Water dynamics and blue-green infrastructure (BGI): Towards risk management and strategic spatial planning guidelines

Abstract

This work aims to demonstrate the importance of concretely defining blue-green infrastructure (BGI) in non-consolidated urban areas as an active element to achieve integrated risk management and strategic spatial planning guidelines to structure future urban development. BGI is seen as a city's structuring element more than an element integrated into a city. For this, a method is proposed and a demonstration of its application is conducted for the city of Paraty, in Brazil. It starts with a diagnosis of the current situation, maps the conflicts experienced by the city regarding water dynamics, and establishes cause-effect relations. Then, the past reference situation and the future trend situation are evaluated, and, with lessons learned, a future urban occupation alternative is defined, using BGI and river restoration approaches. Finally, the two future situations are compared in terms of environmental enhancement. The analyses are supported by mathematical modelling and a multicriteria index (Urban River Restoration Index). The results indicate that the future trend situation worsens flood risks, while the BGI proposal reduces them, besides improving the watersheds environmental quality and setting strategic spatial planning guidelines. Thus, understanding the role of water in a city is crucial to define a BGI approach focused on delivering urban water management solutions and strategically structuring future urban development, being the water a structural part of the city itself.