Tidal Hydrodynamics along Gulf of Khambhat, West Coast of India

Abstract

In coastal hydrodynamics, tides play a major role and it is important to understand the complexity of their characteristics along the difficult coastal areas like creeks, estuaries, bays and gulfs for any kind of engineering activities like harbor, jetty, dams and protection measures. In this study, six tidal constituents (K1, M2, N2, O1, P1 and S2) variations along the Gulf of Khambhat, west coast of India were studied with the spatially varied friction coefficient. A two-dimensional finite element-based numerical model (Telemac-2D) was developed and zones of different friction coefficients were identified by comparing numerically estimated levels and currents with that of measured and reported by earlier studies. Based on the comparisons, the gulf was divided into five zones of different bottom friction values. The numerical model was used to predict the tidal constituent's propagation along the gulf with the spatially varied bottom friction values and the amplitude and currents were analysed along the gulf. From the results, it was observed that the M2 (semi-diurnal) and K1 (diurnal) constituents influence the hydrodynamics of the gulf of Khmabhat significantly, compared to the other constituents. Further, a composite tide, inclusive of all six tidal constituents was applied to the offshore boundary of the numerical model and the tidal levels and currents were analysed along the gulf locations. It was observed that the combined effect of the constituents further increase the tidal amplitude up to 10m and the velocity up to 4ms-1. The validation of the numerical model showed good agreement.