Silt excluders are constructed:
- Aon the river bed downstream of the head regulator
- Bon the river bed upstream of the head regulatorCorrect
- Con the canal bed downstream of the canal head regulator
- Dnone of the above
Solution
Concept
Location of silt excluder construction
Formula
NONE
Step-by-step solution
1. Silt excluders are devices designed to prevent heavy silt from entering the main canal. 2. They are constructed on the river bed in front of (upstream of) the canal head regulator. 3. They divert the silt-laden bottom water back into the river downstream through under-sluices while allowing clear top water into the canal. Answer: B
Explanation
Silt excluders are devices designed to prevent silt from entering the main canal by removing it directly in the riverbed. They are constructed on the river bed upstream of the canal head regulator in front of the under-sluices. This allows the silt-laden bottom layer of water to pass through the under-sluices while allowing relatively clean top water into the canal.
Why the other options are wrong
A) Placing the structure downstream of the head regulator would allow silt to enter the canal first. C) Devices constructed on the canal bed downstream of the regulator are called silt ejectors. D) Option B is correct because silt excluders are positioned on the river bed upstream of the regulator.
Shortcut
Silt Excluder = River bed UPSTREAM; Silt Ejector = Canal bed DOWNSTREAM.
Common mistake
Confusing silt excluders built upstream on the river bed with silt ejectors constructed downstream in the canal bed.
Correct answer: B) on the river bed upstream of the head regulator