Spatiotemporal dynamics and drivers of evapotranspiration in the Shule River Basin

TANG Wenjun; HUI Lei; SUN Dongyuan; LI Shizhu; WANG Xingfan; WU Lanzhen; CUI Yanqiang; MA Yali; SHU Heping

doi:10.13522/j.cnki.ggps.2025123

Abstract：[Objective]Evapotranspiration(ET)is a key process in water and energy cycles,influencing water availability,productivity,as well as water resource management in both natural and managed ecosystems.Understanding its spatiotemporal variation and driving factors can help in achieving sustainable water management.This paper analyzes the variation of ET and the underlying driving factors in the Shule River Basin in northwestern China.[Method]Using hydrological data measured from 1972 to 2022 at Panjiazhuang,Changmabao,and Dangchengwan stations,we analyzed the abrupt changes in ET and its underlying drivers using the Mann-Kendall trend test and the Budyko-based elasticity coefficient method,from which we further evaluated the contributions of precipitation,potential evapotranspiration(PET),and land surface changes to variations in ET.[Result]①From 1972 to 2022,annual ET,PET and actual ET at all three stations showed an increasing trend,with abrupt changes detected in 1979,1987 and 1988.During the baseline period,PET increased by 47.61 mm,164.46 mm and 42.95 mm at Panjiazhuang,Dangchengwan and Changmabao station.② Changes in annual ET varied among stations.At Panjiazhuang,PET increased by 1.28 mm/a while actual ET decreased by 0.13 mm/a;at Dangchengwan,PET increased by 0.05 mm/a and actual ET increased by 0.34 mm/a;at Changmabao,PET increased by 0.81 mm/a and actual ET increased by 0.66 mm/a.③ The contribution of precipitation,PET and land surface to the variations of ET at Changmabao,Panjiazhuang and Dangchengwan station was 37.62%,90.47%and 15.21%;15.14%,19.91%and 33.83%;and 77.52%,210.38%and 149.04%,respectively.ET was most sensitive to land surface changes and least to PET,with precipitation in between.[Conclusion]From 1972 to 2022,annual ET in the Shule River Basin increased significantly.Spatially,it increased from the southeast to the northwest.Land surface was the dominant driver of ET variations,reflecting the increased impact of human activities on basin hydrology.