAY OF THE YANGTZE ESTUARY, AND EVALUATION OF ENGINEERING MEASURES

  • Min Gao
  • Yuanyang Wan

Abstract

Since the 92.2km-long , 350m-wide and -12.5m-deep draft channel was successfully achieved in the South Channel and the North Passage in the year 2010 , high siltation was found to temporally take place in the wet seasons , and spatially concentrate in the middle reach of the North Passage, where is consistent with the location of the traditional turbidity maximum zone (TMZ) of the Yangtze Estuary. The data from 2011 to 2015 show that the average annual siltation in the draft channel reached 80 Million m3 per year. With systematic analysis of the sediment source and comprehensive investigation on the mechanism of the flow and sediment transportation and siltation in the North Passage, this paper reveals a major cause of the back-siltation in the middle reach and subsequently discusses several engineering measures proposed to reduce the siltation . The final-selected engineering measure has been implemented quite recently , and the preliminary study shows that desired effect has been produced by the engineering measure.

References

Burchard, H., Hetland, R.D., Schulz, E., Schuttelaars, H.M., 2010. Drivers of Residual Estuarine Circulation in Tidally Energetic Estuaries: Straight and Irrotational Channels with Parabolic Cross Section. Journal of Physical Oceanography 41 (3), 548-570.

Cheng, P., Wilson, R.E., Chant, R.J., Fugate, D.C., Flood, R.D., 2009. Modeling Influence of Stratification on Lateral Circulation in a Stratified Estuary. Journal of Physical Oceanography 39 (9), 2324-2337.

ECSRC, 2014. Mechanisms of the sedimentation in the -12.5m deepwater navigational channel of the Yangtze Estuary, Report. Shanghai Estuarine and Coastal Science Center. pp. 187. (in Chinese)

Geyer, W.R., Farmer, D.M., 1989. Tide-Induced Variation of the Dynamics of a Salt Wedge Estuary. Journal of Physical Oceanography 19 (8), 1060-1072.

Geyer, W.R., Lavery, A.C., Scully, M.E., Trowbridge, J.H., 2010. Mixing by shear instability at high Reynolds number. Geophysical Research Letters 37 (22), L22607.

Guo, L., He, Q., 2011. Freshwater flocculation of suspended sediments in the Yangtze River, China. Ocean Dynamics 61 (2), 371-386.

Kirby, R., 2011. Minimising harbour siltation-findings of PIANC Working Group 43. Ocean Dynamics 61 (2-3), 233-244.

Liu, G., Zhu, J., Wang, Y., Wu, H., Wu, J., 2011. Tripod measured residual currents and sediment flux: Impacts on the silting of the Deepwater Navigation Channel in the Changjiang Estuary. Estuarine, Coastal and Shelf Science 93 (3), 192-201.

Manning, A.J., 2004. The observed effects of turbulence on estuarine flocculation. Journal of Coastal Research, 90-104.

Mehta, A.J., 2014. An Introduction to Hydraulics of Fine Sediment Transport. World Scientific Publishing Company, Singapore.

Shao, Y., Yan, Y., Maa, J., 2011. In Situ Measurements of Settling Velocity near Baimao Shoal in Changjiang Estuary. Journal of Hydraulic Engineering 137 (3), 372-380.

Song, D., Wang, X.H., 2013. Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 2. Numerical simulations. Journal of Geophysical Research: Oceans 118 (10), 5568-5590.

Uncles, R.J., Ong, J.E., Gong, W.K., 1990. Observations and analysis of a stratification-destratification event in a tropical estuary. Estuarine, Coastal and Shelf Science 31 (5), 651-665.

van Maren, D.S., van Kessel, T., Cronin, K., Sittoni, L., 2015. The impact of channel deepening and dredging on estuarine sediment concentration. Continental Shelf Research 95, 1-14.

Wan, Y., 2015. Multiscale physical processes of fine sediment in an estuary, UNESCO-IHE. Delft University of Technology & UNESCO-IHE, Delft, The Netherlands, p. 180.

Wan, Y., Gu, F., Wu, H., Roelvink, D., 2014. Hydrodynamic evolutions at the Yangtze Estuary from 1998 to 2009. Applied Ocean Research 47 (0), 291-302.

Wan, Y., Wang, L., 2017. Numerical investigation of the factors influencing the vertical profiles of current, salinity, and SSC within a turbidity maximum zone. International journal of sediment research 32 (1), 20-33.

Wang, Y., Yu, Q., Gao, S., 2011. Relationship between bed shear stress and suspended sediment concentration: annular flume experiments. International journal of sediment research 26 (4), 513- 523.

Wang, Y.P., Voulgaris, G., Li, Y., Yang, Y., Gao, J., Chen, J., Gao, S., 2013. Sediment resuspension, flocculation, and settling in a macrotidal estuary. Journal of Geophysical Research: Oceans 118 (10), 5591-5608.

Wang, Z.B., Winterwerp, J.C., He, Q., 2014. Interaction between suspended sediment and tidal amplification in the Guadalquivir Estuary. Ocean Dynamics 64 (10), 1487-1498.

Winterwerp, J.C., 2011. Fine sediment transport by tidal asymmetry in the high-concentrated Ems River: indications for a regime shift in response to channel deepening. Ocean Dynamics 61 (2-3), 203-215.

Wu, J., Liu, J.T., Wang, X., 2012. Sediment trapping of turbidity maxima in the Changjiang Estuary. Marine Geology 303-306 (0), 14-25.

Published
2018-12-30
How to Cite
Gao, M., & Wan, Y. (2018). STUDY ON MECHANISM OF BACK-SILTATION IN THE DEEP-DRAFT WATERWAY OF THE YANGTZE ESTUARY, AND EVALUATION OF ENGINEERING MEASURES. Coastal Engineering Proceedings, 1(36), papers.23. https://doi.org/10.9753/icce.v36.papers.23