Risk Assessment of the Urban Runoff Collection Networks Using Spatial Multi Criteria Decision-Making (Case Study: District 11 of Tehran)

Urban runoff management as well as collecting and transferring surface waters are the major concerns for officials and managers in urban affairs. The Multiple components of runoff drainage systems, the close interrelationships between the functionalities of the components and the relationship between the runoff collection network and the individual and social assets within the cities lead to a doubled complication in management plans. Flooding risk is generally subjected to numerous factors and the integrated management of these factors makes the urban runoff management a multi-criteria problem. The current research offers a comprehensive method for risk management in management of surface water collection networks. The necessary measures taken to implement this method include modeling the study area in Autodesk SSA software, specifying the layer of hydrology, hydraulics, social, traffic, environment, urban appearance and structures. Weights were extracted from the ideas inquired from the urban affairs experts and based on AHP multi criteria decision-making. Eventually, the map for canals’ flooding risk was generated by taking advantage of GIS capabilities and spatial MCDM methods such as SAW and TOPSIS. The implementation of the proposed method on degree 3 and degree 4 canals in District 11 of the Tehran Municipality is indicative of high and very high flooding risks for a length of about 6% to 9% of the total canals