1 dimensional flood modelling of Değirmendere

In this study, one-dimensional flood modeling was carried out for the Değirmendere/Trabzon includes the length of 18.6 km starting from Esiroğlu Treatment Plant, covering part of the city center and reaching to the Black Sea. Point and regional flood frequency analysis was performed to calculate the various flood quantiles to be used in the analyses. Within the scope of regional frequency analysis, the distribution parameters of the annual maximum flow data of the stations in the region were calculated by the L-moments method. As a result of the analysis, the flood flow rates for return periods of T=2, 5, 10, 25, 50, 100, 200, 500 and 1000 calculated with the regional flood frequency analysis method were used in the flood modeling analysis. By using the HEC-RAS computational fluid dynamics software, the route of the main channel of the river was determined, the bottom elevations and river sections were obtained. Then the roughness coefficients were defined, and the roughness map was also obtained. Flood flows with different returning periods are modeled under steady flow conditions using the mass conservation/momentum equations. As a result of the analysis, water depths and areas to be flooded were determined for flow rates with different returning periods. Then, improvement suggestions were made in order to prevent possible floods in the region. Key words: L-moments, flood modelling, steady flow, HEC-RAS, water surface profile, Değirmendere