Publication Date:
2016-08-11
Description:
In burned steeplands, the peak depth and discharge of post-wildfire runoff can substantially increase from the addition of debris. Yet, methods to estimate the increase over water flow are lacking. We quantified the potential amplification of peak stage and discharge using video observations of post-wildfire runoff, compiled data on post-wildfire peak flow ( Q p ), and a physically based model. Comparison of flood and debris flow data with similar distributions in drainage area ( A ) and rainfall intensity ( I ) showed that the median runoff coefficient ( C = Q p / A I ) of debris flows is 50 times greater than that of floods. The striking increase in Q p can be explained using a fully predictive model that describes the additional flow resistance caused by the emergence of coarse-grained surge fronts. The model provides estimates of the amplification of peak depth, discharge, and shear stress needed for assessing post-wildfire hazards and constraining models of bedrock incision.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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