Question

According to the Central Board of Irrigation and Power, the PA ratio for graded aquifer should be _______________

(a) 9 – 12.5

(b) 12 – 15.5

(c) > 15.5

(d) < 9

The question was posed to me during an online interview.

This interesting question is from Tube Well-1 in portion Ground Water for Irrigation through Wells and Tubewells of Irrigation Engineering

Answer 1

Correct option is (b) 12 – 15.5

The best explanation: The Central Board of Irrigation and Power suggested the following criteria for PA ratio.

i. For uniform aquifers (having Cu < or = 2.0), the PA ratio should be in between 9 – 15.5

ii. For graded aquifers (having Cu > 2.0), the PA ratio should be in between 12 – 15.5.