The challenges of urban river restoration and the proposition of a framework towards river restoration goals

Abstract

River restoration is gaining significance as an approach for river system management, even in urban areas, where the flood risks and morphological imbalances are more evident. In cities, the highly modified environment and the lack of open spaces make it harder to apply the concept of river restoration in its whole extent, raising doubts about the feasibility of adopting restoration approaches for urban rivers. In some cases, the implementation of green and blue infrastructure strategies alone is not enough to support the river restoration goals so the adoption of gray infrastructure is necessary. In order to explore aspects related to the theme, this article discusses four questions proposed from a bibliometric study of urban river restoration: Is it worth restoring urban rivers? How much does it cost? If the watershed is heavily modified, can it sustain the restored fluvial spaces? How can the success of this approach be measured? Throughout the discussion, it is clear that due to cities’ complexity and the absence of available open spaces, there is no simple answer to these questions, each case being unique and deserving particular assessment. However, even when performed partially, without significant positive impacts on the natural environment, river restoration can bring several benefits to the urban environment, creating an opportunity of reintegrating the river as a valuable element of the landscape. Additionally, we propose a framework to assist managers in identifying and implementing potential river restoration actions.