The agricultural land lying below the level of the main canal, which can be irrigated by the canal, forms the canal's:

The command area of an irrigation project is the area of farmland that can be supplied with water by its canal system. Because canals carry water by gravity, only land lying below the level of the main canal (and its branches) can be irrigated, and this land forms the command area.

Gross and net command area:

The gross command area is the total area the canal system could serve, including villages, roads and ponds. Removing the land that cannot be farmed gives the area that can actually be cultivated and irrigated.

Command Area Development (CAD) Programme:

• It was launched by the central government in 1974-75.
• Its aim is to make better use of the irrigation potential created by major and medium irrigation projects and to close the gap between the potential created and the area actually irrigated.
• It includes field channels, field drains, land levelling, warabandi (rotational water supply) and water users' associations.

It was later renamed the Command Area Development and Water Management (CADWM) programme and is now part of the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY), launched in 2015 with the slogan "Har Khet Ko Pani" ("water for every field").

Problems in command areas:

• Waterlogging and soil salinity caused by over-irrigation and poor drainage, as seen in parts of the Indira Gandhi Canal and Sharda Sahayak command areas.
• Unequal distribution: farmers at the head of a canal often get more water than those at the tail end.

Related terms:

Catchment area: the area from which rainwater drains into a river, lake or reservoir. It is above the dam, while the command area is below it.

Watershed: the boundary (high ground) dividing two drainage basins; the term is also used for a small drainage basin.

Why not the other options?

• ✗Catchment area supplies water to the reservoir, rather than receiving it from the canal.
• ✗Flood plain is the flat land beside a river that is flooded at high water.
• ✗Watershed is a dividing ridge or a small drainage unit.