Changes of lake areas and its response to the climatic factors in Tibetan Plateau since 2000

Abstract

Plenty of lakes in the Tibetan Plateau are sensitive to climate change and play an important role in the natural of water cycle and water balance. Using MODIS MOD09A1 and SRTM DEM as data sources, the lake boundary over 50 km2 in high flow period in the Tibetan Plateau are extracted from 2000 to 2016. The patterns and trends of lake area changes are analyzed in the respects of internal and external flow zoning, main sources of recharge, and the salinity of the lakes since 2000. Meanwhile, combining with meteorological data in Tibetan Plateau in recent 36 years, according to the meteorological elements zoning of change trend, the relationship between the lake area changes and the climatic factors is primary discussed in Tibetan Plateau. The main conclusions are as follows: 138 lakes more than 50 km2 are overall tend to expand significantly, with 2340.67 km2 increased in area and a growth rate of 235.52 km2/a. Among them, dilated lakes, shrinked lakes and stable lakes are accounted for 67.39%, 12.32% and 20.29%, respectively. The expansion trend of inflow lakes is significant, while the outflow lakes is less significant. Lakes with glacier water as the main source of recharge is expanded significantly, so do lakes with surface runoff and river recharge as main sources. Saline and semi-saline lakes also exhibit a trend of expansion. As for the freshwater lakes, the three types of expansion, atrophy, and stabilization are relatively balanced. The climate of the Tibetan Plateau presents a warmer and more humid tendency. Meanwhile, there are distinguished regional correlation between lake area changes and climate change. The results of change trend zoning of air temperature and precipitation indicate that the degree of lake expansion of Zone Ⅰ where air temperature and precipitation are increasing significantly is greater than that of Zone Ⅴ where air temperature decreases and precipitation increases. In turn, Zone Ⅱ with increasing air temperature and precipitation, Zone Ⅳ in which air temperature is decreasing and precipitation is increasing, and Zone Ⅲ with increasing air temperature and decreasing precipitation in Tibetan Plateau. The recharge of glacier melt water caused by air temperature rise has a significant effect on the expansion of lake area in Zone Ⅰ, Ⅱ, and Ⅲ. In addition, the rate of lake expansion is significantly increasing due to the increase of precipitation. The lake area expansion in Zone Ⅳ and Ⅴ is mainly affected by the increase of precipitation. On the whole, air temperature mainly affects lakes with glacier melt water as the main source of recharge and precipitation mainly affects lakes with precipitation and surface runoff as the main sources of recharge.