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Irrigation
Irrigation
is the application of controlled amounts of water to plants at needed intervals. Irrigation
Irrigation
helps grow agricultural crops, maintain landscapes, and revegetate disturbed soils in dry areas and during periods of less than average rainfall. Irrigation
Irrigation
also has other uses in crop production, including frost protection,[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 dry land farming. Irrigation
Irrigation
systems are also used for cooling livestock, dust suppression, disposal of sewage, and in mining. Irrigation
Irrigation
is often studied together with drainage, which is the removal of surface and sub-surface water from a given area.

Irrigation
Irrigation
canal in Osmaniye, Turkey

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

Irrigation
Irrigation
has been a central feature of agriculture for over 5,000 years and is the product of many cultures. Historically, it was the basis for economies and societies across the globe, from Asia to the Southwestern United States.

Contents

1 History

1.1 China 1.2 Korea 1.3 North America

2 Present extent 3 Types of irrigation

3.1 Surface irrigation 3.2 Micro-irrigation

3.2.1 Drip irrigation

3.3 Sprinkler irrigation

3.3.1 Center pivot 3.3.2 Irrigation
Irrigation
by Lateral move (side roll, wheel line, wheelmove)[32][33] 3.3.3 Lawn sprinkler systems 3.3.4 Hose-end sprinklers

3.4 Subirrigation

3.4.1 Subsurface textile irrigation

4 Water
Water
sources 5 Efficiency 6 Technical challenges 7 Impact on society 8 See also 9 References 10 Further reading

10.1 Journals

11 External links

History[edit]

Animal-powered irrigation, Upper Egypt, ca. 1846

Archaeological investigation has found evidence of irrigation where natural rainfall was insufficient to support crops for rainfed agriculture. Perennial irrigation was practiced in the Mesopotamian plain whereby crops were regularly watered throughout the growing season by coaxing water through a matrix of small channels formed in the field.[4] Ancient Egyptians
Ancient Egyptians
practiced Basin irrigation using the flooding of the Nile
Nile
to inundate land plots which had been surrounded by dykes. The flood water was held until the fertile sediment had settled before the surplus was returned to the watercourse.[5] There is evidence of the ancient Egyptian pharaoh Amenemhet III
Amenemhet III
in the twelfth dynasty (about 1800 BCE) using the natural lake of the Faiyum Oasis
Faiyum Oasis
as a reservoir to store surpluses of water for use during the dry seasons. The lake swelled annually from flooding of the Nile.[6]

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

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

Irrigation
Irrigation
in Tamil Nadu, India

In sub-Saharan Africa irrigation reached the Niger River
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
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
5th millennium BCE
were found under the 4th millennium canal.[11] Sophisticated irrigation and storage systems were developed by the Indus Valley Civilization
Indus Valley Civilization
in present-day Pakistan and North India, including the reservoirs at Girnar
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
Ancient Persia
(modern day Iran) used irrigation as far back as the 6th millennium BCE
6th millennium BCE
to grow barley in areas where natural rainfall was insufficient.[14] The Qanats, developed in ancient Persia
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 irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE, in the reign of King Pandukabhaya and under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world. In addition to underground canals, the Sinhalese were the first to build completely artificial reservoirs to store water. Due to their engineering superiority in this sector, they were often called 'masters of irrigation'.[by whom?] Most of these irrigation systems still exist undamaged up to now, in Anuradhapura
Anuradhapura
and Polonnaruwa, because of the advanced and precise engineering. The system was extensively restored and further extended during the reign of King Parakrama Bahu
Parakrama Bahu
(1153–1186 CE).[17] China[edit]

Inside a karez tunnel at Turpan, Xinjiang, China

The oldest known hydraulic engineers of China
China
were Sunshu Ao (6th century BCE) of the Spring and Autumn period
Spring and Autumn period
and Ximen Bao (5th century BCE) of the Warring States
Warring States
period, both of whom worked on large irrigation projects. In the Sichuan
Sichuan
region belonging to the State of Qin of ancient China, the Dujiangyan Irrigation
Irrigation
System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast 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 a lower elevation to a higher one.[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] Korea[edit] 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
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] North America[edit]

