1986-2019年哈拉湖面积动态变化及其成因分析

Analysis of Dynamic Change and Causes of the Area of Hala Lake from 1986 to 2019

湖泊面积的动态监测不仅有利于分析区域气候变化的情景,而且还能为区域水资源评估等带来可靠的数据源。利用1986—2019年的多源卫星资料,提取了哈拉湖水体面积,并结合哈拉湖周边德令哈和托勒2个气象台站观测资料,对哈拉湖近36年湖泊年代际、年际及年内动态变化及其成因进行了分析。结果表明:1980s至2010s哈拉湖面积呈现先减小后增大趋势,其中20世纪90年代平均面积最小,2010年以来哈拉湖年平均面积最大;1986—2019年哈拉湖面积呈现先减小后增大的趋势,1986—2001年湖泊面积呈缓慢下降趋势,2002—2019年湖泊呈扩张趋势;从年内变化来看,近3年来,1—12月湖泊面积呈先减小后增大趋势,其中,2019年与前两年相比,湖泊面积除4月和12月与2018年大致相当外,其余各月面积均大于前两年,且近3年月面积最大和最小之间的差值分别为10.08、12.52 km 2;此外,哈拉湖湖岸线变化较明显的区域位于哈拉湖东南部和西南部。气象和冰川资料分析表明:1961—2018年哈拉湖地区气候呈增暖增湿趋势,气温上升速率为0.4℃/(10a)(R=0.296),降水增加速率为19.3 mm/(10a)(R=0.562,P<0.01)。气候的暖湿化与冰川面积的退缩共同导致了湖泊面积的扩张,但以降水作用为主。

The dynamic monitoring of lake area not only contributes to the analysis of regional climate change scenarios,but also provides reliable data sources for regional water resources assessment.Based on the multi-source satellite data from 1986 to 2019,this paper extracts the water area of Hala Lake,and analyzes the inter-decadal,inter-annual and annual dynamic changes and their causes of the Hala Lake in the last 36 years in combination with the observation data of Delingha and Tuole meteorological stations around Hala Lake.The results show that:The area of Hala Lake decreased first and then increased between 1980 s and 2010 s,among which the area decreased slowly from 1986 to 2001,and then expanded from 2002 to 2019.The average area is the smallest in 1990s and the largest since 2010.Within a year,the lake area first decreased and then increased in the past three years.The lake area in 2019 was larger than that in the previous two years,except in April and December when was about the same as that in 2018,and the difference between the maximum and minimum monthly area in the past three years was 10.08 km 2 and 12.52 km 2 respectively.The area with obvious changes in the shoreline is located in the southeast and southwest of the Hala lake.After the analysis of meteorological and glacier data,it indicates that the climate in the Hala Lake shows a warming and humidifying trend from 1961 to 2018,with the temperature rising rate of 0.4℃/(10a)(R=0.296),and the precipitation increasing rate of 19.3 mm/(10a)(R=0.562,P<0.01).Therefore,it can be concluded that the climate warming and humidifying and the reduction of glacier area together lead to the expansion of the lake area,which is mainly caused by precipitation.