This research investigates the hydrological and human variables contributing to northeastern Iran’s flooding. In the past few decades, the riverbed encroachment and urbanization increased the impervious area. This has increased exposure to floods and increased vulnerability. Due to the region’s mild summer climate and fertile soil for the cultivation of rice, this region has experienced land use change, population growth, and urbanization in recent years. Furthermore, the number of reported flood incidents and subsequent damage has significantly grown. In order to achieve this purpose, we explored how changes in land use and precipitation affected the highest levels of discharge. We compared the peak flood flow volume before and after the city’s expansion by using aerial photos and land use maps. Furthermore, the peak discharge’s sensitivity to the curve number (CN) was examined. According to the results, variations in rainfall have far less impact on the peak discharge rate than variations in the CN. Peak flood discharge can grow between 2.7 and 4 times with a 10% increase in CN, according to the results of the sensitivity analysis. As a result, it can be concluded that an increase in CN and encroachment on the riverbed is the main cause of flood damage and increased vulnerability.

Keywords