Irrigation
Irrigation
ditch in Montour County, Pennsylvania

Main article: Hohokam The earliest agricultural irrigation canal system known in the U.S. dates to between 1200 B.C. and 800 B.C. and was discovered in Marana, Arizona (adjacent to Tucson) in 2009.[23] The irrigation canal system predates the Hohokam
Hohokam
culture by two thousand years and belongs to an unidentified culture. In North America, the Hohokam
Hohokam
were the only culture known to rely on irrigation canals to water their crops, and their irrigation systems supported the largest population in the Southwest by AD 1300. The Hohokam
Hohokam
constructed an assortment of simple canals combined with weirs in their various agricultural pursuits. Between the 7th and 14th centuries, they also built and maintained extensive irrigation networks along the lower Salt and middle Gila rivers that rivaled the complexity of those used in the ancient Near East, Egypt, and China. These were constructed using relatively simple excavation tools, without the benefit of advanced engineering technologies, and achieved drops of a few feet per mile, balancing erosion and siltation. The Hohokam
Hohokam
cultivated varieties of cotton, tobacco, maize, beans and squash, as well as harvested an assortment of wild plants. Late in the Hohokam
Hohokam
Chronological Sequence, they also used extensive dry-farming systems, primarily to grow agave for food and fiber. Their reliance on agricultural strategies based on canal irrigation, vital in their less than hospitable desert environment and arid climate, provided the basis for the aggregation of rural populations into stable urban centers.[24] Present extent[edit]

Irrigation
Irrigation
of land in Punjab, India

In year 2000, the total fertile land was 2,788,000 km² (689 million acres) and it was equipped with irrigation infrastructure worldwide. About 68% of this area is 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
Nile
river in Egypt and Sudan In the Mississippi-Missouri river basin, the Southern Great Plains, and in parts of California

Smaller irrigation areas are spread across almost all populated parts of the world.[25] Only eight years later, in 2008, the area of irrigated land had increased to an estimated total of 3,245,566 km² (802 million acres), which is nearly the size of India.[26] Types of irrigation[edit] There are several methods of irrigation. They vary in how the water is supplied to the plants. The goal is to apply the water to the plants as uniformly as possible, so that each plant has the amount of water it needs, neither too much nor too little. Surface irrigation[edit] Main article: Surface irrigation

Basin flood irrigation of wheat

Surface irrigation
Surface irrigation
is the oldest form of irrigation and has been in use for thousands of years. In surface (furrow, flood, or level basin) irrigation systems, water moves across the surface of an agricultural lands, in an 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 and still used in most parts of the world. Where water levels from the irrigation source permit, the levels are controlled by dikes, usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to the level of the land. The water application efficiency of surface irrigation is typically lower than other forms of irrigation.

Residential flood irrigation in Phoenix, Arizona

Surface irrigation
Surface irrigation
is even used to water landscapes in certain areas, for example, in and around Phoenix, Arizona. The irrigated area is surrounded by a berm and the water is delivered according to a schedule set by a local irrigation district.[27] Micro-irrigation[edit] Main article: Micro-irrigation

Drip irrigation
Drip irrigation
– a dripper in action

Micro-irrigation, sometimes called localized irrigation, low volume irrigation, or trickle irrigation is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Traditional drip irrigation using individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinkler irrigation, and mini-bubbler irrigation all belong to this category of irrigation methods.[28] Drip irrigation[edit]

Drip irrigation
Drip irrigation
layout and its parts

Main article: Drip irrigation

Micro-sprinkler

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
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,[29] if managed properly, evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90 percent when managed correctly. In modern agriculture, drip irrigation is often combined with plastic mulch, further reducing evaporation, and is also the means of delivery of fertilizer. The process is known as fertigation. Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long or if the delivery rate is too high. Drip irrigation
Drip irrigation
methods range from very high-tech and computerized to low-tech and labor-intensive. Lower water pressures are usually needed than for most other types of systems, with the exception of low energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from a computerized set of valves. Sprinkler irrigation[edit]

Crop sprinklers near Rio Vista, California

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

Further information: Irrigation
Irrigation
sprinkler In sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system utilizing sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by a ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 40 to 130 lbf/in² (275 to 900 kPa) and flows of 50 to 1200 US gal/min (3 to 76 L/s), usually with nozzle diameters in the range of 0.5 to 1.9 inches (10 to 50 mm). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging. Sprinklers can also be mounted on moving platforms connected to the water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these utilize a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When the sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water. Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable. Center pivot[edit]

