Francis Rengers
I investigate landslide and debris flow processes, primarily after wildfire.
General Research Statement:
My work leverages high-resolution topography from airborne and ground-based lidar, as well as drone-based structure-from-motion, to characterize the controls on mass movement after wildfire. I also use modeling and field-instrumentation to characterize how wildfire creates the hydrologic and soil conditions that lead to sedimentation hazards. My work is primarily focused in the semi-arid portions of the Western United States, and I have worked on projects in Australia, New Zealand, and Sri Lanka. In addition, I serve as an adjunct professor at the Colorado School of Mines, I advise USGS post-docs, and I am currently serving on Ph.D. thesis committees at several universities.
Education:
- Ph.D., Geology, University of Colorado, Boulder, CO. 2014. The Influence of Transient Perturbations on Landscape Evolution: Exploring Gully Erosion and Post-Wildfire Erosion.
- M. S., Geology, Colorado State University, Fort Collins, CO. 2005. Grain Size Trends of Gravel Bars on the Rio Chagres, Panama
- B. S., Geology, Summa Cum Laude, West Virginia University, Morgantown, WV. 2003. Spatial Analysis of Landforms on Reclaimed Surface Mines of Monongalia County
- B. A., French, Summa Cum Laude, West Virginia University, Morgantown, WV. 2003
Professional Appointments:
2016-present Research Geologist
2014-2016 Mendenhall Postdoctoral Research Fellow
Staley, D.M., Kean, J.W., Rengers, F.K. 2020. The recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States. Geomorphology. https://doi.org/10.1016/j.geomorph.2020.107392
Rengers, F.K., McGuire, L.A., Oakley, N.S., Tang, H., Kean, J.W., and Staley, D.M. 2020. Landslides after Wildfire: initiation, magnitude, and mobility after fire. Landslides. https://doi.org/10.1007/s10346-020-01506-3
Rengers, F.K., Kean, J.W., Reitman, N.G., Smith, J.B., Coe, J.A., McGuire, L.A., 2020. The Influence of Frost Weathering on Debris Flow Sediment Supply in an Alpine Basin. Journal of Geophysical Research: Earth Surface 125, e2019JF005369. https://doi.org/10.1029/2019JF005369
Wall, S., Roering, J., Rengers, F.K., 2020. Runoff-initiated post-fire debris flow Western Cascades, Oregon. Landslides. https://doi.org/10.1007/s10346-020-01376-9
Rapstine, T.D., Rengers, F.K., Allstadt, K.E., Iverson, R.M., Smith, J.B., Obryk, M.K., Logan, M. Olsen, M.J. 2020. Reconstructing the velocity and deformation of a rapid landslide using multiview video. Journal of Geophysical Research: Earth Surface. https://doi.org/10.1029/2019JF005348
Kean, Jason W., Staley, D.M., Lancaster, J.T., Rengers, F.K., Swanson, B.J., Coe, J.A., Hernandez, J.L., Sigman, A.J., Allst
Science and Products
Post-wildfire debris-flow monitoring data, Las Lomas, 2016 Fish Fire, Los Angeles County, California, November 2016 to February 2017
Debris-flow inundation and damage data from the 9 January 2018 Montecito Debris-Flow Event
Las Lomas Hillside Lidar
Silverado California Thermoluminescence Data
Hydrogeomorphic recovery and temporal changes in rainfall thresholds for debris flows following wildfire
Movement of sediment through a burned landscape: Sediment volume observations and model comparisons in the San Gabriel Mountains, California, USA
The timing and magnitude of changes to Hortonian overland flow at the watershed scale during the post-fire recovery process
Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards
Extreme precipitation across adjacent burned and unburned watersheds reveals impacts of low severity wildfire on debris-flow processes
Time since burning and rainfall characteristics impact post-fire debris flow initiation and magnitude
Using high sample rate lidar to measure debris-flow velocity and surface geometry
Modeling hydrologic processes associated with soil saturation and debris flow initiation during the September 2013 storm, Colorado Front Range
Wildfire and landscape change
Wildfire and Earth surface processes
The recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States
Landslides after wildfire: Initiation, magnitude, and mobility
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
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Filter Total Items: 16
Post-wildfire debris-flow monitoring data, Las Lomas, 2016 Fish Fire, Los Angeles County, California, November 2016 to February 2017
This data release includes time-series data from a monitoring site located in a small (0.12 km2) drainage basin in the Las Lomas watershed in Los Angeles County, CA, USA. The site was established after the 2016 Fish Fire and recorded a series debris flows in the first winter after the fire. The station is located along the channel at the outlet of the study area (34 9'18.50"N, 117 56'41.33"W, WGS8Debris-flow inundation and damage data from the 9 January 2018 Montecito Debris-Flow Event
