Evaluating the effects of topographic and radar based DEMs on the simulation results of geomorphologic models

In recent years, Radar based DEMs due to ease of access and being free of charge are extensively used in hydrological modeling and deriving the geomorphological properties of watersheds. One of the most important questions on application of rainfall runoff models is the effect of DEMs from different sources on simulation results. On this basis, this research focused on evaluation of the effects of DEMs derived from topographical maps at the scale of 1: 25000 and the SRTM DEM, on the performance of the KW-GIUH as a geomorphologic rainfall runoff model. The results showed that the SRTM DEM gives sub-watershed's slope, the average slope of channels and the number of channels more than that was derived from topographic based DEM, while the overland flow length and average length of channels from the latter source are greater. The outcomes of the research showed that the Q-peak, hydrograph base time and the slope of hydrograph rising limb from Radar based DEM regarding different thresholds for artificial channel network derivation have a difference of about 1-12% with that was obtained from the model when using the topographic based DEM.