A small center pivot system from beginning to end

Rotator style pivot applicator sprinkler

Center pivot with drop sprinklers

Wheel
Wheel
line irrigation system in Idaho, 2001

Main article: Center pivot irrigation

Center pivot irrigation

Center pivot irrigation
Center pivot irrigation
is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length.[30] 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. As of 2017[update] most center pivot systems have drops hanging from a U-shaped pipe attached at the top of the pipe with sprinkler heads 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
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.[31] Irrigation
Irrigation
by Lateral move (side roll, wheel line, wheelmove)[32][33][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. Water
Water
is supplied at one end using a large hose. After sufficient irrigation has been applied to one strip of the field, the hose is removed, the water drained from the system, and the assembly rolled either by hand or with a purpose-built mechanism, so that the sprinklers are moved to a different position across the field. The hose is reconnected. The process is repeated in a pattern until the whole field has been irrigated. This system is less expensive to install than a center pivot, but much more labor-intensive to operate - it does not travel automatically across the field: it applies water in a stationary strip, must be drained, and then rolled to a new strip. Most systems use 4 or 5-inch (130 mm) diameter aluminum pipe. The pipe doubles both as water transport and as an axle for rotating all the wheels. A drive system (often found near the centre of the wheel line) rotates the clamped-together pipe sections as a single axle, rolling the whole wheel line. Manual adjustment of individual wheel positions may be necessary if the system becomes misaligned. Wheel
Wheel
line systems are limited in the amount of water they can carry, and limited in the height of crops that can be irrigated. One useful feature of a lateral move system is that it consists of sections that can be easily disconnected, adapting to field shape as the line is moved. They are most often used for small, rectilinear, or oddly-shaped fields, hilly or mountainous regions, or in regions where labor is inexpensive. Lawn sprinkler systems[edit] A lawn sprinkler system is permanently installed, as opposed to a hose-end sprinkler, which is portable. Sprinkler systems are installed in residential lawns, in commercial landscapes, for churches and schools, in public parks and cemeteries, and on golf courses. Most of the components of these irrigation systems are hidden under ground, since aesthetics are important in a landscape. A typical lawn sprinkler system will consist of one or more zones, limited in size by the capacity of the water source. Each zone will cover a designated portion of the landscape. Sections of the landscape will usually be divided by microclimate, type of plant material, and type of irrigation equipment. A landscape irrigation system may also include zones containing drip irrigation, bubblers, or other types of equipment besides sprinklers. Although manual systems are still used, most lawn sprinkler systems may be operated automatically using an irrigation controller, sometimes called a clock or timer. Most automatic systems employ electric solenoid valves. Each zone has one or more of these valves that are wired to the controller. When the controller sends power to the valve, the valve opens, allowing water to flow to the sprinklers in that zone. There are two main types of sprinklers used in lawn irrigation, pop-up spray heads and rotors. Spray heads have a fixed spray pattern, while rotors have one or more streams that rotate. Spray heads are used to cover smaller areas, while rotors are used for larger areas. Golf course rotors are sometimes so large that a single sprinkler is combined with a valve and called a 'valve in head'. When used in a turf area, the sprinklers are installed with the top of the head flush with the ground surface. When the system 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 pressure in the lateral line, the sprinkler head will retract back into the ground. In flower beds or shrub areas, sprinklers may be mounted on above ground risers or even taller pop-up sprinklers may be used and installed flush as in a lawn area.

An impact sprinkler watering a lawn, an example of a hose-end sprinkler.

Hose-end sprinklers[edit] There are many types of hose-end sprinklers. Many of them are smaller versions of larger agricultural and landscape sprinklers, sized to work with a typical garden hose. Some have a spiked base allowing them to be temporarily stuck in the ground, while others have a sled base designed to be dragged while attached to the hose. Subirrigation[edit] Subirrigation has been used for many years in field crops in areas with high water tables. It is a method of artificially raising the water table to allow the soil to be moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and thereby control the water table. Subirrigation is also used in commercial greenhouse production, usually for potted plants. Water
Water
is delivered from below, absorbed upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10–20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor savings through reduced system maintenance and automation. It is similar in principle and action to subsurface basin irrigation. Another type of subirrigation is the self-watering container, also known as a sub-irrigated planter. This consists of a planter suspended over a reservoir with some type of wicking material such as a polyester rope. The water is drawn up the wick through capillary action.[34][35] Subsurface textile irrigation[edit] Main article: Subsurface textile irrigation

