The Partitioning of Catchment Evapotranspiration Fluxes as Revealed by Stable Isotope Signals in the Alpine Inland River Basin

Abstract

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.

Stable isotopes and remote sensing techniques reveal changes in water surplus and loss in alpine inland river basins

“…The Shaliu River basin (37 10'55.92 00 -37 51'2.16 00 N, 99 37'10.20 00 -100 17'9.96 00 E) is located at the north of Qinghai Lake in the northeastern of QTP. Its area of catchment is 1679.2 km 2 (Figure 1) (Wang, Cao, et al, 2022a). The basin has a growing season from May to September, when its average temperature is about 2-8 C, and an average temperature of about 10-11.5 C in July.…”

“…It was calculated by the Craig-Gordon model. The calculation equation was as follows (Guo et al, 2017;Wang, Cao, et al, 2022a):…”

“…The E soil :T ratio was calculated using vegetation cover area and bare soil area (Guo et al, 2017;Wang, Cao, et al, 2022a):…”

“…(Fan et al, 2021; Ma et al, 2018; Wang, et al, 2022). The Shaliu River is the second largest river in the Qinghai Lake Basin (Wang, Cao, et al, 2022a; 2022b). The Shaliu River basin is relatively enclosed and is a typical alpine inland river basin.…”

“…The Shaliu River basin is relatively enclosed and is a typical alpine inland river basin. Its water cycle process is greatly representative, which is an ideal area for studying water resources changes in alpine inland river basins (Wang, Cao, et al, 2022a; 2022b).…”