Fig. 10. Parameter analysis based on the Campbell-type model, Eq. [13]. (a) Model fit of air permeability and gas diffusivity relations for soil L1. (b) Slope of Campbell-type model, , as a function of Campbell pore-size distribution index, b. The interval for water permeability is calculated by the Alexander and Skaggs (1986) and Campbell (1974) expressions ( = b + 3 and 2b + 3). The values for the remaining parameters are based on data from Olesen et al. (1999) and Schjønning et al. (1999) for soils L1 through L6