## 2 Materials and Methods
### Methodology and Database  
The development of flood hazard and risk maps should show several important elements of flood scenarios: flood extent, water surface elevation, water depth and flow at different critical cross sections. In order to achieve the main purpose of this work, several methodological steps have been followed (Figure 2). The first stage consisted of delineating the 1% floodplain using the HEC-GeoRAS extension for Esri ArcGIS v.10.8 and HEC-RAS v.5.0.7. The numerical elevational terrain model used to build the hydrographic database and finally the 1% floodplain was designed with a spatial resolution of 5 m and a discretization error correction coefficient of 0.5, by interpolating the levelling and drainage network taken from military topographic maps at a scale of 1:25,000 [57], with a contour equidistance equal to 10 m. The interpolation method was specifically designed for the creation of hydrologically correct digital elevation models (DEMs) and implemented in ArcGIS/ArcMap software that is accessible through the Topo to Raster tool. It is based on the ANUDEM program developed by [PERSON] (1988, 1989, 1996, 2000, 2011) [30]. The first sub-stage consisted of the creation of the bed geometry elements using the HEC-GeoRAS extension for Esri Arc GIS. The hydrographic database was obtained: the hydrographic network (Stream Centerline), the banks of the drainage channel (Bank Lines), the 20,401-meter-long Flow Path Channel, the maximum extension of the study area (Flow Paths Left and Right) and 139 of the cross-sectional profiles of the computational sections (XS Cut Lines). After the creation of the attribute database, specific to both the hydrographic network and the cross-sectional profiles, the databases were exported from the shapefile format (.shp) to the RAS data format, to be run and used in the HEC-RAS program. Figure 1: Location of the 1% floodplain on the Turcu River (Olt basin) from the Bran–Dragoslavele Corridor (Romania). Figure 2: Methodological Workflow. The second sub-stage allowed the determination of the water level in the profiles based on the Manning equation (Q = A/n \(\times\)R% \(\times\) S%, where Q is the river flow, A--the surface of the drainage profile, R--the hydraulic radius, S--the bed slope and n--Manning's roughness coefficient) implemented in the HEC-RAS program. The following operations were performed to accomplish this: importing the GIS databases (obtained in the first sub-stage) related to the riverbed geometry through the Geometric Data module; filling the tabular database with Manning's roughness coefficient [53; 58] for each profile (for riverbed, left and right banks/sides); performing the flow calculations and tabulating them for each profile in the Steady Flow Data module; performing the bed slope calculations (downstream-downstream and upstream-upstream) for the 11 sectors of the slope network, followed by entering the results in the Steady Flow Data module window. Water level results were obtained for each profile by running the hydraulic model in the Steady Flow Analysis module. The third sub-stage allowed for the visualization of the hydraulic model results (HEC-RAS); export of the databases from RAS format to GIS format (.shp) to be imported, run and used in the HEC-GeoRAS extension; modeling of the 1% floodplain, resulting in vector and corresponding raster databases. In the second stage, a flood hazard map was produced for the Turcu River in the 1% floodplain area, as previously defined.