中国西部寒区流域冰川水文调节功能研究

Study on hydrological regulation function of glaciers in the cold region basins of western China

冰川作为固体水库以“削峰填谷”的形式显著调节径流丰枯变化,冰川的水文调节功能对于中国西北干旱区至关重要。使用现有VIC-CAS模型模拟得到中国西部寒区2014—2100年径流预估数据,从趋势和波动变化相结合的视角,基于径流变差系数法,构建了冰川水文调节指数(GlacierR),分析了9个寒区流域冰川径流变化的稳定性,详细剖析了历史时期(1971—2010年)和未来到21世纪末这些流域冰川水文调节功能的强弱变化。结果表明:历史时期及RCP2.6和RCP4.5情景下,除长江流域外,青藏高原其余流域的冰川径流减小时间节点为2020s,西北内陆河流域则为2010s。历史时期及RCP2.6和RCP4.5情景下至21世纪末,尽管西部寒区大部分流域的冰川径流呈减少趋势,但波动幅度减小或无明显变化,冰川径流稳定性增强或无变化。总体上,西北内陆河流域的冰川水文调节功能较高,青藏高原流域的冰川水文调节功能较低。RCP2.6和RCP4.5情景下,至21世纪末,西部寒区各流域冰川水文调节功能均呈现减弱趋势,西北内陆河流域减弱更加显著,如RCP4.5情景下,木扎提河冰川水文调节功能降幅达25.4%,而青藏高原各流域的冰川水文调节功能一直处于较低水平。从年代际变化来看,1970s—2010s是寒区流域冰川水文调节功能较强的时期,1980s和2000s两个时段冰川水文调节功能尤强;RCP2.6和RCP4.5情景下,未来到21世纪末,冰川调节功能明显减弱。减弱的时间节点不同,最早为1970s,最晚为2020s。

As a solid reservoir,glaciers play a significant role in regulating the variation of runoff abundance and dieback in the form of“peak-cutting and valley-filling”.The hydrological regulation function of glaciers is very important in cold regions,especially in the arid regions of Northwest China.The runoff estimation data from 2014 to 2100 were simulated by the VIC-CAS model in the cold region of western China.With perspec⁃tives of combinations of trend and fluctuation characteristics,glacier hydrological regulation index(GlacierR)was constructed based on the runoff variation coefficient method to analyze the stability of glacier runoff in 9 cold region basins of western China.The changes of the hydrological regulation function of glaciers in these ba⁃sins are analyzed in detail during the historical period(1971—2010)and in the future to the end of the 21st cen⁃tury.The results show that:In the historical period and under the RCP2.6 and RCP4.5 scenarios,except for the Yangtze River basin,the decrease time node of glacier runoff in other basins of the Tibetan Plateau is 2020s,and that in the northwest inland basins is 2010s.In historical period and under the global emission scenarios of RCP2.6 and RCP4.5 to the end of the 21st century,although the glacier runoff in most of cold region basins in western China showed a decreasing trend,the fluctuation range decreased or had no obvious change,and the sta⁃bility of glacier runoff increased or had no change.Overall,hydrological regulation function of glaciers is high in the northwest inland river basins,while function is low in the basins of the Qinghai-Tibet Plateau.Under the global emission scenarios of RCP2.6 and RCP4.5,to the end of the 21st century,the hydrological regulation function of glaciers showed a weakening trend in all cold region basins of western China,and the weakening was more significant in the inland river basins of Northwest China.Under the global emission scenario of RCP4.5,the hydrological regulation function of glaciers in the Muzati River decreased by 25.4%,and all the basins of the Qinghai-Tibet Plateau remained at a low level.With the perspective of decadal variation,the hydrological regu⁃lation function of glaciers in the cold region basins of western China was strong during the period of 1970s—2010s,especially in the 1980s and 2000s.Under the global emission scenarios of RCP2.6 and RCP4.5,the hy⁃drological function of glaciers showed a weakening trend obviously in the future to the end of 21st century.The earliest time node in the cold region basins is 1970s,and the latest is 2020s.