Assessment of flash and incessant rainfall risks in India: Integrating the influence of global oscillations and socio-economic vulnerability

Abstract:

Extreme rainfall risks in India include risks due to flash rainfall events and extremely long wet spells. Variability in the rainfall in the country has been found to be affected by various global scale modes of climate variabilities/oscillations such as El Niño/Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and North Atlantic Oscillation (NAO). Further, IPCC reports, with high confidence that the severity of the impacts of extreme climatic events is strongly governed by the level of exposure and vulnerability. Comprehensive assessment of these factors in triggering extreme rainfall events is necessary for making efficient disaster risk reduction strategies. This study investigates the influence of ENSO, IOD and NAO in augmenting flash and extremely long wet spell risks in 637 districts across 29 states of India using nonstationary extreme value theory under Bayesian setting. It is found that at least 50% of the districts in 8 out of 29 states are at high risk. This risk is observed in 198 (~31%) and 249 (~39%) districts caused by flash and extremely long wet spells respectively. Moreover, it is also observed that the risk was underestimated using conventional stationary models. This study provides a framework to incorporate the natural as well as the socio-economic factors in framing extreme rainfall-induced disaster risk reduction strategies.