On 9 January 2018, intense rain above Montecito, California triggered a series of debris flows from steep catchments in the Santa Ynez Mountains. These catchments were burned three weeks earlier by the 1140 km2 Thomas Fire. After exiting the mountain front, the debris flows traveled over 3 km down a series of alluvial fans, killing 23 people and damaging over 400 homes. To understand the flow dynaLas Lomas Hillside Lidar
This data release contains point clouds obtained from three terrestrial laser scanner (TLS) surveys of a hillslope burned by the 2016 Fish Fire in the San Gabriel Mountains, CA, USA. The TLS surveys were completed with a Leica ScanStation C10. All point data are in local coordinates and the units are in meters. The first survey was made on 19 November 2016 prior to the first post-wildfire rainstorSilverado California Thermoluminescence Data
This dataset represents thermoluminescence (TL) data that was obtained after a series of experiments to investigate how TL techniques can indicate the depth of soil heating. This project was attempted to ultimately predict changes in erosion properties in burned areas subject to debris flow hazards. The soil samples were obtained from an area burned by the Silverado wildfire (September 12 to 20, 2 - Multimedia
- Publications
Filter Total Items: 54
Hydrogeomorphic recovery and temporal changes in rainfall thresholds for debris flows following wildfire
Wildfire-induced changes to soil and vegetation promote runoff-generated debris flows in steep watersheds. Postfire debris flows are most commonly observed in steep watersheds during the first wet season following a wildfire, but it is unclear how long the elevated threat of debris flow persists and why debris-flow potential changes in recovering burned areas. This work quantifies how rainfall intAuthorsOlivia J. Hoch, Luke A. McGuire, Ann M. Youberg, Francis K. RengersMovement of sediment through a burned landscape: Sediment volume observations and model comparisons in the San Gabriel Mountains, California, USA
Post-wildfire changes to hydrologic and geomorphic systems can lead to widespread sediment redistribution. Understanding how sediment moves through a watershed is crucial for assessing hazards, developing debris flow inundation models, engineering sediment retention solutions, and quantifying the role that disturbances play in landscape evolution. In this study, we used terrestrial and airborne liAuthorsFrancis K. Rengers, Luke A. McGuire, Jason W. Kean, Dennis M. Staley, Mariana Dobre, Peter R. Robichaud, Tyson SwetnamThe timing and magnitude of changes to Hortonian overland flow at the watershed scale during the post-fire recovery process
Extreme hydrologic responses following wildfires can lead to floods and debris flows with costly economic and societal impacts. Process-based hydrologic and geomorphic models used to predict the downstream impacts of wildfire must account for temporal changes in hydrologic parameters related to the generation and subsequent routing of infiltration-excess overland flow across the landscape. HoweverAuthorsTaojun Liu, Luke A. McGuire, Haiyan Wei, Francis K. Rengers, Hoshin Gupta, Lin Ji, David C. GoodrichPostwildfire soil‐hydraulic recovery and the persistence of debris flow hazards
Deadly and destructive debris flows often follow wildfire, but understanding of changes in the hazard potential with time since fire is poor. We develop a simulation‐based framework to quantify changes in the hydrologic triggering conditions for debris flows as postwildfire infiltration properties evolve through time. Our approach produces time‐varying rainfall intensity‐duration thresholds for ruAuthorsMatthew A. Thomas, Francis K. Rengers, Jason W. Kean, Luke A. McGuire, Dennis M. Staley, Katherine R. Barnhart, Brian A. EbelExtreme precipitation across adjacent burned and unburned watersheds reveals impacts of low severity wildfire on debris-flow processes
In steep landscapes, wildfire-induced changes to soil and vegetation can lead to extreme and hazardous geomorphic responses, including debris flows. The wildfire-induced mechanisms that lead to heightened geomorphic responses, however, depend on many site-specific factors including regional climate, vegetation, soil texture, and soil burn severity. As climate and land use change drive changes in fAuthorsLuke A. McGuire, Ann M. Youberg, Francis K. Rengers, Nathan S. Abramson, Indujaa Ganesh, Alex N. Gorr, Olivia Hoch, Justin C. Johnson, Patt Lamom, Alexander B. Prescott, Jessica Zanetell, Brendan FenertyTime since burning and rainfall characteristics impact post-fire debris flow initiation and magnitude
