Abstract: This study constructs a HEC-HMS model to simulate flood hydrographs to examine the effect of DEM data sources and resolutions on the simulations. We take an ASTER 30 m digital elevation model (DEM) and unmanned aerial vehicle (UAV) 3D tilt photography 7 cm high-resolution DEM as the data sources, and obtain ten DEMs with the resolutions of 1m, 5m, 10m, 20m and 30m by resampling. This method has been applied to 20 flood events in the semi-arid and sub-humid Liulin watershed of the 1995-2021 period. The results show that the model constructed by the 1m resampling DEMs from the 7 cm high-resolution data sources has relatively good performance; its mean relative errors are 16.4% and 15.7% for flood peak flow and runoff depth simulations, respectively, with a mean NSE value of 0.657. For the ASTER 30 m DEMs-based model, its errors are 16.0% and 18.7% and its mean NSE value is 0.646. The other DEMs-based HEC-HMS models, featured with different resolutions and data sources, show little difference in flood simulations.

Key words: HEC-HMS hydrological model, digital elevation model, data source, resolution, resample, flood hydrograph simulation