The MSU Geography Graduate Group welcomed Dr. Allen G. Hunt from Wright State University. Dr. Hunt will present "A Critical Journey into the Critical Zone and the Water Balance." for a Triple G Colloquium event on October 14, 2022. 

Abstract:

The critical zone, with the soil at its center, is a foundation of life, carbon and nutrient cycling, and the water cycle. In order to understand the mathematical foundations of soil formation, vegetation growth and productivity, it turns out to be necessary to understand and/or formulate simultaneously: 1) the physics of solute transport in porous media, 2) the chemical basis of weathering, 3) a general principle of ecology, and 4) the principal fluxes of hydrology. 

Let us try to understand why the traditional understanding in all of these disciplines needs revision. For example, the result that chemical weathering rates decay in time as a power-law with time dependence similar to diffusion, but at a rate proportional to the water flux through the medium, invalidates the use of any variant of the traditional advection-dispersion equation for solute transport, from which you can derive the proportionality to flow (if advection dominates), or the time dependence, (if diffusion dominates), but not both simultaneously. The dominance of advection (flow) in weathering is then matched by the dominance of flow (transpiration) in vegetation growth, allowing a comprehensive understanding of the basic critical zone processes and the water balance.

Our journey, however, started with a new theoretical basis for solute transport, but we found that a nice shortcut of Muhammad Sahimi’s could do nearly as well and help generate a suite of scaling relationships that form a firm foundation for understanding the above fusion of disciplines in the crucible of the critical zone – a voyage of discovery followed by an opportunity to organize knowledge as not previously supposed possible. 

Bio:

Dr. Allen Hunt is Professor of Physics at Wright State University 

Ph.D. Theoretical Condensed Matter Physics (of disordered systems), 1983, UC Riverside  

Fulbright scholar 1985-1987, Philipps University, Marburg, FRG, physics. Fulbright finalist 2018-2019 Sheffield, England, agricultural engineering)

Subsequent (re)education in f eld geomorphology (M.S., Duke University, 1996), employment in Climate Dynamics (PNNL, 1999-2002), Hydrology (NSF, 2002-2003).  

Edited Volumes. Philosophica Magazine, 2001, Michael Pollak Festschrift, Fractals: Concepts and Applications (co-editor, after Behzad Ghanbarian), Hydrogeology, Chemical Weathering and Soil Formation (with co-editors, Markus Egli and Boris Faybishenko), AGU Bestseller 2021, and Complex Media and Percolation Theory (co-editor, after Muhammad Sahimi). 

Published Books, Percolation Theory for Flow in Porous Media, Lecture Notes in Physics (three editions) and, together with Stefano Manzoni, Networks on Networks: The Physics of Geobiology and Geochemistry, Morgan and Claypool for Institute of Physics.