Role of continental shelf on non-linear interaction of storm surges, tides and wind waves: An idealized study representing the west coast of India

The study reports role and dependence of continental shelf geometry on the non-linear interaction of storm surges, tides, and wind waves. As a case study, the shelf geometry representing the west coast of India is considered and numerical simulations are executed using the standard representation of a tropical cyclone. The idealized experiments assume the west coast of India as a straight coastline with varying continental shelf width ranging from 35 km in the south to 330 km in the north. For the experiments, ADCIRC model in standalone mode and coupled ADCIRC+SWAN are used by considering 13 idealized cyclone tracks covering the study domain. It is noticed that an amplification of peak storm surge of ∼12 cm for every 10 km increase in the shelf width. During different phases of the tide, the surge-wave interaction modifies the water level elevation and its occurrence as the tidal range increases towards north. The interaction of tides on surges and wind waves is observed maximum at low-tide and minimum at flood tide over the wide shelf regions. In general, the non-linear interaction is found to be 15%-20% for any cyclone track or tidal phase. The wave setup caused by wind waves is marginally varies with change of amplitude and phase of the tide, however, its profile is significantly modified, particularly over the wider shelf widths.