# Impacts of Drought and Heatwave on the Vegetation and Ecosystem in the Yangtze River Basin in 2022
## 3 Results
### Spatiotemporal Dynamics of the 2022 Drought and Heatwave in the Yangtze River Basin

Table 2: Monthly average environmental indices for the year 2022. Red indicates an increase in the monthly average compared to the mean for the base years (2018–2021), while blue indicates a decrease. Figure 3: Spatial distributions of SM1, SM2, SM3, and SM4 anomalies in the Yangtze River Basin during July ((**a,e,i,m**) in 1 st row), August ((**b,f,j,n**) in 2 nd row), September ((**c,g,k,o**) in 3 rd row), and October ((**d,h,l,p**) in 4 th row) in 2022. To be more specific, in 2022, temperatures stayed above average from June to December (Figure 4a), peaking in August at 23.35 \({}^{\circ}\)C, compared to the usual peak of 21 \({}^{\circ}\)C (Table 2). Precipitation peaked unusually early in June at 213.31 mm, differing from previous years, in which the peak was in July at 232.12 mm (Figure 3c and Table 2). Also, VPD levels exceeded normal from June, peaking in August before gradually returning to normal (Figure 4e,f). Figure 5, combined with Tables 2 and 3, showed that SM1-SM4 from July to October were all below the annual average. From Figure 5a,c,e and Figure 5b,d,f, it is evident that the trends of SM1-SM3 are highly similar, all reaching their lowest values of the year in August, with the most significant deviation from previous years occurring in the same \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Month** & **\(\Delta\)Temperature** & **\(\Delta\)Precipitation** & **AVPD** & **\(\Delta\)SM1** & **\(\Delta\)SM2** & **\(\Delta\)SM3** & **\(\Delta\)SM4** \\ \hline January & 0.06185 & 20.84159 & \(-\)23.98909 & 0.53817 & \(-\)0.36934 & \(-\)1.52415 & 0.56513 \\ February & \(-\)1.25051 & 10.63857 & \(-\)31.36631 & 2.76613 & 3.88524 & 3.52919 & 0.89134 \\ March & 0.63128 & 21.81804 & 23.08826 & \(-\)2.04043 & \(-\)1.48528 & 0.31253 & 0.878 \\ April & 0.03043 & 36.95338 & 5.30185 & 2.64044 & 3.664 & 3.22362 & 1.34068 \\ May & \(-\)0.40948 & \(-\)6.13164 & \(-\)12.95424 & 1.75255 & 2.43307 & 4.98721 & 2.08927 \\ June & 0.06897 & 0.05786 & 4.03657 & 0.6669 & 1.02995 & 2.73307 & 2.60974 \\ July & 0.38508 & \(-\)39.68248 & 44.26614 & \(-\)11.71673 & \(-\)11.72808 & \(-\)10.25374 & \(-\)0.19815 \\ August & 0.78578 & \(-\)47.18728 & 59.76322 & \(-\)22.60341 & \(-\)21.04353 & \(-\)16.17213 & \(-\)2.98858 \\ September & 0.06414 & \(-\)63.5857 & 37.59321 & \(-\)13.06911 & \(-\)13.03871 & \(-\)13.49273 & \(-\)4.75427 \\ October & 0.20108 & \(-\)54.758 & 42.21785 & \(-\)10.25648 & \(-\)10.33978 & \(-\)10.45781 & \(-\)4.98396 \\ November & 0.82659 & \(-\)32.15983 & 11.78168 & \(-\)5.07065 & \(-\)7.43555 & \(-\)10.00847 & \(-\)4.9414 \\ December & 0.06544 & \(-\)67.41344 & 21.05722 & \(-\)3.86582 & \(-\)2.82911 & \(-\)5.42747 & \(-\)4.66375 \\ \hline \end{tabular} In this table, the unit for all numbers is %.  
\end{table} 
Table 3: The change percentages of all environmental indices for the year 2022 compared to the average values from 2018 to 2021. Positive values are shown in red, indicating an increase in the monthly average for that index in 2022 compared to the average of base years. Negative values are shown in blue, indicating a decrease. Figure 4: The seasonal cycles of different environmental metrics: (**a**) temperature (\(\kappa\)), (**c**) precipitation (mm), and (**e**) VPD (hPa). The corresponding change percentages for the year 2022 compared to the average values from 2018 to 2021 are shown in (**b**) temperature, (**d**) precipitation, and (**f**) VPD. In (**a**,**c**,**e**), the black line represents the monthly average for 2022, and the red line represents the monthly average value from 2018 to 2021. In (**b**,**d**,**f**) the blue part represents the proportion of value in 2022 that exceeds the average from 2018 to 2021, while the red part represents the proportion of value in 2022 that falls below the average from 2018 to 2021.  
month. In contrast, the decrease in SM4 was relatively smooth (Figure 5g,h). Additionally, as soil depth increased, the decrease in SM gradually diminished, with the maximum decrease decreasing from 22.6% in Layer 1 to 4.9% in Layer 4.