Detectability of the trend and hysteresis in rainfall across Kali Gandaki River Basin, Central Himalaya, Nepal

Streamflow alteration is one of the most noticeable effects of changes in rainfall patterns (both intensity and amount) in the Himalayan region. Additionally, the impact of climate change on the localized rainfall patterns is particularly significant, which is more crucial in the Himalayas. This study carries out a comprehensive analysis on temporal variability of the rainfall and its relation to streamflow in a typical mountain river basin, located in the southern aspect of central Himalayas. The primary objective of this study is to analyze seasonal and annual rainfall trends across rain gauge stations within the selected Kali Gandaki (KG) River Basin. Monthly rainfall data were used to examine the rainfall and streamflow trends. Mann-Kendall (MK) trend test, Sen’s slope, and sequential MK (SQMK) analysis were employed to evaluate monotonic trends on homogenized time series data. Our findings revealed the formation of an anticlockwise hysteresis loop between streamflow and rainfall within the catchment. Understanding the relationship between streamflow and rainfall would provide a foundation for effective water resources management.