Irrigation in India includes a network of major and minor canals from Indian rivers, groundwater well based systems, tanks, and other rainwater harvesting projects for agricultural activities. Of these groundwater system is the largest. In 2013–14, only about 36.7% of total agricultural land in India was reliably irrigated, and remaining 2/3 cultivated land in India is dependent on monsoons. 65% of the irrigation in India is from groundwater. Currently about 51% of the agricultural area cultivating food grains is covered by irrigation. The rest of the area is dependent on rainfall which is most of the times unreliable and unpredictable.
Indian government launched a demand side water management plan costing ₹6000 crore or USD854 million across 8,350 water stressed villages of 78 districts in seven states – Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan and Uttar Pradesh – over five years from 2021–2022 to 2026–27, with the view to harvest rainwater, enhance water table, water recharge rate with village panchayat level water management plans. Most of the canal irrigation is in the canal network of Ganges-Yamuna basin mainly in the states of Punjab, Haryana, and Uttar Pradesh and somewhat in Rajasthan and Bihar, while small local canal networks also exist in the south in Tamil Nadu, Karnataka, and Kerala. The largest canal in India is Indira Gandhi Canal, which is about 650 km long. India has an ambitious river linking national project to enhance the coverage of canal-irrigated area, reduce floods and water shortage.
Irrigation in India helps improve food security, reduce dependence on monsoons, improve agricultural productivity and create rural job opportunities. Dams used for irrigation projects help produce electricity and transport facilities, as well as provide drinking water supplies to a growing population, control floods and prevent droughts.
History
Ancient India
The earliest mentions of irrigation are found in Rigveda chapters 1.55, 1.85, 1.105, 7.9, 8.69 and 10.101. The Veda mentions only well-style irrigation, where kupa and avata wells once dug are stated to be always full of water, from which varatra (rope strap) and cakra (wheel) pull kosa (pails) of water. This water was, state the Vedas, led into (broad channels) and from there into khanitrima (diverting channels) into fields.
Later, the 4th-century BCE Indian scholar Pāṇini, mentions tapping several rivers for irrigation. The mentioned rivers include Sindhu, Suvastu, Varnu, Sarayu, Vipas and Chandrabhaga. Buddhist texts from the 3rd century BCE also mention irrigation of crops. Texts from the Maurya Empire era (3rd century BCE) mention that the state raised revenue from charging farmers for irrigation services from rivers.
Patanjali, in Yogasutra of about the 4th century CE, explains a technique of yoga by comparing it to "the way a farmer diverts a stream from an irrigation canal for irrigation". In Tamil Nadu, the Grand Anicut (canal) across the Kaveri river was implemented in the 3rd century CE, and the basic design is still used today.
Medieval era
The most widespread irrigation system in India was undertaken in India in the medieval period by the Sultanate rulers. Firoz Shah Tughlaq (1309-1388) built the most extensive canal irrigation system around the Indo-Gangetic doab and the region west of the river Yamuna in the fourteenth century. These canals provided vast resources of water to agricultural lands in northern India as well as vital supplies of water to urban and rural settlements. These irrigation projects were continued by the subsequent rulers of northern India, particularly the Mughal rulers till the early eighteenth century. The British built the colonial canal networks on these medieval canal systems.
Colonial era
In 1800, some 800,000 hectares were irrigated in India. The Britishers by 1940 built significant number of canals and irrigation systems in Uttar Pradesh, Bihar, Punjab, Assam and Orissa. The Ganges Canal reached 350 miles from Haridwar to Kanpur in Uttar Pradesh. In Assam, a jungle in 1840, by 1900 had 1.62m hectares under cultivation, especially in tea plantations. In all, the amount of irrigated land multiplied by a factor of eight. Historian David Gilmour states British colonial government had built irrigation network with Ganges canal and that, "by the end of the century the new network of canals in the Punjab" were in place.