黄河源区径流波动变化对气候要素的响应特征

黄河源区径流属典型的寒区径流,降水、冰雪冻土融水等共同成为径流量的补给来源,径流量的变化同时受到区域内降水量和气温变化的影响。采用互谱分析方法研究表明,黄河源区降水与径流周期波动间的关系明显好于气温与径流之间的关系,降水对径流量的主要周期波动变化有较明显的控制作用。气温虽然对径流量的部分周期波动变化有一定的影响,但明显不如降水的影响。黄河源区径流量的波动变化对区域内生态环境有显著的影响,1980年代后期以来径流大幅下降使与河流水体相连并进行水量交换的湖泊、沼泽湿地疏干退化,生态环境明显恶化。

Analysis on the Runoff Change and its Response to the Climatic Factors at the Source Regions of Yellow River

Runoff at the source regions of Yellow River were feed mostly by precipitation and the melt-water from glaciers,snow and frozen earth.Change of the temperature and its impact on the ablation of the glaciers and snow influencedthe runoffdirectly and was as important as the precipitation.We analyzed how the runoff changes respond to the temperature and precipitation's fluctuationby means of cross-spectral analysis.By the cross-amplitude function(CAF) and the simple-density spectrum,we calculated some new function such as coherence function、gain function and phase spectrum function.Result indicated that the runoff's fluctuation influenced much by the precipitation.However,temperature influencedthe fluctuation of the runoff slightly and couldn't compare with precipitation.Runoff at the source regions of Yellow River declined much more since late 1980's,which arosethe shrink of the lakes,swamp and frozen earth and the worsenof the environment either.