An Investigation on the Effects of DEM Creation Methods on Performance of the TOPMODEL

Digital Elevation Models (DEMs), due to their simple structure and high performance, are favorably being used for rainfall runoff modeling in modern hydrology. There are different methods for DEM creation via topographical data interpolation. To create DEM in this research, 6 different methods of IDW, Kriging, and Co-Kriging, embedded in ARCGIS, were used. The TOPMODEL which is a semi distributed topographic-based rainfall runoff model were investigated to search about the effects of the DEM creation method on the results of these types of models. The results showed that the TOPO index, as the most important basic parameter for the TOPMODEL, is highly sensitive to the DEM creation method. The consequences of this sensitivity, was illustrated by different extent and distribution of the saturated zones across the watershed. Accordingly, the amount of surface runoff was highly affected by the DEM creation method, while this effect on the total amount of river discharge was negligible and the Nash- Sutcliff index variation could be ignored.