About

Luke McGuire is an associate professor in the Department of Geosciences at the University of Arizona. He earned his PhD from the University of Arizona, where his dissertation focused on modeling the evolution of rill networks, debris fans, and cinder cones, exploring the connections between sediment transport processes and landscape development. His research involves understanding sediment transport processes and their impact on geological formations, contributing to the field of geosciences through his academic and research activities.

Research topics

• Environmental science
• Geography
• Geology
• Physical geography
• Geomorphology
• Oceanography
• Meteorology
• Ecology
• Geotechnical engineering

Selected publications

• Probabilistic prediction of post-fire debris-flow runout and implications for prefire assessments of post-fire hazards

  International Journal of Wildland Fire · 2026-01-06 · 1 citations

  article

  Background Debris-flow runout modeling is a valuable component of the prefire assessment of post-fire hazards. The application and benefits of runout modeling are limited by uncertainty in debris-flow volume as well as model parameters related to flow mobility. Aims In this study, we assess and reduce the uncertainty associated with flow-mobility parameters by calibrating a debris-flow runout model to 12 runoff-generated debris flows in the western United States. Methods For each debris flow, we determined optimal flow-mobility parameters using back analyses and generated a posterior distribution of the parameters using a Bayesian approach. We assessed the relative sensitivity of the model to the flow-mobility parameters, rainfall intensification and fire burn severity when applied to three post-fire debris flows. Key results Yield strength, one of the flow-mobility parameters, exhibits a negative, linear relationship with soil clay content. Modeled area inundated is most sensitive to the flow-mobility parameters, followed by a rainfall intensification factor. Conclusions Well-constrained flow-mobility parameters will improve post-fire debris-flow runout modeling, though prefire assessments of post-fire hazards could also benefit from accounting for the effects of rainfall intensification. Implications This study improves our ability to simulate debris-flow runout and assess associated hazards.

  PublisherDOI

• Effects of successive high severity fires on sediment yield and debris-flow volume

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Assessing postfire flow hazards before a fire begins: Challenges and opportunities

  Abstracts with programs - Geological Society of America · 2025-01-01

  article1st authorCorresponding
  PublisherDOI

• Modeling Post-fire Debris-flow Likelihood in the Southwest USA.

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Cascading land surface hazards as a nexus in the Earth system

  Science · 2025-06-26 · 30 citations

  review

  This Review synthesizes progress and outlines a new framework for understanding how land surface hazards interact and propagate as sediment cascades across Earth's surface, influenced by interactions among the atmosphere, biosphere, hydrosphere, and solid Earth. Recent research highlights a gap in understanding these interactions on human timescales, given rapid climatic change and urban expansion into hazard-prone zones. We review how surface processes such as coseismic landslides and post-fire debris flows form a complex sequence of events that exacerbate hazard susceptibility. Moreover, innovations in modeling, remote sensing, and critical zone science can offer new opportunities for quantifying cascading hazards. Looking forward, societal resilience can increase by transforming our understanding of cascading hazards through advances in integrating data into comprehensive models that link across Earth systems.

  PublisherDOI

• Quantifying fire effects on debris flow runout using a morphodynamic model and stochastic surrogates

  2025-01-14 · 1 citations

  preprintOpen access

  Abstract. Fire affects soil and vegetation, which in turn can promote the initiation and growth of runoff-generated debris flows in steep watersheds. Postfire hazard assessments often focus on identifying the most likely watersheds to produce debris flows, quantifying rainfall intensity-duration thresholds for debris flow initiation, and estimating the volume of potential debris flows. This work seeks to expand on such analyses and forecast downstream debris flow runout and peak flow depth. Here, we report on a high-fidelity computational framework that enables debris flow simulation over two watersheds and the downstream alluvial fan, although at significant computational cost. We then develop a Gaussian Process surrogate model, allowing for rapid prediction of simulator outputs for untested scenarios. With a modest training of debris flow simulations, this surrogate is able to approximate peak flow depth with a mean squared error that is generally in the range of 0.1–0.2 m. We utilize this framework to explore model sensitivity to rainfall intensity and sediment availability as well as parameters associated with saturated hydraulic conductivity, hydraulic roughness, grain size, and sediment entrainment. Simulation results are most sensitive to hydraulic roughness and grain size. Further, we use this approach to examine variations in debris flow inundation patterns at different stages of postfire recovery, and we find that the area inundated by postfire flows decreases substantially over a time period as short as 9 months. In this case, we also see that temporal changes in hydraulic roughness and grain size following fire would be particularly beneficial for forecasting debris flow runout throughout the postfire recovery period. The emulator methodology presented here also provides a means to compute the probability of a debris flow inundating a specific downstream region, consequent to a forecast or design rainstorm. This workflow could be employed in prefire scenario-based planning or postfire hazard assessments.

