Research Information System
JOURNAL OF THE FACULTY OF ENGINEERING AND ARCHITECTURE OF GAZI UNIVERSITY, vol.40, no.4, pp.2205-2218, 2025 (SCI-Expanded, Scopus, TRDizin)
This study analyzes the flood in Cevizdere, Unye (Ordu) on August 8, 2018, aiming to produce flood hazard maps for return periods and to evaluate structural measures for future events. Flood observations from 2016 and 2018 supported model calibration and validation. Hydrological and hydraulic modeling used WMS, HEC-HMS, and HEC-RAS. First, the rainfall-runoff relationship was simulated in HEC-HMS with observed hourly rainfall data. The model was calibrated with streamflow from the August 8-9, 2018 storm and validated with the May 28-30, 2016 storm. The Nash-Sutcliffe (NS) efficiency was calculated as 0.78 for calibration and 0.57 for validation. HEC-RAS was used to simulate flood dynamics and delineate inundation areas for different return periods. Hazard maps were derived by combining modeled velocity and depth with standard hazard classes. The inundation area estimated for August 8, 2018 was 3.51 km(2); for the 500-year event it increased to 8.56 km(2). Analyses indicate that urbanization and channel modifications along the downstream corridor have amplified flood impacts. A structural measure to reduce damages from the 50-, 100-, 200-, and 500-year floods is proposed. The study also highlights the need to consider historical river courses and past settlement plans in flood modeling and mitigation.