L-moments based regional frequency analysis on 1D flood analysis by solving regular energy equations in the urban areas

The aim of this study was to employ flood frequency analysis integrated with GIS and HEC-RAS models to provide hazard maps for various return periods of flood discharge in the Değirmendere Basin, Trabzon, Türkiye. Point and regional flood frequency analyses were performed to estimate the flow rates for varying return periods. The L-moments method was used to calculate the distribution parameters of the annual maximum flow data from the regional stations. Based on the results of the regional flood frequency analysis, the HEC-RAS computational fluid dynamics software was employed to simulate the water surface profiles of Değirmendere using the mass conservation/momentum equations under steady flow conditions. Flood hazard maps were developed for flow rates with varying return periods. The results of the model provide a good representation of the flood risk region based on the detailed analysis of flood quantiles. The findings of this study can be used to inform flood management strategies and to enhance the resilience of urban regions to flood events.