About

Roman DiBiase is an Associate Professor in the Department of Geosciences at Penn State. His research focuses on quantifying the mechanisms of erosion and sediment transport responsible for shaping Earth’s surface, with applications ranging from post-wildfire erosion to landscape evolution. He is motivated by developing surface process models that satisfy both modern observations and longer-term geologic constraints, aiming to better predict landscape responses to changing climate and land use conditions, mitigate natural hazards, and understand the dynamic interactions between surface and deep Earth processes. His work involves fieldwork, topographic and photogrammetric analysis, cosmogenic radionuclides, and modeling. DiBiase's research investigates the interactions between tectonic geomorphology, Earth surface processes, and landscape evolution. His specific interests include post-wildfire erosion in southern California, soil production and the transition between soil-mantled and bare-bedrock landscapes, and river incision with feedbacks between tectonics, rock strength, and topography in Taiwan. His contributions are documented through numerous publications, including work on the Susquehanna Shale Hills Critical Zone Observatory, and he actively applies mechanistic models to understand the dynamic processes shaping Earth's surface.

Research topics

• Geotechnical engineering
• Geology
• Geomorphology
• Soil science
• Oceanography

Selected publications

• Pleistocene Smoothing and Resurfacing of Appalachian Ridgelines by Periglaciation

  Geophysical Research Letters · 2026-02-11

  articleOpen accessSenior author

  Abstract Pleistocene cold periods created widespread periglacial conditions across mid‐latitudes, but isolating their geomorphic impact from modern climate, tectonics, and rock strength is challenging. We studied Appalachian (Eastern U.S.) ridgelines across a paleoclimate gradient, controlling for bedrock and structure, to test if colder periglacial conditions led to flatter hilltops and longer hillslopes, features typical of permafrost landscapes. We find that hilltop curvature and hillslope length vary with paleotemperature, not modern climate or uplift. Despite gentler slopes, erosion rates near the Last Glacial Maximum ice margin are similar or higher than southern sites for resistant bedrock units, suggesting frost cracking and solifluction enhanced hilltop lowering and valley infilling. Hillslope morphometry patterns resemble landscapes responding to modern Arctic climate gradients, implying a long‐lived geomorphic signature of permafrost‐driven processes. This cold‐climate legacy can remain imprinted in modern mid‐latitude terrain, complicating efforts to link current climate with landscape form where erosion rates are slow.

  PublisherOA PDFDOI

• Untangling Climate and Lithologic Controls on Rocky Hillslope Evolution in Steep Landscapes of Eastern California

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

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  PublisherDOI

• Crustal Conditions of a Collisional Orogen: Using Electron Backscatter Diffraction (EBSD) to Understand Deformation in Taiwan

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

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  PublisherDOI

• Comment on gchron-2024-28

  2025-01-07

  peer-reviewOpen access1st authorCorresponding

  <strong class="journal-contentHeaderColor">Abstract.</strong> OCTOPUS v2.3 includes updated <em>CRN Denudation</em> datasets, adding 1,311 new river basins to the <em>CRN International</em> and <em>CRN Australia</em> collections. The updates bring the total number of basins with recalculated ¹⁰Be denudation rates to 5,611, and those with recalculated ²⁶Al rates to 561. To improve data relevance and usability, redundant data fields have been removed, retaining only those relevant to each collection. Additional updates include the introduction of several new data fields: the latitude of the basin centroid and the effective basin-averaged atmospheric pressure, both of which improve interoperability with online erosion rate calculators. Other new fields record the extent of present-day glaciers and their potential impact on denudation rates, as well as estimates of the percentage of quartz-bearing lithologies in each basin &mdash; providing a basis for evaluating data quality. The updated data collections can be accessed at <a href="https://octopusdata.org" target="_blank" rel="noopener">https://octopusdata.org</a> (last access: 01 Dec 2024). The <em>CRN International</em> and <em>CRN Australia</em> data collections can also be accessed via their respective digital object identifiers (DOIs).

