The canal alignment may be changed so that crossing is shifted to d/s where drainage bed is low if conditions are not suitable for construction of a siphon-aqueduct. Thus, sufficient headway becomes available for constructing an aqueduct. The CD works are finalized before canal alignment.

Joint fillers are normally compressible sheets or strip materials that are used as spacers and y are fixed to face of first placed concrete. The maximum permissible expansion or contraction is of order of 10 mm.

Canal wings or land wings provide a strong connection between sides of canal trough and earn canal banks. Drainage wings or water wings or river wings provide a vertical cut-off for water seeping from canal into drainage bed. It also protects earn slopes and guide drainage water and join it to guide banks.

A complete contraction joint is one in which both concrete and reinforcing steel is interrupted. A partial contraction is one in which only concrete is interrupted reinforcing steel running through. A distinction should also be made between m.

The maximum spacing of 30 m is provided between successive expansion joints or between ends of structure. The provision of movement joints in each element can be considered independently where sliding joints are provided between walls and eir floor or roof.

A watershed line or ridgeline crosses minimum number of drains and contour canal crosses maximum number of drains. When a canal is aligned as contour canal it requires more CD works. It is a costly construction and should be avoided as far as possible.

This is a type of cross-drainage works in which canal water and drain get intermixed. The arrangement is generally adopted when a huge canal crosses a large torrent carrying a high short-lived flood.

The point of crossing is shifted upstream or downstream of drainage by suitably changing canal alignment. It manipulates bed levels of canal and drainage.

The permissible velocity through barrels is generally limited to 2 to 3 m/sec. A higher value of velocity requires higher and longer marginal banks since it causes quick abrasion of barrel surfaces by rolling grit and results in a higher amount of afflux on U/s side of aqueduct.

The use of sealing compounds is not very successful for vertical joints. A stepped joint with a water bar incorporated in joint and sealing compound packed round corrugation of water would be much more successful instead of straight through-joint.