Tidal propagation in the Gulf of Khambhat, Bombay High, and surrounding areas

The continental shelf on the west coast of India is widest off Bombay and l eads into a strongly converging channel, the Gulf of Khambhat. Tides in the Gulf are among the largest on the coast. We use data on amplitude and phas e of major semi-diurnal and diurnal constituents at forty-two ports in the Gulf and surrounding areas to define characteristics of the tides. We then use a barotropic numerical model based on shallow water wave equations to s imulate the sea level and circulation in the region. The model is forced by prescribing the tide along the open boundaries of the model domain. Observ ed sea level at Bombay and currents from the Bombay High region at the cent re of the model domain and from a shallow station off the port of Dahanu co mpare favourably with the fields simulated by the model. The simulated ampl itudes and phases of the four most prominent tidal constituents also compar e favourably with those observed along the coast, except at a few locations where the model spatial resolution (6.37 km x 6.37 km) appears to be inade quate to resolve the local geometry. Though this encourages us to conclude that the circulation in the region is dominated by barotropic tides, a conc ern is that the observational database on hydrography and directly measured currents in the region is weak.