In case of irrigation canal, the seepage losses depend upon
- Athe condition of the canal; the seepage through a silted canal is more than that from a new canal
- Bamount of silt carried by the canal; the less the silt, lesser are the losses
- Cvelocity of canal water; the more the velocity, the more will be the losses
- Dcross-section of the canal and its wetted perimeterCorrect
Solution
Concept
Factors affecting seepage
Formula
Seepage ∝ wetted perimeter
Step-by-step solution
1. Seepage takes place through the wetted perimeter, so it depends on the cross-section and wetted perimeter (d). 2. A silted canal has LESS seepage than a new one (a is false), and more silt reduces seepage (b is false). 3. Velocity is not the governing factor.
Explanation
Silt deposited on the bed and sides seals the pores, so the seepage falls with age and silt load. The loss through the wetted area is proportional to the wetted perimeter.
Why the other options are wrong
(a) and (b) reverse the effect of silt. (c) is not the main factor.
Shortcut
Seepage loss ∝ wetted perimeter, ↓ with silt.
Common mistake
Believing that silted canals leak more.
Correct answer: D) cross-section of the canal and its wetted perimeter