Spatiotemporal analysis of water area annual variations using a Landsat time series: a case study of nine plateau lakes in Yunnan province, China

Lakes are sensitive to both climate change and human activities, and therefore serve as an excellent indicator of environmental change. Based on a time series of Landsat images over the last 16 years, this article attempts to provide a first picture of the annual variations in area of nine plateau lakes in Yunnan province, China. The modified normalized difference water index (MNDWI) and object-based image analysis (OBIA) are used to extract the waterbodies. Compared with the visual interpretation (VI) of the lakes, the precision of the combined method is greater than 99.7%. A spatiotemporal analysis is also carried out for the lakes. The results show that the water areas of most of the plateau lakes have been stable over the last 16 years, although some years have shown significant changes. However, it should be noted that Lake Qilu and Lake Yilong shrunk significantly after 2011. Moreover, the orientation of the shrinkage is different. Limited evidence suggests that the differences in the area change of the nine plateau lakes are caused by both climate change and human activities.