  PublisherDOI

• A short-term critical zone geophysics program designed to recruit, retain, and foster community amongst 1st and 2nd year undergraduates historically marginalized in geosciences

  Journal of Geoscience Education · 2025-07-21

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  PublisherDOI

• Understanding Rock Strength in a Collisional Orogen: Field and Laboratory Measurements of Rock Strength in Taiwan

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

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  PublisherDOI

• Hillslope and vegetation response to postglacial warming at Bear Meadows Bog, Pennsylvania, USA

  Quaternary Research · 2024-01-01 · 1 citations

  articleOpen accessSenior author

  Abstract Connecting changes in erosion and vegetation is necessary for predicting topographic and ecologic change in thawing permafrost landscapes. Formerly periglacial landscapes serve as potential analogs for understanding modern permafrost landscape change, yet compared to paleoenvironmental records at these sites, less is known about concurrent geomorphic processes, particularly their rates and relationships to climate change. Here, we target sediments preserved in a central Appalachian peat bog to reconstruct sedimentation across the last deglacial warming. We use ground-penetrating radar and geochemistry of cored bog sediments to quantify sedimentation timing, style, and provenance. Using 14 C dating of sedimentary and geochemical shifts, we connect depositional changes to global climate and local vegetation change. We show that deglacial warming promoted deep soil disturbances via solifluction at ca. 14 ka. In contrast, relatively wetter conditions from ca. 10–9 ka promoted shallow disturbance of hillslopes via slopewash, which corresponds to a time of vegetation change. Our results highlight climate-modulated erosion depth and processes in periglacial and post-periglacial landscapes. The existence of similar erosion and vegetation records preserved regionally implies these dynamics were pervasive across unglaciated Appalachian highlands, aiding in reconstructing erosion responses to warming at a resolution with implications for predicting high-latitude landscape responses to disturbance.

  PublisherOA PDFDOI

• USING ELECTRON BACKSCATTER DIFFRACTION (EBSD) TO CHARACTERIZE STRESS AND CRUSTAL RHEOLOGY IN TAIWAN

  Abstracts with programs - Geological Society of America · 2024-01-01

  articleSenior author
  PublisherDOI

• The grain size of sediments delivered to steep debris‐flow prone channels prior to and following wildfire

  Earth Surface Processes and Landforms · 2024-04-05 · 7 citations

  articleOpen access

  Abstract Debris flows are powered by sediment supplied from steep hillslopes where soils are often patchy and interrupted by bare‐bedrock cliffs. The role of patchy soils and cliffs in supplying sediment to channels remains unclear, particularly surrounding wildfire disturbances that heighten debris‐flow hazards by increasing sediment supply to channels. Here, we examine how variation in soil cover on hillslopes affects sediment sizes in channels surrounding the 2020 El Dorado wildfire, which burned debris‐flow prone slopes in the San Bernardino Mountains, California. We focus on six headwater catchments (&lt;0.1 km 2 ) where hillslope sources ranged from a continuous soil mantle to 95% bare‐bedrock cliffs. At each site, we measured sediment grain size distributions at the same channel locations before and immediately following the wildfire. We compared results to a mixing model that accounts for three distinct hillslope sediment sources distinguished by local slope thresholds. We find that channel sediment in fully soil‐mantled catchments reflects hillslope soils ( D 50 = 0.1–0.2 cm) both before and after the wildfire. In steeper catchments with cliffs, channel sediment is consistently coarse prior to fire ( D 50 = 6–32 cm) and reflects bedrock fracture spacing, despite cliffs representing anywhere from 5% to 95% of the sediment source area. Following the fire, channel sediment size reduces most (5‐ to 20‐fold) in catchments where hillslope sources are predominantly soil covered but with patches of cliffs. The abrupt fining of channel sediment is thought to facilitate postfire debris‐flow initiation, and our results imply that this effect is greatest where bare‐bedrock cliffs are present but not dominant. A patchwork of bare‐bedrock cliffs is common in steeplands where hillslopes respond to channel incision by landsliding. We show how local slope thresholds applied to such terrain aid in estimating sediment supply conditions before two destructive debris flows that eventually nucleated in these study catchments in 2022.

  PublisherDOI

• POST-WILDFIRE DRY RAVEL LOADING AND SUBSEQUENT DEBRIS FLOW SCOUR FOLLOWING THE 2020 APPLE, BOBCAT, AND EL DORADO FIRES IN SOUTHERN CALIFORNIA

  Abstracts with programs - Geological Society of America · 2024-01-01

  articleSenior author
  PublisherDOI

Recent grants

• Fracture density and grain size controls on the relief structure of bedrock landscapes

  NSF · $315k · 2016–2021

• CAREER: Quantifying the controls of wildfire, climate, and tectonics on the transition between soil-mantled and bedrock hillslopes

  NSF · $542k · 2019–2026

Frequent coauthors

• K. X. Whipple

  University of Arizona

  29 shared

• Alexander B. Neely

  University of Tübingen

  24 shared

• Arjun M. Heimsath

  Arizona State University

  21 shared

• Joanmarie Del Vecchio

  William & Mary

  17 shared

• G. Mount

  13 shared

• Michael P. Lamb

  California Institute of Technology

  11 shared

• Paul R. Bierman

  10 shared

• J. L. Hayes

  Dickinson College

  9 shared