Numerical simulation on pollutant tracking released from the Xuliujing node transect

A coupled hydrodynamic-ecological(COH ERENS) model,with anorthogonal horizontal coordinates and a σ-vertical coordinate,was combined with a 3-D Lagrangian drifter tracking module and a water quality module to construct the hydrodynamic part of the modeling system.The COHERENS model was used to study water exchange and pollutant transport in the Changjiang Estuary.The particle tracking method,as applied in the sing lerelease experiments,provides a picture of the residual flow in the certain parts of the Changjiang Estuary.The COHERENS model had been modified by means of the changing grid technology and the dry-wet method to deal with the moving boundary.The model was calibrated and validated using tidal data available for represent ativestations.Both the magnitude and phase of the water elevation and velocity were reasonably reproduced.The numerical simulation was performed of the tidal current and pollutant diffusion from the Xuliu River node transect in the Changjiang Estuary to reveal suspended particle matter and dissolved pollutant transport in this area.By calculation of the track of Lagrange particle(or particles mass centre) and Eulerian dissolved contaminant mass centre realsed from the Xuliu River node transect,the effects of current fields on the pollutant transport and diffusion were analyzed. The current field characteristics and the pollutant transport rule were discovered.