The dispersal processes within the tide‐modulated Changjiang River plume,China

The dispersal processes of the tide‐modulated Changjiang River plume, China, are studied by using a three‐dimensional hydrodynamical module of the COHERENS (A COupled Hydrodynamical–Ecological model for REgional and Shelf Seas). The model is driven by the river discharge and the M₂ tidal constituent. Modelled results show: (1) the fresh water, which forms the Changjiang River plume expanding southeastwards, is discharged mostly into the North Channel, the North Passage, and the South Passage; (2) the larger horizontal gradient outside the North Channel and the North Passage forms a strong plume front; (3) the Changjiang River plume is homogeneous vertically, and dispersing gradually within the computational domain, with an averaged propagating rate of 3.38 km/day, while the plume front is surface‐to‐bottom type, and trapped between ?10 and ?18m isobaths; and (4) both the plume length and the plume front intensity vary periodically. The maximum plume length occurs about 2 h after low slack water and the minimum plume length during high slack water. The maximum plume front intensity occurs during high slack water and the minimum plume front intensity during low slack water. Copyright © 2007 John Wiley & Sons, Ltd.