The Failure of Beaver Dams and Resulting Outburst Flooding: A Geomorphic Hazard of the Southeastern Piedmont

Beaver are geomorphic agents through their building of dams and creation of pond environments. In the southeast United States, the successful reintroduction of beaver has vastly increased the number of ponds impounded by beaver dams. These dams may fail, producing rapid and potentially catastrophic draining of beaver ponds, a geomorphic hazard which has not gained sufficient notice. This paper examines several cases of known dam failure and subsequent rapid drainage of beaver ponds. Reconstructions of the discharge from these ponds was accomplished using standard hydrologic relationships of stream dimensions or pond volume to discharge. Peak flood discharges may be catastrophically high. The maximum hazard for beaver-dam failure and pond outburstflooding occurs on the Piedmont, where periodic intense rainstorms combine with rapid surface runoff and limited surface infiltration to produce high-discharge floods.