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Irrigation canal near Channagiri, Davangere District, India
Irrigation in a field in New Jersey, United States
An irrigation sprinkler watering a lawn
Irrigation canal in Osmaniye, Turkey

Irrigation is the artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall. Additionally, irrigation also has a few other uses in crop production, which include protecting plants against frost,[1] suppressing weed growth in grain fields[2] and preventing soil consolidation.[3] In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed or dryland farming. Irrigation systems are also used for dust suppression, disposal of sewage, and in mining. Irrigation is often studied together with drainage, which is the natural or artificial removal of surface and sub-surface water from a given area.


Animal-powered irrigation, Upper Egypt, ca. 1840
An example of an irrigation system common on the Indian subcontinent. Artistic impression on the banks of Dal Lake, Kashmir, India.
Inside a karez tunnel at Turpan, Uyghurstan.




The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia some time between the third and second millennium BCE.[7] It largely depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan.[8]

In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet season flooding and water harvesting.[9][10]

Terrace irrigation is evidenced in pre-Columbian America, early Syria, India, and China.[5] In the Zana Valley of the Andes Mountains in Peru, archaeologists found remains of three irrigation canals radiocarbon dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE. These canals are the earliest record of irrigation in the New World. Traces of a canal possibly dating from the 5th millennium BCE were found under the 4th millennium canal.[11] Sophisticated irrigation and storage systems were developed by the Indus Valley Civilization in present-day Pakistan and North India, including the reservoirs at Girnar in 3000 BCE and an early canal irrigation system from circa 2600 BCE.[12][13] Large scale agriculture was practiced and an extensive network of canals was used for the purpose of irrigation.

Ancient Persia (modern day Iran) as far back as the 6th millennium BCE, where barley was grown in areas where the natural rainfall was insufficient to support such a crop.[14] The Qanats, developed in ancient Persia in about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in Asia, the Middle East and North Africa. The system comprises a network of vertical wells and gently sloping tunnels driven into the sides of cliffs and steep hills to tap groundwater.[15] The noria, a water wheel with clay pots around the rim powered by the flow of the stream (or by animals where the water source was still), was first brought into use at about this time, by Roman settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water.[16]


The oldest known hydraulic engineers of China were Sunshu Ao (6th century BCE) of the Spring and Autumn Period and Ximen Bao (5th century BCE) of the Warring States period, both of whom worked on large irrigation projects. In the Szechwan region belonging to the State of Qin of ancient China, the Dujiangyan Irrigation System was built in 256 BCE to irrigate an enormous area of farmland that today still supplies water.[18] By the 2nd century AD, during the Han Dynasty, the Chinese also used chain pumps that lifted water from lower elevation to higher elevation.[19] These were powered by manual foot pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen.[20] The water was used for public works of providing water for urban residential quarters and palace gardens, but mostly for irrigation of farmland canals and channels in the fields.[21]

In 15th century Korea, the world's first rain gauge, uryanggye (Korean:우량계), was invented in 1441. The inventor was Jang Yeong-sil, a Korean engineer of the Joseon Dynasty, under the active direction of the king, Sejong the Great. It was installed in irrigation tanks as part of a nationwide system to measure and collect rainfall for agricultural applications. With this instrument, planners and farmers could make better use of the information gathered in the survey.[22]

In the Americas, extensive irrigation systems were created by numerous groups in prehistoric times. One example is seen in the recent[when?] archaeological excavations near the Santa Cruz River in Tucson, Arizona. They have located a village site dating from 4,000 years ago .[citation needed] The floodplain of the Santa Cruz River was extensively farmed during the Early Agricultural period, circa 1200 BC to AD 150. These people constructed irrigation canals and grew corn, beans, and other crops while gathering wild plants and hunting animals.

Present extent[edit]

In the mid 20th century, the advent of diesel and electric motors led to systems that could pump groundwater out of major aquifers faster than drainage basins could refill them. This can lead to permanent loss of aquifer capacity, decreased water quality, ground subsidence, and other problems. The future of food production in such areas as the North China Plain, the Punjab, and the Great Plains of the US is threatened by this phenomenon.[23][24]

At the global scale, 2,788,000 km² (689 million acres) of fertile land was equipped with irrigation infrastructure around the year 2000. About 68% of the area equipped for irrigation is located in Asia, 17% in the Americas, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found:

  • In Northern India and Pakistan along the Ganges and Indus rivers
  • In the Hai He, Huang He and Yangtze basins in China
  • Along the Nile river in Egypt and Sudan
  • In the Mississippi-Missouri river basin and in parts of California

Smaller irrigation areas are spread across almost all populated parts of the world.[25] Only 8 years later in 2008, the scale of irrigated land increased to an estimated total of 3,245,566 km², what is nearly the size of India.[26]


Basin flood irrigation of wheat
Irrigation of land in Punjab, Pakistan

Various types of irrigation techniques differ in how the water obtained from the source is distributed within the field. In general, the goal is to supply the entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little. The modern methods are efficient enough to achieve this goal. Water use efficiency in the field can be determined as follows:

Field Water Efficiency (%) = (Water Transpired by Crop ÷ Water Applied to Field) x 100


In surface (furrow, flood, or level basin) irrigation systems, water moves across the surface of agricultural lands, in order to wet it and infiltrate into the soil. Surface irrigation can be subdivided into furrow, borderstrip or basin irrigation. It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land. Historically, this has been the most common method of irrigating agricultural land.



