DEM is the most important input of hydrological modeling. In this paper two DEMs are used to calculate some causative factors. SRTM DEM is used also to get a new flash flood hazard map for the same study area. Some of spatial maps for causative factor (which are dependent on used DEM like runoff, drainage density and surface slope) should be recalculated. Other causative factors (soil type, surface roughness, distance to main channel and land use) will remain the same for used two models, only their resolution should be adjusted to 90 m instead of 10 m. A threshold value of 15 square km2 is used in stream definition step for both used DEMs. Table 11 shows a comparison between drainage density and river lengths for both used DEMs. Maximum obtained drainage density from SPOT is almost two times than that of one SRTM.