Predicting potential postfire debris-flow hazards across California prior to wildfire

Rebecca K. Rossi; Paul W. Richardson; David B. Cavagnaro; Stefani G. Lukashov; Mary Ellen Miller; Donald N. Lindsay

doi:10.1071/WF24225

RESEARCH ARTICLE (Open Access)

Previous Next Contents Vol 34(7)

Predicting potential postfire debris-flow hazards across California prior to wildfire

Rebecca K. Rossi

^A ^* , Paul W. Richardson ^B , David B. Cavagnaro ^A , Stefani G. Lukashov ^A , Mary Ellen Miller ^C and Donald N. Lindsay ^B

+ Author Affiliations

- Author Affiliations

^A California Geological Survey, Burned Watershed Geohazards Program, Sacramento, CA 95814, USA.

^B California Geological Survey, Burned Watershed Geohazards Program, Redding, CA 96002, USA.

^C Michigan Technological University, Michigan Tech Research Institute, Ann Arbor, MI 48105, USA.

^* Correspondence to: rebecca.rossi@conservation.ca.gov

International Journal of Wildland Fire 34, WF24225 https://doi.org/10.1071/WF24225

Submitted: 21 December 2024 Accepted: 26 May 2025 Published: 3 July 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Wildfires and consequent postfire hazards, specifically runoff-generated debris flows, are a major threat to California communities.

Aim

To help prefire planning efforts across California, we identified areas that are most susceptible to postfire debris flows before fire occurs.

Methods

We developed a calibration method for an established model that relates existing vegetation type to fire severity, a critical input to the US Geological Survey’s postfire debris-flow likelihood model. We calibrated the model for eight regions with data from 81 wildfires that occurred in 2020 and 2021 in California.

Key results

We predicted debris-flow likelihood, volume, and combined hazard classification, and created statewide maps that use simulated fire frequency and rainfall data to predict the probability that a basin will experience a wildfire and subsequent debris flow.

Conclusions

We suggest that the model predictions are useful for identifying areas that pose the greatest risk of postfire debris-flow hazard for a simplified wildfire scenario.

Implications

Although actual patterns of wildfire severity may vary from our simulated products, we show that applying a consistent methodology for all of California is useful for identifying areas that are likely to pose the greatest postfire hazards, which should help focus prefire mitigation efforts.

Keywords: annual probability of postfire debris flow, California wildfires, existing vegetation type, geohazards, postfire debris flows, prefire hazard mitigation, risk assessment, runoff-generated debris flow, simulated burn severity, simulated fire, statewide prefire planning.

References

Barnhart KR, Jones RP, George DL, McArdell BW, Rengers FK, Staley DM, Kean JW (2021) Multi‐model comparison of computed debris flow runout for the 9 January 2018 Montecito, California post‐wildfire event. Journal of Geophysical Research: Earth Surface 126(12), e2021JF006245.
| Crossref | Google Scholar |

Belongia MF, Hammond Wagner C, Seipp KQ, Ajami NK (2023) Building water resilience in the face of cascading wildfire risks. Science Advances 9(37), eadf9534.
| Crossref | Google Scholar | PubMed |

Birch DS, Morgan P, Kolden CA, Abatzoglou JT, Dillon GK, Hudak AT, Smith AM (2015) Vegetation, topography and daily weather influenced burn severity in central Idaho and western Montana forests. Ecosphere 6(1), 1-23.
| Crossref | Google Scholar |

California Department of Forestry and Fire Protection (2024) Statistics. Available at https://www.fire.ca.gov/our-impact/statistics [accessed 7 May 2024]

California Geological Survey (1997) ‘California Geomorphic Provinces’. Note 36. (California Division of Mines and Geology)

Cannon S, Gartner JR, Michael J, Rea A, Parrett C (2010) Predicting the probability and volume of post-wildfire debris flows in the intermountain west, USA. Geological Society of America Bulletin 122(1/2), 127-144.
| Crossref | Google Scholar |

Disaster Mitigation Act (2000) Public Law 106-390. 114 Stat. 1552.

