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Alpine wetland ecosystems play significant roles in water regulation and regional ecological safety on the Qinghai-Tibet Plateau due to large water conservation potential. The knowledge of evapotranspiration (ET) in various alpine wetland ecosystems is of great significance for understanding the water balance of wetland ecosystems and carrying out eco-environment conservation. Therefore, two alpine wetland ecosystems as lakeside and headwater of Qinghai Lake basin were selected, and their ET characteristics and influencing factors were researched over two years. The daily ET in the lakeside ecosystem showed 'double peak' curve, and the headwater ecosystem showed the 'multiple peak' ET curve. The monthly ETs in two respective wetlands ranged from 9.88 to 111.56 mm and from 0.23 to 75.5 mm, respectively. The annual ET in the lakeside ecosystem was averagely 1.89 times more than that of the headwater. Stepwise multiple linear regressions indicated that monthly average net radiation (R n) and leaf area index (LAI) explained 96% variance in monthly ET in the lakeside ecosystem; R n and monthly average wind speed (WS) explained 94% variance in monthly ET in the headwater ecosystem. These results indicated that the ET is variable in two alpine wetland ecosystems and R n was their primary driving factor on monthly scale. [ABSTRACT FROM AUTHOR]

Evapotranspiration is an important process in the water budget of an ecosystem. Quantifying the components of evapotranspiration is of great significance in revealing the ecohydrological process of alpine inland river basins. In this study, the evapotranspiration fluxes in the Shaliu River basin were classified by hydrogen and oxygen stable isotope technology and remote sensing technology. The results showed the following: (1) The average value of soil fractional evaporation (E1) in the summer of 2018 and 2019 was 7.59 mm and 2.10 mm, respectively. (2) The average ratio of soil evaporation (Esoil) in the summer of 2018 was 48.82%, 68.11%, 54.99%, respectively. The average ratio of Esoil in the summer of 2019 was 66.86%, 57.50%, 55.53%, respectively. The average value of Esoil in the summer of 2018 and 2019 was 42.84 mm and 35.36 mm, respectively. (3) The average ratio of vegetation transpiration (T) in the summer of 2018 was 51.18%, 31.89%, and 45.01%, respectively. The average ratio of T in the summer of 2019 was 33.14%, 42.50%, and 44.47%, respectively. The average value of T in the summer of 2018 and 2019 was 32.59 mm and 26.23 mm, respectively. Obviously, the soil fractionation was stronger in the summer of 2018 than that in the summer of 2019. At the same time, both soil evaporation and plant transpiration in summer 2018 were higher than those in summer 2019, and soil evaporation in the Shaliu River basin was greater than plant transpiration in summer during the study period. The results of this study can provide data reference for mastering the eco-hydrological process of the Shaliu River basin. [ABSTRACT FROM AUTHOR]

As the "Asian Water Tower", understanding the hydrological cycles in Qinghai Province and its interior is critical to the security of terrestrial ecosystems. Based on Moderate Resolution Imaging Spectroradiometer (MODIS)16 evapotranspiration (ET) remote sensing data, we used least squares regression, correlation analysis, and t-test to determine the temporal and spatial changes and trends of ET in Qinghai Province and its five ecological functional regions, located on the Qinghai–Tibet Plateau (Plateau) Western China from 2000 to 2020. In addition, we discussed the main factors affecting the changes of ET in different regions of Qinghai Province over the first two decades of the 21st century along spatial as well as altitudinal gradients. The results showed that: (1) the average annual ET in Qinghai Province was 496.56 mm/a, the highest ET value appeared in the southeast of the study area (684.08 mm/a), and the lowest ET value appeared in the Qaidam region in the northwest (110.49 mm/a); (2) the annual ET showed an increasing trend with a rate of 3.71 mm/a (p < 0.01), the place where ET decreased most was in the Three-River Source region (−8–0 mm/a) in the southwest of the study area, and the ET increased the most in the Hehuang region in the east of the study area (9–34 mm/a); (3) temperature (T) was the dominant ET change factor in Qinghai Province, accounting for about 65.27% of the region, followed by the normalized difference vegetation index (NDVI) and precipitation (P) for 62.52% and 55.41%, respectively; and (4) ET increased significantly by 2.84 mm/100 m with increasing altitude. The dominant factors changed from P to NDVI and T as the altitude increased. The research is of practical value for gaining insight into the regional water cycle process on the Plateau under climate change. [ABSTRACT FROM AUTHOR]