Geologists: The Devastating Helene Flood Event In The Southern Appalachians

“The Devastating Helene Flood Event In The Southern Appalachians” by Dr. J. Ryan Thigpen and Summer J. Brown

From September 26-29, 2024, precursor storms followed by the remnants of Hurricane Helene produced >30 inches of rainfall over parts of the southern Appalachian Blue Ridge. In affected areas of North Carolina and Tennessee, many rivers greatly surpassed their historic flood-of-record levels, with some rivers like the Nolichucky and Swannanoa reaching >300 times their normal flow. The event initiated thousands of slope failures, including some of the largest and deadliest debris flows ever documented in the eastern US. Widespread and pronounced bank erosion exposed previously unrecognized paleo-flood and landslide deposits, including deposits interpreted to represent the largest magnitude flood event in the last 10,000 years, providing a unique chance to quantify recurrence intervals of past extreme events. This presentation will share on-the-ground photos, videos, and the preliminary results of ongoing surveying efforts that started five days after the flood. The integration of ground, LIDAR, and photogrammetric analysis of the affected area will ultimately contribute to development of better mountain flood warning systems, a better understanding of conditions that trigger catastrophic debris flows, and significant insight for the Holocene record of catastrophic flooding and debris flows in the southern Appalachians.

Live at the Teton County Library & Via Zoom (online)

Join Zoom Meeting: https://us02web.zoom.us/j/4555651818?pwd=U09ObDNZOEIyZmRtMEtsdUowQnJqdz09