1970−2021年阿尔金山国家级自然保护区湖泊面积变化研究

Lake area variations in the Altun Mountain National Nature Reserve 1970-2021

以阿尔金山国家级自然保护区内湖泊为研究对象,通过对大比例尺地形图和中高分辨率遥感影像的配准和目视解译,并结合保护区周边4个气象站1970−2021年气温、降水、蒸散量数据,系统分析了区内面积>1 km2湖泊的面积变化及其对气候因子的响应.结果表明:1)近51 a保护区的湖泊呈现扩张、稳定和萎缩3种变化趋势,但大部分湖泊处于扩张状态.其中:大型湖泊均呈扩张之势,并以20世纪90年代中期为节点,前期扩展缓慢,后期出现明显扩展增速;中型湖泊面积变化呈现扩张、稳定和萎缩3种趋势;小型湖泊面积变化呈现扩张和萎缩2种趋势;湖泊面积的变化趋势与湖泊自身的规模无关,只与其补给和支出平衡有关.2)沙子湖、小沙子湖是部分河段被沙埋的流经湖,多年湖面积变化较小,湖泊周围沙丘未出现大范围朝湖向移动.3)保护区湖泊的面积与气温和降水呈正相关,与蒸发量呈显著负相关,气温和降水对湖泊面积的影响大于蒸发.保护区内湖泊属降雨和冰川融水补给型湖泊,且冰川融水的补给量大于降水.研究结果有助于了解该地区气候变化控制下水资源演变过程,可作为进一步评估区域气候变化和湖泊变化的依据.

Lakes in the Qinghai-Xizang Plateau are very sensitive to climate changes and play an important role in regional water cycle and ecological environment balance.Area variations of 10 lakes greater than 1 km2 in the Altun Mountain National Nature Reserve from 1970 to 2021 were investigated.Lake areas were extracted from largescale topographic maps and remote sensing images of QuickBird and Landsat.The relationships of lake area and annual air temperature,precipitation and evaporation of four meteorological stations around the reserve were analyzed.The lakes in the reserve have shown three trends:expansion,stability,and shrinkage in the past 51 years,but most expanded.Large lakes are showing a trend of expansion,with the mid-1990s as the node.In the early stage,expansion was slow,but in later stages,significant rate of expansion was found.Variations in the area of mediumsized lakes show three trends:expansion,stability,and shrinkage.Two trends prevail for small lakes expansion and contraction.The trend of variations in lake area is not related to the size of the lake,but to balance of supply and expenditure.Shazi Lake and Xiaoshazi Lake have some river sections buried under sand.The lake area has changed relatively little over the years,indicating no large-scale movement of sand dunes towards the lake.The area of lakes in the reserve is positively correlated with temperature and precipitation,and significantly negatively correlated with evaporation.The lakes within the reserve are replenished by both rainfall and glacier meltwater,but the amount of glacier meltwater replenishment is greater than precipitation.The impact of temperature and precipitation on the area of expanding lakes is greater than evaporation.These results are helpful to understand the evolution of water resources controlled by climate change in the region,and can be used for further assessment of regional climate change and lake change.