# A Practical Approach on Reducing the Flood Impact: A Case Study from Romania
## 2 Study Area and Data Series
### Methods  
Figure 5 shows the stages of our study, starting from its goal, which is to determine factors that favor flood hazards, then quantifying the damages and providing a solution to reduce their impacts on settlements and terrains [36]. First, it was necessary to identify and confirm the risk via field trips and collecting data. Then, this study involved data analysis, developing hazard maps, quantifying damage, and proposing solutions. The fieldwork consisted of identifying the railway embankments, bridge position, number of pillars, and proximity of the buildings to the Varbilau River, their destination, and the land use. Pictures have been taken to support the research. Available data, such as the floods with an exceedance probability of 1%, the embankment length, and the bridge opening, were analyzed to prepare for the following stages [37]. The flood hazard maps were designed for the following scenarios:  
1. The current situation, called Scenario 1, involves the bridge having three pillars, a 100 m opening, and the existing embankments. The bridge is designed to resist floods with an exceedance probability of 1% [38; 39; 40];
2. The proposed solution, Scenario 2, involves entirely removing the embankments and replacing them with the railway bridge, resulting in an opening of 280 m. Seven more pillars are added to the existing three. This is the extreme case. The opening length of 280 m is chosen because it is close to the width of the flooded zone upstream of the rail bridge;
3. An intermediary case, called the intermediary scenario, when the opening is widened, resulting in a bridge with an opening of 200 m and seven pillars. This scenario was proposed with the goal of a possible cost reduction but a sufficient enlargement. Therefore, doubling the bridge length is proposed. This solution also supposes building four more pillars. Still, the optimum number of pillars and the exact length of the bridge should be determined to comply with the design norms [38; 39; 40], as well as the cost and estimated damages. This analysis will be the object of another analysis, as already mentioned in the Introduction. Figure 5: The study flowchart. All scenarios are applied to the flood with an exceedance probability of 1%. Damage evaluation was performed for each case. We used GIS data (Digital Terrain Model of Romania or short DEM, shapefiles), data available on the site inundatii.ro and the Romanian Waters National Administration, and data obtained through fieldwork and GIS measurements. The Stereo 1970 (31700) coordinate system was utilized [41]. The resolution of the Digital Terrain Model was 30 m. According to [42; 43], a higher resolution implies a better representation of land features compared to a lower resolution that smooths the details. It enables users to have a consistent view of water surfaces and, therefore, can be used to indicate flood-prone zones. Extended descriptions of the methodology, data collecting, and step-by-step computational details are presented in [44]. The software utilized was the Geographic Information System ArcGIS 10.2.2 (ArcMap and ArcScene), the 2D hydraulic modeling software HEC-RAS 6.2, the HEC GeoRAS extension (to export data from ArcMap to HEC-RAS 6.2), and the RAS Mapper extension (employed to export data from HEC-RAS 6.2 to ArcGIS 10.2.2). Steady flow was used to simulate the flooding. Therefore, the application will show the flooding expansion. Manning's coefficient was introduced based on the terrain. The \"\(n\)\" value belonging to Manning's equation was also set in HEC-RAS. Thus, for the thalweg, the correspondent to a gravely, the earth surface was entered, while for both banks, the values for grass and earth terrain were also entered. Leveses, the equivalent of embankments, have been added into HEC-RAS to see how the flood band will look with embankments considering different openings: 100 m, 280 m, and 200 m. The flow values have been added to observe the flood bands.