Assessment of Droughts and Floods During the Indian Summer Monsoon Using the Coupled Model Intercomparison Project Phase 6 Historical and Future Simulations

Abstract

Indian summer monsoon (ISM) is the prominent global monsoon system, which occur annually from June to September and impacts the lives of over a quarter of the world's population. Studies show that global warming is one of the key reasons for the extreme events such as droughts and floods, and that also alter regional dynamics of ISM. Consequently, a comprehensive investigation of flood and drought events in India is imperative, because of their important role in the economy of the country. Here, we employ simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6) models to evaluate the intensity and frequency of droughts and floods across historical (1950–2014) and future (2015–2100) periods. We explore the best-performing model for the ISM rainfall (ISMR) to unravel the characteristics of floods and droughts by analysing rainfall data from 53 models. Although majority of the models successfully replicate the annual cycle of ISMR, there exists a significant difference in rainfall amounts. Following an initial screening to identify the most efficient models, eight are selected for an in-depth assessment. The chosen models slightly overestimate drought conditions, although they demonstrate a commendable concurrence in simulating the flood occurrences in India. Regarding the future projections, we analyse the Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) for near (2015–2035)-, mid (2047–2067)- and far (2079–2099)-future periods, in addition to the total projection period (2015–2100). Our analysis reveals an increasing trend of droughts in the near-future, compared to an increase in floods during the far-future. It is also highlighted that the intensity of droughts is projected to amplify in the far-future, while the intensity of floods is likely to diminish. Therefore, this study serves as a valuable resource for decision-making processes, particularly in the flood, drought and agricultural disaster preparedness.