Prewildfire Assessments of Postwildfire Debris-Flow Hazards

Science Center Objects

Debris flows are high-density slurries of water, rock fragments, soil, and mud that can have enormous destructive power. Wildfire can drastically increase the probability of debris flows in landscapes that have otherwise been stable. In 2010, the USGS developed the Cannon model to estimate postwildfire debris-flow probabilities and volumes in burned areas. In 2013, with the help of U.S. Forest Service fire modelers, the USGS began application of the Cannon model in mountainous regions of New Mexico before wildfire burns. This prewildfire assessment approach is valuable to resource managers because the analysis of the debris-flow threat is made before a wildfire occurs, which facilitates prewildfire management, planning, and mitigation.

Prewildfire Assessments of Postwildfire Debris-Flow Hazards

(Public domain.)

Approach

  • Model burn probabilities and estimated burn severities in the Jemez Mountain area using Fsim
  • Apply Cannon empirical models to estimate probability, volume and¬†combined relative hazard ranking of a debris flow from individual drainage basins in response to a given storm event in the Jemez Mountains

 

Objective

Estimate the potential for and magnitude of postwildfire debris flows for subbasins in the Jemez Mountains area.

Apex of large debris flow, tributary to Whitewater Canyon, Gila National Forest, Glenwood, NM

Apex of large debris flow, tributary to Whitewater Canyon, Gila National Forest, Glenwood, NM

(Public domain.)