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3.
Underlying theoretical principles
Hydraulic conductivity k
u
as a function of water tension h in soils or other open-pored materi-
als near saturation can be described according to G
ARDNER
(1958):
)
.
(
h
f
u
e
k
k
(1)
k
f
- saturated hydraulic conductivity
h - hydraulic pressure head (pos. In overpressure range)
α
- Gardner-Koeffizient
Such approach allows an analytical solution for a large number of two- and three-dimensional
flow processes. It is the regular basis for the interpretation of test results with the infiltrome-
ter systems common so far.
According to W
OODING
(1968), the following applies to the steady-state flow Q (volume/time)
from a circular infiltration area (radius a) into the infinite soil:
)
4
1
(
2
a
k
a
Q
u
(2)
For experimental determination of k
f
and
, the infiltration test can be run with different wa-
ter tensions (hydraulic pressure heads) or the infiltration gets fed from source areas with dif-
ferent radii for equal water tensions. However, infiltration from different source areas makes
sense only in largely homogeneous soils.
