A numerical model for residual circulation and pollutant transport in a tidal estuary (Hooghly) of NE coast of India

Abstract

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