Definition in canal irrigation management: What does the “intensity of irrigation” quantify for a command area?

Introduction / Context:

Planning and operating an irrigation project requires clear metrics for how much land gets water. “Intensity of irrigation” is a core planning term used to size canals, allocate water across seasons, and schedule rotations (warabandi). It is expressed as a percentage and specifically relates to land that can actually be cultivated.

Given Data / Assumptions:

• Command areas are categorized as Gross Commanded Area (GCA) and Culturable Commanded Area (CCA).
• Intensity of irrigation is reported for a year or season (kharif/rabi) as a percentage.
• Objective is to reflect how much of the cultivable command is planned to receive irrigation water.

Concept / Approach:

GCA includes all land within the hydraulic command, whereas CCA excludes unculturable parts (roads, village sites, water bodies, rocky outcrops). Intensity of irrigation therefore uses CCA in the denominator to indicate the planned extent of actual cropped land to be irrigated. Typical values might be, for example, 40% in kharif and 40% in rabi, giving 80% annual intensity.

Step-by-Step Solution:

Verification / Alternative check:

Project reports and irrigation manuals quote intensity explicitly with respect to CCA (not GCA), reaffirming that option (a) is the correct definition.

Why Other Options Are Wrong:

• GCA: Overstates the base by including non-culturable land.
• Mean of CCA and GCA: Not a standard metric.
• Total depth by number of waterings: That describes seasonal depth delivered, not intensity.
• Duty ratio: Relates discharge to area irrigated; it is not the definition of intensity.

Common Pitfalls:

• Confusing annual intensity with seasonal intensity; projects often list both and sum them for the year.
• Interchanging CCA and GCA in percentage calculations.

Final Answer:

Percentage of culturable commanded area (CCA) to be irrigated annually