2024 Post-Wildfire Debris-Flow Hazard Assessments

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey (USGS) conducts debris-flow hazard assessments for recent wildfires. This collection holds all postfire debris-flow hazard assessments produced by the USGS in 2024.

Each child item holds the results for a specific hazard assessment. Each assessment maps the modeled likelihood, potential volume, and combined hazard of debris flows across the burn area for a series of design rainstorms. Each assessment also includes estimates of the rainfall rates required to trigger debris flows. These results are generally representative of the conditions immediately after the fire. The results are provided as raw model outputs, so the number of digits following a decimal point does not represent the number of significant figures.

The hazard assessments were designed to implement:

* The "M1" debris-flow likelihood model of Staley and others (2017)
* The "emergency" potential sediment volume model of Gartner and others (2014)
* The debris-flow combined hazard classification scheme of Cannon and others (2010)

and the assessments were produced by USGS personnel running the beta version of the ocelote package. Operational personnel may have also modified stream network delineation and modeling parameters for individual assessments in order to ensure quality. The beta version is represented by the ocelote commits prior to the v1.0.0 release. These commits can be found in the ocelote source repository.

References:
Cannon, S.H., Gartner, J.E., Rupert, M.G., Michael, J.A., Rea, A.H., and Parrett, C., 2010, Predicting the probability and volume of postwildfire debris flows in the intermountain western United States: Geological Society of America Bulletin, v. 122, no. 1-2, p. 127-144, https://doi.org/10.1130/B26459.1

Gartner, J.E., Cannon, S.H., and Santi, P.M., 2014, Empirical models for predicting volumes of sediment deposited by debris flows and sediment-laden floods in the transverse ranges of southern California: Engineering Geology, v. 176, p. 45-56, https://doi.org/10.1016/j.enggeo.2014.04.008.

Staley, D.M., Negri, J.A., Kean, J.W., Laber, J.L., Tillery, A.C., and Youberg, A.M., 2017, Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States: Geomorphology, v. 278, p. 149-162, https://doi.org/10.1016/j.geomorph.2016.10.019.