Spatiotemporal variations of evapotranspiration and associated environmental factors in the Jialing river basin from 2001 to 2023

Evapotranspiration (ET) plays a crucial role in the hydrological cycle and ecosystem processes. This study investigated the spatiotemporal variations and associated factors of ET in the Jialing River Basin during 2001–2023 using the PML-V2 ET dataset, Theil–Sen median trend analysis, Mann–Kendall test, partial correlation analysis, and ridge regression. Results showed that: (1) The mean annual ET was 547.94 mm, with a non-significant decreasing trend of −0.71 mm yr−1. Spatially, ET was higher in the southern and northwestern regions and lower in the central area, with 63.04% of the basin showing a decreasing trend. (2) Seasonal ET decreased in spring and summer but increased in autumn and winter, with the highest ET occurring in summer. (3) Partial correlation analysis revealed negative associations of ET with temperature and precipitation in most areas, while solar radiation and NDVI showed positive associations, with solar radiation exhibiting the most extensive positive association. (4) Ridge regression analysis revealed that temperature exhibited the highest relative contribution to annual ET variability (30.93%), followed by precipitation (25.59%), NDVI (25.19%), and solar radiation (18.30%). NDVI showed the highest seasonal contribution in spring, summer, and winter, whereas solar radiation had the highest contribution in autumn.