Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Gregory Tucker

Research Interests

My interests lie in geomorphology and landscape evolution. My group seeks to understand the physics of diverse geomorphic processes, and how these processes interact to shape terrain and move sediment. Some of our efforts are geared toward understanding the evolution of the earth's surface over geologic time; others focus on contemporary issues such as gully development and erosional threats to toxic waste repositories. We also develop and share open-source software technology to support computational modeling of diverse earth-surface processes. Through teaching, I strive to equip students with the skills in writing and quantitative analysis that they need to understand, investigate, and make informed decisions about our fascinating and dynamic planet. I also direct the Community Surface Dynamics Modeling System (CSDMS), an organization that facilitates computational modeling in earth-surface sciences by providing support for community, computing, and education.

Current Research

Some recent research themes in my group include:

  • Facets and scarps on active fault-bounded mountain ranges, and what they can tell us about tectonic and geomorphic processes (Tucker et al., 2011)
  • Morphology and evolution of steep, rocky hillslopes, and cellular automaton methods for modeling them (Tucker et al., 2018; Tucker et al., 2016)
  • Using natural experiments to test and compare landscape evolution models (Barnhart et al., in review, a,b,c)
  • Developing flexible software libraries and code packages to facilitate numerical modeling of earth-surface processes (Hobley et al., 2017; Shobe et al., 2017; Barnhart et al., 2019)

Research Example: Modeling Long-Term Erosion in the Context of Hazardous Waste

When hazardous waste material sits in a location that may be susceptible to erosion, how do we estimate the likelihood of future contaminant release? This is a question that Greg Tucker’s group has been grappling with, in the context of a former nuclear fuel reprocessing plant in western New York State. During its operational life in the late 1960s and early 1970s, the plant generated a variety of radioactive waste products; much of this material remains entombed at the site today. The plant lies atop a plateau underlain by soft late Pleistocene glacial sediments. Active erosional processes, including landsliding and gully propagation, are gradually gnawing at the plateau edges. In a project spearheaded by CIRES researcher and NSF Postdoctoral Fellow Katy Barnhart, Greg and his team (whose CU members also included postdoc Matt Rossi and (then) PhD students Charlie Shobe, Rachel Glade, and Harrison Gray) undertook a computational modeling study of past and future long-term erosion at the site. They took advantage of a unique aspect of the site’s recent geologic history: the last recession of glacial ice about 13,000 years ago left behind a relatively smooth surface that has subsequently been deeply incised by stream valleys. By reconstructing this smooth post-glacial surface and running a suite of erosion models forward in time from the late Pleistocene to the present day, the team was able to test and calibrate a collection of alternative models. The models were crafted using Landlab Toolkit, a Python-language modeling framework developed by Greg’s group and CSLMS. In addition to providing a basis for making projections of future erosion, the results shed new light on the key principles of long-term landscape evolution in this type of post-glacial environment, and yielded a new method for testing quantitative models.