Question

Consider the following terms relating to irrigation requirements:

For a given set up, which one of the following is the correct relation?

• A. 1 > 2 > 3 > 4
• B. 1 < 2 < 3 < 4
• C. (1 = 2) < 3 < 4
• D. 1 < (2 = 3) < 4

Answer 1

The correct option is B 1 < 2 < 3 < 4

Consumptive Irrigation Requirement,

$CIR=C_u-R_u$

$C_u$ is Consumptive use of crop
$R_e$ is Effective rainfall
Net Irrigation Requirement (NIR) = CIR + Water lost as percolation in satisfying other needs such as leaching.

Field Irrigation Requirement,

$FIR=\frac{NIR}{\text{Water application efficiency}\left({\eta }_a\right)}$

Thus,
FIR + NIR + percolation losses in field watercourses and field channels

Gross Irrigation Requirement (GIR)

$=\frac{FIR}{\text{Efficiency of Water Conveyance}\left({\eta }_c\right)}$

$\therefore$ GIR = FIR + Conveyance losses in distributaries upto the field.

So GIR > FIR > NIR > CIR