Effect of DEM resolution in flood modeling: a case study of Gorganrood River, Northeastern Iran

This study evaluated the efficiency of different Digital Elevation Models (DEMs), including ALOS-12.5 m, SRTM-30 m, SRTM-90 m, and ASTER-30 m v3 when being applied for the hydraulic simulation of flood inundation areas. HEC-RAS-2D model was employed to simulate inundation extent of a 400-year flood (Mar 17, 2019, with peak discharge ~ 547.92 m 3 /s) along 70 km reach of low-gradient Gorganrood River, northeastern Iran. Fit percentage indicator (FI) and BIAS percentage indicator (BI) were used to evaluate the results in comparison with the remotely sensed inundated area data. The results revealed that the accuracy and capability of the ALOS and SRTM-30 m were higher in simulation of flood extend area (FI ~ 52, BI ~ − 22) and in deriving peak discharge in downstream of the study reach (RMSE ~ 20%). The ASTER showed the worst performance in both floods extend area and peak discharge, despite dramatic improvements in the new version. The results of this study can be considered as a baseline for the selection of DEM sources for deriving flood inundation mapping.