Assessment of climatic trends using Rclimdex indices in the Mandakini Watershed, Uttarakhand, India

The analysis of historical observed data plays a vital role in recognizing the current effects of climate change compared to the past and preventing future water-related disasters in the watersheds, a detailed investigation of trends (magnitude) in climate variables should be performed. The current research investigated the rainfall variability, magnitude, and trend over the Mandakini River watershed with multi-temporal rainfall records and 41-year (1981–2022) gridded rainfall datasets obtained from the India Meteorological Department (IMD). This study analyzes climate trends in Kedarnath, Okhimath, and Rudraprayag, revealing key changes in temperature and precipitation patterns. The annual average rainfall, Tmin, and Tmax (1981–2022) analyses all show increasing trends, with slopes of 9.26 mm/year, 0.0279 °C/year, and 0.0165 °C/year, respectively. The last two decades (2001–2010 and 2011–2022) exhibit higher mean monthly maximum value of daily maximum temperature (TXx) values compared to the 1980s and 1990s, suggesting that extreme temperature events are becoming more frequent. The extreme precipitation indices, including RX5day, R10mm, R95p, and R20mm, exhibit increasing trends, with the most recent decade (2011–2022) witnessing a substantial rise in heavy rainfall events. The increase in extreme rainfall and warming temperatures could accelerate glacier melting, disrupt hydrological cycles, and impact agriculture. This study examines a strong spatial correlation between increasing extreme precipitation trends and rainfall-induced landslides in the Rudraprayag district, highlighting how intensifying rainfall patterns contribute to landslide distribution across the Mandakini valley. These findings underscore the need for long-term monitoring, improved water resource management, and climate adaptation strategies to mitigate the risks associated with changing climate patterns in the Himalayan region.