Tidal hydrodynamics and flushing characteristics of Gulf of Khambhat, west coast of India – A numerical approach

Tidal hydrodynamics of the Gulf of Khambhat (GoK) were studied with the observed and simulated datasets. The flushing time of the Gulf was estimated using the 2D-model calibrated and validated with the tide and current speed observations. Model simulations were carried out with the influence of tide, wind, and tide and wind combinedly. Wind-driven flushing was found to be the least with the flushing time magnitude of more than 25 days. The flushing time was found to be much lower for the surrounding sea irrespective of the seasonal and tidal variations. The model-derived tidal circulation revealed the seasonal variability and the dominance of flood tide over ebb in GoK. Maximum current speed was during spring-flood conditions in the southwest monsoon, whereas minimum current speed was during the neap-ebb condition of pre-monsoon. High-frequency radar data, from the southern GoK ascertain the increase in current speed from south to north. The Simpson–Hunter parameter, calculated in several locations of the Gulf established the enhancing mixing capacity of GoK from south to north. During low current speed conditions, the Gulf experiences the formation of a barrier at the southern region which interrupts flushing between the Gulf and the north-eastern Arabian Sea during northeast monsoon and pre-monsoon season. Highlights Tidal hydrodynamics of Gulf of Khambhat studied with the observed and simulated datasets Amplification in the mixing capacity of the Gulf is observed towards the north Least flushing was observed during pre-monsoonal months