Diagram showing the structure of an example SSTI installation

Subsurface Textile Irrigation
Irrigation
(SSTI) is a technology designed specifically for subirrigation 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 2 m from the dripper. The impermeable layer effectively creates an artificial water table. Water
Water
sources[edit]

Irrigation
Irrigation
is underway by pump-enabled extraction directly from the Gumti, seen in the background, in Comilla, Bangladesh.

Irrigation
Irrigation
water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. A special form of irrigation using surface water is spate irrigation, also called floodwater harvesting. In case of a flood (spate), water is diverted to normally dry river beds (wadis) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions. While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting is usually not considered as a form of irrigation. Rainwater harvesting
Rainwater harvesting
is the collection of runoff water from roofs or unused land and the concentration of this. Around 90% of wastewater produced globally remains untreated, causing widespread water pollution, especially in low-income countries. Increasingly, agriculture uses 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
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. Significant health hazards can result from 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
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.[36] The World Health Organization
World Health Organization
has developed guidelines for safe water use. There are numerous benefits of using recycled water for irrigation, including the low cost (when compared to other sources, particularly in an urban area), consistency of supply (regardless of season, climatic conditions and associated water restrictions), and general consistency of quality. Irrigation
Irrigation
of recycled wastewater is also considered as a means for plant fertilization and particularly nutrient supplementation. This approach carries with it a risk of soil and water pollution through excessive wastewater application. Hence, a detailed understanding of soil water conditions is essential for effective utilization of wastewater for irrigation.[37] In countries where humid air sweeps through at night, water can be obtained by condensation onto cold surfaces. This is practiced in the vineyards at Lanzarote
Lanzarote
using stones to condense water. Fog collectors are also made of canvas or foil sheets. Using condensate from air conditioning units as a water source is also becoming more popular in large urban areas.

Grapes in Petrolina, only made possible in this semi arid area by drip irrigation

Efficiency[edit] Modern irrigation methods are efficient enough 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.[38] Water
Water
use efficiency in the field can be determined as follows:

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

Until 1960s, 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.[39] 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.[40] 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.[41] Technical challenges[edit] Main article: Environmental impact of irrigation Irrigation
Irrigation
schemes involve solving numerous engineering and economic problems while minimizing negative environmental impact.[42]

Competition for surface water rights.[43] Overdrafting
Overdrafting
(depletion) of underground aquifers. 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
China
Plain, the Punjab, and the Great Plains
Great Plains
of the US is threatened by this phenomenon.[44][45]

Ground subsidence (e.g. New Orleans, Louisiana) Underirrigation or irrigation giving only just enough water for the plant (e.g. in drip line irrigation) gives poor soil salinity control which leads to increased soil salinity with consequent buildup of toxic salts on soil surface in areas with high evaporation. This requires either leaching to remove these salts and a method of drainage to carry the salts away. When using drip lines, the leaching is best done regularly at certain intervals (with only a slight excess of water), so that the salt is flushed back under the plant's roots.[46][47] Overirrigation because of poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution.[48] Deep drainage (from over-irrigation) may result in rising water tables which in some instances will lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage.[49][50] Irrigation
Irrigation
with saline or high-sodium water may damage soil structure owing to the formation of alkaline soil Clogging of filters: It is mostly algae that clog filters, drip installations and nozzles. UV[51] and ultrasonic[52] method can be used for algae control in irrigation systems.

