Impact of Approach Angle of an Impinging Cyclone on Generation of Storm Surges and Its Interaction with Tides and Wind Waves

Abstract

AbstractDetailed investigation is made on the effect of cyclone's approach angle on generation of storm surges and its nonlinear interaction with tides and wind waves using a standalone 2DDI ADCIRC and a coupled ADCIRC+SWAN model. Numerical experiments are executed using 17 idealized straight cyclone tracks of same intensity moving at constant forward speed. The study domain considers an idealized bathymetry with straight coastline and uniform shelf width. All cyclones make landfall at the same location with angles approaching from 10° to 170° with an increment of 10°. The simulations show that the maximum storm surge is computed for tracks land falling with 60o–90o. Increase in the peak storm surge is seen about 15% from 10o–60o, while it decreases by about 13% from 90o–170o. Surge‐wave interaction modifies the maximum water level by about 21–26%. The maximum wave contribution is seen for track with 90o followed by 160o and 20o. During different phases of tide, surge‐tide interaction modifies peak surge, its occurrence, and location as cyclone makes landfall at different angles. The extent of affected coastal stretch is maximum on either side of the landfall for the tracks moving close to the coast, while it is minimum for the perpendicular track (90o), confined only to the right of the landfall. The peak surge‐tide‐wind wave interaction along the coast at both high and low tide is seen about 2–4 hr after the landfall. The interaction along the coast depends on approach angles of the cyclone; however, the total water level is mainly modified by both tidal phase and approach angle.