## 3 Results and Analysis  
### Analysis of NDVI Trends from 2001 to 2020  
Examining the annual interannual variation trends of NDVI means in the Shanxi section of the Yellow River Basin and various mining areas from 2001 to 2020 (Figure 2), it is evident that both the Shanxi section of the Yellow River Basin and the individual mining areas have shown an overall increasing trend during this period. Specifically, the multi-year NDVI mean in the Shanxi section of the Yellow River Basin has increased from 0.54 in 2001 to 0.73 in 2020, with an annual growth rate of 1.82%. Among the eight mining areas, the Xiangning, Liulin, Hebaopian, Lishi, and Huozhou mining areas have all exhibited higher annual growth rates than the Shanxi section of the Yellow River Basin, with rates of 1.92%, 2.79%, 4.93%, 1.95%, and 2.39%, respectively. Notably, the Hebaopian mining area has seen a remarkable doubling in NDVI mean values, rising from 0.21 to 0.42, while the Qin Yuan mining area had a relatively lower annual growth rate of 0.97%. Overall, the NDVI trends in the mining areas are generally consistent with the overall trend in the Shanxi section of the Yellow River Basin. From 2001 to 2013, they all exhibited increasing trends, while from 2014 to 2020, they showed fluctuating trends. In 2015, there was a significant decrease in NDVI values in both the Shanxi section of the Yellow River Basin and the various mining areas. This decline may be attributed to an increase in geological disasters such as landslides and ground collapses. The NDVI in the Shanxi section of the Yellow River Basin varied between 0.54 and 0.73, with an annual mean of 0.68, reaching its highest value in 2013. In contrast, the NDVI in the various mining areas ranged from 0.2 to 0.5, with an annual mean falling between 0.2 and 0.4, consistently lower than that of the Shanxi section of the Yellow River Basin. These results collectively indicate a year-on-year improvement in vegetation cover in the Shanxi section of the Yellow River Basin and the various mining areas.  
This paper quantitatively examines the trends in the NDVI within the study area using trend analysis. It calculates the proportion of areas falling into each trend category and, based on the results of significance tests, categorizes the NDVI trends into five levels. According to Table 2 and Figure 3, in the Shanxi section of the Yellow River Basin, the proportions of areas with increased, relatively stable, and decreased NDVI are 80.56%, 17.51%, and 1.93%, respectively. This indicates a significant increase in vegetation cover in the Shanxi section of the Yellow River Basin, with 71.25% of the area experiencing a significant increase and only 1.93% of the area showing a slight decrease in vegetation cover. Among the eight mining areas, Jincheng Mining Area has the lowest proportion of areas with increased vegetation cover, at 56.24%, while the other mining areas have proportions exceeding 80%. The research findings demonstrate that over the nearly 20-year period from 2001 to 2020, there has been a significant overall increase in vegetation cover in the Shanxi section of the Yellow River Basin, and significant improvements in vegetation cover have been observed in all mining areas.