Impact on society[edit] A 2016 study found that countries whose agriculture depended on irrigation are more likely to be autocratic than other countries. The authors of the study "argue that the effect has historical origins: irrigation allowed landed elites in arid areas to monopolize water and arable land. This made elites more powerful and better able to oppose democratization."[53] See also[edit]

Agriculture
Agriculture
and Agronomy portal

Deficit irrigation Environmental impact of irrigation Farm water Gezira Scheme Irrigation
Irrigation
district Irrigation
Irrigation
management Irrigation
Irrigation
statistics Leaf Sensor Lift irrigation schemes List of countries by irrigated land area Nano Ganesh Paddy field Qanat Surface irrigation Tidal irrigation

References[edit]

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Heritage Systems. UN Food
Food
and Agriculture Organization. Retrieved 2007-01-10.  ^ Encyclopædia Britannica, 1911 and 1989 editions ^ de Silva, Sena (1998). " Reservoirs
Reservoirs
of Sri Lanka
Sri Lanka
and their fisheries". UN Food
Food
and Agriculture
Agriculture
Organization. Retrieved 2007-01-10.  ^ China – history. Encyclopædia Britannica,1994 edition.  ^ Needham, Joseph (1986). Science and Civilization
Civilization
in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering. Taipei: Caves Books Ltd. Pages 344-346. ^ Needham, Volume 4, Part 2, 340-343. ^ Needham, Volume 4, Part 2, 33, 110. ^ Baek Seok-gi 백석기 (1987). Jang Yeong-sil
Jang Yeong-sil
장영실. Woongjin Wiin Jeon-gi 웅진위인전기 11. Woongjin Publishing Co., Ltd.  ^ "Earliest Canals in America - Archaeology Magazine Archive".  ^ James M. Bayman, "The Hohokam
Hohokam
of Southwest North America." Journal of World Prehistory
Prehistory
15.3 (2001): 257-311. ^ 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. CS1 maint: Multiple names: authors list (link) ^ The CIA World Factbook, retrieved 2011-10-30  ^ " Flood
Flood
Irrigation
Irrigation
Service". City of Tempe, Arizona. Retrieved 29 July 2017.  ^ Frenken, K. (2005). Irrigation
Irrigation
in Africa in figures – AQUASTAT Survey – 2005 (PDF). Food
Food
and Agriculture
Agriculture
Organization of the United Nations. ISBN 92-5-105414-2. Retrieved 2007-03-14.  ^ Provenzano, Giuseppe (2007). "Using HYDRUS-2D Simulation Model to Evaluate Wetted Soil
Soil
Volume in Subsurface Drip Irrigation
Irrigation
Systems". J. Irrig. Drain Eng. 133 (4): 342–350. doi:10.1061/(ASCE)0733-9437(2007)133:4(342).  ^ Mader, Shelli (May 25, 2010). "Center pivot irrigation revolutionizes agriculture". The Fence Post Magazine. Retrieved June 6, 2012.  ^ Gaines, Tharran (January 7, 2017). " GPS
GPS
SWING ARMS PROVE THEIR WORTH". Successful Farming. Retrieved February 1, 2018.  ^ Peters, Troy. "Managing Wheel
Wheel
‐ Lines and Hand ‐ Lines for High Profitability" (PDF). Retrieved 29 May 2015.  ^ Hill, Robert. "Wheelmove Sprinkler Irrigation
Irrigation
Operation and Management" (PDF). Retrieved 29 May 2015.  ^ "Polyester ropes natural irrigation technique". Entheogen.com. Archived from the original on April 12, 2012. Retrieved 2012-06-19.  ^ "DIY instructions for making self-watering system using ropes". Instructables.com. 2008-03-17. Retrieved 2012-06-19.  ^ Wastewater
Wastewater
use in agriculture: Not only an issue where water is scarce! International Water
Water
Management Institute, 2010. Water
Water
Issue Brief 4 ^ http://www.hydrol-earth-syst-sci.net/17/4339/2013/hess-17-4339-2013.pdf ^ " Water
Water
use efficiency - agriwaterpedia.info".  ^ Chartres, C. and Varma, S. Out of water. From Abundance to Scarcity and How to Solve the World's Water
Water
Problems FT Press (USA), 2010 ^ "Reengaging in Agricultural Water
Water
Management: Challenges and Options". The World Bank. pp. 4–5. Retrieved 2011-10-30.  ^ Molden, D. (Ed). Water
Water
for food, Water
Water
for life: A Comprehensive Assessment of Water
Water
Management in Agriculture. Earthscan/IWMI, 2007. ^ ILRI, 1989, Effectiveness and Social/Environmental Impacts of Irrigation
Irrigation
Projects: a Review. In: Annual Report 1988, International Institute for Land
Land
Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 – 34 . On line: [1] ^ Rosegrant, Mark W., and Hans P. Binswanger. "Markets in tradable water rights: potential for efficiency gains in developing country water resource allocation." World development (1994) 22#11 pp: 1613–1625. ^ "A new report says we're draining our aquifers faster than ever". High Country News. 2013-06-22. Retrieved 2014-02-11.  ^ "Management of aquifer recharge and discharge processes and aquifer storage equilibrium" (PDF). Groundwater
Groundwater
storage is shown to be declining in all populated continents...  ^ EOS magazine, september 2009 ^ World Water
Water
Council ^ Hukkinen, Janne, Emery Roe, and Gene I. Rochlin. "A salt on the land: A narrative analysis of the controversy over irrigation-related salinity and toxicity in California's San Joaquin Valley." Policy Sciences 23.4 (1990): 307-329. online Archived 2015-01-02 at the Wayback Machine. ^ Drainage
Drainage
Manual: A Guide to Integrating Plant, Soil, and Water Relationships for Drainage
Drainage
of Irrigated Lands. Interior Dept., Bureau of Reclamation. 1993. ISBN 0-16-061623-9.  ^ "Free articles and software on drainage of waterlogged land and soil salinity control in irrigated land". Retrieved 2010-07-28.  ^ UV treatment http://www.uvo3.co.uk/?go=Irrigation_Water ^ ultrasonic algae control http://www.lgsonic.com/irrigation-water-treatment/ ^ Bentzen, Jeanet Sinding; Kaarsen, Nicolai; Wingender, Asger Moll (2016-06-01). " Irrigation
Irrigation
and Autocracy". Journal of the European Economic Association: n/a–n/a. doi:10.1111/jeea.12173. ISSN 1542-4774. 

