Approach for using measured soil gas diffusion coefficients in Hydrus 1D with examples from forest soils

Abstract

The use of Hydrus-1D for modeling soil gas fluxes can be improved by introducing a parameter f obtained by fitting the Millington–Quirk (MQ) tortuosity model to measured gas diffusion coefficients. The approach was tested for data from soil horizons of two sandy forest sites located in Northeast-Germany. f-values ranged between 0.41 and 0.54, indicating a more tortuous pore systems than predicted by MQ model (f = 1). The parameter optimization procedure can be carried out by using the statistical software R and the enclosed R-script.