Agriculture Reference
In-Depth Information
Solution
We get
S
0.5
0
L
×
10
−
6
)
q
min
=
(5.95
×
×
n
Here
L
300 m
S
0
=
=
=
0.3%
0.003
Assuming
n
=
0.15
0.000978 m
3
/s-m (Ans.)
We get
q
min
=
Check
CS
−
0.75
0
According to SCS, max. non-erosive flow rate
q
max
=
0.013262 m
3
/s-m
Taking
C
=
0.00017,
S
0
=
0.003;
q
max
=
Assuming limiting case for ponding (
∼
0.15 m) and adopting Manning's
formulation,
1
n
y
5
/
3
max
S
1
/
2
q
max
=
0
n
0.1
y
max
=
=
0.15 m
S
0
=
0.003
Putting the values,
q
max
=
0.0232
The minimum flow rate (
q
min
) is lower than the
q
max
under different limiting
conditions; thus it is safe.
3.2.7 Simulation Modeling for Border Design
Design and management of border layouts (and also for other surface irrigation
systems) requires knowledge of the hydraulics of overland flow, infiltration, and
drainage behavior. The simulation model is useful in integrating all the relevant and
interacting processes.
Border irrigation system can be modeled using one-dimensional or two-
dimensional flow analysis. In one-dimensional analysis, the pattern of water flow
over and under the soil surface is assumed to be repeated across the width of the
field. With respect to field behavior, this assumption cannot be fully justified. But
for simplicity, one-dimensional assumption is frequently used in border or other
surface irrigation systems.
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