Further reading[edit]

Elvin, Mark. The retreat of the elephants: an environmental history of China
China
(Yale University Press, 2004) Hallows, Peter J., and Donald G. Thompson. History of irrigation in Australia ANCID, 1995. Howell, Terry. "Drops of life in the history of irrigation." Irrigation
Irrigation
journal 3 (2000): 26-33. the history of sprinker systems online Hassan, John. A history of water in modern England and Wales (Manchester University Press, 1998) Vaidyanathan, A. Water
Water
resource management: institutions and irrigation development in India (Oxford University Press, 1999)

Journals[edit]

Irrigation
Irrigation
Science, ISSN 1432-1319 (electronic) 0342-7188 (paper), Springer Journal of Irrigation
Irrigation
and Drainage
Drainage
Engineering, ISSN 0733-9437, ASCE Publications Irrigation
Irrigation
and Drainage, ISSN 1531-0361, John Wiley & Sons, Ltd.

External links[edit]

Look up irrigation in Wiktionary, the free dictionary.

Wikimedia Commons
Commons
has media related to Irrigation.

" Irrigation
Irrigation
techniques". USGS. Archived from the original on December 2, 2005. Retrieved December 8, 2005.  Royal Engineers Museum: 19th century Irrigation
Irrigation
in India International Commission on Irrigation
Irrigation
and Drainage
Drainage
(ICID) Irrigation
Irrigation
at the Water
Water
Quality Information Center, U.S. Department of Agriculture AQUASTAT: FAO's global information system on water and agriculture

 This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Irrigation". Encyclopædia Britannica (11th ed.). Cambridge University Press. 

v t e

Water resources
Water resources
management and irrigation by country

Africa

Burkina Faso Egypt Mali Morocco South Africa Sudan Tanzania

Asia

Afghanistan Bangladesh China Iran Iraq India Israel Kazakhstan Pakistan Saudi Arabia Syria Turkey Turkmenistan

Europe

Belgium Italy Russia

North America

Belize Canada Costa Rica Dominican Republic El Salvador Guatemala Honduras Jamaica Mexico Nicaragua United States

Oceania

Australia New Zealand Indonesia Philippines

South America

Argentina Bolivia Brazil - supply Brazil - irrigation Chile Colombia Peru Uruguay

List of countries by irrigated land area

v t e

Agricultural water management

Irrigation

Surface irrigation Drip irrigation Tidal irrigation Irrigation
Irrigation
statistics Irrigation
Irrigation
management Irrigation
Irrigation
environmental impacts

