## 5 Conclusions  
Based on the PT-JPL model, the actual evapotranspiration in the Yliuo River Basin was estimated, and the temporal and spatial variation characteristics and influencing factors of evapotranspiration in the basin from 2001 to 2020 were analyzed by combining mathematical statistics methods. The main conclusions are as follows:1. The actual evapotranspiration of the basin was tested against the actual evapotranspiration estimated by the PT-JPL model through the water balance equation, and the results of the PT-JPL model were generally small, but the accuracy in the Yliuo River Basin basically met the requirements. The PT-JPL model has good applicability, and the characteristics of evapotranspiration changes in the Yliuo River Basin can be analyzed based on this.
2. From the interannual variation of actual evapotranspiration, the total actual evapotranspiration in the Yliuo River Basin showed a decreasing trend, with a decreasing rate of 2.5 mm/a; the Cv values of most of the pixels were high, which indicated a large degree of interannual ETa variability in the basin; the ETa distribution in the basin generally showed the characteristics of high in the south and low in the north, high in the upper mountainous area and low in the lower river valley; and from the results of the Sen slope and the M-K test, the area where ETa showed a decreasing trend accounted for the total area of the basin approximately 80% of the total, and the area with an increasing trend only accounted for approximately 13%.
3. From the intra-annual variation of actual evapotranspiration, the lowest multiyear average ETa was found in January and December, and the highest in July; ETa in all seasons showed a decreasing trend; and the actual evapotranspiration in all seasons differed significantly, in descending order: summer (240 mm) > spring (120 mm) > autumn (119 mm) > winter (45 mm).
4. The monthly trends of actual evapotranspiration were consistent with the vegetation growth pattern and the intra-annual variation process of temperature and precipitation. Monthly ETa correlated well with monthly temperature, monthly NDVI, and monthly precipitation, with ETa having the strongest correlation with temperature. This was contrary to the results of the interannual variation in ETa, NDVI, P, and T (ETa and P both showed a decreasing trend, and NDVI and T both showed an increasing trend).  
Conceptualization, M.L.; methodology, M.L.; software, Y.Y.; validation, M.L., Y.Y. and X.G.; data curation, C.X., L.Y., Q.X. and M.L.; writing--original draft preparation, Y.Y.; writing--review and editing, M.L., Y.Y., X.G. and C.X.; visualization, Y.Y. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key R&D Program of China (2021 YFC3200204) and the National Natural Science Foundation of China (NO. 52079125).  
Not applicable.  
Restrictions apply to the availability of these data. The remote sensing data was obtained from the MODIS product of NASA and are available at [[http://search.earthdata.nasa.gov/](http://search.earthdata.nasa.gov/)]([http://search.earthdata.nasa.gov/](http://search.earthdata.nasa.gov/)) with the permission of the MODIS product of NASA. The meteorological data were obtained from the China National Meteorological Science Data Sharing Service Platform and available at [[http://data.cma.cn/](http://data.cma.cn/)]([http://data.cma.cn/](http://data.cma.cn/)) with the permission of the China National Meteorological Science Data Sharing Service Platform.  
The authors declare no conflict of interest.