Spatial modeling of dry ravel in three dimensions development of Ravel RAT: The Ravel Risk Assessment Tool

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Conference Paper/Presentation

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Dry ravel describes the down slope movement of soil and rock particles due to gravity in the absence of water. Dry ravel occurs mostly in steep mountainous, semi-arid regions where slopes are greater than the ravel particle's angle of repose (the steepest angle at which the particles are stable). In these regions, vegetation can trap particles behind their stems and hold materials on slopes with their root structure. After a fire, the removal of vegetation frees the particles to roll, slide, and/or bounce down the hill. Land managers are interested in predicting post-fire dry ravel movement, as these materials can load channels and gullies with sediment that can later be transported into streams and reservoirs. Researchers have developed a spatial mass flux dry ravel model to help predict and estimate dry ravel movement. This model is being further developed using field data from four small watersheds in the San Dimas Experimental Forest in California. The model parameters being optimized include particle velocity and spatially varied burn depth. New improvements are currently being made on optimizing burn depth using Monitoring Trends in Burn Severity (MTBS) burn severity classes derived from remote sensing data from the 2002 Williams Fire, which burned three of the study watersheds. We have optimized each burn severity class to different burn depths in order to increase the accuracy of model predictions of both dry ravel production and deposition for burned chaparral vegetation.

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© 2013 American Geophysical Union.

Publication Title

AGU Fall Meeting 2013