19
SATURO
Figure28 Water tank
3.3 THEORY
Field saturated hydraulic conductivity, K
fs
(cm/s) is a fundamental soil hydraulic property
that describes the ease with which a fluid (usually water) can move through pore spaces or
fractures under field saturated conditions. One of the oldest and simplest methods for in situ
determination of K
fs
has involved the measurement of ponded infiltration (D) from within a
single ring (with a radius b) pushed a small distance into the soil (d) (Figure29). The original
analysis used the measured steady flow rate, Q
s
(cm
3
/s), and assumed one-dimensional,
vertical flow to obtain K
fs
from Bouwer (1986) and Daniel (1989).
Mariotte
cylinder
Wetting
front
cylinder
D
d
b
Water
Figure29 Cross section of a single-ring infiltrometer