Factors in deciding canal alignment

The alignment should give the maximum command at minimum cost and be safe. The factors are:

1. Command: keep the canal on the highest ground (watershed/ridge) so that gravity irrigation covers the largest area, with the full supply level above the field levels.
2. Topography and contours: avoid unnecessary deep cuttings and high fillings; follow the ground slope as far as possible; keep near the balancing depth for economy of earthwork.
3. Cross-drainage works: keep the number of drainage crossings (aqueducts, culverts) to a minimum, as each is costly.
4. Geology and soil: avoid rocky, sandy, porous or landslide-prone areas, and saline or swampy ground.
5. Straight and smooth alignment: avoid sharp bends (use curves of radius at least 5 times the bed width), and avoid cutting through villages and fertile land.
6. Land acquisition and existing structures: avoid roads, houses and religious places, to keep compensation low.
7. Head and drops: the length and bed slope should provide the needed head with the fewest falls.
8. Command and field boundaries: align along property boundaries; avoid splitting farms.
9. Future extension and drainage: allow for extension and avoid waterlogging.
10. Accessibility for construction and O&M, and nearness of construction material (borrow area).