Spatiotemporal Patterns of Evapotranspiration in Central Asia from 2000 to 2020

Abstract

Evapotranspiration (ET) affects the dry and wet conditions of a region, particularly in arid Central Asia, where changes in evapotranspiration profoundly influence society, the economy, and ecosystems. However, the changing trends in and driving factors of evapotranspiration in Central Asia remain unclear. Therefore, we used estimated ET and reanalysis data to answer research questions. Our results showed that (1) potential evapotranspiration (PET) and ET showed a generally downward trend, in which PET and ET decreased in 37.93% and 17.42% of the total area, respectively. However, PET and ET showed opposite trends in 59.41% of the study area, mainly showing a decrease in PET and an increase in ET. (2) The absolute contribution rates of vegetation–human activity coupling factor (VH), PET, and precipitation (P) to ET were 43.19%, 40.02%, and 16.79%, respectively, and the VH was the main determiner of ET. (3) Transpiration (ETc) dominated the change in ET in 56.4% of the region, whereas soil evaporation (ETs) dominated the change in ET in the rest of the region. The coverage threshold that determines the dominant contributions of ETc and ETs to ET was approximately 18–19%. Below this coverage threshold, the contribution rate of ETs to ET exceeded that of ETc and vice versa. In the context of global climate change, this study can provide scientific support for the restoration of water resources and sustainability evaluation of water resources.