It is important to understand how actual evapotranspiration (ET_a) changes occur and what the dominant contributing factors are. This study investigated the impacts of climatic factor and vegetation coverage on the variations of ET_a using a Budyko-based framework. Climatic seasonal index and vegetation coverage index were selected as indicating factors. Two reservoir watersheds, i.e. the Wangkuai Reservoir Watershed and the Xidayang Reservoir Watershed, of the Daqing River Basin were selected as case studies. Also, relationships between the ET_a and climatic and vegetation factors were analyzed. Results showed that the improved vegetation conditions positively contributed to the ET_a changes, leading to an increase of 42.15 and 58.56 mm of ET_a in the two watersheds, while the increasing climate seasonality had a negative effect, resulting in a drop of 11.48 and 13.47 mm of ET_a. Vegetation coverage was recognized as the dominant factor to the changes of ET_a, compared to the climatic factor. Our research could offer supporting information for water resources management, agricultural production improvement and eco-environment construction in arid regions.

重要的是要了解实际的蒸散量（ET _a）如何发生变化以及主要的影响因素是什么。本研究使用基于Budyko的框架研究了气候因子和植被覆盖对ET _a变化的影响。选择气候季节指数和植被覆盖指数作为指示因子。选择了大庆河流域的望开水库集水区和信达洋水库集水区这两个水库流域作为案例研究。此外，还分析了ET _a与气候和植被因子之间的关系。结果表明，改善的植被条件对ET _a产生了积极影响变化，导致两个流域的ET _a分别增加42.15和58.56 mm ，而气候季节性增加则产生负面影响，导致ET _a减少11.48和13.47 mm 。与气候因素相比，植被覆盖度被认为是ET _a变化的主要因素。我们的研究可以为干旱地区的水资源管理，农业生产改善和生态环境建设提供支持信息。