The water and wastewater facilities’ vulnerability in North of Tehran against Runoff (ABFA region 1)

Urban runoff is one of the destructive phenomena, which can destroy urban structures. The facilities and equipment of ABFA in region 1 of Tehran are vulnerable for runoff during rainfalls due to the extent of upper field areas, high slope, increase of precipitation compared to other regions of Tehran, ground leveling, and inability of watercourses to surface water control. This study has been done using 10 meters resolution DEM, 1:100000 geologic maps, regional soil maps, statistical and meteorological data of study area between 1972 and 2013, population statistics of 2006, spatial data from aid and service centers, hazardous areas, and land use/land cover information. This research contains different steps. First, effective sub-criteria of vulnerability of the study are have been introduced. Then, they have been weighted using AHP-Fuzzy algorithm, and the impact of each criteria over the vulnerability of these parameters was defined using the TOPSIS algorithm. The results show the following parameters have the most impact over the increase of the vulnerability on northern part of Tehran, which all caused to prevent facilities installation in high depth: density of risk centers (gas stations and power transmission lines), urban decay, slope, relative population density, the facilities and equipment conditions (in terms of diameters and applied depth), and existence of north Tehran watercourses (Darakeh, Darband, Velenjak, Maghsoudbeyk, Jamshidieh, Darabad, and Larak). Furthermore, the results indicate that in case of an emergency in central, and northern part of study area, which have dense water supply installations, there are no specific places to install the emergency water supply structures. Contrariwise, in southern part of study area, having more urban green spaces lead to find more space to install the water supply structures in case of emergency.