## 4 Results
### Comprehensive Analysis and Research Limitation  
The spatial variation of EE quality in the typical CLP region generally agrees with the NDVI and WET indicators. The initial implementation of the GGP from 1999 to 2005 led to changes in vegetation types, but did not provide sufficient ecological benefits for soil water retention. However, due to the lagging effect of the GGP, vegetation cover in the typical CLP region increased and the EE quality significantly improved by around 2010.  
Large-scale underground coal mining activities take place every year in the Huanglong coal base, causing significant subsidence on the surface. The groundwater level in the mining region and surrounding buffer zone has dropped significantly, and soil nutrients have been lost, resulting in the destruction of the levelness and water storage functions of arable land, causing farmers to abandon farming and impairing vegetation growth or causing it to die. According to statistics, the subsidence regions in the Guangdong coal base are not continuously distributed, and the area of subsidence regions formed by mining in each mine each year generally does not exceed 5 km\({}^{2}\). Therefore, the impact of coal mining activities on the EE is small in area and spatially discontinuous. It should be noted that with the Chinese government's increasingly stringent requirements for environmental protection in mining areas, coal mining enterprises have begun to carry out land remediation and ecological restoration in subsidence regions since 2015. Additionally, the recovery effect of rising temperatures and increased rainfall on the EE of subsidence regions has helped to mitigate the damage caused by coal mining activities, so the scope of the EE damage caused by coal mining activities is relatively small.  
Since 2000, the Chinese government has proposed the China Western Development initiative, which has increased support for the Guangzhou district. The excessive economic development and population growth coincided with an increase in construction areas, leading to the occupation of nearby arable land and the expansion of industrial activities, increasing environmental pressures. The urbanization process has accelerated due to the creation of economic and high-tech zones, and the rapid growth of GDP per capita reflects the significant development achieved in the last two decades. The river valley plain area, with Xi'an as its central city, has experienced significant ecological degradation due to rapid urbanization, becoming the economic development center in western China. As a result, construction land and roads have expanded into grasslands and arable land. In 2012, the government proposed a strategy to promote ecological civilization, placing increasing emphasis on developing eco-cities [56]. The number of green belts and urban parks within the city has increased, contributing to the removal of urbanization's harmful effects on the local ecology [57].  
Regarding landform, the EE of the loess hilly-gully region in the Loess Plateau mining area improved the most. Although coal mining has an impact on the nearby region, the GGP greatly improved the EE of the loess hilly-gully region, which entered the ecological succession stage at around 2020. Conversely, urban development led to EE deterioration in the river valley plain region, but thanks to the local government's urban environmental protection policies, published roughly in 2020, the EE of the river valley plain region has gradually improved and will continue to do so in the future.  
It should be noted that this study mainly used RSEI to evaluate the EE quality in the typical region of CLP, which still has some limitations in terms of evaluation indices and data reliability. The study utilized MODIS remote sensing data with a spatial resolution of 500 m, and higher resolution remote sensing images will be utilized for future studies. Additionally, for EE prediction, the trend prediction will be changed to predicting the time period in the future to make the prediction more accurate.