Ranking extreme precipitation events of different duration over the Brahmaputra river basin during the Indian Summer Monsoon and their association with moisture transport

As the temperature rises due to climate change, the moisture-holding capacity of the atmosphere increases, which contributes to more frequent and intense extreme precipitation events. In recent years, there has been a significant increase in flooding caused by extreme multi-day precipitation, and this trend is projected to continue in the future. The Brahmaputra river basin has a greater risk of flooding compared to other regions in India. These major floods usually occur during the summer monsoon season, which can be attributed to their higher vulnerability, probability of hazard, and exposure as transboundary river basins, thus becoming a major concern. Therefore, it is crucial to characterize and rank precipitation extremes to comprehend the risk and impact and examine the underlying drivers that contribute to their occurrence and intensification. In this study, we ranked extreme precipitation events of different durations (1 to 7 days) on the basis of intensity and spatial extent during the Indian summer monsoon (ISM) season over the Brahmaputra basin using a high-resolution daily precipitation dataset for 71 years period (1951 - 2021). Further, we attempt to evaluate the association between moisture transport and these extreme precipitation events by quantifying moisture transport during identified top-ranked extreme precipitation events. Our analysis indicates strong moisture transport persisting over the extreme precipitation occurrence regions during the identified top-ranked extreme precipitation events. Quantifying the connection between extreme precipitation to moisture transport might help in the early prediction of extreme precipitation events and lower the associated risks.