Table of Contents
POINTS TO BE CONSIDERED WHILE FIXING CANAL ALIGNMENT
- The following points should be considered while fixing the alignment of a canal:
- The canal should be straight.
- Such a canal would be minimum in length.
- Length being minimum losses due to percolation and evaporation are bound to be minimum.
- The canal should follow the ridge as far as possible.
- This will cause irritation of the areas lying on both sides of the canal.
- If somewhere a canal leaves the ridge, our effort should be to catch the ridge again as soon as possible.
- Cross-drainage works should be minimum, as such works are very costly.
- The canal should not pass through a village or town, but by the side of it.
- Canal taking off from a river is a contour canal for some length.
- Every effort should be made to mount if the main watershed, as soon as possible.
- Alignment should avoid deep cuttings and high embankments.
- Idle length of the canal i.e. length of the canal not providing any irrigation, should be minimum.
- The alignment should avoid rock, fissured, and brakish formations.
- Fissured formations cause loss of water through fissures and brakish formations render water useless.
- Rocky tracks envolve lot of labour for the construction of canals.
- Suitable foundations for works like falls, cross regulators, head regulators etc.
- should be available. Besides this, materials of constructions should be available in the vicinity.
- Unnecessary curves in the canals should be avoided.
- The curves should be of as large radius as possible.
Radii of curves for canals, of various discharges should be as follows:
- The canal section should be partly in cutting and partly in filling.
- Cutting should equal filling if work has to be most economical.