Brass Impact type sprinkler head


Subsurface Textile Irrigation[edit]

Diagram showing the structure of an example SSTI installation.

Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subsurface irrigation in all soil textures from desert sands to heavy clays. A typical subsurface textile irrigation system has an impermeable base layer (usually polyethylene or polypropylene), a drip line running along that base, a layer of geotextile on top of the drip line and, finally, a narrow impermeable layer on top of the geotextile (see diagram). Unlike standard drip irrigation, the spacing of emitters in the drip pipe is not critical as the geotextile moves the water along the fabric up to 2m from the dripper.


Drip irrigation - a dripper in action
Grapes in Petrolina, only made possible in this semi arid area by drip irrigation.

Drip (or micro) irrigation, also known as trickle irrigation, functions as its name suggests. In this system water falls drop by drop just at the position of roots. Water is delivered at or near the root zone of plants, drop by drop. This method can be the most water-efficient method of irrigation,[28] if managed properly, since evaporation and runoff are minimized. The field water efficiency of drip irrigation is 80 to 90 percent.


Drip irrigation layout and its parts



Sprinkler irrigation of blueberries in Plainville, New York, United States.


A traveling sprinkler at Millets Farm Centre, Oxfordshire, United Kingdom.


Center pivot[edit]

A small center pivot system from beginning to end
The hub of a center-pivot irrigation system
Rotator style pivot applicator sprinkler

Center pivot irrigation is a form of sprinkler irrigation consisting of several segments of pipe (usually galvanized steel or aluminum) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length.[29] The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are found and used in all parts of the world and allow irrigation of all types of terrain. Newer systems have drop sprinkler heads as shown in the image that follows.

Center pivot with drop sprinklers

Most center pivot systems now have drops hanging from a u-shaped pipe attached at the top of the pipe with sprinkler head that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. Crops are often planted in a circle to conform to the center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water powered. These were replaced by hydraulic systems (T-L Irrigation) and electric motor driven systems (Reinke, Valley, Zimmatic). Many modern pivots feature GPS devices.[citation needed]

Wheel line irrigation system in Idaho, 2001.

Lateral move (side roll, wheel line)[edit]

A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint and sprinklers along its length, are coupled together at one edge of a field. Water is supplied at one end using a large hose. After sufficient water has been applied, the hose is removed and the remaining assembly rotated either by hand or with a purpose-built mechanism, so that the sprinklers move 10 m across the field. The hose is reconnected. The process is repeated until the opposite edge of the field is reached. This system is less expensive to install than a center pivot, but much more labor-intensive to operate, and it is limited in the amount of water it can carry. Most systems utilize 4 or 5-inch (130 mm) diameter aluminum pipe. One feature of a lateral move system is that it consists of sections that can be easily disconnected. They are most often used for small or oddly shaped fields, such as those found in hilly or mountainous regions, or in regions where labor is inexpensive.




Manual using buckets or watering cans[edit]

These systems have low requirements for infrastructure and technical equipment but need high labor inputs. Irrigation using watering cans is to be found for example in peri-urban agriculture around large cities in some African countries. This type of irrigation is also practiced in poor or developing countries. It is also practiced in small gardens.

Automatic, non-electric using buckets and ropes[edit]

Besides the common manual watering by bucket, an automated, natural version of this also exists. Using plain polyester ropes combined with a prepared ground mixture can be used to water plants from a vessel filled with water.[30][31][32]

The ground mixture would need to be made depending on the plant itself, yet would mostly consist of black potting soil, vermiculite and perlite. This system would (with certain crops) allow to save expenses as it does not consume any electricity and only little water (unlike sprinklers, water timers, etc.). However, it may only be used with certain crops (probably mostly larger crops that do not need a humid environment; perhaps e.g. paprikas).[citation needed]

Using water condensed from humid air[edit]

In countries where at night, humid air sweeps the countryside, water can be obtained from the humid air by condensation onto cold surfaces. This is for example practiced in the vineyards at Lanzarote using stones to condense water or with various fog collectors based on canvas or foil sheets.

