39.2.2. Mathematical Expression

Try these first

1. 1.

   Define Duty in irrigation engineering.

   Hint

   Think about what Duty refers to in terms of irrigation.

2. 2.

   What unit is Duty expressed in?

   Hint

   Consider where you see water flow and land area.

3. 3.

   What is the definition of Duty in irrigation?

   • Area irrigated by unit discharge
   • Volume of water flow
   • Efficiency of water use

   Hint

   Think about how we express irrigation needs.

4. 4.

   True or False: Net Duty is always greater than Gross Duty.

   • True
   • False

   Hint

   Which duty takes into account real losses?

5. 5.

   A canal system has a discharge of 5 cumecs and is designed to irrigate an area of 15,000 hectares. What is the Duty? Then, if the base period for the crop is 150 days, calculate the Delta.

   Hint

   Use the formulas for Duty and Delta.

6. 6.

   If a farmer is given a plot of 500 hectares that requires 1000 hectares/cumec as Duty, what is the discharge needed for the plot?

   Hint

   Remember to rearrange the Duty formula.