## 4 Discussion  
### Spatial Distribution Analysis of Drought Characteristics  
We found an obvious spatial heterogeneity in the frequency, duration, and intensity of meteorological drought in the study area [57]. The development of spatial patterns of drought distribution under climatic conditions is fundamental to understanding drought features in the Shendong mining area. The frequency and duration of drought in the eastern part of the study area were lower than those in the western part, since the eastern part is closer to the semi-humid and semi-arid area, with a wetter climate and more rainfall. In this area the soil moisture is sufficient and can persist in providing vegetation to meet its standard water requirements [58]. This is consistent with the results of this study. At the same time, this study found that the frequency, duration, and intensity of meteorological drought did not show synchronization, and there was no obvious linear correlation between them. Secondly, the influence of soil characteristics on drought characteristics cannot be ignored. The soil types in the study area are shown in Figure 16. The main soil types in the study area are Huangmian soil, chestnut soil, and semi-fixed sandy soil [59]. These soil types have a loose structure, low organic matter content, and poor water retention capacity. This makes the soil in the study area vulnerable to wind and water erosion, exacerbating the duration and intensity of ecological drought. In addition, human activities, especially coal mining activities, have a significant impact on the meteorological drought characteristics of the Shendong mining area. Coal mining leads to subsidence of the Earth's surface and a drop in the water table, further increasing the frequency and intensity of droughts. Some scholars have shown that the annual mean Temperature Vegetation Drought Index (TVDI) in subsidence areas is higher than that of non-subsidence areas, which indicates that coal mining activities have a significant impact on drought characteristics [60]. The ecological drought in the study area showed obvious characteristics. Firstly, the frequency of ecological drought in the study area was low. This low frequency indicates that the vegetation in this region is relatively stable and the water imbalance is not frequently occurring. Secondly, the ecological drought lasted a long time. In conjunction with drought frequency, we can reaffirm that the ecosystem in this region is relatively stable yet situated in a critical vulnerability zone, due to the prolonged duration of each ecological drought. Thirdly, the intensity of ecological drought was low. Some scholars believe that while the duration of ecological drought was prolonged, the intensity of individual ecological droughts was minimal, resulting in a negligible impact on ecosystem changes in the study area [61]. Although meteorological drought had a high frequency, short duration, and high intensity, ecological drought had a low frequency, long duration, and low intensity. First, ecosystems have the capacity to buffer and recover. When meteorological drought occurs frequently and with high intensity in the study area, the buffer capacity of the ecosystem will be gradually exhausted, which can easily lead to the cumulative effect of ecological drought. This cumulative effect makes the duration of ecological drought significantly longer. Secondly, there is a lag in the response of ecosystems to drought. The vegetation