基于高分1号卫星数据的青海湖扩张及湖滨沙地变化特征分析

Analysis of Qinghai Lake expansion and lakeside sandy land change characteristics based on GF-1 satellite

基于多源卫星数据和气象站点资料,分析了2013—2020年青海湖面积、湖滨沙地面积、沙区植被覆盖度动态变化特征,结合流域气候环境变化讨论了影响湖泊及周边沙地演变的因素。结果表明:(1)青海湖持续扩张,2017年以来布哈河入湖口、沙柳河入湖口、沙岛、鸟岛、泉湾等区域扩张明显;尕海与主体湖协同一致变化,但扩张速率小于主体湖。(2)湖泊扩张导致曲折低洼处、湖滨沙地和沙堤被淹没,其中鸟岛沙区已被完全淹没,岸线长度呈现波动缩减趋势,2017年以后岸线缩减明显。(3)沙区植被总体呈现覆盖度偏低、分布不均匀、空间聚集、年际间波动变化明显、稳定性不足等特征。(4)青海湖流域总体呈现气候暖湿化、积雪面积增大、积雪日数增多、冰川退缩、季节冻土年最大深度减小的态势。(5)流域降水增多,积雪季积雪面积增大,积雪日数增多等补给入湖河流,与湖泊面积变化呈极显著相关(P<0.01);气温升高、季节性冻土退化、冰川退缩,间接影响流域水资源分配。区域暖湿化气候背景下,湖泊扩张对区域生境的改善值得关注,也为干旱区沙区生态修复工程创造了良好的契机,青海湖扩张已对鸟类栖息地和周边基础设施产生一定影响,需进一步注意防范区域潜在生态风险。

In the context of climate change, the ecological environment of the Qinghai-Tibet Plateau has undergone a series of changes, including the increase in the lake area. As the largest inland plateau saltwater lake in China,Qinghai Lake is located in the Northeast of the Qinghai-Tibet Plateau and is an important part of the“Asian water tower.”Since 2005, Qinghai Lake has demonstrated area expansion. Therefore, understanding the causes of changes in Qinghai Lake and the impact of such changes on the surrounding environment(such as lakeside sandy) is crucial. Based on multisource satellite and meteorological station data, combined with the snow cover,glacier, permafrost, and meteorological data in the basin, this paper analyzed the dynamic change characteristics of the lake area, lakeside sand area, and sand vegetation coverage in Qinghai from 2013 to 2020. The following results are presented.(1) Qinghai Lake continued to expand in recent years, especially after 2017. The expansion affected the areas of Buha River entering the lake, Shaliu River entering the lake, Sand Island, Bird Island, and Spring Bay. The interannual fluctuation and expansion trend of the Gahai sublake affiliated to Qinghai Lake is consistent with that of the main lake, and its expansion rate is lower than that of the main lake.(2) The expansion of the lake led to the extensive inundation of the zigzagging low-lying areas, and the shoreline length showed a trend of fluctuating reduction, especially after 2017. The shoreline significantly decreased mainly due to the inundation of the lake in the lakeside sandy land and sand dike, leading to a fluctuating reduction trend in the area of the lakeside sand area;among which, the Bird Island sand area was completely submerged.(3) The vegetation in the sand region is characterized by low coverage, uneven distribution, spatial aggregation, obvious interannual fluctuation, and insufficient stability.(4) The Qinghai Lake basin presents a trend of warm and humid climate,increasing snow cover area and snow cover days, glacier retreat, and shallow maximum frozen soil depth.(5) The precipitation in the basin increased, and the snow cover area increased in winter. The increase in snow cover days affected lakes and rivers, which was significantly correlated with the change in lake area(P < 0.01). Temperature rise, seasonally frozen ground degradation, and glacier retreat indirectly affect water resource allocation in the basin and have an impact on the inflow of Qinghai Lake. The method and extent of the impact of frozen soil on the lake need further study.(6) The regional warm and humid climate background has created a good opportunity for ecological restoration projects in arid sand areas. Meanwhile, the expansion of Qinghai Lake has had a certain impact on bird habitats and surrounding infrastructure. However, focusing on the prevention of regional potential ecological risks is still necessary.