Irrigation and Major Canals of India: Exam Notes

Agriculture in India depends on a monsoon that arrives in a few months and is unevenly spread, so irrigation is what turns one crop a year into two or three. Nearly half of the cropped area of the country is irrigated, and the works that do it range from a village tank in Tamil Nadu to the Indira Gandhi Canal running into the sands of the Thar. For an examination the subject breaks into three parts: the sources of irrigation and where each dominates, the names and headworks of the major canals, and the government programmes that fund irrigation today. These notes take them in that order.

Sources of irrigation

Irrigation in India is drawn from three traditional sources and a growing fourth. Wells and tube wells account for the largest share of the net irrigated area of the country, and their spread since the Green Revolution is the single biggest change in Indian agriculture; they are most important in Uttar Pradesh, Punjab, Haryana, Bihar, Rajasthan and Gujarat, where the alluvium holds groundwater that a shallow pump can reach. Canals come second and are concentrated in the northern plains, because level land, soft alluvial soil and perennial Himalayan rivers make digging cheap and a steady supply possible. Tanks come third and belong to peninsular India, especially Telangana, Andhra Pradesh, Tamil Nadu and Karnataka, where hard crystalline rock makes wells difficult, the rivers are seasonal and an undulating surface gives natural hollows that can be bunded. The fourth source is micro irrigation, that is drip and sprinkler systems, which deliver water to the root zone and are the most efficient method in use.

Canals are of two kinds. An inundation canal is taken out of a river without a barrage and carries water only when the river is in flood, which is why the older canals of the Punjab plains were unreliable. A perennial canal is fed from a dam or barrage that stores and regulates the flow, and almost all the important canals of today are of this type.

The major canals of India

The Western Yamuna Canal is the oldest of the great canals of north India; a channel was first cut from the Yamuna in the fourteenth century in the reign of Firoz Shah Tughlaq and the modern canal, taken from the barrage at Tajewala in Haryana, follows that line. The Upper Ganga Canal was opened in 1854, was built under the engineer Proby Cautley, takes off from Haridwar and irrigates the Doab of western Uttar Pradesh; the Lower Ganga Canal starts at Narora. The Agra Canal leaves the Yamuna at the Okhla barrage near Delhi and serves Agra and Mathura. The Sharda Canal of Uttar Pradesh is taken from Banbasa on the Sharda river.

In Punjab, the Sirhind Canal draws from the Sutlej at Ropar, the Upper Bari Doab Canal from the Ravi at Madhopur, and the Bhakra canal system from the Nangal dam below Bhakra. The longest canal in the country is the Indira Gandhi Canal of Rajasthan, which was begun in 1958 as the Rajasthan Canal and renamed in 1984. It takes its water from the Harike barrage in Punjab, where the Beas joins the Sutlej, runs through a feeder and a main canal for about six hundred and fifty kilometres, and carries irrigation into Sri Ganganagar, Hanumangarh, Bikaner, Churu, Jodhpur, Jaisalmer and Barmer in the Thar desert.

In the east, the Sone canals of Bihar, taken from the Sone at Dehri, are among the earliest canal works of the country, and the Gandak and Kosi projects serve north Bihar. In the south the Cauvery delta is watered by canals from the Grand Anicut, or Kallanai, a dam thrown across the Cauvery by the Chola king Karikala in the second century and still in use, and by the Mettur system above it. The Tungabhadra and Nagarjuna Sagar canals irrigate the Krishna basin in Karnataka, Telangana and Andhra Pradesh. The Buckingham Canal is different from all of these, for it was dug along the Coromandel coast as a navigation canal linking the backwaters between Vijayawada and Chennai rather than as an irrigation work.

Major canals and their headworks

Programmes and the shift to efficiency

A canal is of no use if the water does not reach the last field, and the Command Area Development Programme of 1974 was begun for exactly that reason, to build field channels and level land below the outlet. The Accelerated Irrigation Benefit Programme of 1996 was meant to finish large projects that had been left incomplete for want of money. Both were folded into the Pradhan Mantri Krishi Sinchayee Yojana, launched in 2015 with the slogan Har Khet Ko Pani, water to every field, and the component called Per Drop More Crop, which promotes drip and sprinkler irrigation. The emphasis has shifted from building new headworks to using the water already stored, because groundwater in the north-west is falling and canal systems lose a large share of their water to seepage and evaporation.