Simulation of three-dimensional cohesive sediment transport in Hangzhou Bay, China
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Simulation of three-dimensional cohesive sediment transport in Hangzhou Bay, China DU Panjun1,2 , DING Pingxing1∗ , HU Kelin1 1
State Key of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
2
Forecast Centers for East China Sea, State Oceanic Administration, Shanghai 200062, China
Received 11 December 2008; accepted 7 April 2009 c The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010
Abstract Sediment transport in the Hangzhou Bay is extremely complicated due to its bathymetry and hydrodynamic conditions. The ECOMSED model is employed to simulate three-dimensional (3-D) cohesive sediment transport in Hangzhou Bay. Dynamical factors such as Coriolis force, tides, salinity, river discharges, and waves are considered in the model. The wave parameters, including the significant wave height, period, and direction, are calculated with the SWAN model. The Grant-Madsen model is introduced for the bed shear stress due to the combined effect of waves and currents. The formulation of bed shear stress used to calculate the sink/source terms is modified based on previous research that sufficiently validated the formulation with measurement data. The integrated model of the above-mentioned models is applied to simulate sediment transport in Hangzhou Bay. The results of the simulation agree well with field observations concerning the distribution of suspended sediment, indicating that the sediments are remarkably suspended in Hangzhou Bay under the action of waves and currents. Key words: waves, currents, suspended sediment, deposition, erosion, Grant-Madsen Model
1 Introduction A better understanding of cohesive sediment transport processes is essential not only for port construction and seabed changes, but also for the study of chemical and biological processes in estuaries and coastal areas. The objective of this paper is to use the ECOMSED model to simulate three-dimensional cohesive sediment transport processes in Hangzhou Bay. Hangzhou Bay (shown in Fig. 1), located on the east coast of China, is the largest macro-tidal bay in China. The width of the bay varies from 100 km at the mouth to 25 km at the head, and the total length from the mouth to the head is about 95 km. In the southeast part of the bay, there are lots of islands and deep channels. Hangzhou Bay abuts on the Changjiang (Yangtze) Estuary, where water and sediment exchange frequently. The results of various studies have indicated that fresh water and sediment from the Changjiang Estuary are transferred in significant amounts into Hangzhou Bay, and especially into its northern part (Chen et al., 1988; Su et al., 1989; Hu et al., 2000; Chen et al., 2001). Furthermore, winds,
waves, and a mix of saline water and fresh water also affect the bay. Under such topographic and hydrodynamic conditions, sediment transport in Hangzhou Bay is extremely complicated. Some basic characteristics of tide and sediment movement in Hangzhou Bay have been discussed through numerous observations and analyses for hydrograph
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