A comparative study on floodplain pathology in Iranian rivers (case study: Cheshmeh Kileh, Tonekabon city)

This research makes a comparative analysis of three flood-related topics: (1) existing regulations concerning flood management, (2) flood zone modeling using software, and (3) the historical development of urban fabric within flood zones. The study, employing a mixed-method approach, focuses on Cheshmeh Kileh River and its surrounding urban space in Tonekabon, Mazandaran Province, Iran. First, relevant Iranian documents and regulations on flood risk mitigation were reviewed. Then, GIS software and one-dimensional mathematical modeling were used to map the boundaries of floodplains for various return periods. Finally, historical aerial images from three time periods (1969, 1994, 2014) were analyzed to generate a historical map of urban development around the river. The findings revealed that the officially designated river buffer areas do not align with the actual flood hazard zones on the ground. Despite legal definitions of river buffer boundaries and growing public awareness of the risks associated with construction near hazardous areas, illegal construction within these zones in Iran has increased exponentially over the past 6 decades. Notably, the last two decades have seen a staggering 505% rise in construction within flood hazard zones. Based on the findings, the factors that increase vulnerability include: (1) failure to enact or timely enact construction management laws in floodplains of urban rivers in Iran, (2) failure to use scientific methods to determine boundaries in the enacted laws, and (3) failure to comply with the River Privacy Law, all three of which require very serious revision.