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

Abstract

Tidal hydrodynamics of the Gulf of Khambhat (GoK) were studied with the observed and simulated datasets. The Cushing 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 inCuence of tide, wind, and tide and wind combinedly. Wind-driven Cushing was found to be the least with the Cushing time magnitude of more than 25 days. The Cushing 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 Cood tide over ebb in GoK. Maximum current speed was during spring-Cood 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 Cushing between the Gulf and the northeastern Arabian Sea during northeast monsoon and pre-monsoon season.