Hydrograph separation and the influence from climate warming on runoff in the north-eastern Tibetan Plateau

摘要

There has been a noticeable change in runoff processes in cold regions under climate warming and a shrinking cryosphere; this is receiving increased scientific attention. This study explored the changing hydrological processes of the Anyuan river basin, in the north-eastern Tibetan Plateau, via stable isotope tracing of 202 samples from precipitation, supra-permafrost water, river water, groundwater, and soil water from 2013 to 2014. The isotopic composition of precipitation was characterized with maximum values in summer and minimum values in winter. The similar variations for stable isotopes of river water, spring water, and well water, confirming the close hydraulic connection among them within the study basin. In terms of soil water, the stable isotope value changes continuously with depth due to recharge by infiltration of precipitation and subsequent transpiration and evaporation. It demonstrated that river water was sourced mainly from precipitation and supra-permafrost water. Hydrograph separation indicated that supra-permafrost water and precipitation contributed 24% and 76% on average, respectively, to river water in the basin. This study will provide a scientific basis for water resource management in the north-eastern Tibetan Plateau.