• 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:

Factors to be Considered While Fixing Canal Alignment

  • The canal section should be partly in cutting and partly in filling.
  • Cutting should equal filling if work has to be most economical.