## 3 Research on Water-Inrush Sources
### Analysis of the Correlation between Mine Water Inflow and Atmospheric Precipitation  
In this study, due to long-term weathering and erosion by rainwater, low-lying sites and ditches have been gradually formed at the exposed limestone of the Changxing Formation. The river water surface is generally wide, and the water flow is slow, allowing atmospheric precipitation to easily collect and infiltrate. Under long-term dissolution, seasonal streams and gullies were widely distributed near the outcrop of the Changxing Formation (Figure 3). This increased the intensity and duration of atmospheric precipitation as well as surface water infiltration into the Changxing Formation limestone. Studies by [PERSON] et al. (2019) and [PERSON] (2019) investigated the close relationship between mine water inrush near the shallow outcrop of coal seams and atmospheric precipitation in the karst landform area of Guizhou. Atmospheric precipitation was the main source of mine water supply. Furthermore, during the shallow coal seam mining, atmospheric precipitation rapidly replenished the mine, and the shortest replenishment time was 2 h. As the burial depth of coal seams increased during mining, the distance of atmospheric precipitation from the coal seam outcrop to the underground mining area increased, thus decreasing the replenishment amount and increasing the time. The Changxing Formation limestone was widely exposed near the coal seam outcrop in the Xinhua mining area of Jinsha County (Figure 3). This limestone served as a reservoir for atmospheric precipitation and transported it deep into the mining area through channels such as dissolution gaps, caves, and fractures in the rock layers. In its original karst fissure state (before it was affected and destroyed by mining), the water supply to the underground mining area of the coal mine through the Changxing Formation limestone was relatively small, and the supply cycle was long. However, after damaging the integrity of the limestone in the shallow mine and completing mining, the water inflow in the deep mine significantly increased. This considerably reduced the time for atmospheric precipitation to supply the underground. For example, after the completion of mining in 2019 at the last 10,508 working face (lower limit elevation 1115.3 m) of the 5\({}^{\#}\) coal seam in the northwest wing of Jinyuan Coal Mine, the mine began to retreat, and the pit was closed. In the deep Guiyuan No.2 mine, the amount of water inflow significantly increased, and the period of atmospheric precipitation recharge was significantly shortened (Figure 6). The water inflow of the mine increased from 84 m\({}^{3}\)/h pre-2019 to 242 m\({}^{3}\)/h in 2022. Additionally, during the rainy season, the time interval between the peak water inflow in mines and the peak rainfall gradually decreased from \(\sim\)10 months before 2019 to 6 months in 2020. From 2021 to 2022, the peak water inflow in mines synchronized with the peak rainfall in the same month. This indicated that the secondary cracks generated after coal seam mining activities led to the connection of primary cracks, dissolution cracks, and caves in the Changxing Formation limestone. The unobstructed water storage and supply capacity in the goaf increased the speed and amount of atmospheric precipitation replenishment for mine water.