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Fluvial discharge is a principal driver of suspended sediment (SS) transport in the Central Himalayan region, Nepal. The study examines the relationship between specific discharge at three hydrometric stations along the main Kali Gandaki (KG) River, four hydrometric stations on its tributaries with rainfalls across the entire basin and its sub basins, in relation to SS transport at a hydropower reservoir. Over the period of 2006–2017, the average monthly rainfall in June (388.39 ± 84.24 mm), July (674.91 ± 105.24 mm), August (571.81 ± 110.77 mm), and September (356.50 ± 104.39 mm) yielded an average of 2.469 ± 1.641, 12.952 ± 4.932, 12.629 ± 7.937, and 4.406 ± 2.363 megatons (Mt) of SS loads, respectively, flowing from the KG catchment into the hill-side dam reservoir. Results indicated that approximately 97% of SS was transported during the monsoon season (June–September). This corresponds to an estimated annual weathering rate in the basin of 4390 tons/km2/year, equivalent to 1.66 mm/year. Notably, both the specific direct runoff discharge and the monsoonal daily erosion rate during major rainfall events (> 30 mm/day) exhibited an upward linear trend with the basin's rainfall. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]