Subsurface drainage

Tile drainage Drainage
Drainage
equation Drainage
Drainage
system (agriculture) Watertable control Drainage
Drainage
research Drainage
Drainage
by wells

Surface water/runoff

Contour trenching Hydrological modelling Hydrological transport model Runoff model (reservoir)

Groundwater

Groundwater
Groundwater
flow Groundwater
Groundwater
energy balance Groundwater
Groundwater
model Hydraulic
Hydraulic
conductivity Watertable

Problem soils

Acid sulphate soils Alkali soils Saline soils

Agro-hydro-salinity group

Hydrology (agriculture) Soil
Soil
salinity control Leaching model (soil) SaltMod
SaltMod
integrated model SahysMod
SahysMod
polygonal model: Saltmod coupled to a groundwater model

Related topics

Sand dam

v t e

Natural resources

Air

Pollution / quality

Ambient standards (USA) Index Indoor

developing nations

Law

Clean Air Act (USA)

Ozone depletion

Emissions

Airshed Trading Deforestation (REDD)

Energy

Law Resources Fossil fuels (peak oil) Geothermal Nuclear Solar

sunlight shade

Tidal Wave Wind

Land

Arable

peak farmland

Degradation Law

property

Management

habitat conservation

Minerals

mining

law sand

peak rights

Soil

conservation fertility health resilience

Use

planning reserve

Life

Biodiversity Bioprospecting Biosphere Bushfood Bushmeat Fisheries

law management

Food Forests

genetic resources law management

Game

law

Gene bank Herbalist plants Marine conservation Non-timber forest products Rangeland Seed bank Wildlife

conservation management

Wood

Water

Types / location

Aquifer

storage and recovery

Drinking Fresh Groundwater

pollution recharge remediation

Hydrosphere Ice

bergs glacial polar

Irrigation Rain

harvesting

Stormwater Surface water Wastewater

reclaimed

Aspects

Desalination Floods Law Leaching Sanitation Conflict Conservation Peak water Pollution Privatization Quality Right Resources

management policy

Related

Commons

enclosure global land tragedy of

Economics

ecological land

Ecosystem services Exploitation

overexploitation Earth Overshoot Day

Management

adaptive

Natural capital

accounting

Nature reserve Systems ecology Urban ecology Wilderness

Resource

Common-pool Conflict (perpetuation) Curse Depletion Extraction Nationalism Renewable / Non-renewable

Portals

Agriculture
Agriculture
and agronomy Energy Environment Fishing Forestry Mining Water Wetlands

Category

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Colleges Natural resources

v t e

Wastewater

Sources

Acid mine drainage Ballast water Bathroom Blackwater (coal) Blackwater (waste) Boiler blowdown Brine Combined sewer Cooling tower Cooling water Fecal sludge Greywater Infiltration/Inflow Industrial effluent Ion exchange Leachate Manure Papermaking Produced water Return flow Reverse osmosis Sanitary sewer Septage Sewage Sewage
Sewage
sludge Toilet Urban runoff

Quality indicators

Adsorbable organic halides Biochemical oxygen demand Chemical oxygen demand Coliform index Dissolved oxygen Heavy metals pH Salinity Temperature Total dissolved solids Total suspended solids Turbidity

Treatment options

Activated sludge Aerated lagoon Agricultural wastewater treatment API oil-water separator Carbon filtration Chlorination Clarifier Constructed wetland Decentralized wastewater system Extended aeration Facultative lagoon Fecal sludge
Fecal sludge
management Filtration Imhoff tank Industrial wastewater treatment Ion exchange Membrane bioreactor Reverse osmosis Rotating biological contactor Secondary treatment Sedimentation Septic tank Settling basin Sewage
Sewage
sludge treatment Sewage
Sewage
treatment Sewer mining Stabilization pond Trickling filter Ultraviolet germicidal irradiation UASB Vermifilter Wastewater
Wastewater
treatment plant

Disposal options

Combined sewer Evaporation pond Groundwater
Groundwater
recharge Infiltration basin Injection well Irrigation Marine dumping Marine outfall Reclaimed water Sanitary sewer Septic drain field Sewage
Sewage
farm Storm drain Surface runoff Vacuum sewer

v t e

Prehistoric technology

Prehistory

timeline outline Stone Age subdivisions New Stone Age

Technology

history

Tools

Farming

Neolithic
Neolithic
Revolution

founder crops New World
New World
crops

Ard / plough Celt Digging stick Domestication Goad Irrigation Secondary products Sickle Terracing