Sources of irrigation water[edit]


Around 90% of wastewater produced globally remains untreated, causing widespread water pollution, especially in low-income countries. Increasingly, agriculture is using untreated wastewater as a source of irrigation water. Cities provide lucrative markets for fresh produce, so are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users (see Water scarcity below), there is often no alternative for farmers but to use water polluted with urban waste, including sewage, directly to water their crops. There can be significant health hazards related to using water loaded with pathogens in this way, especially if people eat raw vegetables that have been irrigated with the polluted water. The International Water Management Institute has worked in India, Pakistan, Vietnam, Ghana, Ethiopia, Mexico and other countries on various projects aimed at assessing and reducing risks of wastewater irrigation. They advocate a 'multiple-barrier' approach to wastewater use, where farmers are encouraged to adopt various risk-reducing behaviours. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in the sunlight, applying water carefully so it does not contaminate leaves likely to be eaten raw, cleaning vegetables with disinfectant or allowing fecal sludge used in farming to dry before being used as a human manure.[33] The World Health Organization has developed guidelines for safe water use.

Water scarcity[edit]

Young engineers, restoring and developing the old Mughal irrigation system during the reign of the Mughal Emperor Bahadur Shah II.

Fifty years ago (as of 2010), the common perception was that water was an infinite resource. At that time, there were fewer than half the current number of people on the planet. People were not as wealthy as today, consumed fewer calories and ate less meat, so less water was needed to produce their food. They required a third of the volume of water we presently take from rivers. Today, the competition for water resources is much more intense. This is because there are now more than seven billion people on the planet, their consumption of water-thirsty meat and vegetables is rising, and there is increasing competition for water from industry, urbanisation and biofuel crops. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently.[34]

Successful agriculture is dependent upon farmers having sufficient access to water. However, water scarcity is already a critical constraint to farming in many parts of the world. With regards to agriculture, the World Bank targets food production and water management as an increasingly global issue that is fostering a growing debate.[35] Physical water scarcity is where there is not enough water to meet all demands, including that needed for ecosystems to function effectively. Arid regions frequently suffer from physical water scarcity. It also occurs where water seems abundant but where resources are over-committed. This can happen where there is overdevelopment of hydraulic infrastructure, usually for irrigation. Symptoms of physical water scarcity include environmental degradation and declining groundwater. Economic scarcity, meanwhile, is caused by a lack of investment in water or insufficient human capacity to satisfy the demand for water. Symptoms of economic water scarcity include a lack of infrastructure, with people often having to fetch water from rivers for domestic and agricultural uses. Some 2.8 billion people currently live in water-scarce areas.[36]

How an in-ground irrigation system works[edit]

Most commercial and residential irrigation systems are "in ground" systems, which means that everything is buried in the ground. With the pipes, sprinklers, emitters (drippers), and irrigation valves being hidden, it makes for a cleaner, more presentable landscape without garden hoses or other items having to be moved around manually. This does, however, create some drawbacks in the maintenance of a completely buried system.

Controllers, zones, and valves[edit]

Most irrigation systems are divided into zones. A zone is a single irrigation valve and one or a group of drippers or sprinklers that are connected by pipes or tubes. Irrigation systems are divided into zones because there is usually not enough pressure and available flow to run sprinklers for an entire yard or sports field at once. Each zone has a solenoid valve on it that is controlled via wire by an irrigation controller. The irrigation controller is either a mechanical (now the "dinosaur" type) or electrical device that signals a zone to turn on at a specific time and keeps it on for a specified amount of time. "Smart Controller" is a recent term for a controller that is capable of adjusting the watering time by itself in response to current environmental conditions. The smart controller determines current conditions by means of historic weather data for the local area, a soil moisture sensor (water potential or water content), rain sensor, or in more sophisticated systems satellite feed weather station, or a combination of these.

Emitters and sprinklers[edit]

When a zone comes on, the water flows through the lateral lines and ultimately ends up at the irrigation emitter (drip) or sprinkler heads. Many sprinklers have pipe thread inlets on the bottom of them which allows a fitting and the pipe to be attached to them. The sprinklers are usually installed with the top of the head flush with the ground surface. When the water is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more water pressure in the lateral line, the sprinkler head will retract back into the ground. Emitters are generally laid on the soil surface or buried a few inches to reduce evaporation losses.

