# Evaluation of Different Simulation Methods for Analyzing Flood Scenarios in the Danube Delta
## 5 Discussion  
After running the software, 64 flood scenarios resulted (32 scenarios for each method), and the most relevant results were extracted for the eight settlements from the Danube Delta targeted in the present work. The results were maps illustrating the potentially floodable areas of the analyzed settlements in the Danube Delta. In more detail, the flooding maps obtained in the present study were overview maps that showed, for each flooding level considered, the flood boundary, which represents the extent of the water for each case (scenario) considered, and the depth or water level, depending on the method. The flooding maps resulting from the application of the dynamic method had a depth class of 0 to 2 m. The flood maps resulting from the static method established the depth as the difference between the considered water level of the flooded surface and the ground level (the elevation of the terrain on the digital terrain model expressed in the Black Sea reference system 75). In approaching the dynamic method, the hydraulic scenario set was developed using the hydraulic model of the Danube Delta to determine the flood surfaces for each settlement. In both methods, the historical maximum level reached in the summer of 2010 was considered for all localities. The results of applying the maximum level were reflected in the flood-stage IV. Subsequently, to obtain flood scenarios at lower water levels than in 2010, flood stages (Table 4) were applied (the differences being a few centimetres or tens of centimetres from the peak), and so several flooding map scenarios resulted for each settlement analyzed, as presented in Figures 11-13. All of these in case of failure of the  
Figure 10: The boundary representation of the flow surface for each settlements: Partizani, Ilganii de Sus, Vulturu, Maliuc, Mila 23, Gorgova, Crisanand Sulina. protective dam. The scenarios in flood stage I corresponded to the lowest level of flooding, while the scenarios in flood stage IV corresponded to the maximum level of flooding, and the scenarios in flood stages II and III corresponded to the intermediate levels of flooding, between the maximum and the lowest level. The most useful way to visualize the results of the hydraulic modeling and GIS processing was with the help of maps, thus being able to refer both to the development in time and in space of the phenomenon. With the help of the hydraulic modeling software, in the first phase, the flood limits (as maps) and the flooding process could be extracted (the scenarios can also be viewed as video). Next, with these results, further processing or interpretation was done in GIS, and other specialized programs. Figure 11: Flood scenarios maps for Partizani (first column group of subfigures), Ilganii de Sus (second column group of subfigures), and Vulturu (third column group of subfigures) settlements, corresponding to the condition of 7 July 2010, by using the 1D/2D HEC-RAS model, at high resolution DTM 0.5 m \(\times\) 0.5 m, dynamic method. Figure 12: Flood scenarios maps for Maliuc (first column group of subfigures), Mila 23 (second column group of subfigures), and Gorgova (third column group of subfigures) settlements, corresponding to the condition of 7 July 2010, by using the 1D/2D HEC-RAS model, at high resolution DTM 0.5 m \(\times\) 0.5 m, dynamic method. The results were presented by Ras Mapper, using the hydraulic model 1D/2D HEC-RAS at high resolution (DTM 0.5 m \(\times\) 0.5 m). Figures 11-13 present the propagation trend of the flood surface depths over the flooded area, after 24 h from the beginning of the simulation. The elevations used in the data processing with the dynamic method were referenced to the Black Sea 75 system (BS75).