Agriculture Reference
In-Depth Information
1
n
y
5
/
3
max
S
1
/
2
q
max
=
(3.3)
0
where
y
max
=
maximum allowable depth of flow assumed to equal 0.15 m
=
∼
n
roughness coefficient (
0.4-0.25)
S
0
=
field slope (m/m) [0.1-0.5%]
Alazba's Empirical Model
Alazba (1998) derived empirical equation for border inflow rate and application time
as follows:
L
1.0562
n
0.1094
k
1.225
a
3.832
×
×
×
q
apl
=
CU
q
(3.4)
S
0.09
×
D
0.823
req
where
inflow rate, m
3
/h/m
q
apl
=
in m
3
/h/m,
CU
q
=
unit conversion factor, equal
to 0.642 for
q
appl
L
in m,
k
in m/h
a
,
and
D
req
in m (and 3.39
10
-4
for FPS unit)
×
L
=
border length in m
kt
a
,
z
is
k
,
a
=
empirical parameter of Kostiakov infiltration equation (
z
=
infiltration depth (m),
t
is time of infiltration (h))
S
0
=
field slope (m/m)
n
roughness coefficient (0.1-0.2)
D
req
=
=
required depth of infiltration (m)
The application time corresponding to design application rate:
L
1.1
n
0.0093
S
0.0203
0
k
0.387
D
0.952
req
×
×
×
×
T
apl
=
CU
T
×
(3.5)
q
1.0885
appl
×
a
0.75
where
T
apl
=
application time, h
CU
q
=
unit conversion factor, equal
to 2.5 for
T
appl
in h,
L
in m,
k
in m/h
a
, and
D
req
in m (and 1.47
10
-2
for FPS unit)
×
inflow in m
3
/h/m
q
apl
=
D
req
=
required depth of infiltration (m)
Other variables are defined earlier.
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