Agriculture Reference
In-Depth Information
formula. Where the change of depth is small, inclined gauge gives accurate reading.
In such case, cumulative value for several days may be taken, and then it should be
averaged. In addition, magnifying glass may be used for easy and accurate reading.
Deep Percolation Fraction or Deep Percolation Ratio
the ratio of the volume of water percolated below the bottom boundary of the crop
root zone to the total volume entered into the soil.
D
F
= (volume of water percolated below the bottom boundary of the crop
root zone)
(4.21)
/
(total volume entered into the soil)
Runoff Fraction or Tailwater Ratio
Runoff fraction (
R
F
) can be defined as the ratio of the volume of runoff to the volume
of water diverted to the plot.
R
F
=
(volume of runoff)/ (volume of water diverted to the plot)
(4.22)
4.2.4.3 Crop and Water Productivity and Acreage
Irrigated Area
Irrigated area refers to the area irrigated in a season under the facility provided by
the irrigation system. It is expressed in hectares (ha).
Irrigation Intensity
Irrigation intensity is defined as the percentage of irrigable command area irrigated
for a season. That is
Irrigation intensity = (Actual area irrigated from a source)
×
(4.23)
100
/
(total irrigable area under the scheme)
Duty of Discharge
The term “Duty” relates to the command area coverage by the water source and the
stream size. Duty (
D
) refers to the irrigation capacity of the unit discharge or flow.
A
Q
D
=
(4.24)
where
A
=
area irrigated with the available supplied water source (ha)
supply capacity (or the discharge of the pump) (m
3
/s)
Q
=
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