  PublisherOA PDFDOI

• Rainfall Thresholds for Postfire Debris‐Flow Initiation Vary With Short‐Duration Rainfall Climatology

  Journal of Geophysical Research Earth Surface · 2025-06-01 · 4 citations

  articleOpen access

  Abstract The size, frequency, and geographic scope of severe wildfires are expanding across the globe, including in the Western United States. Recently burned steeplands have an increased likelihood of debris flows, which pose hazards to downstream communities. The conditions for postfire debris‐flow initiation are commonly expressed as rainfall intensity‐duration thresholds, which can be estimated given sufficient observational history. However, the spread of wildfire across diverse climates poses a challenge for accurate threshold prediction in areas with limited observations. Studies of mass‐movement processes in unburned areas indicate that thresholds vary with local climate, such that higher rainfall rates are required for initiation in climates characterized by frequent intense rainfall. Here, we use three independent methods to test whether initiation of postfire runoff‐generated debris flows across the Western United States varies similarly with climate. Through the compilation of observed thresholds at various fires, analysis of the spatial density of observed debris flows, and quantification of feature importance at different spatial scales, we show that postfire debris‐flow initiation thresholds vary systematically with short‐duration rainfall‐intensity climatology. The predictive power of climatological data sets that are readily available before a fire occurs offers a much‐needed tool for hazard management in regions that are facing increased wildfire activity, have sparse observational history, and/or have limited resources for field‐based hazard assessment. Furthermore, if the observed variation in thresholds reflects long‐term adjustment of the landscape to local climate, rapid shifts in rainfall intensity related to climate change will likely induce spatially variable shifts in postfire debris‐flow likelihood.

  PublisherOA PDFDOI

• Confronting Debris Flow Hazards After Wildfire

  Eos · 2025-02-19

  articleOpen access

  Scientists and practitioners have identified research priorities to improve scientific understanding of postfire debris flows and meet decisionmaking challenges posed by this growing hazard.

  PublisherDOI

• Temporal persistence of postfire flood hazards under present and future climate conditions in southern Arizona, USA

  Natural hazards and earth system sciences · 2025-10-24

  articleOpen accessCorresponding

  Abstract. Changes to soil hydraulic properties that reduce infiltration capacity following fire can increase flash flood risks. These risks are exacerbated by rainfall intensification associated with a warming climate. However, the potential effects of climate-change-driven rainfall intensification on postfire floods remain largely unexplored. Using rainfall and runoff observations from a 49.4 km2 watershed in southern Arizona, USA, and a hydrologic model (KINEROS2), we examined the temporal evolution following a historic fire of three crucial hydrologic parameters: soil saturated hydraulic conductivity (Ksp), net capillary drive (Gp), and hydraulic roughness (nc). We explored how the effect of fire on these parameters may influence peak flow under future climate scenarios derived from CMIP6, specifically the medium emissions scenario (SSP2-4.5) and high emissions scenario (SSP5-8.5). Results demonstrate an increase in Ksp from 11 mm h−1 in the first postfire year to 60 mm h−1 in postfire year 3. Gp similarly increased from 19 mm in the first postfire year to 30 mm in the third, while nc was relatively constant. The highest simulated Qp occurred in the first postfire year. Under the SSP2-4.5 scenario, the likelihood of a 100-year flood is projected to be twice as large by the middle of the century relative to its historical magnitude. Simulations further indicate that the maximum expected discharge associated with a postfire flood, as derived from historical data, could be triggered by a 10-year rainstorm under the SSP5-8.5 scenario by the late century. Simulations also demonstrate that rainfall intensification will lead to greater persistence of elevated flood hazards following fire by the late century under both the SSP2-4.5 and the SSP5-8.5 scenarios.

  PublisherOA PDFDOI

• Insights into temporal changes in debris flow susceptibility following fire in the Southwest USA from monitoring and repeat estimates of soil hydraulic and physical properties

  Earth Surface Processes and Landforms · 2025-02-01 · 5 citations

  articleOpen accessCorresponding

  Abstract Wildfire influences geomorphic process rates, increasing the potential for runoff‐generated debris flows in steep watersheds. Runoff‐generated postfire debris flows (PFDFs) often initiate when overland flow rapidly mobilizes sediment from steep hillslopes and channels. Fire effects on soil hydraulic properties, including their magnitude and temporal persistence, can therefore play an influential role in determining the degree to which fire increases debris‐flow potential and the time period for heightened debris‐flow hazards following fire. There is a paucity of measurements that quantify the timing of changes in soil hydraulic properties throughout the first 1–2 years after fire. Here, we monitored rainfall and debris‐flow activity in two watersheds burned by the 2022 Contreras Fire in Arizona, USA, over the first 1.5 years following fire. We quantified changes in soil hydraulic properties during 11 site visits using in‐situ measurements with a tension infiltrometer to provide insight into the temporal persistence of heightened debris‐flow hazards. Specifically, we estimated field‐saturated hydraulic conductivity ( K fs ), wetting front potential ( h f ) and sorptivity ( S ). We further tracked changes in soil water repellency, ground cover and soil physical and chemical properties, including bulk density, carbon and organic matter content to help explain temporal trends in soil hydraulic properties. Seasonal variations in K fs , h f and S were substantial, leading to non‐monotonic relationships between these properties and time since fire. Rainfall‐runoff modelling demonstrates that the magnitude of these seasonal changes are sufficient to influence runoff ratios and suggest postfire debris‐flow susceptibility could change over timescales as short as several months. A comparison of K fs , h f and S at similar times during the first and second postfire years indicates that K fs h f and S decreased immediately following the fire. We observed two debris flows, which occurred during the first three months after the fire. The relatively short time associated with notable fire effects on soil hydraulic properties, combined with substantial increases in ground cover during the first postfire year, help explain observations that PFDFs primarily initiate in the first rainy season following fire in the Southwest USA.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Steepland dynamics and steady-state forms resulting from debris flows

  NSF · $351k · 2020–2025

Frequent coauthors

• A. Youberg

  77 shared

• Francis K. Rengers

  United States Geological Survey

  72 shared

• Jason W. Kean

  United States Geological Survey

  53 shared

• Dennis M. Staley

  45 shared

• Rebecca Beers

  34 shared

• Alexander Gorr

  33 shared

• Jon D. Pelletier

  23 shared

• Nina S. Oakley

  United States Geological Survey

  22 shared