## 3 Results
### Model Performance
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Catchment**} & \multicolumn{2}{c}{**Atmospheric**} & \multicolumn{2}{c}{**Temperature**} & \multicolumn{2}{c}{**Humidity**} & \multicolumn{2}{c}{**Precipitation**} & \multicolumn{2}{c}{**Windspeed**} & \multicolumn{2}{c}{**Sunshine Duration**} & \multicolumn{2}{c}{**CO\({}_{2}\)**} \\  & \multicolumn{2}{c}{**Pressure**} & & & & & & & & & & & & & \\ \hline BGC & \(-0.01\) & \(-1.2\) & \(0.01\) & \(0.75\) & \(-0.13\) & \(-1.27\) & \(10.51\) & \(2.37\) \({}^{***}\) & \(-0.01\) & \(-2.11\) \({}^{**}\) & \(0.01\) & \(0.29\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ JMC & \(-0.01\) & \(-1.2\) & \(0.02\) & \(1.27\) & \(-0.08\) & \(-0.68\) & \(7.54\) & \(2.24\) \({}^{**}\) & \(0.00\) & \(-0.68\) & \(-0.01\) & \(-1.33\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ BSC & \(0.00\) & \(0.88\) & \(-0.04\) & \(-17.2\) \({}^{**}\) & \(0.20\) & \(1.52\) & \(11.15\) & \(2.17\) \({}^{**}\) & \(0.01\) & \(0.36\) & \(-0.05\) & \(-2.89\) \({}^{**}\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ THC & \(0.00\) & \(0.23\) & \(0.03\) & \(1.78\) \({}^{**}\) & \(-0.25\) & \(-22.4\) \({}^{**}\) & \(5.36\) & \(1.52\) & \(0.00\) & \(0.1\) & \(-0.02\) & \(-1.14\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ DSC & \(0.00\) & \(0.75\) & \(0.04\) & \(1.98\) \({}^{**}\) & \(-0.27\) & \(-2.43\) \({}^{***}\) & \(8.64\) & \(2.43\) \({}^{***}\) & \(-0.01\) & \(-1.98\) \({}^{**}\) & \(-0.02\) & \(-1.33\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ CHC & \(0.00\) & \(1.4\) & \(0.03\) & \(1.4\) & \(-0.12\) & \(-0.88\) & \(11.98\) & \(2.37\) \({}^{***}\) & \(-0.03\) & \(-2.43\) \({}^{***}\) & \(-0.04\) & \(-2.76\) \({}^{***}\) & \(2.24\) & \(6.13\) \({}^{***}\) \\ \hline \hline \end{tabular} In a two-side test, when \(Z_{\rm e}<-Z_{\rm I-\alpha/2}\), it indicates a decreasing trend, and when \(Z_{\rm e}>Z_{\rm I-\alpha/2}\) indicates an increasing trend, \(\alpha\), is the significance level. In this study, \(\alpha\) was set to be \(0.01\), \(0.05\) and \(0.1\) indicating the changing trend is extreme strong, strong and obvious, respectively. The corresponding value of \(Z_{\rm I-\alpha/2}\) is \(2.32\), \(1.96\) and \(1.64\) for the three levels, respectively, while the value was below \(1.64\), indicating no obvious changing trend. \({}^{***}\), \({}^{**}\) and \({}^{*}\) indicate significance levels of \(0.01\), \(0.05\) and \(0.1\), respectively.  
\end{table} 
Table 4: Annual changes of the climate variables and CO\({}_{2}\) in the six catchments. Figure 6: Mann–Kendall trends in the climate variables in the six catchments. (2) Land-use and cover change  
Land-use and cover change (LUCC) is recognized as important factors that influence evapotranspiration and vegetation carbon assimilation. Therefore, the land use changes were also investigated in the six catchments as shown in Figure 7. In the six catchments, the dominant land coverage is forest, grassland and cropland, covering almost nearly 95% of the whole basin. In the BGC, the major land cover is forest (83%) and grassland (9%). The forest decreases to 64% in the JMC and the rest are mainly grassland (22%), cropland (10%). While in the BSC, the main land cover is grassland (49%), the forest decreases to 36%, cropland is about 10%, respectively. In the THC, the grassland increases to 51% and the cropland increases to 21%, while the forest decreases to 22%. In the DSC, the chief land cover is still grassland (57%), while the cropland decreases to 7% and the forest increase to 32%. In the CHC, the main land covers are forest (48%), grassland (38%) and the cropland constitutes about 8%. Figure 7 displays the land-coverage changes from 2000 to 2020 in the six catchments. Generally, the study area is a mountainous region with relatively few human activities, and the urban area increased by only 0.8% due to urbanization. A growth of 0.2% in the forest was found in the BGC. While in the JMC, the cropland and forest both decreased by 0.2% and the urban area increased by 0.4%.