Flood Vulnerability Assessment in Northwestern Areas of Tehran

Abstract

Many factors affect the flood vulnerability of the northwestern areas of Tehran. Urban infrastructure and the development of urban areas in river basins have changed the natural drainage patterns in the region. This has resulted in flooding, inundation, and higher costs for urban maintenance. Tehran is located on the southern slopes of the Alborz mountain range and downstream from several basins. The expansion of the urban area into elevated areas has exposed the city to many disasters including flooding. Districts 2 and 5 in the northwestern area of Tehran are vulnerable to floods because of their close vicinity to expansive basins, a high proportion of construction projects, a high population and housing density, land use changes, the development of the urban areas in river basins, and the unsuitable exploitation of watercourses. This research used topographic, land use, climatic, and hydrometric data. Criteria were selected, weighted by an analytic hierarchy process, and combined by fuzzy functions to obtain a vulnerability map. To understand the significant factors, we applied water profiles and hydrographs to determine priorities through a multi-layer perceptron network. The final vulnerability map indicated that the most vulnerable areas are outside the urban lands near the river channels. The results also indicated that a combination of urban factors and drainage basin agents intensified the vulnerability of the study area. Although the near channel areas outside the urban areas are more vulnerable to flooding, other factors, including deteriorated fabric, curvature profile, and curvature, are significant in urban areas.