Problems in irrigation[edit]

Main article: Environmental impact of irrigation

Irrigation can lead to a number of problems:[37]

Academic resources[edit]

Irrigation by country[edit]

See also[edit]


  1. ^ Snyder, R. L.; Melo-Abreu, J. P. (2005). "Frost protection: fundamentals, practice, and economics – Volume 1" (PDF). Food and Agriculture Organization of the United Nations. ISSN 1684-8241. 
  2. ^ Williams, J. F.; S. R. Roberts, J. E. Hill, S. C. Scardaci, and G. Tibbits. "Managing Water for Weed Control in Rice". UC Davis, Department of Plant Sciences. Retrieved 2007-03-14. 
  3. ^ "Aridpoop -05-15". Retrieved 2012-06-19. 
  4. ^ Hill, Donald: A History of Engineering
  5. ^ a b p19 Hill
  7. ^ G. Mokhtar. Ancient civilizations of Africa. p. 309. Retrieved 2012-06-19. 
  8. ^ Richard Bulliet, Pamela Kyle Crossley, Daniel Headrick, Steven Hirsch. Pages 53-56 (2008-06-18). The Earth and Its Peoples, Volume I: A Global History, to 1550. Retrieved 2012-06-19. 
  9. ^ "Traditional technologies". Retrieved 2012-06-19. 
  10. ^ "Africa, Emerging Civilizations In Sub-Sahara Africa. Various Authors; Edited By: R. A. Guisepi". Retrieved 2012-06-19. 
  11. ^ Dillehay TD, Eling HH Jr, Rossen J (2005). "Preceramic irrigation canals in the Peruvian Andes". Proceedings of the National Academy of Sciences 102 (47): 17241–4. doi:10.1073/pnas.0508583102. PMC 1288011. PMID 16284247. 
  13. ^ "Ancient India Indus Valley Civilization". Minnesota State University "e-museum". Retrieved 2007-01-10. 
  14. ^ The History of Technology – Irrigation. Encyclopædia Britannica, 1994 edition. 
  15. ^ "Qanat Irrigation Systems and Homegardens (Iran)". Globally Important Agriculture Heritage Systems. UN Food and Agriculture Organization. Retrieved 2007-01-10. 
  16. ^ Encyclopædia Britannica, 1911 and 1989 editions
  17. ^ de Silva, Sena (1998). "Reservoirs of Sri Lanka and their fisheries". UN Food and Agriculture Organization. Retrieved 2007-01-10. 
  18. ^ China – history. Encyclopædia Britannica,1994 edition. 
  20. ^ Needham, Volume 4, Part 2, 340-343.
  21. ^ Needham, Volume 4, Part 2, 33, 110.
  22. ^ Baek Seok-gi 백석기 (1987). Jang Yeong-sil 장영실. Woongjin Wiin Jeon-gi 웅진위인전기 11. Woongjin Publishing Co., Ltd. 
  23. ^ "A new report says we're draining our aquifers faster than ever". High Country News. 22/06/2013. Retrieved 11/02/2014. 
  24. ^ "Management of aquifer recharge and discharge processes and aquifer storage equilibrium". "Groundwater storage is shown to be declining in all populated continents..." 
  25. ^ Siebert, S.; J. Hoogeveen, P. Döll, J-M. Faurès, S. Feick, and K. Frenken (2006-11-10). "The Digital Global Map of Irrigation Areas – Development and Validation of Map Version 4" (PDF). Tropentag 2006 – Conference on International Agricultural Research for Development. Bonn, Germany. Retrieved 2007-03-14. 
  26. ^ CIA - Central Intelligence Agency. "The World Factbook". Retrieved 2011-10-30. 
  27. ^ Frenken, K. (2005). "Irrigation in Africa in figures – AQUASTAT Survey – 2005" (PDF). Water Report 29. Food and Agriculture Organization of the United Nations. ISBN 92-5-105414-2. Retrieved 2007-03-14. 
  28. ^ Provenzano, Giuseppe (2007). "Using HYDRUS-2D Simulation Model to Evaluate Wetted Soil Volume in Subsurface Drip Irrigation Systems". J. Irrig. Drain Eng. 133 (4): 342–350. doi:10.1061/(ASCE)0733-9437(2007)133:4(342). 
  29. ^ Mader, Shelli (May 25, 2010). "Center pivot irrigation revolutionizes agriculture". The Fence Post Magazine. Retrieved June 6, 2012. 
  30. ^ "Polyester ropes natural irrigation technique". Retrieved 2012-06-19. [dead link]
  31. ^ "Polyester rope natural irrigation technique 2". Retrieved 2012-06-19. 
  32. ^ "DIY instructions for making self-watering system using ropes". 2008-03-17. Retrieved 2012-06-19. 
  33. ^ Wastewater use in agriculture: Not only an issue where water is scarce! International Water Management Institute, 2010. Water Issue Brief 4
  35. ^ "Reengaging in Agricultural Water Management: Challenges and Options". The World Bank. pp. 4–5. Retrieved 2011-10-30. 
  37. ^ ILRI, 1989, Effectiveness and Social/Environmental Impacts of Irrigation Projects: a Review. In: Annual Report 1988, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 - 34 . On line: [1]
  38. ^ EOS magazine, september 2009
  39. ^ World Water Council
  41. ^ "Free articles and software on drainage of waterlogged land and soil salinity control in irrigated land". Retrieved 2010-07-28. 
  42. ^ UV treatment
  43. ^ ultrasonic algae control

External links[edit]
