雅鲁藏布江流域水循环要素时空演变及径流驱动因素OA

[Objective]The better understanding of the water cycle evolution mechanisms in alpine river basins under changing environments provides a theoretical foundation for basin-scale water resources management.[Methods]The Yarlung Zangbo River basin was selected as the study area.Based on the multi-source data,including ground observations,remote sensing,and reanalysis,the spatiotemporal evolution characteristics of water cycle components from 1982 to 2015 were systematically analyzed from the perspective of basin water balance.The components included precipitation(P),runoff depth(R),evapotranspiration(ET),snow cover fraction(SC),snow depth(SD),and snow water equivalent(SWE).The dynamic variations of water balance across different periods and regions and their driving effects on runoff variations were quantitatively analyzed.[Results]Precipitation(P)in the basin showed an overall increasing trend.Variations in ET and R were generally consistent with P,but with distinct regional differences.The middle and western parts of the middle reaches responded markedly,whereas the upstream and eastern parts of the middle reaches responded more weakly.The annual average SC,SD,and SWE generally exhibited decreasing trends.By time period,during 1982-1998,P increased,but runoff and the runoff coefficient did not change significantly.The increased P mainly offset the rise in ET and snow consumption,maintaining a relatively balanced water cycle in the basin.During this period,the correlation coefficient between R and P exceeded 0.61,indicating that P was the main driving factor of runoff variations.After 1998,P decreased,and temperature increased.Both R and snow indicators(SC,SD,and SWE)generally decreased,accompanied by synchronous decreases in ET in the middle and western parts of the middle reaches.The runoff coefficient changed significantly,and the basin water balance underwent a marked alteration.The correlation between R and snow indicators strengthened,with the coefficient exceeding 0.4.[Conclusion]From the upper reaches to the eastern part of the middle reaches,as underlying surface conditions gradually become more complex,the effects of vegetation regulation and human activities intensify,reducing the contribution of P to runoff.Meanwhile,climate warming amplifies the influence of snow,and runoff formation shifts from a single precipitation-driven mechanism to the combined action of multiple factors.