Dynamics of lake area on the Qinghai-Tibet plateau from 2000 to 2015
The distribution of lakes in space and its change over time are closely related to many environmental and ecological issues, and are important factors that must be considered in human socio-economic development. In this paper, the water detection method is utilized to derive monthly water bodies, and then a seed set expansion approach was explored to extract lakes larger than 0.1 km2. Since lakes number and size can effectively reflect the distribution characteristics of water bodies, their change of the number, area and distribution are analyzed. The results shows there is a prominent power exponent relation between lake size and lake number for the Qinghai-Tibet plateau (QTP), which is similar to existing analysis of global scale. The number density of medium size of lakes on the QTP is higher than other types of lakes. The number of lakes displayed a decreasing trend from 2000 to 2015 with the R2 of 0.41. There was an increasing trend with an increasing rate of 356.86 km2/year (0.72%). Specifically, 46.54% of lakes area are increasing, and mostly distributed in Alpine grassland and shrub woodlands zone of the central Tibetan plateau. Shrinking lakes mostly with the area less than 10 km2 are situated on the woodland and shrub and grass areas in south-eastern Tibet. Finally, the analysis of monthly lake area of four lakes at the source of the Yellow River demonstrates the lakes area of each month from June to September witness an increasing trend, and the largest increasing rate is on June, which has a strong seasonality.