43.2.6. Effective Rainfall

Try these first

1. 1.

   What is effective rainfall?

   Hint

   Think about how farmers use rainwater.

2. 2.

   Name one component that is excluded from effective rainfall.

   Hint

   Consider what happens to water when it doesn't reach the roots.

3. 3.

   What is effective rainfall?

   • a) The total rainfall measured in a season
   • b) Rainfall that is available for crop use
   • c) Rainfall contributing to surface runoff

   Hint

   Think about what water goes directly to crops.

4. 4.

   True or False: Effective rainfall includes deep percolation.

   • True
   • False

   Hint

   Consider the definition of effective rainfall.

5. 5.

   A field receives 120 mm of rain, with 30 mm lost to deep percolation and 25 mm lost to surface runoff. Calculate the effective rainfall and determine the irrigation requirement if the water requirement is 100 mm.

   Hint

   Use the proper calculations for effective rainfall and the irrigation requirement.

6. 6.

   Discuss the potential agricultural impacts if a region frequently experiences effective rainfall below the crop water requirement, particularly in drought conditions.

   Hint

   Consider the effects of inefficient water use and crop management strategies.