1960—2018年博斯腾湖水位变化特征及其影响因素分析

结合博斯腾湖1960—2018年水位、出入湖径流以及气象站点实测资料,采用集合经验模态分解(Ensem?ble Empirical Mode Decomposition,EEMD)、水量平衡和气候弹性方法,对近60 a博斯腾湖水位变化及其影响因素进行了详细分析。结果表明:(1)1960—2018年博斯腾湖水位总体呈下降态势,具体表现为“下降-上升-下降-上升”四个阶段。(2)在年际尺度上水位存在准3~4 a、准8~9 a的周期性振荡,而年代际尺度上表现出准29~30 a和准33~34 a的周期性变化。(3)1960—2018年降水、气温和潜在蒸散发对开都河、黄水沟和焉耆径流的累积贡献率分别达85.1%、42.1%和23.8%,而下垫面、其他气象变量和人为等因素累积对径流的贡献率分别约为14.9%、57.9%和76.2%。(4)对不同阶段博斯腾湖水位变化原因分析:1960—1987年水位急剧下降的主要原因同入湖径流减少和湖面蒸发量大有关;气温升高和降水量增加导致入湖水量增加是1988—2002年水位显著升高的主要原因;入湖径流减少和出湖水量增多,导致2003—2014年水位显著下降;博斯腾湖入湖水量的显著增加及对出湖水量的严格控制是2015—2018年水位明显上升的主要原因。

Analysis of the change in water level and its influencing factors on Bosten Lake from 1960 to 2018

Using measurements of the water level and runoff into the lake as well as data from meteorological stations of Bosten Lake from 1960 to 2018,this paper provides a detailed analysis of the trend in water level change based on ensemble empirical mode decompsition and the water balance model.In addition,this paper uses the climate elasticity method to explore the response of the water level to hydroclimatic factors in different time periods,and then analyzes the complex response of the lake water level to climate change and human activities.The results revealed the following:(1)The lake level shows a significant decreasing trend from 1960 to 2018,which is shown in the four periods as“descending-rising-descending-rising”.(2)Ensemble empirical mode decomposition analysis results show that the water level of Bosten Lake has periodic oscillations of 3-4 a and 8-9 a on the interannual scale,and 29-30 a and 33-34 a on the interdecadal scale.(3)The contributions of precipitation,temperature,and potential evapotranspiration to runoff to the Kaidu River,Huangshui River,and Yanqi Basin from 1960 to 2018 were approximately 85.1%,42.1%,and 23.8%,respectively.Other factors contributed approximately 14.9%,57.9%,and 76.2%to the runoff.(4)The prime reason for the decline in water level in Bosten Lake from 1960 to 1987 was the decrease in runoff into the lake and substantial evaporation of the lake surface.Increase in lake water intake due to the climate change was the main cause of rise in water level from 1988 to 2002.The decrease in runoff into the lake and increase in the amount of lake water are responsible factors for the decreased water level from 2003 to 2014.An increase in lake water intake and strict controls on discharge from 2015 to 2018 were the major reasons for the rising water level in Bosten Lake.