## 3 Results
### Modeling Results Prognosis  
After calibration (for the average GWL values) and verification of the model (for the maximum GWL situation for April 2006), we were able to proceed to the next simulation. Due to the fact that the TEN-T connection route will be built in certain sections in a sealed construction pit, it was necessary to design another variant of the model to simulate impermeable construction pits (specified in the TEN-T project documentation [18]). The locations of the mentioned construction pits in the model are evident in Figure 16. These sealed pits are highlighted in black. Since the TRIWACO simulation software system only considers groundwater flow through a porous medium, we designed the impermeable pits to have a very low hydraulic conductivity value (in the order of hundreds to thousands of m/day) at the location for each future sealed pit. The result of the simulation with the designed sealed pits (for the average condition) is evident from the floor plan in Figure 17. However, this figure does not have much informative value, and therefore, we preferred to present the direction of groundwater flow with a future sealed pit, as shown in Figure 18, and the difference in GWL, as shown in Figure 19.  
Figure 14: Course of simulated GWL isolines (m a.s.l.) for the maximum GWL state (for the month of April 2006): zoomed-in views of (**a**) the center of Bratislava and (**b**) the Petrzalka region [17]. Figure 15: Course of simulated GWL isolines (m a.s.l.) with a simulated direction of groundwater flow for the average GWL state (for the period 1995–2020): zoomed-in views of (**a**) the center of Bratislava and (**b**) the Petrzalka region [17]. Figure 16: Short sections of the impermeable construction pits along the proposed railway route (black): zoomed-in views of (**a**) the center of Bratislava and (**b**) the Petrzalka region. Figure 17: The simulated course of GWL, assuming the construction of short sections of the impermeable construction pits (referred to the average condition): zoomed-in views of (**a**) the center of Bratislava and (**b**) the Petrzalka region. Figure 18: Simulated course of GWL with a simulated direction of groundwater flow, assuming the construction of short sections of the impermeable construction pits (referred to the average condition): zoomed-in views of (**a**) the center of Bratislava and (**b**) the Petrzalka region [17]. As can be seen in the previous figures, the construction of underground mined station sections in the Petrzalka region and the sealing walls at the airport in Bratislava had no significant impacts. However, in the section of the underground railway track designed to sink from the surface under the protection of the bracing structures, which will at the same time provide protection against the seepage of groundwater into the railway tunnel [13], i.e., in the RWS Slovany-RWS Filialka section, there could be an increase in groundwater level in some sections by up to 2.5 and even up to 3.5 m from the northwest. Conversely, there could also be a decrease in the groundwater level by 1.5 to 2.5 m from the northeast. Therefore, the research that followed focused specifically on this section, which is shown in more detail in Figure 20.  
Figure 19: Simulated course of the GWL difference, assuming the construction of the impermeable construction pits (referred to the average condition): (**a**) solution for the entire area, and zoomed-in views of (**b**) the center of Bratislava and (**c**) the Petrzalka region. Figure 17.0 (**a**) Simulated groundwater flow direction with GWL course—natural state; (**b**) simulated groundwater flow direction with GWL course, assuming the construction of the impermeable construction pits; and (**c**) simulated course of the GWL difference. Detailed view in the section RWS Slovany–RWS Filiälka.