黑河230 a以来3～6月径流的变化

利用祁连山中段树木年轮资料,重建了黑河230a来春季至夏初(3～6月)的径流变化,发现枯水年与历史记载的相对干旱时期比较吻合,证明了重建结果的可靠性.230a来黑河3～6月径流的变化振幅在各时段强弱不同:19世纪初之前丰枯变化振幅强,19世纪中后期至20世纪初变化幅度减弱,20世纪20年代以来,丰枯变化幅度又趋于增强.在过去的230a,黑河3～6月径流以丰水为主,目前正处于相对枯水阶段.奇异谱分析表明,230a来3～6月径流具有明显的24a和3a周期.

March to June Runoff of Heihe River since 1 770 Reconstructed from Tree-Ring Data

In this paper, the relationship between tree-ring of %Picea Crassifolia% in the middle section of the Qilian Mountains and runoff of the Heihe River is studied. Tree-ring width correlates most significantly to March to June runoff.Using well-replicated tree-ring data from %Picea crassifolia% in the Qilian Mountains, March to June runoff of the Heihe River has been reconstructed for the period from 1770 to 1995.Cross-verification testing of the reconstruction passes significance tests. Sign tests of the reconstructed series and the observed series are made, and product mean and error reduction are calculated, which prove that the reconstruction is reliable.The reconstructed March to June runoff shows that the Heihe River has experienced obvious high and low water periods, mainly in a high water state, since 1770. Now, it is in a low water period and seems to be lower and lower. Moreover, the low water periods are well corresponding to the recorded drought disasters periods. Periods of 24 and 3 a have been seen in the reconstructed runoff series since 1770.