# Dynamic Monitoring of the Water Flowing Fractured Zone during the Mining Process under a River
## 4 Results and Discussion
### TEM Survey Results
By the 4 th day, the low resistivity area near a depth of 40 m had migrated downward to 60-80 m. This indicates that the water from the overlying aquifer continued to flow downward, and the yield of water decreased significantly compared to the second day. By the 8 th day, the low resistance area near the original aquifer gradually disappeared, indicating that the water had moved downward to 80-100 m. Along with the diffusion of the low resistivity area, the resistivity became higher because there was no water  
Figure 8: Comparison of the late time-induced electromotive forces. The horizontal axis represents the survey station number, the vertical axis represents the induced voltage, and the latter is logarithmic. The different colored lines refer to the curves of the induced electromotive forces of the different survey stations at the same time. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Day** & **Date** & **Position (m)** \\ \hline
1 & Jan. 28 th & 1251.5 \\
2 & Jan. 29 th & 1265.5 \\
3 & Jan. 30 th & 1275.7 \\
4 & Jan. 31 st & 1283.3 \\
5 & Feb. 1 st & 1294.4 \\
6 & Feb. 2 nd & 1302.0 \\
7 & Feb. 3 rd & 1313.1 \\
8 & Feb. 4 th & 1319.0 \\
9 & Feb. 5 th & 1326.7 \\
10 & Feb. 6 th & 1336.9 \\
11 & Feb. 7 th & 1345.4 \\
12 & Feb. 8 th & 1350.5 \\
13 & Feb. 9 th & 1355.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The 8101 longwall face position during the survey. supply from the surface. By the 13 th day, the low resistivity area was almost the same as the 8 th day, only more inconspicuous. The water distribution in the overlying strata had become stabilized. The survey results of line 2 are shown in Figure 10b. The arrow indicates the location of the aquifer (apparent resistivity 15 \(\Omega\cdot\)m and below, at a depth of approximately 60-100 m). The water level was stable. The results of line 2 showed that the water level of the aquifer was relatively low. The different water levels of line 2 could result from fault(s) in the overlying strata, as the fault zone is often filled with water, and the nearby water level will be affected. If the fault zone is disturbed by mining, the fault structure will form a water flowing channel, and the water transmitting ability of it will be greatly enhanced [30; 31]. By the second day, the resistivity of this area became higher, indicating a reduction of the water volume. By the 4 th day, the water content continued to decrease and moved further downward (the resistivity of the area near 100-130 m became lower). By the 8 th day, the water had almost finished moving downward (the low resistance area near the original aquifer gradually disappeared). By the 13 th day, the low resistivity area was almost the same as the 8 th day, only more inconspicuous. The water distribution in the overlying rock strata had become stabilized. The survey results of line 3 are shown in Figure 10c. The arrow indicates the location of the K\({}_{\text{Lzh}}\) unconfined aquifer (apparent resistivity 15 \(\Omega\cdot\)m and below, at a depth of approximately 20-40 m). The water level was stable. By the second day, the water from the overlying aquifer had begun to flow down (to 60 m and below). By the 4 th day, the low resistivity area near 40 m had migrated downward to 60-100 m. This indicates that the water from the overlying aquifer continued to flow downward through the WFFZ, and the yield of water decreased significantly compared to the second day. By the 8 th day, the low resistance area near the original aquifer had gradually disappeared, indicating that the mining fractures had connected to the aquifer and the water had moved downward to 70-100 m.  
Figure 9: Comparison of the TEM observation results and the geological log profile. The cyan area is the low resistivity zone, with a depth of 20–40 m and an apparent resistivity value of 15 \(\Omega\cdot\)m and below. By the 13 th day, the low resistivity area was almost the same as the 8 th day, only more inconspicuous. The water distribution in the overlying rock had become stabilized.