Irrigation Systems

India's net irrigated area has expanded dramatically since independence, but the method of irrigation used varies sharply by region, tracking terrain, groundwater availability, and historical investment patterns rather than any single national pattern.

Canal irrigation is the traditional backbone of irrigated agriculture in the flat, perennial-river-fed plains of the northwest — Punjab and Haryana's canal networks (many tracing back to British-era works like the Upper Bari Doab Canal and the Sirhind Canal) are a direct enabler of the Green Revolution's success in exactly that belt. Its main limitation is that it requires both a reliable river source and gentle, even terrain, which is why it is far less prevalent across the hard-rock, undulating Deccan plateau.

Well and tube-well irrigation has overtaken canal irrigation as India's largest single source of irrigated area in recent decades, driven by cheap or free agricultural electricity in several states and the falling cost of bore-well drilling — but this same growth is the direct mechanism behind the groundwater-depletion crisis discussed in the Green Revolution section, since tube-well extraction in low-rainfall zones like Punjab draws down aquifers faster than monsoon recharge can replenish them.

Tank irrigation is the oldest indigenous irrigation tradition in peninsular India, dating back over a thousand years in some Tamil Nadu and Andhra Pradesh tank systems (many originally built or maintained under Chola- and Vijayanagara-era patronage) — it suits the hard, impermeable crystalline rock terrain of the Deccan, where canal-building is difficult and groundwater is harder to access, by capturing and storing surface runoff during the monsoon for release through the dry season. Its relative share of national irrigated area has been declining for decades as canal and tube-well irrigation expand faster, a trend frequently cited as a loss of traditional, low-carbon water management infrastructure.

Micro-irrigation (drip and sprinkler) is the newest and most water-efficient method, using far less water per unit of crop output than any surface method — it is especially suited to horticulture, orchards, and cash crops (sugarcane, cotton, fruits, vegetables) rather than flooded staples like rice, and its promotion is now central government policy specifically as a response to groundwater stress, formalised under PMKSY's "Per Drop More Crop" component (2015 onward).

Memory hook — "C-W-T-M, four letters, four regions": Canal → Punjab/Haryana (flat, perennial rivers). Well/tube-well → UP/Rajasthan (groundwater-rich alluvium/aquifers). Tank → Tamil Nadu/Andhra/Karnataka (hard Deccan rock, ancient tank tradition). Micro-irrigation → Maharashtra/AP (horticulture, water-scarce cash-crop tracts).

Practice Recall: Before reading on, name the four major irrigation systems of India and the one region each is most associated with.

Answer: Canal irrigation (Punjab/Haryana/western UP), Well/tube-well irrigation (UP/Punjab/Rajasthan — now India's largest single source), Tank irrigation (Tamil Nadu/Andhra Pradesh/Karnataka, the Deccan's traditional method), Drip/sprinkler micro-irrigation (Maharashtra/AP/Karnataka, horticulture-focused).

PMKSY and the Push Toward Water-Use Efficiency

The Pradhan Mantri Krishi Sinchayee Yojana (PMKSY), launched in 2015 under the slogan "Har Khet Ko Pani" (water to every field), is the umbrella scheme that now coordinates almost all central irrigation policy, and is built on four components worth remembering as a set: Accelerated Irrigation Benefit Programme (AIBP) — completing long-pending major/medium irrigation projects; Har Khet Ko Pani — creating new water sources and improving distribution; Per Drop More Crop — promoting micro-irrigation (drip/sprinkler) for water-use efficiency, the component most directly linked to this book's Micro-irrigation entry above; and Watershed Development — treating rain-fed areas through ridge-to-valley soil and water conservation. A separate, longer-standing policy idea worth recognising by name even though it remains only partly implemented is the interlinking of rivers (National Perspective Plan), which proposes connecting water-surplus river basins (like the Brahmaputra and Ganga) to water-deficit basins (like those in peninsular India) via a network of canals — the Ken-Betwa Link, connecting a water-surplus stretch of the Ken river (Madhya Pradesh) to the deficit Betwa basin, became the first such interlinking project to receive formal Cabinet approval and construction start, making it a frequently tested "first" in this specific policy area.

Memory hook (PMKSY's four components): "Accelerate the old projects, Har Khet gets its water, Per Drop grows More Crop, Watershed holds the rain." AIBP → Har Khet Ko Pani → Per Drop More Crop → Watershed Development.

Practice Recall: Before reading on, name PMKSY's four components and which one directly promotes drip/sprinkler irrigation.

Answer: Accelerated Irrigation Benefit Programme (AIBP), Har Khet Ko Pani, Per Drop More Crop, and Watershed Development — "Per Drop More Crop" is the micro-irrigation component.

Net Sown Area, Net Irrigated Area, and Cropping Intensity — Three Numbers Worth Telling Apart

A cluster of closely related statistics is a favourite source of exam confusion precisely because the terms sound interchangeable but measure different things. Gross Cropped Area is the total area sown across a year counting a plot more than once if it grows two or more crops in the same year (once for each crop sown); Net Sown Area is the same physical land counted only once, regardless of how many crops it grows in a year; and Cropping Intensity is the ratio of Gross Cropped Area to Net Sown Area, expressed as a percentage — a cropping intensity of 150% means the average plot in that area is effectively cropped one-and-a-half times a year. Punjab and Haryana, again reflecting their assured-irrigation advantage, have among the highest cropping intensities in the country, since irrigation is precisely what allows a second (or third) crop to be grown in a season where a rain-fed plot would otherwise lie fallow. In exactly the same way, Net Irrigated Area (physical area receiving irrigation from any source, counted once) is distinct from Gross Irrigated Area (counting an irrigated plot once for each crop it grows in a year) — the same single-count-versus-multiple-count logic applies to irrigation statistics as to cropped-area statistics, and recognising this shared logic lets you reason out either pair of terms even if a question phrases it in an unfamiliar way.

Memory hook: "Net counts the land, Gross counts the harvests." Net Sown/Irrigated Area counts each plot once; Gross Cropped/Irrigated Area counts it once per crop grown that year — the same single-count-vs-multiple-count logic applies to both the "sown" pair and the "irrigated" pair.

Practice Recall: Before reading on, explain the difference between Net Sown Area and Gross Cropped Area, and state what Cropping Intensity measures.

Answer: Net Sown Area counts a plot of land once regardless of how many crops it grows in a year; Gross Cropped Area counts the same plot once for each crop sown on it that year. Cropping Intensity is the ratio of Gross Cropped Area to Net Sown Area (as a percentage), reflecting how many times, on average, land in that area is cropped annually.