Re. Smith et B. Diekkruger, EFFECTIVE SOIL-WATER CHARACTERISTICS AND ENSEMBLE SOIL-WATER PROFILESIN HETEROGENEOUS SOILS, Water resources research, 32(7), 1996, pp. 1993-2002
One-dimensional vertical flows through spatially heterogeneous areas a
re studied with numerical solutions for a variety of soil types, to as
certain the behavior of the ensemble. Soil heterogeneity is treated us
ing the distributions of parameters describing the characteristic rela
tions of conductivity, water content, and pressure head. Values of the
critical parameters, taken from a modified Brooks-Corey or van Genuch
ten model, have previously [Smith and Diekkruger, 1992] been shown in
two extensive data sets to exhibit little interdependence. The static
ensemble characteristics, except for saturated and residual water cont
ent parameters, are shown to have regular bias compared to a soil with
the mean characteristic parameters. The measured data also are shown
not to support the popular similar media heterogeneity model. Using bo
th analytic approximate flow models and an ensemble solution of Richar
ds' equation, the effective dynamic ensemble characteristics in three
example soils are studied. As suggested in previous studies, such effe
ctive characteristics are conditional to flow conditions and are here
shown to be quite different from ensemble static characteristics. This
indicates that irrespective of the sample size, effective soil dynami
c characteristics are not measurable for-samples possessing significan
t heterogeneity.