Given their important roles in the regulation and storage functions for river flow and in the regional ecological environment and ecosystem services, natural lakes are essential for the ecological protection and high-quality development of the Yellow River Basin. We used the Landsat TM/OLI remote sensing data to analyze the area changes of Dongping Lake, Gyaring Lake, and Ngoring Lake, three representative large natural lakes in the Yellow River Basin from 1990 to 2020. We used the landscape ecology approach to study the morphological characteristics of lake shoreline and shoreland changes and the relationship between the landscape indices. The results showed that the main areas of Gyaring Lake and Ngoring Lake were mainly in the trend of expansion, while the main area of Dongping Lake significantly reduced during 1990-2000 and 2010-2020. The changes in the area of lake all occurred mainly near the lake inlet of the river. The shoreline morphology of Dongping Lake was more complex, with the fragmentation and aggregation of shoreland landscape significantly changed. The circularity ratio of Gyaring Lake gradually decreased with the expansion of the lake area, and the number of patches in its shoreland changed significantly. The fractal dimension index-mean of the shoreland of Ngoring Lake was relatively high, the complexity of its shoreline landscape was stronger, and the number of patches had increased significantly from 2000 to 2010. Meanwhile, there was a significant correlation between certain lake shoreline (shoreland) landscape indices. The changes in circularity ratio and shoreline development coefficient caused changes in the patch density of shoreland.
天然湖泊对黄河流域的河道流量具有重要的调蓄功能,对区域生态环境、生态系统服务具有重要作用,是黄河流域生态保护和高质量发展的重要保障。本研究采用Landsat TM/OLI遥感影像,研究了1990—2020年黄河流域内东平湖、扎陵湖、鄂陵湖3个具有代表性的大型天然湖泊的面积变化,并采用景观生态学方法,分析岸线、岸带的形态特征变化,以及各景观指标间的关系。结果表明: 扎陵湖和鄂陵湖的湖泊主体面积主要呈扩张趋势,而东平湖主体面积在1990—2000、2010—2020年间明显收缩,3个湖泊的面积变化均主要位于河流入湖口附近。东平湖岸线形态较复杂,其湖岸带景观的破碎程度和聚集程度发生显著变化;扎陵湖的岸线近圆率随着湖泊面积的扩张呈逐渐下降趋势,其湖岸带斑块数量变化明显;鄂陵湖的湖岸带景观分维数均值相对较高,其湖岸带景观的复杂性较强,并且2000—2010年间的湖岸斑块数量显著增长。同时,存在某些湖泊岸线及岸带景观指数显著相关的现象,湖泊近圆率、岸线发育系数的变化显著引起了岸带斑块密度的变化。.
Keywords: Yellow River Basin; lake area; lake morphology; lake shoreline; remote sensing monitoring.