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Abstract Multiphase water transformation has great effects on alpine hydrology, but these effects remain unclear in the third pole region. Taking the Qilian Mountains as an example, the climate background and relative rates of multiphase water transformation were analyzed, and the runoff effect was evaluated based on long-term field observations. There are three climatic aspects driving multiphase water transformation, including lengthening ablation period, accelerative warming after 1990, and larger warming in the cryosphere belt than in the vegetation belt. The accelerative multiphase water transformation was quantified by three facts: the glacier area retreat rate accelerated by 50% after 1990, the percentage of snowfall in precipitation decreased by 7% after 1990, and the contribution from recycling moisture to precipitation increased by 60% from 1961–1990 to 1991–2016. Under the multiphase water transformation, the outlet runoff for three inland rivers increased by 5 × 108 m3/10 a after 1990. This runoff increase was concentrated mainly in the ablation period. For the seasonal runoff pattern, maximum runoff lagged maximum precipitation by one month under increasing glacier snow meltwater and thickening permafrost active layer. Meltwater from the cryosphere is a crucial runoff component in the Qilian Mountains. At present, these multiphase water transformations are accelerating, along with the yearly runoff increase, which will obviously have a profound impact on water resources management and flood control in the third pole region. Graphical abstract Unlabelled Image Highlights • Finding the lengthening ablation period and the larger warming in cryosphere belt. • Glaciers area retreat rate has accelerated by 50% after 1990. • The percent of snowfall accounting for precipitation has decreased by 7% after 1990. • Contribution from the recycling moisture to precipitation has increased by 60%. • The outlet runoff increased and seasonal pattern changed. [ABSTRACT FROM AUTHOR]

Terrestrial evapotranspiration (ET a) reflects the complex interactions of climate, vegetation, soil and terrain and is a critical component in water and energy cycles. However, the manner in which climate change and vegetation greening influence ET a remains poorly understood, especially in alpine regions. Drawing on the Global Land Evaporation Amsterdam Model (GLEAM) ET a data, the interannual variability of ET a and its ties to precipitation (P), potential evaporation (ET p) and vegetation (NDVI) were analysed. The Budyko framework was implemented over the period of 1982 to 2015 to quantify the response of ET a to climate change's direct (P and ET p) and indirect (NDVI) impacts. The ET a , P, ET p and NDVI all showed significant increasing trends from 1981 to 2015 with rates of 1.52 mm yr−1, 3.18 mm yr−1, 0.89 mm yr−1 and 4.0 × 10−4 yr−1, respectively. At the regional level, the positive contribution of increases in P and NDVI offset the negative contribution of ET p to the change in ET a (∆ET a). The positive ∆ET a between 1982 and 2001 was strongly linked with the concomitant increase in NDVI. Increases in vegetation contributing to a positive ∆ET a differed among landscape types: for shrub, meadow and steppe they occurred during both periods, for alpine vegetation between 1982 and 2001, and for desert between 2002 and 2015. Climate change directly contributed to a rise in ET a, with P as the dominant factor affecting forested lands during both periods, and alpine vegetation between 2002 and 2015. Moreover, ET p was a dominant factor for the desert between 1982 and 2001, where the variation of P was not significant. The contributions of factors having an impact on ∆ET a are modulated by both the sensitivity of impact factors acting on ET a as well as the magnitudes of factor changes. The greening of vegetation can influence ET a by increasing vegetation transpiration and rainfall interception in forest, brush and meadow landscapes. These findings can help in developing a better understanding of the interaction of ecosystems and hydrology in alpine regions. Unlabelled Image • ET a , P, ET p and NDVI showed significant increasing trends from 1981 to 2015 in QLM. • The positive contribution of increases in P and NDVI offset the negative contribution of ET p to the ∆ET a • Climate change contributed to a rise in ET a , with P as a dominant factor for forested lands. • Increase in vegetation dominated the positive ETa trends for shrub, meadow and steppe. • ET a was controlled by the sensitivity of factors to ET a as well as their change magnitudes. [ABSTRACT FROM AUTHOR]

In the transition zone between the Tibetan Plateau and the arid region of northwestern China, the spatiotemporal patterns and environmental controls of stable isotopes in precipitation remain unclear. A network of 19 sampling stations was established across the Qilian Mountains to observe stable isotopes in precipitation, and 1310 precipitation event-scale samples were collected. The local meteoric water line (LMWL) was obtained and expressed as δD = 7.99δ18O + 14.57 (R 2 = 0.96). The spatiotemporal patterns of the stable isotopes were mainly dominated by the co-influence of the water vapor sources and the local environment. The westerly circulation, monsoon circulation, and Arctic circulation accounted for 79%, 13%, and 8% of all precipitation events in the study region, respectively. The rainout process also caused oxygen isotope depletion for continuous precipitation events. When the temperature increased by 1 °C, δ18O increased by 0.47‰, but this increase varied with the temperature range. The effect of precipitation amount was apparent in summer and was caused by sub-cloud evaporation. In addition, δ18O decreased by 0.13‰ for every 100 m increase in altitude in the Qilian Mountains. Future research should focus on quantifying the co-influence of sub-cloud evaporation, local moisture recycling, and water vapor sources on stable isotopes in precipitation. Water vapor sources of all precipitation events in eastern, middle and western Qilian Mountains. Unlabelled Image • Transitional characteristics are evident for stable isotopes in precipitation. • Summer precipitation effects (-0.4 ‰/100m) caused by sub-cloud evaporation. • δ18O increased by 0.47‰ with a temperature increase of 1 °C. • δ18O decreased by 0.13‰ with an altitude rise of 100m. • The westerly circulation accounted for 79% of all precipitation events. [ABSTRACT FROM AUTHOR]