Geomorphic response to tornado impact in Abrams Creek, Smoky Mountains National Park, Tennessee

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University of Alabama Libraries

Tornadoes have the potential to alter river geomorphology. Considering the frequency and intensity of tornado events in the U.S., it is likely that tornadoes are an unaccounted source of natural disturbance in fluvial systems. This study reviews the potential effects of tornado impact on rivers and presents findings from a study of tornado impacts conducted in Abrams Creek located in the Great Smoky Mountains National Park, Tennessee. In April 2011, an EF4 tornado touched down in Abrams Creek watershed. The National Parks Service left all the damage untouched. I studied two ~1 km stream reaches: an upstream reach directly impacted by the tornado and a downstream reach which was not. I measured the morphology of pools, including maximum length, average width, and residual pool depth, under base flow conditions (July-October 2015) in both study reaches and compared them using a t-test. Statistical differences in residual pool depth existed between the upstream and downstream reach (p value = .027). This difference is likely the result of increased hydraulic erosion in the upstream reach and an influx of sediment in the downstream reach. The results of this study suggest tornadoes can and do affect river geomorphology, with their effects persisting years after the event. The geomorphic disturbance initiated by tornadoes have short and long-term implications for in-stream ecological functions. A better understanding of the geomorphic and ecological implications following a tornado could help guide management strategies and decisions for river conservation and restoration efforts.

Electronic Thesis or Dissertation
Physical geography, Geomorphology