Compound hazard mapping for tropical cyclone-induced concurrent wind and rainfall extremes over India

Abstract

India is the worst affected region in the world by tropical cyclones (TCs), causing an average 2% annual GDP loss. TCs instigate many other natural hazards that have a compounding effect on the adversely affected population and present significant challenges to the resilience of emergency response systems and infrastructure. Hence, any risk assessment on TC is inherently multivariate/compound in nature. This study investigates co-occurring wind and rainfall extremes during TCs across India (1979–2020) using a novel quasi-Lagrangian approach, focusing on location-specific hazards. Eastern coastal states and adjacent inland areas experience the highest frequency (≥10 cyclones in 40 years) of concurrent extremes (wind gusts ≥ 16 m/s and rainfall ≥ 18 mm/h). Whereas duration-wise, the eastern coastal states and Gujarat state experience frequent concurrent extremes lasting more than a day annually, with the Krishna–Godavari delta region particularly vulnerable to highly severe events (duration of concurrent extremes ≥ 24 h). This study provides a high-resolution cartographic product of compound hazard from TC-induced extremes for the first time over the entire India, highlighting regional heterogeneity and aiding targeted national-level risk mitigation and adaptation planning.