Civil and Geoengineering Letters Editorial Office info@jcivilgeo.com mEDRA 20260525 DOI Registration 01

06 10.22034/CGEL.3.1.e100051 https://jcivilgeo.com/article/e100051 Civil and Geoengineering Letters mEDRA 01 01 3115-8129 Civil and Geoengineering Letters Editorial Office IR 01 3115-8129 JB 3 1 01 202605 1 1 A01 Mohammad Yazdani Yazdani, Mohammad Mohammad Yazdani 2 A01 Shabnam Sadegi Sadegi, Shabnam Shabnam Sadegi 3 A01 Zeynep Arslan Arslan, Zeynep Zeynep Arslan 4 A01 Nader Azimi Azimi, Nader Nader Azimi 01 eng 202605 03 00 Among natural disasters, floods, earthquakes, and droughts are of particular importance due to the financial and human losses they cause. In fact, natural disasters result from the interaction between human activities and random natural phenomena. This point is especially significant in the case of floods due to the relative concentration of human economic activities in floodplains. Given that floods cause considerable financial and human losses around the world every year, the importance of flood control and damage mitigation becomes evident. Furthermore, identifying inundated land uses is essential for effective urban management and planning strategies. In this study, the HEC-RAS hydraulic simulation model was used to simulate floods with different return periods, predict flow behavior, and perform flood zoning. The GIS (Geographic Information System) was employed as a tool to link flood modeling outputs and calculate the floodplain area for the inundated zones. The case study focuses on the urban flood of the Western Flood Diversion Channel located in Tehran, Iran. Using the 2D HEC-RAS model, floodplains corresponding to various return periods were determined. These were then analyzed in GIS using regional digital elevation model layers to derive the flood extent for each return period. The results indicate that with an increase in the flood return period, the channel is unable to convey the incoming flow, leading to a significant expansion of the floodplain and a greater number of land uses being submerged. 20 Flood zoning; 2D Hydraulic simulation; HEC-RAS; ArcGIS 01 00 20260111 02 00 20260320 2026 Nader Azimi