Assessing past and future climatological shift trend in vellar river Basin, India using CMIP6

This study aims to investigate the historical (1951–2024) and future projected (2026–2099) climate trends and change points in the Vellar River Basin under Shared Socioeconomic Pathways (SSP) using time series observations and downscaled Global Climate Model (GCM). Trends of rainfall and temperature were assessed based on the Mann–Kendall test. The change points detection were carried using Pettitt’s test, Standard Normal Homogeneity test, Buishand's range test and Von Neuman ratio test. The results revealed that historical rainfall found a declining trend seasonally as well as annually, with significant change points at 1979, 1981, and 1988. Future projections showed decreasing trend in rainfall, with notable change points at 2058, 2067, and 2084. The station Virudhachalam during Kharif, Vazhapadi and Karumandurai during Rabi and Annual period recorded more significant decreasing trend. The result of historical and future temperature projection displayed a significant upward trend. The historical minimum and maximum temperatures increased from 0.44 °C to 0.88 °C and 1.11 °C to 1.7 °C, respectively with change points for minimum temperature at 1996 and maximum temperature at 1979. The future predicts of temperature recorded an increasing trend of 1.5 °C, 2.0 °C, and 3.0 °C for maximum temperatures and 0.9 °C, 1.2 °C, and 1.5 °C for minimum temperatures under SSP 2.6, SSP 4.5, and SSP 8.5 scenario, respectively. Change points in maximum temperature are expected in the 2050s and 2060 for SSP 2.6 and SSP 4.5. Whereas SSP 8.5 anticipates at later 2080s, indicating a two-stage warming pattern with an early gradual increase followed by rapid rise towards the end of the century. These findings concluded by recommending the policy makers to develop climate adaptation strategies for agricultural and water management to mitigate the potential impacts of future climate condition.