A review of nature-based infrastructures and their effectiveness for urban flood risk mitigation

Anthropogenic climate change and rapid urbanization are contributing to more frequent and intense urban flooding. There is widespread agreement that traditional gray infrastructure, a single-purpose solution, fails to address the problem properly and contributes to adverse direct and indirect environmental impacts. As such, Nature-based Solutions (NbS) can provide improved outcomes to flood risk management along with co-benefits to society and the economy, as they have numerous benefits incuding often a smaller carbon footprint or even sometimes sequestering carbon. However, there is ambiguity and misconception about NbS and the uptake of NbS for flood management, which is still inadequate compared to traditional gray infrastructure. This research seeks to explore various nature-based infrastructures including their present status of application for flood risk management to build resilience to urban flooding through a systematic literature review. The robustness of some NbS is questionable and varies across different spatial scales from plot to watershed. NbS can work stand-alone in many cases as well as supplement traditional gray infrastructure to achieve wider benefits. The review provides a comparison of nature-based solutions with gray infrastructure, identifies flood mitigation infrastructures that include nature-based elements, and provides an overview of their effectiveness across different scales. The research findings should contribute to a better understanding of appropriate and diverse options of NbS, gray, and hybrid designs by policymakers and decision-makers to enable them in effectively designing and implementing urban flood risk mitigation measures. This article is categorized under: Climate and Development > Urbanization, Development, and Climate Chang Vulnerability and Adaptation to Climate Change > Learning from Cases and Analogies