A NUMERICAL-MODEL FOR RESIDUAL CIRCULATION AND POLLUTANT TRANSPORT INA TIDAL ESTUARY (HOOGHLY) OF NE COAST OF INDIA

To study pollutant dispersal in the estuary a non-linear vertically in tegrated numerical model has been applied to the Hooghly estuary along the east coast of India. The horizontal density gradient terms are in cluded in a two-dimensional depth-averaged hydrodynamic model. Biochem ical oxygen demand (BOD) was adopted as a tracer for water quality. Th e model uses a realistic tidal forcing, fresh water flow based on obse rvations and climatic winds over the region of interest. The effects o f wind and horizontal density gradients on the residual circulation ar e found to be significant. Pollutants discharged in the upper estuary do not affect the Haldia channel. The model predictions compare reason ably well with observed elevations and currents in the estuary. For ve rification of pollutant transport model, observational data is present ly unavailable, however, the salinity distribution compares well with the observations.