Published: April 9, 2024 By

Urban rivers have 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. For a reach of the South Platte River, 2D modeling software was used to estimate flood stage impacts resulting from increasing vegetation density. Manning鈥檚 roughness coefficient was used as an indicator of vegetation density for three flood events under two different vegetation regimes. Preliminary results indicate minimal threat to nearby buildings, even in overgrown conditions in high flood events. While results for each unique project and reach will vary, this method has potential to quantify increased flood risk in restored urban riverways related to maintenance uncertainty and vegetation growth potential. Risk can be mitigated further through informed planting and adaptive management choices, focusing on high-sensitivity areas identified in the model. This informed approach allows decision-makers and designers to expand the use of green infrastructure and nature-based solutions in our flood-sensitive urban river corridors. This has potential to provide numerous socio-ecological benefits to the urban community, including expanded recreation opportunities, increased bank stabilization, habitat enhancement, higher biodiversity, natural resource preservation, heat mitigation, and benefits to public health and wellness.