Monday, June 1, 2009

Structures - Super Passage, Under Tunnel, Canal Syphon, Aqueduct.

What is Super Passage?
When the canal is in full cutting and there is sufficient head way for the canal water a Super Passage may be proposed. That is if the Full supply level (F.S.L) of canal is below a depth of free board required for canal from bed level of drain crossing, at this point a super passage may be constructed to let the discharge of drain without causing any damage to the canal.
What is Aqueduct?
Aqueduct is a structure that may be proposed on canal that is running in full embankment and there is sufficient way to pass the discharge of drain. That is if the Maximum Flood Level (M.F.L) of drain is below a depth of free board required in drain from Bed Level Canal, at this point an aqueduct may be proposed to let the discharge of drain below canal without causing any damage to the canal.
What is Under Tunnel (Type-2 Aqueduct)?
When the canal is running in partial or full embankment and there is no sufficient head way to pass the discharge of drain below the canal then an Under Tunnel may be proposed. That is if the (MFL +Freeboard) of drain is above the bed level of canal, then a barrel will be provided below the canal bed level by depressing the bed level of the drain.
What is Canal Syphon?
When the canal runs partially in cutting, the canal syphon may be adopted. A barrel will be provided below the bed level of drain to pass the discharge of canal by depressing canal Full supply level (F.S.L) before the drain crossing and again lift it back after crossing the drain. Sufficient head may be provided to force the water from up stream of canal to down stream of canal. This is often provided for drain crossing that have huge discharge and an Under Tunnel may not be economic.

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