Hydro-climatic extremes in a medium range River Basin in western Nepal: Learning from analysis of observed data.

Hydro-climatic extremes, such as floods and droughts, are influenced by climate change and climate variability, significantly affecting natural ecosystems, human lives, and livelihood. It is crucial to advance the understanding of long-term trends of hydro-climatic extremes for effective water resource planning and management. We analyzed 25 climatic extremes-related indices and 33 hydrologic extremes-related indices in a medium-range river basin in western Nepal, the Babai River Basin. We used RClimDex and Indicators for Hydrologic Alterations to analyze extreme climatic and hydrologic parameters. We computed monotonic trends to evaluate temporal changes in extreme events. The results show a positive trend of total precipitation at Kusum (+ 2.2 mm/year) and Bargadaha (+ 17.7 mm/year) stations and a negative trend at Gulariya (− 5.7 mm/year), Nayabasti (− 7.0 mm/year), Luwamjula (− 5.9 mm/year), and Ghorai (− 18.5 mm/year) stations. Similarly, we observe that almost all temperature extreme indices have a rising trend except the percentage of the days when the maximum temperature is less than the 10th percentile index at Rani Jaruwa station, located at a low elevation. Notably, the cold day temperature index falls at 0.13 days per year. Overall, the hydrologic alteration value shows moderate variability and reduction in the median flow for the second half. The findings of this study indicate that the study area is subjected to a reduced flow regime with a medium degree of variability. [ABSTRACT FROM AUTHOR]