Preparation and analyzing of flood hazard map using HEC RAS hydraulic model and Auto CAD Civil3D In the RAS Mapper ( A case study: Sokecham River)

Floods are natural disaster that can endanger lives and property infrastructures in the urban and rural area. The main aim of this study is to analyze the flood risk elements and prepare a flood risk map in the Suk Cham River basin located in Kashan city, Isfahan province. For this propose, a topographic map was prepared for the study period using Google Earth and Gloobal mapper software. The prepared topographic map then was transferred to AutoCAD Civil 3D software to construct the surface and cross sections. To simulate floods in the return period of 25, 50, 100, 200 years, the cross sections were transferred to HEC RAS software. Kolmogorov–Smirnov test was used to convert the maximum daily flow to the maximum instantaneous according to the P-value. The results of flood frequency analysis showed that the log Pearson type III distribution is the most suitable distribution to estimate flood level in difference return periods. According to the results, the flood surface zones were 0.77, 0.9, 1.15, 1.47 square kilometers for the return periods of 25, 50, 100, 200 years, respectively. The results also shows that 41.5 and 4.5 percent of the two villages surface (Khancheh and Baronagh; villages located next to the river) are at moderate to very high flood risk in the 100-year return. Keywords: Flood Risk Map, Hydraulic Model, AutoCAD Civil 3D, Suk Cham River Watershed Keywords: Flood Risk Map, Hydraulic Model, AutoCAD Civil 3D, Suk Cham River Watershed .