Question

how to compare the performance of the Brooks and corey (1964) , van genuchten (1980) and fredlund and xing (1994) models in terms of goodness of fit ?

(in relation SWCC curves )

Answer 1

The selected best-fit SWCC equations and the kr equations form a matrix as shown in Table 1. A combination of each pair (i.e., one SWCC equation and one kr equation) will result in one unsaturated permeability estimation model. The matrix shown in Table 1 was created as the standard procedure to study the effect of SWCC and kr equations. The designated names of each model as shown in Table 1 are based on the SWCC and kr equations used in the model. In addition, two existing permeability estimation models, a combination of limited form of van Genuchten SWCC equation with Mualem kr equation as proposed by van Genuchten (1980) (shown as VG-1980 in this study) and a combination of the Fredlund and Xing SWCC equation and the Childs and Collis-George kr equation as proposed by Fredlund et al. (1994) (shown as F&X-1994 in this study), are shown under the appropriate column in the matrix in Table 1.