## 4 Discussion
The forest and vegetation coverage, the leaf area index increased significantly during the past two decades [64], which significantly increased Ei from 2000 to 2020. Moreover, Ei was directly related to PT, and PT presented a similar changing trend to that of Ei (Figures 4 and 8). Generally, the land use change from cultivated land and grassland to shrubs and forest [33], as well as the increase of Ta and VPD, leading to the increase inthe degree of stomatal opening, can enhance the process of vegetation transpiration and increase the Ec [65; 66]. However, the Ec did not show significant increasing trend; this may be due to the exponential increase of Ec with increasing Ta (Figure 9). Although Ta showed a weak significant increase and the interannual variation trend of Ta was very similar to that of Ec (Figures 4 and 8), the increase and decrease effect of Ta would be magnified to the change of Ec, so the Ec change was more drastic and its linear change trend was not significant. Previous studies suggested that Es correlated significantly with soil temperature, VPD, and PT [61]. The Ta, VPD, and PT showed increasing trends during the study period (Figure 8). The increase of Ta and VPD will increase Es to meet the need of atmospheric demand [67]. However, Es decreased significantly with the rate of \(-2.92\) mm/y, this may be due to the increased vegetation coverage and the leaf area index. With the increase of Ta, vegetation growth accelerated, vegetation coverage and the leaf area index increased, so that Es showed an increasing at first and then a decreasing trend, with the increase of Ta (Figure 9). Moreover, the land use change and ecological restoration could also increase vegetation coverage, which offset the effect of increasing Ta, VPD, and PT [33; 36]. Therefore, increase of vegetation coverage was the main factor responsible for the decrease of Es in most areas of TGRA. 83.56 mm, respectively, accounting for 56.06%, 29.64%, and 14.3% of ET in the studying area. ET, Ec, and Ei showed a similar pattern of seasonal variation with a single peak appeared on the 209 th day for ET and Ec, and on the 193 rd day for Ei, while Es presented a bimodal pattern with two peaks on the 105 th day and the 257 th day, 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 and Ec increased by 7.7% and 12.2% from stage 1 to stage 2, mainly in the head of TGRA, while they changed little from stage 2 to stage 5. Es in the urban area increased significantly by 27.8% from stage 1 to stage 2, but it decreased sharply from stage 2 to stage 5. The Ei in TGRA increased persistently from stage 1 to stage 5. Es decreased and Ei increased most obviously in cultivated areas, and the increase of vegetation coverage was the main factor responsible for the change of Es and Ei in TGRA. Among the employed climate factors, Ta, VPD, and SSD were the dominant factors affecting the variation of ET, Ec, and Es, while for Ei, the dominant factors were Ta, VPD, and PT. Moreover, the influence of Ta and VPD, on the variation of ET and Ec, was more pronounced than that on Es and Ei. Author Contributions: Y.J. : Conceptualization, Visualization and Writing--original draft. Q.T. : Software, Methodology. L.Y. ([PERSON]): Formal analysis. S.W. : Reviewing and Supervision. L.Y. ([PERSON]): Funding acquisition and Writing--review. D.T. : Funding acquisition. J.C.: Conceptualization, Validation and Writing--review. Q.C. : Reviewing and Validation. All authors have read and agreed to the published version of the manuscript. This research was funded by the Youth Innovation Promotion Association (no. 2018417), Key Laboratory of Mine Geological Hazard Mechanism and Prevention and Control (no. 2018-08), Science and Technology Project of Jingjiang Hydrology and Water Resources Survey Bureau (no. 2020-01), and the National Natural Science Foundation of China (no. 42061015, 51779241 and 41901130).