39.2. Duty (D)

Try these first

1. 1.

   What is the formula for Duty (D)?

   Hint

   Use the terms Area and Discharge.

2. 2.

   Define Gross Duty.

   Hint

   Think about the water measurement at the start.

3. 3.

   What does Duty (D) represent?

   • Area of irrigated land per water unit
   • Total water supply
   • Crop yield

   Hint

   Think about water allocation to crops.

4. 4.

   Is Net Duty the same as Gross Duty?

   • True
   • False

   Hint

   Remember the definitions of both terms.

5. 5.

   Calculate the Duty for an irrigation system that discharges 15 cumecs and serves an area of 45,000 hectares. What is Delta if the base period is 60 days?

   Hint

   Follow the Duty formula for the first part and the Delta relationship for the second.

6. 6.

   Discuss the impact of soil type on Duty and how different irrigation methods can mitigate low Duty in sandy soils.

   Hint

   Consider characteristics of different soil types.