Modeling Post-Wildfire Debris-Flow & Flooding Assessment: Coconino County, Arizona

Cover shot of AZGS Open-File Report

Over the past decade the Southwestern U.S. has seen a surge in the number and intensity of wildland fires. In Arizona, wildfire season overlaps with the annual monsoon, resulting in post-wildfire debris flows and floods that threaten life and property.

The Arizona Geological Survey just released a report identifying areas in Coconino County, Arizona, at risk from flooding and debris flows in the aftermath of a reasonable-wildfire scenario. This report was a joint research project with JE Fuller Hydrology and Geomorphology, Inc., with offices in Tucson, Tempe, Flagstaff, Arizona, and Silver City, New Mexico.

The 63-page report, ‘Post-Wildfire Debris-flow and Flooding Assessment: Coconino County, Arizona’, includes six appendices. The report and appendices are online and free to download from the AZGS Online Document Repository.

According to first author Joe Loverich, this work can propel ‘forest health initiatives forward in these at risk watersheds’. This Thursday, Ann Youberg and Joe Loverich will be presenting some of their results at the Arizona Hydrological Society’s 30th Annual Symposium in Flagstaff.

The research team conducted a county-wide reconnaissance evaluation, before focusing on two pilot-study areas: Fort Valley and the City of Williams. The report results integrate field studies, two-dimensional FLO2D pre- and post-wildfire flood modelling, and debris-flow probability, volume and runout modeling to provide risk maps and identify mitigation options and opportunities. Conversations to implement mitigation options are in progress.

Citation. Loverich, J.B., Youberg, A.M., Kellogg, M.J. and Fuller J.E., 2017, Post-Wildfire Debris-flow and Flooding Assessment: Coconino County, Arizona. Arizona Geological Survey Open-File Report (OFR-17-06), 63 p., 6 appendices.

Appendices

• Appendix A - Pilot Area Justification Memo, Kellogg, M.J., Loverich, J.B., Youberg, A.M. and Fuller J.E.
• Appendix B - Pre- and Post-Wildfire Hydrologic Modeling, Loverich[AY1] , J.B., Kellogg, M.J. and Fuller J.E.
• Appendix C - Pre-Wildfire Debris-Flow Risk Assessment, Youberg, A.M.
• Appendix D - Post-Wildfire Debris-Flow Modeling, Loverich, J.B.
• Appendix E - Post-Wildfire Debris-Flow, Youberg, A.M.
• Appendix F - Flood and Risk Zone Maps, Loverich, J.B., Kellogg, M.J. and Fuller J.E.

Posted M.Conway 9/5/2017