Seasonal variations of a glacier river runoff components as relative to changes of air temperature and precipitation in southeast Tibetan Plateau

The glacier river is highly sensitive to the temperature and precipitation change in the alpine regions. However, to what extent of this sensitivity is still not clear. In this work, a procedure to quantify the impact of temperature and precipitation on water runoff components is proposed with a benchmark study at a typical temperate glacier catchment of Mingyong in the southeastern Tibetan Plateau (SETP). Firstly, we use Bayesian Monte Carlo Mixing Model to calculate contributions of different recharging sources to runoff from 213 water samples within a whole hydrological year (from August 2017 to July 2018). Hydrograph separation results show that the meltwater occupied the highest proportion in runoff from June to September (up to 58.4%) and the contribution of groundwater to runoff reached the maximum in January. Secondly, by establishing the relationships between temperature, precipitation and fractions of runoff components, we find that temperature change contributes about 78% to affecting the runoff components in Mingyong catchment at the intra-annual scale. Meanwhile, precipitation change occupies approximately 22% in influencing contributions of different endmembers to stream mainly by accelerating the melting process of glacier and accumulated snow as well as recharging the river directly. Finally, a conceptual model is developed to show the influence of temperature and precipitation on the runoff components in Mingyong catchment. The findings can not only provide essential evidence on gaining more insights into the mechanism of glacier river flow variation but also benefit for the strategy making for water resources management in alpine regions.