Estes BL, Knapp EE, Skinner CN, Miller JD, Preisler HK (2017) Factors influencing fire severity under moderate burning conditions in the Klamath Mountains, northern California, USA. Ecosphere 8(5), e01794.
| Crossref | Google Scholar |

Feller W (1991) ‘An introduction to probability theory and its applications.’ Vol. 2(81). (John Wiley and Sons)

Gartner JE, Cannon SH, Santi PM (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 176, 45-56.
| Crossref | Google Scholar |

Jain P, Coogan SC, Subramanian SG, Crowley M, Taylor S, Flannigan MD (2020) A review of machine learning applications in wildfire science and management. Environmental Reviews 28(4), 478-505.
| Crossref | Google Scholar |

Kane VR, Cansler CA, Povak NA, Kane JT, McGaughey RJ, Lutz JA, Churchill DJ, North MP (2015) Mixed severity fire effects within the Rim fire: relative importance of local climate, fire weather, topography, and forest structure. Forest Ecology and Management 358, 62-79.
| Crossref | Google Scholar |

Kean JW, Staley DM (2021) Forecasting the frequency and magnitude of postfire debris flows across southern California. Earth’s Future 9(3), e2020EF001735.
| Crossref | Google Scholar |

Kean JW, Staley DM, Cannon SH (2011) In situ measurements of post-fire debris flows in southern California: comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions. Journal of Geophysical Research: Earth Surface 116(F4), F04019.
| Crossref | Google Scholar |

Kean JW, Staley DM, Lancaster JT, Rengers FK, Swanson BJ, Coe JA, Hernandez JL, Sigman AJ, Allstadt KE, Lindsay DN (2019) Inundation, flow dynamics, and damage in the 9 January 2018 Montecito debris-flow event, California, USA: opportunities and challenges for post-wildfire risk assessment. Geosphere 15(4), 1140-1163.
| Crossref | Google Scholar |

King J (2023) pfdf - Python library for postfire debris-flow hazard assessments and research, version 1.1.0: U.S. Geological Survey software release. 10.5066/P13RSBEE

Klimas KB, Yocom LL, Murphy BP, David SR, Belmont P, Lutz JA, DeRose RJ, Wall SA (2025) A machine learning model to predict wildfire burn severity for pre-fire risk assessments, Utah, USA. Fire Ecology 21, 8.
| Crossref | Google Scholar |

LandFire (2022) Existing vegetation type. Available at https://www.landfire.gov/index.php [accessed 29 March 2024]

Li S, Banerjee T (2021) Spatial and temporal pattern of wildfires in California from 2000 to 2019. Scientific Reports 11(1), 8779.
| Crossref | Google Scholar | PubMed |

MTBS (2022) Monitoring Trends in Burn Severity. Burned Areas Boundaries Dataset. Available at https://www.mtbs.gov/direct-download [accessed 29 March 2024]

Parsons A, Robichaud PR, Lewis SA, Napper C, Clark JT (2010) ‘Field guide for mapping post-fire soil burn severity.’ (US Department of Agriculture, Forest Service, Rocky Mountain Research Station: Fort Collins, CO, USA)

Perica S, Dietz S, Heim S, Hiner L, Maitaria K, Martin D, Pavlovic S, Roy I, Trypaluk C, Unruh D, Yan F (2014) ‘NOAA Atlas 14, precipitation-frequency Atlas of the United States, 6 (Version 2.3) [California].’ (National Oceanic and Atmospheric Administration: Silver Spring, MD) Available at https://hdsc.nws.noaa.gov/hdsc/pfds/index.html [accessed 29 March 2024]

Radeloff VC, Helmers DP, Kramer HA, Mockrin MH, Alexandre PM, Bar-Massada A, Butsic V, Hawbaker TJ, Martinuzzi S, Syphard AD, Stewart SI (2018) Rapid growth of the US wildland-urban interface raises wildfire risk. Proceedings of the National Academy of Sciences 115(13), 3314-3319.
| Crossref | Google Scholar | PubMed |

Rossi RK, Richardson PW, Cavagnaro DB, Lukashov SG, Miller ME, Lindsay DN (2025) Predicting potential postfire debris-flow hazards across California prior to wildfire [Dataset]. Zenodo. 10.5281/zenodo.15313560

Rundio DE, Spence BC, Chase DM, Ostberg CO (2024) Using environmental DNA to assess the response of steelhead/Rainbow Trout and Coastrange Sculpin populations to postfire debris flows in coastal streams of Big Sur, California. North American Journal of Fisheries Management 44, 1167-1182.
| Crossref | Google Scholar |

Schwartz GE, Alexander RB (1995) Soils data for the conterminous United States derived from the NRCS State Soil Geographic (STATSGO) Database: U.S. Geological Survey Open-File Report 95-449. Available at https://water.usgs.gov/GIS/metadata/usgswrd/XML/ussoils.xml [accessed 29 March 2024]

