Preparation and analysis of flood risk map using HEC RAS and RAS MAPPER hydraulic model (Case study: Sok Cham river of Kashan).

Floods are a common natural disaster that can endanger urban and rural infrastructure. The purpose of this study was to prepare and analyze the flood risk map of Khancheh and Baronagh villages along a part of Suk Cham river. First, the topographic map was created using Google Earth and Global mapper. Then, using a topographic map made in AutoCAD Civil 3D software, the surface was created for the study interval. In the next step, using the constructed surface of cross sections, longitudinal profiles, river channel, right, and left flood banks of Suk Cham river were constructed in AutoCAD Civil 3D software environment. To simulate floods at return periods of 25, 50, 100, and 200 years, the cross sections were transferred to HEC RAS software. The Phil-Steiner method was used to convert the maximum daily flow rate to the maximum instantaneous flow rate according to the P-value of the Kolmogorov-Smirnov test (0.9). The results of flood frequency analysis showed that Pearson type 3 log distribution is the most suitable distribution. Based on the results, the flooding level for the return periods of 25, 50, 100, 200 years was 0.77, 0.9, 1.15, 1.47 km2, respectively. According to the flood risk map in the 100-year return period (high risk area), about 41.5% and 4.5% of the two villages of Khancheh and Baronagh had at moderate to very high risk of flood, respectively. Establishing coastal walls and organizing the river along the river route through these two villages is essential, which can mitigate the risks of floods. The use of prepared plans for flood control measures, flood forecasting and warning systems, flood insurance and in general for structural and non-structural flood control measures in the region is recommended. [ABSTRACT FROM AUTHOR]