# Change and Driving Factor Analysis of Eco-Environment of Typical Lakes in Arid Areas
## 4 Discussion
### Analysis of the Suitable Area of Taitema Lake  
Taitema Lake is difficult to maintain at a fixed and large scale [43], and it is not necessary to do so. Currently, it is the only lake downstream of the Tarim River, serving as a terminal lake where the Tarim River and the Cherchen River converge. As an inland lake at the end of the desert, Taitema Lake has no other source of water supply except for the water inflow of the Cherchen River and the Tarim River. Therefore, the size of the lake is mainly  
Figure 11: Structural equation model analysis of the factors affecting the area change in Taitema Lake. Figure 12: Driving factor fitting curves. (**a**) Correlation between ecological water conveyance and Lake Taitema and (**b**) correlation between rainfall and the area of Lake Taitema. affected by the water inflow of the two rivers. The total water inflow into the lake is closely related to the water inflow of the two rivers. However, due to the obvious intra-annual concentration (about 70% of the water inflow from July to September), there are significant inter-annual differences in the natural runoff of the rivers in the arid area [44]. In addition, the strong evapotranspiration of the lake area, the flat lake-bottom shape, and other factors determine that there must be strong intra-annual and inter-annual changes in the lake area of Taitema Lake. From 2000 to 2020, the average ecological water conveyance to Taitema Lake was 4.02 \(\times\) 10\({}^{8}\) m\({}^{3}\) per year, while the average lake area during this period was 114.79 km\({}^{2}\). The analysis showed a significant linear relationship between ecological water conveyance and the lake area (\(p<0.05\)), which can be used to estimate the lake area at different water levels. Based on the linear fitting equation, the lake area reached its maximum in 2017, which was also the year with the highest water conveyance. The increase in lake area in 2003 was also due to an increase in water conveyance. In the drought years from 2007 to 2009, the lake area decreased to about 35 km\({}^{2}\) in 2007, and the vegetation area decreased by 4.97% in 2008 and 2009. The lake and its surrounding areas formed fish-scale sand dunes again in 2008 and 2009 [45], leading to mild desertification. If the lake area of Taitema Lake is continuously less than 30 km\({}^{2}\), the ecological environment in the Taitema Lake area will rapidly deteriorate. It was not until ecological water conveyance exceeded 2 \(\times\) 10\({}^{9}\) m\({}^{3}\) in 2010 that the trend of ecological degradation was reversed. Therefore, in order to avoid serious ecological degradation in the lake area, the surface area of Taitema Lake should not be less than 30 km\({}^{2}\). Using data analysis of the vegetation area, the average RSEI value, and the lake area around Lake Taitema, it was estimated that when the lake reaches its maximum area of 110 km\({}^{2}\), the corresponding vegetation area is 232 km\({}^{2}\). Without maintaining a large lake area, the natural vegetation area and quality of the lake area can be maintained in good condition. At the same time, from the results of the RSEI, it is possible to see that the vegetation of the lake area can adapt to the strong annual and inter-annual variations in the lake area. Therefore, it is not necessary to maintain a larger and fixed lake area. A too-small lake area would cause poor water conditions for vegetation distribution, especially in the vegetation distribution areas far away from the lake area [46], affecting the normal growth of vegetation. Prolonged \"small lake area\" conditions would lead to ecological environmental problems such as decreased vegetation quality and decreased area. The restoration of Lake Taitema marks the end of the dry season in the main stream of the Tarim River and the lower reaches of the Cherchen River, and the restoration of ecological water supply to the downstream green corridor, achieving the goal of comprehensive management of the Tarim River basin in the near future.