Duty and Delta

a. Delta (Δ) :

• It is the total depth of water required by crop during the entire period of the crop in the field.
• Values of delta of :

b. Duty (D):

• It is the relationship between the volume of water and area of the crop it nutures.
• The volume of water discharged for a time equal to the base period of the crop is called the base of duty.

Duty(D) = Area(A)/ Discharge

c. Base period (B) or base of the crop:

• The time between the first watering of the crop at the time of each sowing to each last watering before harvesting is called base period.

d. Crop period:

• It is the time in days that a crop takes from its sowing to its harvest.

e. Gross Command Area (GCA):

• It is the total area which can be irrigated by a project or a distributary or a canal including area covered by road, buildings, villages, uncultivable land, etc within the cultured area.

f. Culturable command area (CCA)

• It is an actual area under irrigation by a project or a distributary or a canal and it is cultivated with crops or culturable in GCA.
• It is divided into two parts:

g. Culturable cultivated area: It is the area in which crop is grown at particular time on a season.

h. Culturable Uncultivated area: It is the area in which crop is not sown in a particular time.