Using Energy and Mass Transfer to Model Pedogenic Environments and Process.

Soil and critical zone (CZ) evolution, structure, and function are driven by energy and mass fluxes into and through the terrestrial subsurface. Internal fluxes and spatial structure coevolve in response to the transfer and transformation of energy and mass through the CZ system. Quantifying these fluxes is central to understanding the CZ and predicting its ability to provide key services to society. Recent work quantifying the transfer of energy and mass to the CZ via carbon derived from net primary production and water in excess of evapotranspiration indicates that these relatively simple-to-derive terms exhibit strong correlations with a range of CZ structural and functional properties. The transfer term is referred to as “effective energy and mass transfer” (EEMT; MJ m^-2 yr^-1) because, while the carbon and water terms approximate only a fraction of the total energy and mass balance of CZ systems, these fluxes are deemed highly relevant to predicting subsurface physical, chemical, and biological properties. EEMT has demonstrated strong correlation with various measures of CZ structure and function and regional scales and has also been modified to account for local variation in topography, water and energy balances, and primary production, allowing for more accurate prediction of CZ properties at hillslope to catchment scales. Further, EEMT has been incorporated into landscape evolution models as an environmental term constraining rates of soil production and sediment transport processes. This presentation will summarize the development of EEMT and its application to prediction of CZ properties and process.