Debris slide and debris flow historical events in the Appalachians south of the glacial border
The central and southern Appalachian region experiences intense rainfall events that trigger episodes of debris slides and debris flows. High rainfalls may be preceded by wet periods, normal conditions, or droughts, and still result in rapid mass movements. Most slides and flows occur in existing hillslope depressions and move downslope. The bedrock-soil contact is the most common movement interface, although slippage and flowage are also common in deep soils. Lithologic, structural, soil, vegetative, and land-use influences on mass movements are identifiable in some areas, yet not apparent in others.
Better data on precipitation thresholds, movement mechanisms, and slide and flow precursors are urgently needed. Accelerating tourism growth rates and development of mountainous areas are accompanied by greater losses of human property and life caused by slope failures. The dangers of rapid debris slides and flows threaten increasing numbers of people in developing areas.