Although El Niño-Southern Oscillation (ENSO) has been widely confirmed to have significant impacts on climate change in Asia, it is unknown whether the climate change in the Yangtze River Basin (YTR basin) is related to the operation of the Three Gorges Reservoir, which is the world’s largest hydropower station. In this study, we used the Standardized Precipitation Evapotranspiration Index (SPEI) as an indicator of climate change and found that the mutation period of the YTR basin was 2003–2006 based on three mutation tests. By analyzing the trends of the SPEI and five related meteorological factors before and after 2003, it was found that the construction of the Three Gorges Reservoir increased the relative humidity and provided a more humid climate for the downstream basin. The relationships between drought events and ENSO and the water level of the reservoir indicated that the basin was more prone to drought in El Niño years and the Three Gorges Reservoir could alleviate agricultural drought in the downstream basin. The spatial impacts of the Three Gorges Reservoir on regional climate change were more pronounced, while the impact of ENSO could not be reflected at the station scale.

尽管厄尔尼诺-南方涛动（ENSO）已被广泛确认会对亚洲的气候变化产生重大影响，但尚不知道长江流域（YTR盆地）的气候变化是否与三峡水库的运行有关，这是世界上最大的水力发电站。在这项研究中，我们使用标准化降水蒸散指数（SPEI）作为气候变化的指标，并基于三个突变测试发现YTR盆地的突变期为2003–2006。通过分析SPEI和2003年前后的五个相关气象因子的变化趋势，发现三峡水库的建设增加了相对湿度，为下游盆地提供了更加潮湿的气候。干旱事件与ENSO和水库水位之间的关系表明，厄尔尼诺年份该盆地更容易发生干旱，三峡水库可以缓解下游盆地的农业干旱。三峡水库对区域气候变化的空间影响更为明显，而ENSO的影响无法在站级得到反映。