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The numerical simulation of non-uniform sediment transport under tidal flow in estuaries is a complicated, yet important, issue in Zhejiang estuaries. In this paper, a depth-averaged two-dimensional (2D) mathematical model for non-uniform sediment transport in estuaries is established and applied in Zhejiang tidal estuaries based on several newly derived formulas by Zhlin Sun et al. The model is validated using data from several experiments, including an aggradation test and an erosion test. Good performance in the tests indicates that the present model can simulate aggradation and erosion processes of non-uniform sediment. The model is also verified by observational data from the Jiaojiang estuary, and calculations agree well with measurements. The model is thus adaptable to simulating flow and non-uniform sediment transport in tidal estuaries. [ABSTRACT FROM AUTHOR]

Dong, H.; Huang, P.; Sun, Z.; Li, Z., and Chong, L., 2020. Numerical simulation of local scour and flow field around pipelines. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 272–278. Coconut Creek (Florida), ISSN 0749-0208. Numerical simulations were conducted where both local scour below pipelines and flow fields around pipelines occur. The evolution, shape, and scale of local scouring at pipelines under different flow velocities and pipeline layouts were calculated. The research area is Huibieyang Sea of Zhejiang, China, where large numbers of submarine pipelines have been laid. Results show that typical accumulations of sand waves cannot form behind the pipelines in this study area due to their fine sediment size. Data from field observations at the water depth where the pipelines are located were collected in this study, on the basis of which preliminary analysis was made on the stability of the seabed and local scouring in the research area in recent years. [ABSTRACT FROM AUTHOR]