Modeling the impact of tropical cyclone Vardah along the Chennai coast

The present study is envisioned to understand the circulation pattern and the storm surge induced by a very severe cyclonic storm, Vardah that made its landfall along the east coast of India on December 2016. The hydrodynamic model, Telemac 2D was applied to examine the water level variations during the extreme event, by generating a high-resolution computational grid. The model was driven by tidal forcing at the ocean boundary. The elevation was considered as a boundary condition in order to understand the interaction of the surge with the tides to examine the variation of the intensity of the surge over the coast. The wind stress as the basic input and wind pressure was applied as a forcing parameter to capture the pressure drop during the cyclonic event. The quality of the wind field is enhanced by applying a parametric cyclone wind model (Holland 1980) with ECMWF wind field. The computed wind speed and surge heights are compared with field measurements. The simulated surge height up to about 1.2m during landfall time is found to follow closely with the field observed data. The wind and tide induced surface elevations are found to be higher and the corresponding flow velocity was high when the surge rises and recedes. The main purpose of this study is to understand the details of the severe tropical cyclone characteristics and to develop a numerical set up that precisely predict the surge heights based on which precautionary measures can be charted out for the future.