Hurricane Helene and Resilient Nature-based Solutions
By Chris Grose, PE
According to the National Weather Service, in September of 2024, Hurricane Helene produced the new flood of record in many locations of Western North Carolina and Eastern Tennessee. The magnitude of this storm, when routed through the steep and narrow valleys of the region, resulted in hydraulic forces that significantly altered channel forms, destroyed infrastructure, deposited sediment and debris, and led to loss of life.
Flooding from the French Broad River in the River Arts District of Asheville, NC
Immediately following Helene, RDE visited many of our past and current projects to triage any damage. Several months later, we visited these projects again for a retrospective look at their recovery. Our intent was to review the effectiveness of the nature-based solutions (NBS), and the study their resiliency when exposed to such an extreme event. We observed few failures during either time frame, including projects in constrained urban settings.
Based on the results of this qualitative assessment, we are encouraged as practitioners to continue to design NBS with fewer robust features and more intentional resiliency. This means designing for self-adjustment and healing. Robust measures inherently trade-off ecological benefits, often through additional land disturbance during construction or the introduction of habitat features that would not form from natural processes. Resilient measures, however, can provide function and stability at varying scales if the initial problem is approached with rigorous design and alternatives analyses. Stream channels will continually self-sort their sediment and reorganize into stable bedforms while floodplains will exchange water, sediment, and carbon through increased connectivity.
Robust Design
Stone Toe with Vegetated Soil Lifts
Hendersonville, NC
Resilient Design
Engineered Woody Jams
Buncombe County, NC
The conclusions we’ve drawn from this retrospective study can be applied to other locations outside of the Helene impact area and should also be incorporated into cleanup and recovery actions to both protect human infrastructure and promote ecological integrity.
Federal disaster recovery—not resilient, Haw Creek/Swannanoa River, Asheville, NC