Geoscience Reference
In-Depth Information
10
3
Sandy Soil
10
1
10
-1
Clay Soil
10
-3
10
-5
-10
1
10
-7
-10
5
-10
3
Soil water pressure head
h
(cm)
Figure 4.19
Typical hydraulic conductivity curves for a sand and a clay soil.
Q
top
z
d
z
S
d
y
y
Q
bottom
Figure 4.20
Vertical water low through an elementary cubic soil volume, including
root water extraction
S
.
where
S
is the water extraction by roots (m
3
m
-3
d
-1
). If we assume water density
ρ
to
be constant, and divide by (
ρ
d
x
d
y
d
z
), we arrive at the continuity equation of water
in variably saturated soil:
∂
∂
=−
∂
θ
t
q
z
∂
−
S
(4.21)
Search WWH ::
Custom Search