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Abstract
This thesis, firstly, provides a general framework in which any number of tidal constituents can be included in the identification of those constituents responsible for asymmetry in any tidal time series. This new method has two features which greatly simplify the attribution of asymmetry to particular constituents: 1) only combinations of two or three constituents can contribute to skewness, regardless of how many constituents are significant in the time series; and 2) of those combinations, only the few meeting frequency conditions will give rise to long-term mean asymmetry.
Secondly, it illustrates the impact of tidal flat reclamation on tidal dynamics (including tidal asymmetry) in the Bohai Sea, Yellow Sea, and East China Sea (BYECS). Different tidal patterns, due to tidal energy redistribution, are shown when tidal flats around the BYECS are removed. Far-field effects on tidal dynamics occur on the west Korean coast when reclamation is carried out over the Jiangsu coastal regions in China. In turn, reclamation on the west coast of Korea may generate far-field effects along the Chinese coast. Furthermore, reclamation in the BYECS can result in a rise in tidal amplitude and onshore sediment transport. The former may enhance coastal hazards such as storm surges; the latter may result in severe siltation.
Finally, it explores the suspended fine sediment transport in a newly completed man-made Deepwater Navigation Channel (DNC) in the North Passage of the Yangtze River Estuary, China. Observations show strong spring-neap tidal asymmetric patterns on suspended sediment transport in the DNC during the dry season in 2009, when the landward transport is determined by the tidal pumping effect on spring tides, but a shear effect on neap tides. Model simulations indicate the turbid water intruded into the DNC is driven by flux from the shoals outside the two dikes. Surface wave breaking relieves the sediment trapping in the DNC, but the bottom wave-current interaction enhances bed erosion. The siltation occurring in the DNC favors a low river-discharge and a northwesterly wind condition.