## 5 Results and Discussion
### Flooding Day  
In order to determine which roads will be faced with speed reduction and which will be closed to traffic, a relationship between vehicle maximum permitted speeds and flood depths is necessary. [PERSON] et al. [6] previously discretized flood threats by relating maximum allowable speed limits along road sections to flood depths along those sections. Table 2 depicts the discrete limits along road sections in relation to flood depths. The input parameters (speed limit) of links within the traffic model are modified using an intersect analysis, which analyzes the depths of water on road surfaces. The characteristics of the 44 national and municipal roads (0.7% of the total number of roads in the traffic network), that were found to be impassable or suffer slower traffic because of a 20-year flood, are listed in Table 3. It is worth noting that the capacities and the location of the flooded links in traffic is more crucial and effective than their proportions. Previous research on integrating traffic models and flood events employed a static flood map [17; 18]. This method is inadequate to represent how flood dynamics change the traffic flow because flood development affects the sequence of the street closures and it is crucial for traffic simulation. Flooding could not be characterized as a binary problem in a transport model, which may be addressed using a start and end of a single flood map. Therefore, one could argue that the given results with different closure periods may be equally correct or incorrect. However, the potential vulnerable locations of the \begin{table}
\begin{tabular}{c c c} \hline
**Flood Depth (m)** & **Maximum Vehicle Speed (km/h)** \\ \hline Depth \textless{} 0.1 & Road Speed Limit \\ \(0.1\leq\text{Depth}<0.3\) & 20 \\ \(0.3\leq\text{Depth}\) & 0 (Road Closed) \\ \hline \end{tabular}
\end{table} 
Table 2: Flood depths’ effect on traffic flows. \begin{table}
\begin{tabular}{c c c c} \hline
**Number of** & **Proportion to the** & **Length of Streets** & **Proportion to the** \\
**Strees** & **Whole Network** & **(m)** & **Overall Length of** \\ \hline Closed streets & 38 & 0.6\% & 231,798.4 & 2.8\% \\ Reduced speed streets & 6 & 0.1\% & 2330.7 & 0.02\% \\ \hline \end{tabular}
\end{table} 
Table 3: Number and length of flooded or reduced speed streets. Deep flooding (over 0.3 m) will result in street closures, while shallow flooding (0.1-0.3 m) will cause traffic to proceed more slowly. transport network could be pointed out. This section describes the flooding impact on traffic considering a dynamic integration between the flood and traffic models. For representing the flood influence in the traffic simulation during a flooding day, the dynamic integration of flood and traffic should be considered. To do so, the traffic model was updated every hour with flood propagation information to provide a spatial and temporal variation of both speed reductions and street closures. The whole period of the simulated flood was one day (24 h). The impact of flooding on the transport system is expressed by rerouters so that vehicles passing through the flood would need to change their routes. Therefore, the initial perturbation in the network can be defined as the number of rerouted cars. Figure 6 shows the change of rerouted vehicles during the day as a direct consequence of the traffic demand changing, the number of street closures, and the spatial dimension of street closures. For example, there was a considerable demand around 9:00 h, even though just in the upper catchment some streets were flooded and did not affect many trips, but as a result of the flooding on the main road, there was an increase in the number of vehicles that were rerouted. As it is shown in Figure 6, because of the non-constant demand during the day, the frequency of closed streets forced cars to be rerouted in a nonlinear manner. Given the fast changes in traffic demand around 13:00, the maximum street closure affected about 5000 vehicles.