The extreme heat from wildfire alters soil properties and incinerates vegetation, leading to changes in infiltration capacity, ground cover, soil erodibility, and rainfall interception. These changes promote elevated rates of runoff and sediment transport that increase the likelihood of runoff-generated debris flows. Debris flows are most common in the year immediately following wildfire, but tempAuthorsLuke A. McGuire, Francis K. Rengers, Nina S. Oakley, Jason W. Kean, Dennis M. Staley, Hui Tang, Marian de Orla-Barile, Ann M. YoubergUsing high sample rate lidar to measure debris-flow velocity and surface geometry
Debris flows evolve in both time and space in complex ways, commonly starting as coherent failures but then quickly developing structures such as roll waves and surges. These processes are readily observed but difficult to study or quantify because of the speed at which they evolve. Many methods for studying debris flows consist of point measurements (e.g., flow height or basal stresses), which arAuthorsFrancis K. Rengers, Thomas D Rapstine, Michael Olsen, Kate E. Allstadt, Richard M. Iverson, Ben Leshchinsky, Maciej Obryk, Joel B. SmithModeling hydrologic processes associated with soil saturation and debris flow initiation during the September 2013 storm, Colorado Front Range
Seven days of extreme rainfall during September 2013 produced more than 1100 debris flows in the Colorado Front Range, about 78% of which occurred on south-facing slopes (SFS). Previously published soil moisture (volumetric water content) observations suggest that SFS were wetter than north-facing slopes (NFS) during the event, which contrasts with soil moisture patterns observed during normal conAuthorsSujana Timilsina, Jeffrey D. Niemann, Sara L. Rathburn, Francis K. Rengers, Peter A. NelsonWildfire and landscape change
Wildfire is a worldwide phenomenon that is expected to increase in extent and severity in the future, due to fuel accumulations, shifting land management practices, and climate change. It immediately affects the landscape by removing vegetation, depositing ash, influencing water-repellent soil formation, and physically weathering boulders and bedrock. These changes typically lead to increased erosAuthorsPaul M. Santi, Francis K. RengersWildfire and Earth surface processes
Wildfire is a worldwide phenomenon that is expected to increase in extent and severity in the future, due to fuel accumulations, shifting land management practices, and climate change. It immediately affects the landscape by removing vegetation, depositing ash, influencing water-repellent soil formation, and physically weathering boulders and bedrock. These changes typically lead to increased erosAuthorsPaul M Santi, Francis K. RengersThe recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States
In the southwestern United States, post-fire debris flows commonly initiate during short bursts of intense rainfall. To date, the frequency of the rainfall rates has not been quantified. Here, we combine an existing database of debris-flow occurrences and corresponding peak storm intensities with a geospatial library of rainfall recurrence interval (RI) information and climate type to determine thAuthorsDennis M. Staley, Jason W. Kean, Francis K. RengersLandslides after wildfire: Initiation, magnitude, and mobility
In the semiarid Southwestern USA, wildfires are commonly followed by runoff-generated debris flows because wildfires remove vegetation and ground cover, which reduces soil infiltration capacity and increases soil erodibility. At a study site in Southern California, we initially observed runoff-generated debris flows in the first year following fire. However, at the same site three years after theAuthorsFrancis K. Rengers, Luke McGuire, Nina S. Oakley, Jason W. Kean, Dennis M. Staley, Hui TangNon-USGS Publications**
Rengers, F., Lunacek, M., and Tucker, G. 2016. Application of an Evolutionary Algorithm for Parameter Optimization in a Gully Erosion Model, Environmental Modelling & Software. 80, 297-305. doi:10.1016/j.envsoft.2016.02.033Rengers, F. and Tucker G. 2015. The evolution of gully headcut morphology: a case study using terrestrial laser scanning and hydrological monitoring. Earth Surface Processes and Landforms. doi: 10.1002/esp.3721Ebel, B., Rengers, F., Tucker, G. 2015. Aspect-dependent soil saturation and insight into debris-flow initiation during extreme rainfall in the Colorado Front Range. Geology. 43, 8, p. 659-652. doi: 10.1130/G36741.1Rengers, F. and Tucker, G. 2014. Analysis and modeling of gully headcut dynamics, North American high plains. Journal of Geophysical Research: Earth Surface. 119, doi:10.1002/2013JF002962.Rengers, F. and Tucker, G. 2013. Processes and rates of headcut migration in eastern Colorado gullies: West Bijou Creek field trip guide. Geological Society of America Field Guide 33.Rengers, F. and Wohl, E. 2006. Trends of grain sizes on gravel bars in the Rio Chagres, Panama. Geomorphology. 83, 3-4, p. 282-293.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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