## 4 Construction of Discriminant Models  
### Selection of the Main Control Factors and Normality Test  
According to the statistics, there are a total of 48 boreholes in the study area, including 30 hydrological boreholes and 18 coal exploration boreholes. The borehole distribution and water table contour map of the weathered bedrock aquifers in the study area is shown in Figure 2.  
The _Rules for Prevention and Control of Water in Coal Mines (2018)_[18] stipulated the classification of aquifer water-bearing properties based on the water inflow per unit from the pumping tests of hydrological boreholes. The water-bearing properties of the aquifer are divided into four levels: very high, high, moderate, and low. Based on the pumping test results for weathered bedrock aquifers, the water-bearing properties in the study area range from low to high. Therefore, within the study area, the water-bearing properties can be further subdivided into four levels: high, moderate, low, and very low, and the water-bearing properties grading of the aquifer can be seen in Table 1.  
The analysis of the development characteristics of weathered bedrock in the study area combined with the results of pumping tests and previous studies reveal that the water-bearing properties of the weathered bedrock aquifer are related to six quantitative indices, namely, the weathered bedrock thickness, the core recovery rate, the degree of weathering, the lithology combination, the elevation of the weathered bedrock surface, and the sand-to-base ratio. 1. Weathered bedrock thickness  
According to the results of previous research, with increasing weathered bedrock thickness, water-bearing properties first increase and then decrease [19], which is attributed to the fact that in boreholes with a large weathered bedrock thickness, the complexity \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Water-Bearing Property Classification** & **High** & **Moderate** & **Low** & **Very Low** \\ \hline Unit water inflow \(q/(L\cdot S^{-1}\cdot m^{-1})\) & \(q\) \textgreater{} 1 & \(1\geq q\) \textgreater{} 0.1 & \(0.1\geq q\) \textgreater{} 0.01 & \(q\leq 0.01\) \\ Value & 4 & 3 & 2 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification of the water-bearing properties of aquifers. Figure 2: Map of borehole distribution and water table contours of the weathered bedrock aquifers in the study area. of lithological combinations reduces the proportion of sandstones with better water-bearing properties;  
2. Core recovery rate  
The core recovery rate is the ratio of the length of recovered core samples to the drilling depth. During the coring process, challenges such as core jamming, disturbance, and structural damage to the core may arise in loose and fractured formations, such as sand layers and gravel layers. These issues can result in low core recovery rates or failure to meet sampling requirements. However, the study area consists of dense sandstone, which eliminates the problem of gravel layers or weak rock formations. Under consistent drilling lithology and coring techniques, a higher core recovery rate indicates a lower degree of fracture development, and the core samples are more complete. The higher the core recovery rate, the lower the degree of fracture development and the weaker the water-bearing properties of the rock formation. Conversely, a lower core recovery rate suggests stronger water-bearing properties. For example, the boreholes J9 and SK1 have similar elevations of the weathered bedrock surface, lithology combination index, and weathering index. However, the core recovery rate index for J9 is 0.66, while for SK1, it is 0.936. As a result, the water inflow per unit of borehole J9 is 0.1117 L/(s\(\cdot\)m), whereas for SK1, it is only 0.0108 L/(s\(\cdot\)m).