Simulation of extreme water levels in response to tropical cyclones along the Indian coast: a climate change perspective

Indian coasts are often influenced by life-threatening water levels caused by tropical cyclones. To have a better long-term planning for the coastal districts due to tropical cyclones, the extreme water levels for different climate change scenarios are important to compute. For this, finite-element mesh is generated with high resolution near the coast to simulate maximum water elevations (MWE) as a response to the nonlinear storm surge interaction at the time of local high tide. Based on the historical cyclone data (1891–2016), the return periods are calculated using the values of pressure drop of the cyclones for each maritime state along the Indian coasts. Synthetic tracks are also generated based on inverse distance weighted method using the inventory of cyclone tracks, ensuring that each coastal district is covered. Experiments are carried out for each return period with possible climate change scenarios by considering wind enhancement of 7% (moderate scenario) and of 11% (extreme scenario) over the normal (present) scenario. The simulations for MWE are performed at every 10 km along the Indian coast. The computed averaged extreme water levels of about 10 m are simulated in the northernmost part of the east coast and Gulf of Khambhat in the west coast of India. An average increase of about 20% and 30% in MWE is estimated in the moderate and extreme climate change scenarios, respectively. The southern Indian peninsular region is seen significantly affected from the extreme scenario.