Erosion, sedimentation, and cumulative effects in the Northern Rocky Mountains

Abstract

Erosion and sedimentation are natural geomorphic processes characterized by large temporal and spatial variability. Recent radionuclide studies suggest that rare episodic events, such as large wildfires, produce massive sediment yields over time scales of thousands of years, thereby causing long-term average sediment production to exceed present-day average erosion rates by a factor of about 10. Even today, in undisturbed forested watersheds, sediment production is highly variable. Early studies of the effects of grazing and wildfire and surveys of river basins provided a foundation for much of the subsequent research on the effects of forest practices on erosion and sedimentation. The erosional and sedimentation effects of wildfire have been documented in many locations - ranging from none to minimal for low-intensity burns to catastrophic for highintensity burns. Management of forestlands to regulate the risk of wildfire effects on erosion and sedimentation is an important present-day concern throughout the region.

Citation

Megahan, Walter F.; King, John G. 2004. Erosion, sedimentation, and cumulative effects in the Northern Rocky Mountains. In: Ice, George G.; Stednick, John D., eds. A century of forest and wildland watershed lessons. Bethesda, Md.: Society of American Foresters: p. 201-222