# Change and Driving Factor Analysis of Eco-Environment of Typical Lakes in Arid Areas
## 3 Results
### Temporal and Spatial Variation Characteristics of Eco-Environmental Quality of Taitema Lake  
Based on the analysis of remote sensing ecological indices of Taitema Lake from 2000 to 2020, it could be observed that the proportion of poor ecological condition showed an overall downward trend, while the proportions of moderate, good, and excellent ecological conditions showed an overall upward trend, indicating that the ecological condition of the area gradually improved (Figure 6).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Date** & **Wood Land** & **Grassland** & **Water** & **Construction Land** & **Unused Land** \\ \hline
2000 & 1.6 & 22.6 & 0.4 & 0.0 & 75.4 \\
2010 & 0.6 & 22.6 & 3.3 & 0.1 & 73.3 \\
2015 & 0.6 & 21.1 & 4.5 & 0.1 & 73.6 \\
2020 & 0.6 & 28.6 & 4.8 & 0.1 & 65.8 \\  & \(-\)0.9 & 6.0 & 4.4 & 0.1 & \(-\)9.6 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Proportion of the land use area of Taitema Lake between 2000 and 2020. (Unit: %.).  
Figure 5: Distribution maps of land use types in 2000, 2010, 2015, and 2020.  
Among them, in 2000, the proportion of poor ecological condition was 94.7%, which decreased to 54.4% by 2020, a decrease of about 40.4%; the proportion of moderate ecological quality increased from 5.3% to 35%, an increase of about 29.7%, which was the largest increase (Figure 7); the increase in the proportion of good ecological quality was second, with 0% in 2000 and 10% in 2020; the proportion of excellent ecological quality increased by 0.6% over the 20 years, indicating that poor ecological quality is gradually being replaced by moderate, good, and excellent quality. Due to ecological water conveyance, the area of Taitema Lake had significant increases in 2012 and 2017. In 2012, the proportion of poor ecological condition was 38.7%, which was the smallest in the selected 20 years. The proportions of moderate and good ecological conditions were 46.1% and 14.7%, respectively. In 2017, the proportions of moderate and good ecological conditions were 38.2% and 13.2%, respectively.  
According to the RSEI mean analysis of 20 a, the proportion of areas with poor habitat quality was 47.7%, while the proportions of areas with medium, good, and excellent habitat quality were 32.6%, 18.4%, and 1.4%, respectively. The sum of the three was greater than the proportion of areas with poor habitat quality, indicating an improvement in the ecological condition of Taitema Lake (Figure 8). Using the Mann-Kendall trend test method to examine the ecological quality change on an element-by-element basis and referring to the trend test value (\(Z_{c}\)), the spatial distribution of the RSEI trend test after ecological water conveyance was obtained. From 2000 to 2020, 56.5% of the area of elements in Lake Taitema showed an increasing trend of the RSEI (\(Z_{c}>0\)), while 43.5% of the area showed a decreasing trend of the RSEI (\(Z_{c}<0\)).  
Figure 6: Spatial distribution of RSEI in Taitema Lake from 2000 to 2020.  
In particular, the proportion of pixels with a significant upward trend of the REEI (\(Z_{c}\ >1.96\)) was 15.6%, while the proportion of pixels with a significant downward trend of the REEI (\(Z_{c}<-1.96\)) was smaller, only 2.1%. The proportions of pixels with a non-significant upward trend (\(0<Z_{c}<1.96\)) and a non-significant downward trend (\(-1.96<Z_{c}<0\)) of the REEI were 40.9% and 41.4%, respectively. Overall, this indicates a  
Figure 8: Trend test chart of REEI average value and MK of Taitema Lake in 20 a.  
Figure 7: Changes in REEI grade proportion in Taitema Lake in 20 a.  
significant improvement in the ecological condition of the Taitema Lake area after ecological water conveyance.