Mapping of cyclone induced extreme water levels along Gujarat and Maharashtra coasts: a climate change perspective
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Mapping of cyclone induced extreme water levels along Gujarat and Maharashtra coasts: a climate change perspective Jismy Poulose1,2 · A. D. Rao1 · S. K. Dube1 Received: 5 August 2019 / Accepted: 16 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Coastal flood mapping associated with tropical cyclone induced extreme water elevations is carried out for the Gujarat and North Maharashtra coasts in the perspective of climate projections for the Arabian Sea. The projections are taken into account by enhancing the present cyclone wind intensity by 7% and 11% based on the IPCC fifth assessment report to study its impact on extreme water elevations and coastal flooding. The coupled ADCIRC + SWAN model is used in this study to map the maximum water elevations resulting from storm surges, astronomical tides, and wind-waves by utilizing the most probabilistic cyclone tracks generated for this region. Results from the study signifies that extreme water elevations ranging between 9.0 and 9.5 m are evident in the Gulf of Khambhat and Kutch under no-climate change scenario, while it enhances to a maximum of 10.0–11.0 m under climate change projections. Maximum extent of coastal inundation is found in the lowlying regions of Great and Little Rann of Kutch, Mumbai, and high-tide mudflats of Bhavnagar. It is notable that climate projections have maximum impact on inundation height, while it is marginal in terms of risk associated with the additional inundation extent. Keyword Numerical modelling · Storm surge-tide-wind wave interaction · Extreme water elevations · Climate projections · Coastal inundation
1 Introduction Coastal regions are dynamic in nature comprising low-lying areas and are exposed to geomorphologic and oceanographic changes (Cowell et al. 2006). About 40% of the global population lives within 100 km of coast and below 100 m of topography above mean sea level (Small and Nicholls 2003). The coastal regions of India are vulnerable to tropical cyclone induced storm surges and associated inundation. Based on data from 1980 to 2000, on average about 370 million people in India are exposed to cyclones annually (https ://ncrmp.gov.in/cyclones-their-impact-in-india). Although the frequency of cyclonic storms are less over the Arabian Sea (AS) as compared to the Bay of Bengal, there are reports of severe cyclonic storms landfalling along the rim countries * Jismy Poulose [email protected] 1
Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi 110016, India
Present Address: Department of Civil Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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surrounding the AS. Out of 41 cyclones that occurred during 1970–2017, about 23 made landfall, of which 8 are categorized as severe cyclonic storms, 7 categorized as very severe cyclonic storms, and one as a Super cyclone, Gonu in 2007. Regions in Gujarat and northern Maharashtra are the most cyclone-affected areas along the west coast of India. Major cyclones in 1975, 1977, 1
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