Optimizing the location of the standard flood map in flood zoning using geomorphological characteristics

One of the new methods for flood zoning is Geomorphological Indexes (GI), which requires little hydraulic-hydrological data. In this method, the standard flood map for a small part of the studied basin is used to increase the accuracy.  The flood peak flows are different due to different standard flood map locations. Thus, the flood zoning results will be different. For this reason, it is necessary to select the best location for the standard flood map. In this research, the standard flood maps were used in the Kashafroud sub-basins including Radkan, Jaghargh, and Agh-Darband. The results showed that the Agh-Darband sub-basin located at the end of this basin had the best results for the standard flood map. The flood zoning results in the sub-basins showed flood zoning high accuracy based on the true positive rate (RTP), and the area under Curve (AUC) values. The flood risk maps results showed that 12.62, 16.30 and 24.64% of urban and rural regions will be exposed to flood risk for 25, 50, and 100-year return periods. The results of this study pointed out that the GI method can be used as an alternative to hydraulic and hydrological modeling for flood modeling due to its proper accuracy and low requirement for much hydraulic and hydrological data.