Geoscience Reference
In-Depth Information
2
r
m
Soil
surface
z
Lower limit
of root zone
Figure D.1
Schematization of root system by equally spaced tubes. Density may
differ in the vertical.
Q
out
length (
r
+ d
r
) d
α
area
A
length
r
d
α
Q
in
d
r
radial angle d
α
r
Figure D.2
Water balance of a radial segment.
As we are dealing with ininite small differences, we may omit higher-order terms
with respect to irst-order terms: the third term in Eq. (
C.3
), and the second term in
Eq. (
C.4
). The water balance of segment
A
can be written with the simpliied equa-
tions (
C.3
) and (
C.4
) as:
∂
∂
θ
=− →
∂
∂
θ
qr rr
q
r
∂
∂
AQ Q
rr
dd
αα
=−
ddd
+
(D.5)
in
out
t
t
Search WWH ::
Custom Search