The Temporal-Spatial Variation and the Cause Analysis of the Thermokarst Lakes Along the Qinghai-Tibet Highway in Recent 30 Years

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As the climate changed, the Qinghai-Tibetan Plateau (QTP) has been experiencing rapid permafrost degradation in the past decades. One of the most remarkable characteristics is the formation of thermokarst lakes. Based on the Google Earth Engine platform (GEE), the distribution of thermokarst lakes along the Qinghai-Tibet Highway (QTH) in recent 30 years (1991-2020) are examined, and the environmental factors affecting the distribution of thermokarst lakes are investigated, combined with field monitoring and Landsat data. Both the number and area of thermokarst lakes along QTH show a trend of decreasing - increasing - rapidly increasing - decreasing. The area of thermokarst lakes increased from 107.14 km² in 1991 to 184.92 km² in 2020. In 2018, the density of thermokarst lakes along the Qinghai-Tibet Highway was 14.4 /100km², which is generally high over QTP. The changes in the number and area of the thermokarst lakes on the QTP were significantly positively correlated with the annual mean temperature (p <0.05), while weakly positively correlated with the annual mean precipitation, indicating that the number and area variations of the thermokarst lakes on the QTP were strongly affected by temperature than precipitation. The study on QTP thermokarst lakes provides an investigation of the impact of climate change on the ecology and environment of permafrost regions, background research for the construction of QTH, and further serve the construction of ecological safety barrier in China.