Irrigation Water Conveyance and Application Methods
Subtopic: Surface, sprinkler and micro irrigation methods
Question Statement:
Two advance curves M and N for surface irrigation are shown (M slower than N). This could be attributed to: P. lower inflow rate; Q. lower intake rate of soil; R. flatter field slope; S. greater hydraulic roughness for N than M.
Figure (reconstruction, not to exact original scale): advance curves M and N vs distance
Options:
(A) P, Q
(B) P, R
(C) Q, S
(D) R, S
Official Answer Key:
B
Step-by-Step Solution & Explanation
A slower advance (curve M taking longer to cover the same distance) results from less water being supplied (P: lower inflow rate means a smaller advancing water wedge) and from less gravity assistance (R: a flatter slope reduces the driving hydraulic gradient, slowing the front). A *lower* soil intake rate (Q) would leave *more* water available to advance the front, which would make the advance *faster*, not slower — so Q is a false cause here, and by construction S (roughness, stated as *greater* for N, i.e. not a property attributed to M) is also excluded from what is being asked about M. Correct pair: P, R.
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