Determination and comparison of flood mitigation measures with distinct river basin characteristics

Sungurlu River is located northeastern part of İstanbul. Sungurlu River disembogue into the Black Sea where Ağva Town is located. This small town is already a tourist attraction for people from İstanbul and also has a great potential for increase in touristic attractions. Therefore, modifications in riverine environment could have detrimental social and economic impacts on the town, which makes nature-based solution (NBS) a supportive measure for flood risk management for study area. In this study, Sungurlu River and Ağva Town is analyzed in regards of flood risk and locations have flood hazard is identified. Hydraulic modelling is completed with HEC-RAS software with full two-dimensional flood modelling. High resolution LiDAR based DEM data, hydrologic data and river bathymetry are obtained from administrations, which increased the accuracy of this study significantly. As per results of the flood hazard analysis, three flood mitigation alternatives were proposed, one with traditional grey infrastructure, other one with only NBS and the last one is a hybrid solution. Performance of these alternatives were evaluated with multi-criteria analysis. As a result of the evaluation, it was concluded that the most suitable alternative for the study area is only traditional and hybrid solutions.