Staley DM (2018) Data used to characterize the historical distribution of wildfire severity in the western United States in support of pre-fire assessment of debris-flow hazards: US Geological Survey Data Release. 10.5066/P9TKYL5K

Staley DM, Kean JW, Cannon SH, Schmidt KM, Laber JL (2013) Objective definition of rainfall intensity–duration thresholds for the initiation of post-fire debris flows in southern California. Landslides 10, 547-562.
| Crossref | Google Scholar |

Staley DM, Negri JA, Kean JW, Laber JL, Tillery AC, Youberg AM (2016) Updated logistic regression equations for the calculation of post-fire debris-flow likelihood in the western United States. US Geological Survey Open-File Report 2016–1106. 10.3133/ofr20161106

Staley DM, Negri JA, Kean JW, Laber JL, Tillery AC, Youberg AM (2017) Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States. Geomorphology 278, 149-162.
| Crossref | Google Scholar |

Staley DM, Tillery AC, Kean JW, McGuire LA, Pauling HE, Rengers FK, Smith JB (2018) Estimating post-fire debris-flow hazards prior to wildfire using a statistical analysis of historical distributions of fire severity from remote sensing data. International Journal of Wildland Fire 27(9), 595-608.
| Crossref | Google Scholar |

Staley DM, Kean JW, Rengers FK (2020) The recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States. Geomorphology 370, 107392.
| Crossref | Google Scholar |

Swanson BJ, Lindsay DN, Cato K, DiBiase RA, Neely AB (2024) Debris flows and sediment transport at Yucaipa Ridge and impacts to Oak Glen and Forest Falls area, southern California, following the 2020 El Dorado and Apple Fires. In ‘From Coastal Geomorphology to Magmatism: Guides to GSA Connects 2024 Field Trips in Southern California and Beyond’. Geological Society of America Field Guide 70. (Eds NJ Van Buer, JJ Schwartz) pp. 45–73. (Geological Society of America) 10.1130/2024.0070(03)

Thomas MA, Lindsay DN, Cavagnaro DB, Kean JW, McCoy SW, Graber AP (2023) The rainfall intensity-duration control of debris flows after wildfire. Geophysical Research Letters 50, e2023GL103645.
| Crossref | Google Scholar |

US Forest Service (2009) ‘Existing Vegetation – CALVEG.’ (USDA-Forest Service, Pacific Southwest Region) Available at https://www.fs.usda.gov/detail/r5/landmanagement/resourcemanagement/ [accessed 29 March 2024]

US Forest Service (2023) The future of fires with FSim: projecting future climate-altered fire regimes using FSim. Available at https://www.fs.usda.gov/research/sites/default/files/2023-11/fsim-fact-sheet-110823.pdf [accessed 10 June 2024]

US Geological Survey (2020) National Hydrography Dataset (NHD) 20200619 for California State or Territory FileGDB 10.1 (Version 2.2.1) [Waterbodies]. [accessed 29 March 2024]

US Geological Survey (2023) Watershed Boundary Dataset (WBD) 20231127 FileGDB – Hydrologic Unit (HU) 8/10. [accessed on 29 March 2024]

US Geological Survey (2024) 3D Elevation Program 10-Meter Resolution Digital Elevation Model [USGS 1/3 Arc Second]. Available at https://apps.nationalmap.gov/downloader/ [accessed 29 March 2024]

van Mantgem PJ, Nesmith JC, Keifer M, Knapp EE, Flint A, Flint L (2013) Climatic stress increases forest fire severity across the western United States. Ecology Letters 16(9), 1151-1156.
| Crossref | Google Scholar | PubMed |

Vogler KC, Brough A, Moran CJ, Scott JH, Gilbertson-Day JW (2021) ‘Contemporary wildfire hazard across California.’ (Pyrologix, LLC)

Wells AG, Hawbaker TJ, Hiers JK, Kean JW, Loehman RA, Steblein PF (2023) Predicting burn severity for integration with post-fire debris-flow hazard assessment: a case study from the Upper Colorado River Basin, USA. International Journal of Wildland Fire 32(9), 1315-1331.
| Crossref | Google Scholar |

Zald H, Dunn CJ (2018) Severe fire weather and intensive forest management increase fire severity in a multi‐ownership landscape. Ecological Applications 28(4), 1068-1080.
| Crossref | Google Scholar | PubMed |

Zekkos D, Stark TD (2023) ‘Highway 1 Rat Creek Embankment Failure’. Geotechnical Special Publication No. 337. (American Society of Civil Engineers) 10.1061/9780784484579