Runoff variation and response to precipitation on multi-spatial and temporal scales in the southern Tibetan Plateau

The Yarlung Zangbo River basin (YZB) in the Tibetan Plateau (TP). Hydro-climatic processes in the TP are greatly sensitive to global climate change, but are not well understood nowadays due to the lack of hydro-climatic observations. In this study, runoff variation and response to precipitation on multi-spatial and temporal scales were identified and quantified by using a comprehensive approach, based on time series of monthly runoff and precipitation during 1961–2015. Annual runoff and flood season runoff mainly showed a downward trend from 1961 to 2015 in the upper-middle reaches of the YZB. Spatially similar non-monotonous changes were also detected with a turning point around 2000, which was greatly affected by precipitation. Periodic changes of annual and flood season runoff were significant on an approximate 3-year, which was well correlated with precipitation and obviously different from dry season runoff. The long-range trend of runoff in 1961–2015 may be related to scaling behaviors in the midstream where about 10.7–14.9% of the trend of runoff were explained by precipitation in flood seasons. Precipitation changes contributed to above 50% of the runoff tendency and thus can be considered as the major driving factor of runoff changes in the upper stream and NY sub-basin. The study provides a new understanding of runoff-precipitation variation through a comprehensive and quantitative analysis. [Display omitted] •Annual/flood season runoff mainly showed a downward trend during 1961–2015•An upward trend was found for the runoff of eastern YZB in different seasons•Runoff variations was affected by precipitation on ~3-year scale in flood seasons•The downward trend of runoff in the midstream may be related to scaling behaviors•Precipitation contributed to over 50% of runoff tendency in upstream/eastern YZB