Discriminating the impacts of vegetation greening and climate change on the changes in evapotranspiration and transpiration fraction over the Yellow River Basin

Yangyang Liu; Ziqi Lin; Zijun Wang; Xu Chen; Peidong Han; Bo Wang; Zhenqian Wang; Zhongming Wen; Haijing Shi; Zhixin Zhang; Wei Zhang

doi:10.1016/j.scitotenv.2023.166926

Discriminating the impacts of vegetation greening and climate change on the changes in evapotranspiration and transpiration fraction over the Yellow River Basin

Sci Total Environ. 2023 Dec 15:904:166926. doi: 10.1016/j.scitotenv.2023.166926. Epub 2023 Sep 7.

Authors

Yangyang Liu¹, Ziqi Lin¹, Zijun Wang², Xu Chen³, Peidong Han¹, Bo Wang⁴, Zhenqian Wang⁵, Zhongming Wen¹, Haijing Shi⁶, Zhixin Zhang¹, Wei Zhang⁷

Affiliations

¹ College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China.
² College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
³ College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
⁴ Xi'an Center of Mineral Resources Survey, China Geological Survey, Xi'an, Shanxi 710100, China.
⁵ Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
⁶ State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China.
⁷ College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China. Electronic address: zwgwyd@163.com.

PMID: 37689185
DOI: 10.1016/j.scitotenv.2023.166926

Abstract

Evapotranspiration (ET) is a vital parameter in terrestrial water-energy cycles. The transpiration fraction (TF) is defined as the ratio of transpiration (T) to evapotranspiration (ET), representing the contribution rate of vegetation transpiration to ecosystem ET. Quantifying the relative contributions of vegetation and climate change on the ET and TF dynamic is of great significance to better understand the water budget between the land and atmosphere. Here, we chose Yellow River Basin (YRB) as the study area and analyzed the spatiotemporal changes of ET, T, and TF from 1982 to 2015 using the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model. Meanwhile, the relative contributions of vegetation and climate change to ET, T and TF change were quantified. Model evaluation showed that the PT-JPL model performs well in the simulation of ET and T. During 1982-2015, the average annual ET, T, and TF increased at a rate of 3.20 mm/a, 0.77 mm/a and 0.003/a over the YRB during 1982-2015, respectively. The regions with significant increases in ET, T and TF almost covered the whole study area except for the upper reaches of the YRB. Vegetation greening was the main factor for the increase of ET and TF in the YRB and enhanced ET and TF at a rate of 0.72 mm/a and 0.57/a, respectively, which mainly observed in the entire Loess Plateau region (over 50 % of the study area). Precipitation (PRE) was also the dominated factor contributing to the increase in ET and TF, and temperature (TEM) showed a positive correlation with the changes in ET and TF in the most areas of YRB, which jointly dominated ET changes in the upper reaches of the YRB and TF changes in the southern part of the basin. Except for the total effects, leaf area index (LAI) also indirectly promoted ET changes by affecting PRE, TEM and relative humidity (RH). While wind speed (WS) and radiation (RAD) had a relatively weak regulatory effect on the changes in ET and TF. These findings were helpful for regional water resources management and formulating water resources-sustainable vegetation restoration strategies for local government.

Keywords: Climate change; Evapotranspiration (ET); Transpiration fraction (TF); Vegetation greening; Yellow River Basin.