Global evapotranspiration from high-elevation mountains has decreased significantly at a rate of 3.923 %/a over the last 22 years

Yunying Wang; Zongxing Li; Qi Feng; Lanping Si; Juan Gui; Qiao Cui; Yue Zhao; Chong Xu

doi:10.1016/j.scitotenv.2024.172804

Global evapotranspiration from high-elevation mountains has decreased significantly at a rate of 3.923 %/a over the last 22 years

Sci Total Environ. 2024 Apr 26:931:172804. doi: 10.1016/j.scitotenv.2024.172804. Online ahead of print.

Authors

Yunying Wang¹, Zongxing Li², Qi Feng³, Lanping Si¹, Juan Gui¹, Qiao Cui¹, Yue Zhao¹, Chong Xu⁴

Affiliations

¹ Observation and Research Station of Eco-Hydrology and National Park by Stable Isotope Tracing in Alpine region/ Gansu Qilian Mountains Ecology Research Center/ Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² Observation and Research Station of Eco-Hydrology and National Park by Stable Isotope Tracing in Alpine region/ Gansu Qilian Mountains Ecology Research Center/ Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China. Electronic address: lizxhhs@163.com.
³ Observation and Research Station of Eco-Hydrology and National Park by Stable Isotope Tracing in Alpine region/ Gansu Qilian Mountains Ecology Research Center/ Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁴ School of Environment and Municipal Engineering, Lanzhou Jiao Tong University, Lanzhou 730070, China.

PMID: 38679095
DOI: 10.1016/j.scitotenv.2024.172804

Abstract

Clarifying the responses of human activities and climate change to the water cycle under variable environments is crucial for accurately assessing regional water balance. An analysis of the changes in actual evapotranspiration and its driving factors was conducted in the global high-elevation mountains during the period from 2001 to 2022. Utilizing 18 formulas for calculating evapotranspiration, which are based on comprehensive, temperature, radiation, and mass transfer, and then simulated the variations in reference evapotranspiration. Furthermore, we optimized the ET simulation model based on the most effective simulation results and projected future changes using scenario simulation data. Our findings reveal that: 1) ET at high-elevation mountains has significantly decreased at an average rate of 3.923 %/a, with monthly values ranging from 31.179 to 33.652 mm and an average of 32.646 mm; 2) The radiation-based model of Irmark-Allen is particularly well-suited for simulating ET at high-elevation mountains, with precision analysis and the Taylor diagram confirming its superior simulation performance. After optimizing the model using the method of least squares, the value of R² before and after the optimization were 0.633 and 0.853, respectively. 3) An upward trend in ET under both SSP245 and SSP585 scenario in future simulation projections. Attribution analysis has identified Vapor Pressure Deficit as the key positive driver influencing the change of ET in global high-elevation mountains. Structural equation modeling further reveals that variations in net radiation and precipitation play a significant role in altering evapotranspiration rates. Meanwhile，The water balance analysis reveals that ET has been declining from 2001 to 2022. This phenomenon can be largely attributed to the substantial decline in vapor pressure deficit, the rise in the Normalized Difference Vegetation Index signifying increased vegetation cover, and the reduction in shallow soil moisture during the same period. These factors collectively explain the notable decrease in ET observed in high-elevation mountains.

Keywords: Evapotranspiration; High-elevation mountains; Modeling; The change of environmental; Water balance.