黄河源区气候向暖湿转变的观测事实及其水文响应

基于黄河河源区干流各水文站和有关气象站、雨量站的气温、降水与径流观测资料, 分析了该区域的气候变化特征与趋势及其水文响应. 结果表明: 在全球变暖的大背景下, 自20世纪80年代后期开始西北地区西部新疆、甘肃河西走廊西部等地降水量显著增加、气候明显由"暖干"转向"暖湿"后, 到21世纪初的年代中期后黄河源区降水量亦出现明显的增长, 气候明显转向暖湿. 最新的观测数据显示, 2005年以来河源区平均年降水量已连续多年超过多年均值进入一个多雨期, 河源区各断面来水量也于2008年后连续多年超过多年均值, 进入一个连续丰水段, 并于2012年达到了自1989年以后20余年来的最大值. 这种变化的前景如何, 目前尚不能确定, 尚需对未来河源区气候在时间与空间上变化的速度和程度进一步观察和分析. 根据对与该区域气候关系密切的东亚季风活动的研究成果以及对河源区气候与径流变化的观测事实及趋势推测, 未来黄河源区气候向暖湿的转化在时间尺度上年代际的可能性较大.

The Fact of Climate Shift to Warm-Humid in the Source Regions of the Yellow River and Its Hydrologic Response

The changing characteristics and trends of regional climate in the source regions of the Yellow River and the response of runoff to climate change are analyzed based on the observational data of air temperature, precipitation and runoff at some hydrologic stations and precipitation stations, as well as some weather stations. The results show that after a strong climate shift from warm-dry to warm-humid in the west of Northwest China, such as Xinjiang and western Hexi Corridor of Gansu in the late 1980s, a similar climate change has occurred since the mid-2000s in the source regions of the Yellow River, which is located in the east of Northwest China. The background is global warming, and the climate change leads to precipitation and runoff increasing in the regions. The new observational data of precipitation and runoff in the regions display that the average annual precipitation in the source regions of the Yellow River has exceeded the long-time average value in most years since 2004, and then the runoffs through all hydrologic sections on the main stream of the Yellow River have also increased incessantly, exceeding the long-term average, since 2008. However, it is difficult to determine the prospects of climate change. It is necessary to do further research and observation on the rate and extent of the climate change in time and space in the regions. It is very possible that the climate shift from warm-dry to warm-humid in the source regions of the Yellow River in the decadal time scale, which is expected from the analysis and forecast of the activity of the East Asian monsoon and from the observed stream runoff change.