Restoration or Flood Risk Management? Overcoming Challenges for an Urban River Restoration Project
Chelsey Radobenko, PE
Merrick & Company
Denver, CO
Authors: Wiese Moore, C., Radobenko, C., PE
Urban rivers have the potential to provide multiple benefits to urban communities, from riparian and wetland ecosystem functions to community enhancement and recreation. However, historical artificial channelization, encroaching urban development, and floodplain disconnection complicate restoring and revitalizing urban rivers. Habitat restoration and greening of waterways is a high priority in urban river restoration projects, but taller and denser vegetation alters channel hydraulics and increases flood levels. Both restoration and flood risk management are important to achieve a resilient future for our urban waterways and neighborhoods. How can we meet both needs instead of putting them at odds, successfully executing multibenefit projects in our flood-sensitive urban river corridors?
By better quantifying the flood risks involved with increased greening, decision-makers and designers can characterize trade-offs between flooding and restoration, and tailor solutions for specific projects and reaches. For a reach of the South Platte River in Denver, CO, we used 2D modeling software to estimate flood stage impacts resulting from increasing vegetation density. Manning’s roughness coefficient was used as an indicator of vegetation density for three flood events under three different vegetation scenarios. The analysis provided estimated maximum flood levels, informing conversations between different stakeholders to apply river restoration in this flood-sensitive area. This analysis also helps us understand which areas of the bank are most sensitive to overgrowth, informing flood risk priorities in vegetation maintenance plans. This has the potential to expand the use of green infrastructure and nature-based solutions in urban communities, providing the numerous socio-ecological benefits of restoration. These benefits range from expanded recreation opportunities to increased bank stabilization, habitat enhancement, higher biodiversity, heat mitigation, and benefits to public health and wellness. In this way, understanding risk and sensitivity can provide needed information to promote collaboration and achieve change.
About Chelsey Radobenko, PE
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