A framework to support the urbanization process on lowland coastal areas: Exploring the case of Vargem Grande – Rio de Janeiro, Brazil

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Urban growth usually triggers environmental imbalances. When the supporting capacity of the watersheds is surpassed, both the natural and the built environment degrade in a negative cycle. In this context, integrating a sustainable urban drainage approach with river restoration concepts, this work proposes a set of guidelines composing a framework to support the urban growth process in lowlands of coastal cities, combining social and natural demands, and improving city resilience to floods. Different tools including mathematical modeling and multi-criteria indexes were combined in this framework and then tested in an exploratory case study in the Vargem Grande district, an expanding coastal area in the west zone of Rio de Janeiro/Brazil. A computational hydrodynamic model –called Urban Flow-Cell Model has been used to provide information on impacts generated by the changes of the urban configuration in the region of interest. The Flood Risk Index and the Urban River Restoration Index were applied to assess risk and estimate environmental restoration effects quantitatively. The results for the applied framework show that sustainable drainage concepts in combination with river restoration measures can support the expansion of the city, meeting social and environmental demands. The expanding area considered in the case study could grow safely when oriented by the proposed framework, while the flooding results could be dramatic worsened in an uncontrolled development.