Prioritization of Bottlenecks in the Main Stormwater Collection System for Rehabilitation Measures, Case Study: Tehran Catchment, Iran

Urban drainage Systems are of the vital infrastructures, which are responsible for the safe transport of runoff. In recent decades, the increase in surface runoff has led to inadequate capacity in some parts of drainage network, which results in over-flowing. Land use and population density around these areas pose a high risk of loss of lives and injuries. Since in previous studies, vulnerability indicators were not considered in the assessment of bottleneck’s risk, in this study, hazards and vulnerability indicators are combined together for calculating the risk index which is used for the prioritization of bottlenecks. In order to prioritize the bottlenecks of urban drainage system in Tehran catchment using the Simple Additive Weighting (SAW) method, the hydraulic modeling and Analytic Hierarchy Process (AHP) has been used for calculating the weight of indicators. For this purpose, five indicators have been defined which are population density around the bottlenecks, density of properties and diversity of land uses at these areas, average percentage of canal/main channel river filling, degree of bottleneck submergence, channel or river rank and flow velocity in canal/river. The results showed that the major critical bottlenecks are located in the eastern sub-basin of Tehran: in Abuzar, Maghsoudbeig and Bakhtar canals.