Match the following types of canals with their types of alignment.
| List-I (Type of Canal) | List-II (Type of Alignment) |
|---|---|
| A.Ridge canal | 1.Aligned roughly at right angles to the contours |
| B.Contour canal | 2.Aligned along the watershed |
| C.Side slope canal | 3.Aligned nearly parallel to the contours |
- AA-3, B-2, C-1
- BA-1, B-2, C-3
- CA-1, B-3, C-2
- DA-2, B-3, C-1Correct
Solution
Concept
Canals are classified by alignment: ridge (watershed) canal along the watershed, contour canal nearly parallel to contours, side slope canal at right angles to contours.
Step-by-step solution
1. A ridge canal (watershed canal) runs along the watershed line, so A-2. 2. A contour canal follows the contours roughly and irrigates one side only, so B-3. 3. A side slope canal runs roughly at right angles to the contours, along the side slope, so C-1. 4. The match is A-2, B-3, C-1. Answer (D).
Explanation
A ridge canal is aligned along the watershed, so it can irrigate both sides and needs no cross drainage works. A contour canal runs nearly parallel to the contours and irrigates only one side. A side slope canal runs at right angles to the contours, roughly parallel to the natural drainage.
Why the other options are wrong
(A) Gives the ridge canal as parallel to contours, which is wrong. (B) Gives the ridge canal as at right angles to contours, which is wrong. (C) Swaps ridge canal and side slope canal.
Shortcut
Ridge = watershed, Contour = parallel to contours, Side slope = perpendicular to contours.
Common mistake
Thinking a ridge canal is perpendicular to contours. That description fits the side slope canal.
Correct answer: D) A-2, B-3, C-1