37.5. Duty, Delta, and Base Period

Try these first

1. 1.

   What does Duty represent in irrigation?

   Hint

   Think about how land can be watered with a given water flow.

2. 2.

   What is the formula for calculating Delta?

   Hint

   Recall the elements that factor into Delta's calculation.

3. 3.

   What does Duty represent in irrigation?

   • Area irrigated per unit discharge
   • Total water needed by a crop
   • Time from first to last watering

   Hint

   Think about how we measure the area that can be watered.

4. 4.

   True or False: The Base Period refers to the time span during which crops are typically harvested.

   • True
   • False

   Hint

   Think about the different stages of crop management.

5. 5.

   A river supplies 8 cumecs of water. If the Duty is 10 hectares/cumec, how many hectares can be irrigated? Next, if a crop's Base Period is 50 days, calculate the Delta.

   Hint

   First calculate the irrigable area, then compute the Delta.

6. 6.

   A field requires 60 mm of water (Delta) for a Base Period of 20 days. What is the Duty for the crop? Use the formula Δ = (8.64 × B) / D to find D.

   Hint

   Focus on the rearranging part of gathering the right values.