Streamflow generation in semi-arid,glacier-covered,montane catchments in the upper Shule River,Qilian Mountains,northeastern Tibetan plateau |
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| Authors: | Jiaxin Zhou Yongjian Ding Jinkui Wu Fengjing Liu Shaoping Wang |
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| Institution: | 1. College of Geography and Environmental Engineering, Lanzhou City University, Lanzhou, China;2. Key Laboratory of Ecohydrology of Inland River Basin, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China;3. College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, USA;4. State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China |
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| Abstract: | Streamflow generation was investigated using isotopic and geochemical tracers in semiarid, glacier-covered, montane catchments in the upper Shule River, northeastern Tibetan Plateau. Samples from stream water, precipitation, glacier meltwater, and groundwater were collected at the Suli and Gahe catchments along the Shule River, with an area of 1908 and 4210 km2, respectively. The samples were analysed for stable isotopes of water and major ions. Results of diagnostic tools of mixing models showed that Ca2+, Mg2+ and Cl?, along with δ18O and δ2H, behaved conservatively as a result of mixing of three endmembers. The three endmembers identified by the mixing analysis were surface runoff directly from precipitation, groundwater, and glacier meltwater. Streamflow was dominated by groundwater, accounting for 59% and 60% of streamflow on average in the Suli and Gahe catchments, respectively, with minimum groundwater contribution in July (47% and 50%) and maximum contribution in October (69% and 70%). The contributions of surface runoff were slightly higher in the Suli catchment (25%) than in the Gahe catchment (19%). However, the contributions of glacier meltwater were higher in the Gahe catchment (21%) compared to the Suli catchment (17%), as a result of a higher percentage of glacier covered area in the Gahe catchment. This difference followed well the non-linear power–law trend of many glacier-covered catchments around the world. As glacier retreat continues in the future, the reduction of streamflow in glacier-covered upper Shule catchment likely will be accelerated and possibly elsewhere in the Tibetan Plateau. This study suggests that it is critical to define the turning point of an accelerated reduction in glacier meltwater for glacier-covered catchments around the world in order to better assess and manage water resources. |
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| Keywords: | diagnostic tools of mixing models endmember mixing analysis stable isotopes streamflow generation |
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