基于小波分析的巴尔喀什湖水位变化特征及其影响因素

根据巴尔喀什湖年平均湖水位、伊犁河中下游径流以及流域气象数据,采用线性倾向率、小波时频分析等方法,研究了巴尔喀什湖1880-2016年平均水位变化特征及规律,针对湖泊水量平衡分析得出伊犁河下游径流量是控制湖水位变化的关键因子,通过交叉小波进一步分析了影响湖水位变化的各种气象因素。结果表明:①巴尔喀什湖水位在2002年左右发生了突变,并存在以83 a为中心尺度的主周期,该尺度下水位变化的平均周期为54 a左右,经历了3个丰枯转换时期,今后将逐步进入枯水期。②交叉小波分析表明,自然状态下降水是影响湖水位变化的主要原因;径流与气温的共振周期相位在20世纪80年代末发生了由负向正的转变,指示气温升高对湖水位的综合影响表现为由蒸发损耗转变为融水补给增加。③大气环流因子通过控制降水,从而影响研究区内入湖径流和湖水位变化,北大西洋涛动(NAO)相较南方涛动(SOI)与径流的关系更为紧密,对湖水位变化的影响较大。

A study of the water level variation of Lake Balkhash: Its influencing factors based on wavelet analysis

Based on the annual average lake level of the Lake Balkhash,runoff of Ili River,and the meteorological data in the basin,we analyzed the characteristics and regularity of the average water level change of Lake Balkhash from 1880 to 2016 by using the wavelet time-frequency analysis method. Water balance data showed that the runoff in the lower reaches of the Ili River is a key factor controlling variation in the lake level. Cross-wavelet analysis was applied to further analyze the relationship between the lake level changes and the main meteorological factors. The results suggested that the main cycle for 83 a is the central scale,with an average period of lake level change for 54 a. The lake level has experienced three transitions in water abundance and dryness since 1880,and it will gradually enter the next dry season in the future. The cross-wavelet analysis revealed that precipitation is the main driver of lake level change under natural conditions. In addition,the transition of the resonance cycle phase between temperature and runoff in the late 1980 s indicates that the increasing meltwater supply due to rising temperature results in the recovery of lake level,instead of a negative effect of evaporation loss. The variation in runoff and lake level can be influenced by atmospheric circulation in the region through its control on precipitation. The relationship of cross-wavelet analysis between NAO and runoff is more closely related than SOI,which plays a more important role in lake level changes.