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Abstract Based on MIKE 21 software, a hydrodynamic and pollutant transport model has firstly been established for the estuarine and coastal waters in the Yanghe River and the Daihe River. Then the model is verified by measured tidal current and concentration of Chemical Oxygen Demand (COD). Finally, the transport processes of COD in the estuarine and coastal waters are simulated and analyzed. Numerical results show that the tidal current in the coastal water of the Yanghe River and the Daihe River can be characterized as a reciprocating flow along the shore while the tide is a standing wave. The directions of flood and ebb currents are NE to SW and SW to NE, respectively. The tidal current velocities increase from estuaries to the offshore in both flood and ebb periods. The direction of COD transport is consistent with that of the tidal current. The high concentration region of COD is pushed towards rivers at the slack of flood with the smallest area, while towards offshore at the slack of ebb with the largest area. The tidal current velocity is quite small in the region around the Putao Island, generally less than 0.14m/s in a tidal cycle, which leads to weak dilution of COD.
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Received: 15 May 2015
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