基于青藏高原冰芯记录的长江源区径流重建

近几十年来长江源区河川径流条件发生了较大变化,研究全球变暖背景下长江源区径流变化特征对于认识气候变化引起的水文效应具有重要的现实意义。利用沱沱河水文站和气象站1960—2019年实测水文气象数据,分析径流演变规律及其与降水、气温、蒸发等气象因素间的关系。采用青藏高原5根冰芯δ¹⁸O记录与冰芯积累量,分析了不同冰芯间δ¹⁸O记录、冰芯积累量之间的关系,以及冰芯记录与沱沱河径流之间的相关性。在此基础上重建沱沱河水文站1900—1960年10 a滑动平均径流系列,并初步分析100多年来沱沱河径流的丰枯变化规律。研究结果表明,沱沱河水文站年径流在2002年前后发生显著增加的趋势,长江源区气温急剧上升导致的冰川和积雪融水增多是长江源区流量急剧增加的重要原因之一。重建沱沱河1900年以来径流系列表明,长江源区经历了多次的丰枯交替变化,径流变化规律与青藏高原3次气候突变时间点基本吻合。研究结果对揭示气候变化条件下长江源区河川径流演变规律及其水文响应提供了参考。

Runoff Reconstruction in the Source Region of Yangtze River Based on Ice Core Records on the Tibetan Plateau

Runoff in the source region of the Yangtze River has undergone great changes in recent decades.It is of great practical significance to study the characteristics of runoff variation under the background of global warming for understanding the hydrological effects caused by climate change.The evolution of runoff and its relationship with meteorological factors such as precipitation, temperature, and evaporation were analyzed based on measured hydro-meteorological data from 1960 to 2019 at Tuotuo River.The relationship between δ¹⁸O records and ice core accumulations among different ice cores, and the correlation between ice core records and runoff in Tuotuo River were examined.The 10-year moving average runoff series of the Tuotuo River from 1900 to 1960 was reconstructed, and the runoff variation of Tuotuo River over the past century was analyzed.Results revealed a siginificant increase trend of annual runoff of Tuotuo River around 2002.The increase in glaciers and snow melt induced by the sharp rise in temperature is an important cause for the sharp increase in flow rate in the source region of the Yangtze River.The reconstruction of the runoff series of Tuotuo River since 1900 demonstrated that the source area of the Yangtze River had experienced many alternating dry-wet changes, and the runoff variation rules are in general consistent with the three abrupt climate changes in the Tibetan Plateau.The research findings provided a basis for revealing the evolution law and hydrological response of river runoff in the source region of the Yangtze River under climate change.