Which one of the following is not a type of groyne ?
- ARepelling groyne
- BAttracting groyne
- CPerpendicular groyne
- DStraight groyneCorrect
Solution
Concept
Types of groynes by orientation
Step-by-step solution
1. Repelling (deflecting) groynes are inclined upstream. 2. Attracting groynes are inclined downstream. 3. Perpendicular (neutral) groynes are at right angles to the bank. 4. "Straight groyne" is not one of the types.
Explanation
Groynes are classified by their inclination into repelling, attracting and perpendicular types, and by shape (T-headed, hockey-shaped and so on).
Why the other options are wrong
Repelling, attracting and perpendicular are the standard orientation types.
Shortcut
Repelling (upstream), attracting (downstream), perpendicular (neutral).
Common mistake
Treating "straight" as a type.
Correct answer: D) Straight groyne