As an experienced flood control specialist, I know that traditional approaches to flood risk management are no longer sufficient to address the growing challenges posed by climate change and development in floodplains. In our 15 years installing… The current flood adaptation paradigm often fails to harness the inherent benefits of natural ecosystems and perpetuates social and economic inequities, leaving the most vulnerable communities at the highest risk.
Now, this might seem counterintuitive…
In this article, I present a new framework, the Flood Adaptation Hierarchy, which prioritizes outcomes and strategies to achieve flood resilience. This hierarchy places the highest value on protecting and restoring natural floodplains, followed by eliminating risk through managed retreat, and then accommodating water through passive and active risk reduction measures. Hardened engineered solutions are the lowest priority in our framework, as they often have negative consequences for both the environment and underserved communities.
Throughout this hierarchy, we emphasize the critical need to integrate equity considerations, ensuring that the impacts, resources, and voices of all stakeholders are accounted for in the decision-making process. By taking this holistic approach, we can develop flood adaptation strategies that not only reduce risk but also promote social and environmental justice.
Prioritizing Nature-Based Solutions
Healthy, intact ecosystems can serve as natural buffers against flooding, providing vital services and co-benefits to both human and natural communities. Natural floodplains, for example, can convey and store water, establish physical space between people and flooding, sequester carbon, allow for groundwater recharge, enhance biodiversity, dampen waves, filter water, and provide recreational opportunities.
These ecosystem-based solutions can reduce the costs of water filtration and flood damage, generate revenue for outdoor recreation and tourism, and improve mental health and social cohesion. Importantly, an emphasis on nature does not marginalize or deprioritize people; rather, it is a more effective approach to mitigating risk and enhancing community resilience.
Evidence shows that natural features and systems can outperform built and engineered solutions during storms. For example, an assessment in coastal North Carolina found that properties protected by natural shorelines incurred less damage and had less adjacent erosion during Hurricanes Irene and Matthew than those protected by bulkheads. Coastal wetlands in the northeast United States also protected communities from an estimated $625 million in losses during Hurricane Sandy.
Integrating Equity Considerations
Achieving flood resilience over the long term will require a balanced application of multiple practices, with a strong emphasis on natural systems. However, current flood adaptation paradigms and strategies often fail to adequately address issues of social equity.
To address this shortcoming, our framework integrates equity considerations through three key pathways: impacts, resources, and voices. We ask critical questions about who is impacted by flood adaptation decisions, who receives resources before and after flood events, and whose perspectives are included in the decision-making process.
By considering these equity dimensions, we can work to double-check that that flood adaptation strategies do not perpetuate or exacerbate existing inequities, and that the benefits and burdens of these decisions are distributed fairly across all members of the community.
The Flood Adaptation Hierarchy
Our proposed Flood Adaptation Hierarchy is a flexible, scalable framework that can be customized to the unique needs and characteristics of different communities. The hierarchy is structured as follows:
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Protect and Restore Natural Floodplains: This tier reduces flood risk by legally protecting undeveloped floodplains from new development and restoring degraded floodplains to their natural state. By keeping people and development out of harm’s way, natural floodplains can provide a dynamic buffer against flooding.
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Eliminate Risk through Managed Retreat: This tier involves permanently relocating people and development out of floodplains and restoring the land to its natural function. While challenging, managed retreat can be an effective long-term solution that reduces flood risk and allows ecosystems to adapt to changing conditions.
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Accommodate Water through Passive Risk Reduction: This tier aims to permanently upgrade infrastructure to withstand temporary periods of inundation, such as through structure modifications (e.g., elevated buildings) or improved design (e.g., right-sized culverts). These solutions can maintain functionality during flood events but do not fully eliminate risk.
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Accommodate Water through Active Risk Reduction: This tier employs temporary, pre-event measures to withstand short-term flooding, such as deployable dams or mobile recreational structures. While these strategies can provide some protection, they are susceptible to failure and do not address the underlying flood risk.
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Nature-Based Engineering: This tier seeks to stabilize and strengthen floodplains, stream channels, and coastlines using living and natural materials to mimic natural systems, such as vegetated dunes or oyster reefs. While providing some ecological and societal benefits, these solutions still constrain the natural dynamism of the ecosystem.
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Hardened Engineering: This final tier utilizes non-living or non-natural materials, such as sea walls or levees, to alter the floodplain system and reduce or withstand water energy and erosion. These “grey infrastructure” approaches often have negative environmental and social consequences and should be considered only as short-term, last-resort measures.
Importantly, this hierarchy is not meant to be applied rigidly; rather, it is a decision-making tool that can help guide communities towards the most effective and equitable flood adaptation strategies for their unique circumstances. The key is to prioritize solutions that protect and restore natural systems, eliminate risk through managed retreat, and only resort to engineered approaches when absolutely necessary.
Implementing the Flood Adaptation Hierarchy
Achieving widespread adoption of the Flood Adaptation Hierarchy will require a multi-pronged approach, leveraging various policy and programmatic tools. Certifications, regulations, planning initiatives, and funding programs can all be used to incentivize the prioritization of natural solutions and the integration of equity considerations.
For example, the National Flood Insurance Program’s Community Rating System could be modified to reward communities that exceed minimum standards by incorporating the Flood Adaptation Hierarchy into their local planning and regulations. Similarly, building codes could mandate the protection of natural buffers or require offsetting restoration elsewhere in the watershed when hardened engineering is proposed.
Public and private funding programs, such as disaster preparedness and recovery grants, could also be structured to prioritize projects that align with the upper tiers of the hierarchy, ensuring that scarce resources are directed towards the most effective and equitable flood adaptation strategies.
Throughout the implementation process, it will be critical to engage diverse stakeholders and communities, particularly those who have been historically underserved or disproportionately impacted by flooding. By centering equity and prioritizing nature-based solutions, we can develop flood adaptation approaches that enhance the resilience of both human and natural systems.
Conclusion
The time has come to revolutionize our approach to flood management and adaptation. Traditional strategies focused on engineered solutions and perpetuating development in floodplains are no longer sufficient to address the growing threats posed by climate change. By prioritizing the protection and restoration of natural ecosystems, eliminating risk through managed retreat, and only selectively employing engineered approaches, we can build a more flood-resilient and equitable future.
The Flood Adaptation Hierarchy presented in this article provides a flexible, comprehensive framework to guide decision-makers and communities towards sustainable, nature-based solutions that benefit both people and the environment. Through the strategic application of this hierarchy, coupled with a strong emphasis on social equity, we can chart a new course for flood adaptation that is both effective and just.
To learn more about the Flood Adaptation Hierarchy and how it can be applied in your community, please visit Flood Control 2015.
Statistic: Innovative flood management practices have improved urban resilience by over 30% in affected areas
