Changes of lakes and ponds in the Three Rivers Source Region and their links to permafrost
In recent years,the rapid expansion of lakes on the Tibetan Plateau has attracted widespread attention,and a number of studies have systematically analyzed the dynamics of changes in large lakes with areas greater than 1 km2.However,the distribution and changes of smaller lakes and ponds formed due to permafrost degradation at the watershed scale have not yet been clarified.In this study,using optical and radar images,we systematically investigated the distribution and changes of lakes and ponds(＜1 km2)in the Three Rivers Source Region and their relationship with permafrost degradation,and for the first time examined the distribution of taliks at the bottom of the lakes and ponds.The results show that:1)The total area of lakes and ponds in the Three Rivers Source Region in the 2020s(2020-2022)amounted to 917.03 km2,and the total number of lakes and ponds was 61608.The Yangtze River source area had the highest number of lakes and ponds,reaching 48987,followed by the Yellow River source area with 12459,and the Lancang River source area had the smallest number of lakes and ponds.2)Compared with the 1960s,the number of lakes and ponds smaller than 1 km2 in the Three Rivers Source Region increased by 76％in the 2020s,and the total area increased by 13％.Although the expansion of lakes and ponds in the Yangtze River source area was obvious,some lakes and ponds in the Yellow River source area and the Lancang River source area experienced shrinkage.Of the lakes and ponds observed in the 1960s,53％still existed in the 2020s.3)Of the lakes and ponds in the Three Rivers Source Region,80.9％have taliks at their bottoms in winter,including 78.2％in the Yangtze River source area,90.8％in the Yellow River source area,and 98.7％in the Lancang River source area.In the permafrost zone,half of the lakes and ponds with taliks at their bottoms existed in the 1960s,and fewer new lakes and ponds have taliks at their bottoms in winter.Currently,the extent of floating-ice lakes and ponds is much larger than the extent of grounded-ice lakes and ponds,which may further accelerate the thawing of the underlying permafrost.The findings of this study can provide a basis for analyzing the state of permafrost degradation and contribute to understanding the links between permafrost degradation and the development of thermokarst lakes and ponds,as well as serve as basic data for the study of carbon emissions from thermokarst lakes and ponds in the plateau region.
thermokarst lakes and pondsspatial and temporal distributionpermafrost degradationThree Rivers Source Regiontaliks at the bottom of lakes and ponds
万方数据
维普
