Bottom Boundary Layer Characteristics in the Hooghly Estuary Under Combined Wave-Current Action

Abstract

The development of a theoretical model for estimating bottom boundary layer characteristics in the Hooghly estuary, located in the east coast of India, under combined effects of waves and currents is reported. Three numerical models, viz a depth averaged hydrodynamic model, SWAN wave model, and bottom boundary layer model, were integrated. In the bottom boundary layer parameters, maximum bottom stress, effective friction factor, and near-bed velocity both during ebb and flood phases of the tidal forcing are investigated and validated for the Haldia channel. The close match seen from results signifies applicability of this model for entire Hooghly basin.

Keywords:

• Bottom boundary layer
• Hooghly estuary
• waves
• currents

Acknowledgements

The authors would like to express their gratitude to Naval Research Board, DRDO New Delhi, for funding this research project.

Notes

∗Values of U_c for station numbers 1–3 taken from measurements reported by Sadhuram et al. (2005); for stations 4–8 numerically obtained from depth averaged hydrodynamic model.

∗∗The significant wave height (H_s) and mean wave period taken from the measurements reported by Purkait (2009).