Gravity canals follow a descending water-surface gradient; lift irrigation uses pumps to move water uphill; balancing reservoirs buffer supply and demand between stages. A long scheme may contain all three. Handri Neeva is a lift example, while delta canals downstream of a barrage rely heavily on controlled gravity delivery.

A dotted route on a textbook map does not prove that every segment is open or has delivered design water. Ask where pumps, regulators and balancing storage are in the chain.

Worked example: Imagine a field above the adjacent canal's water level. Gravity alone cannot serve it; a pump or lift stage may be needed. A balancing reservoir can buffer deliveries along a long route but does not create additional water. Handri Neeva illustrates why a route's name is not enough to infer its energy needs. Map arrows show direction, while contour and elevation explain the engineering choice.

Active recall: Locate the named river or project on the relevant map, name its function, and state which facts need a dated source.