Integrated assessment of climate-induced variability in precipitation extremes in a tropical river basin

Abstract

This study assesses spatiotemporal patterns of extreme rainfall in the Cauvery River Basin (CRB) using 27 Global Climate Models for the historical (1960-2014) period and future projection (2015-2100) under SSP585. Expert Team on Climate Change Detection and Indices (ETCCDI) based precipitation extremes were analyzed. Trends identified using the Mann-Kendall test, Sen’s slope, and Innovative Trend Analysis, and rainfall variability assessed through Continuous Wavelet Transform. The historical analysis revealed predominantly weak to moderate declining trends (Sen’s slope: -1.249 to -0.223 days yr⁻1) across several parts of the basin. Wavelet power spectra showed strong power in the 8-16 months band, signifies episodic storm activity preceding and following the monsoon period across the basin. SSP585 projections indicated intensified variability, with some regions displaying strengthened high-frequency rainfall cycles and a potential increase in extreme-rainfall episodes. Overall, the findings indicate that the CRB may experience increased hydrological stress due to changing rainfall magnitude and variability.