## 4 Conclusions  
This paper addresses the accumulation of floodwater in the subway station and its subsequent outflow through the tunnel when the water level rises to a level that causes flooding. The objective of the numerical simulation of incoming floods is to develop a contingency plan for future emergencies:  
1. The manner in which floodwater ingress occurs into subway stations remains consistent regardless of the varying flood heights. In the majority of cases, floodwater enters the subway via the entrance, flows through the station hall level, descends via staircases to the platform level, and eventually reaches the tunnels. Irrespective of the internal configuration of the station, the floodwater is subject to the force of gravity and continues to spread in a downward direction from the entrance of the metro station.
2. As flood levels outside the station rise, the speed and extent of floodwater ingress into the subway station increase in parallel. This results in a greater extent of inundation and an increase in the volume of water accumulating within the station. As the height of the floodwater outside the subway station increases, so too does the volume of water accumulating within the station.
3. When the flood elevation intruding into a subway station is uniformly constant, the mass flow rate of flood water entering the station varies with time and has the following pattern. It can be demonstrated that for a specific duration, the mass flow rate of floodwater into the tunnel increases in a linear fashion over time. Prior to this, the rate of increase in floodwater mass flow into the tunnel is observed to accelerate. Subsequently, the rate of increase stabilises and becomes constant.
4. The present study is limited in several respects, which suggest avenues for future research. The article does not consider the drainage capacity of the station itself. In practice, the station's infrastructure is capable of accommodating a proportion of the water. Additionally, the actual floodwater levels at the entrance are subject to fluctuations due to external factors such as precipitation and runoff, which were not accounted for in this study. Furthermore, the accumulation of sediment at the flood bottom has the potential to impact the pumping rates, a factor that was not addressed in this study.  
Conceptualization, J.L., Z.L.and H.L.; methodology, J.L., Z.L.and H.L; software, J.L. and Z.L.; validation, J.L., Z.L. and H.L.; formal analysis, J.L.; investigation, Z.L.; resources, H.L.; data curation, J.L.; writing--original draft preparation, J.L.; writing--review and editing, J.L. and H.L.; visualization, J.L. and H.L.; supervision, H.L.; project administration, H.L.; funding acquisition, H.L. All authors have read and agreed to the published version of the manuscript.  
This paper received its funding from the Guangxi Emergency Management Department 2024 Innovation and Technology Research project (2024 GXYJ006); the First National Natural Disaster Comprehensive Risk Survey in Hunan Province (2022-70); the Guizhou Provincial Major Scientific and  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Option** & **Water Pump/set** & **Pumping Time/h** \\ \hline Option 1 & 1 & 14.9 \\ Option 2 & 2 & 7.5 \\ Option 3 & 3 & 5.0 \\ Option 4 & 4 & 3.7 \\ \hline \hline \end{tabular}
\end{table}
Table 5: _Cont._Technological Program (2023-425); the Hunan Provincial Department of natural resources geological exploration project (2023 ZRBSHZ056); and is a Key Project of the Hunan Provincial Department of Education (22A0566). The authors wish to acknowledge these supporters.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data used to support the findings of this study are available from the corresponding author upon request.  
**Conflicts of Interest:** The authors declare no conflicts of interest.