Drippy soil and bouncing sand: The stuff that landscapes are made of

Rachel Glade, University of Rochester

Zoom Address

Abstract: Earth’s surface is constantly changing as wind, water, and gravity shape landscapes through the transport of sediment on timescales ranging from seconds to millions of years. Landscape material, composed of a mixture of heterogeneous grains (e.g., soils, river cobbles, beach sand) and fluids can behave as solids, fluids, or anywhere in between. Thus landscapes operate as a natural laboratory, a new frontier in which we can study the behavior of complex matter at length and timescales rarely previously considered. Here I present two ongoing projects that illustrate the challenging, interdisciplinary problems embedded within natural landscapes. First, we will look at large-scale arctic soil patterns and explore how their formation and morphology are analogous to contact line instabilities (e.g., paint or cake icing drips) found in fluids. Next, we’ll look at a coupled CFD-DEM model to better understand how particle shape affects fluid-driven granular motions, with an eye toward sediment transport in rivers. Throughout the talk, we’ll explore how a combination of theory, laboratory experiments, numerical modeling, and fieldwork are needed to understand the rheology of sediment and emergent patterns in landscapes.  

Biosketch: Rachel received a B.A. in Geology from the University of Pennsylvania, where she worked with Doug Jerolmack to study the formation of windblown sand ripples. She went on to do a Ph.D. at the University of Colorado, Boulder, where she worked with Bob Anderson to develop simple numerical models of hillslope evolution in the presence of large boulders. She recently finished a postdoc at Los Alamos National Lab working with Joel Rowland to better understand the formation of frozen soil patterns as they relate to fluid flow instabilities. She arrived at the University of Rochester as an assistant professor this past summer in the Earth and Environmental Sciences department.