Are We Failing our Floodplains?
AJ Jones, PE
Wolf Water Resources
Portland, OR
Design approaches such as Natural Channel Design and Process Based Restoration provide guidelines for restoring a stream, but how are factors of the stream’s floodplain considered? Is activating the floodplain at the bankfull discharge enough? How do we create restoration solutions that consider floodplain function, ecological value, and storage so we do not fail our floodplains?
Restoring the channel and floodplain as an interconnected, complex system may provide the greatest habitat uplift per valley acre, but this approach also comes with challenges. Federal and local regulations have made slowing water down and increasing the wetted area an expensive and complicated process that counteracts the ability to store water in the floodplain. Stricter FEMA regulations fail to see the benefit of storing water on the floodplain—ever more important as seasonal hydrographs are affected by climate change—which can actually add resiliency and reduce flood risks to downstream reaches.
This presentation will dive into the benefits and challenges of designing beyond the stream channel and provide case studies of two multiphase projects that restored the stream-floodplain complex, incorporating channel fill, large wood, and floodplain expansion. These projects required working with the County and FEMA, and had similar outcomes, but varied significantly in the level of effort and associated risk.
About AJ Jones, PE
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