###### Abstract  
Identifying the spatiotemporal variations and influencing climate factors of evapotranspiration (ET) and its components (vegetation transpiration (Ec), soil evaporation (Es), and canopy interception evaporation (Ei)) can greatly improve our understanding of water cycle, carbon cycle, and biogeochemical processes in a warming climate. As the world's largest hydropower project, the construction of the Three Gorges Project (TGP) coupled with the significant land use/land cover change affected the regional water and energy exchange in the Three Gorges Reservoir Area (TGRA). This study aimed to reveal the spatiotemporal variations and influencing climate factors in ET and its components using PML-V2 products in TGRA during 2000-2020. Results showed that the mean annual ET, Ec, Es, and Ei in TGRA were 585.12, 328.49, 173.07, and 83.56 mm, respectively. The temporal variation of ET was dominated by Ec, with no significant change in the time trend. Es decreased (2.92 mm/y) and Ei increased (1.66 mm/y) significantly mainly in the cultivated land. ET, Ec, and Ei showed a similar seasonal variation pattern with a single peak, while Es presented a bimodal pattern. From the pre-impoundment to the first impoundment period, ET and Ec mainly increased in the head of TGRA, meanwhile, Es in urban area increased significantly by 27.8%. In the subsequent impoundment periods, ET and Ec changed slightly while Es sharply decreased. The Ei increased persistently during different impoundment period. The dominant climate factors affecting changes in Ec and Es were air temperature, vapor pressure deficit, and sunshine hours, while the variation of Ei was mainly affected by air temperature, vapor pressure deficit, and precipitation. evapotranspiration; components; climate change; PML-V2; Three Gorges Reservoir 13 2021 29  
The lysimeter, eddy covariance systems and Bowen ration energy balance systems were widely used to measure ET at point scale, while the micro-lysimeters, isotopes, and sap flux made reliable verification of individual ET components possible [6]; thus, many studies were conducted to partition ET using the measured data at farmland [7], orchard [8], grassland [9], and dry land [10]. While at regional scales, ET and its components were estimated by evapotranspiration models with meteorological data coupled with remote sensing data [5; 11], these model including Penman-Monteith-Leuning (PML) model [12; 13], Shuttleworth-Wallace (S-W) model [14; 15], FAO dual-Kc model [15; 16], and the two-source energy balance (TSEB) model [17]. Due to the difference in atmospheric conditions, climatic features, hydrological regimes, vegetation and soil, the ET and its components, the proportion of components and the influencing factors varied greatly from site to site [18; 19; 20]. Ec was dependent on vegetation coverage and water demand, which varied with plant types, plant phenology, hydrologic controls, and water-use efficiency [13]. Es was mostly driven by the atmospheric demand for vapor, soil moisture, and the amount of vegetation above the soil [21]. Ei was mainly affected by the occurrence of low intensity and frequent rainfall and the characteristics of the vegetation stand [13; 22]. Generally, Ec accounted for the major part of ET globally [13; 18], especially in vegetated systems with low precipitation, Ec was the most important part among the three components [18]. While for areas with low vegetation coverage, yet high precipitation and air temperature, Es became the largest component [23]. Compared to Ec and Es, Ei accounted for a little proportion of ET, while it was an indispensable component of surface-water balance, particularly for the vegetated areas with higher vegetation coverage and leaf area index, combined with low intensity and frequent rainfall [13; 22]. The dominant factors affecting the variation of ET components varied significantly, and their responses to climate and environmental change were different.