Evaluation of the Two-Dimensional Hydraulic Model LISFLOOD-FP in Floodplain Predictions of Various Return Periods

Hydraulic models are the primary tools used to plan and develop structural and non-structural flood management and mitigation methods. The purpose of employing such tools is to simulate flood damage in a given area, depending on several flood scenarios with various intensity, duration, and return periods. Recently, raster-based hydraulic models have been considered in modeling the determination of floodplain and flood hydraulics. In this paper, a 2D hydraulic model, i.e., LISFLOOD-FP was applied to predict floodplains of various return periods over a 4.5 km reach from the Khorramabad River in Lorestan province. The model was calibrated based on a flood event using the parameters of floodplain and channel roughness coefficients against the observed floodplain depth at the hydrometric station. The roughness coefficient parameters were estimated by the calibration process to minimize the relative error (E) index between the observed floodplain depth and the predicted depth. This model was validated using two separate flood events. The relative error (E) index was 2.9% at the calibration stage and 1.7 and 15.4% at the validation stage for both flood events. Finally, the calibrated model was used to predict the floods of various return periods.