Food
Food
processing

Fire Basket Cooking

Earth oven

Granaries Grinding slab Ground stone Hearth

Aşıklı Höyük Qesem Cave

Manos Metate Mortar and pestle Pottery Quern-stone Storage pit

Hunting

Arrow Boomerang

throwing stick

Bow and arrow

history

Nets Spear

Spear-thrower baton harpoon woomera Schöningen Spears

Projectile points

Arrowhead Bare Island Cascade Clovis Cresswell Cumberland Eden Folsom Lamoka Manis Site Plano Transverse arrowhead

Systems

Game drive system

Buffalo jump

Toolmaking

Earliest toolmaking

Oldowan Acheulean Mousterian

Clovis culture Cupstone Fire hardening Gravettian
Gravettian
culture Hafting Hand axe

Grooves

Langdale axe industry Levallois technique Lithic core Lithic reduction

analysis debitage flake

Lithic technology Magdalenian
Magdalenian
culture Metallurgy Microblade technology Mining Prepared-core technique Solutrean
Solutrean
industry Striking platform Tool stone Uniface Yubetsu technique

Other tools

Adze Awl

bone

Axe Bannerstone Blade

prismatic

Bone tool Bow drill Burin Canoe

Oar Pesse canoe

Chopper

tool

Cleaver Denticulate tool Fire plough Fire-saw Hammerstone Knife Microlith Quern-stone Racloir Rope Scraper

side

Stone tool Tally stick Weapons Wheel

illustration

Architecture

Ceremonial

Göbekli Tepe Kiva Standing stones

megalith row Stonehenge

Pyramid

Dwellings

Neolithic
Neolithic
architecture British megalith architecture Nordic megalith architecture Burdei Cave Cliff dwelling Dugout Hut

Quiggly hole

Jacal Longhouse Mud brick

Mehrgarh

Neolithic
Neolithic
long house Pit-house Pueblitos Pueblo Rock shelter

Blombos Cave Abri de la Madeleine Sibudu Cave

Stone roof Roundhouse Stilt house

Alp pile dwellings

Wattle and daub

Water
Water
management

Check dam Cistern Flush toilet Reservoir Water
Water
well

Other architecture

Archaeological features Broch Burnt mound

fulacht fiadh

Causewayed enclosure

Tor enclosure

Circular enclosure

Goseck

Cursus Henge

Thornborough

Oldest buildings Megalithic architectural elements Midden Timber circle Timber trackway

Sweet Track

Arts and culture

Material goods

Baskets Beadwork Beds Chalcolithic Clothing/textiles

timeline

Cosmetics Glue Hides

shoes Ötzi

Jewelry

amber use

Mirrors Pottery

Cardium Grooved ware Linear Jōmon Unstan ware

Sewing needle Weaving Wine

Winery wine press

PrehistArt

Art of the Upper Paleolithic Art of the Middle Paleolithic

Blombos Cave

List of Stone Age
Stone Age
art Bird stone Bradshaw rock paintings Cairn Carved Stone Balls Cave
Cave
paintings

painting pigment

Cup and ring mark Geoglyph Golden hats Guardian stones Megalithic art Petroform Petroglyph Petrosomatoglyph Pictogram Rock art

Stone carving

Sculpture Statue menhir Stone circle

list British Isles and Brittany

Venus figurines

Burial

Burial mounds

Bowl barrow Round barrow

Mound Builders
Mound Builders
culture

U.S. sites

Chamber tomb

Severn-Cotswold

Cist

Dartmoor kistvaens

Clava cairn Court tomb Cremation Dolmen

Great dolmen

Funeral pyre Gallery grave

transepted wedge-shaped

Grave goods Jar burial Long barrow

unchambered Grønsalen

Megalithic tomb Mummy Passage grave Rectangular dolmen Ring cairn Simple dolmen Stone box grave Tor cairn Tumulus Unchambered long cairn

Other cultural

Astronomy

sites lunar calendar

Behavioral modernity Origin of language

trepanning

Prehistoric medicine Evolutionary musicology

music archaeology

Prehistoric music

Alligator drum flutes Divje Babe flute gudi

Prehistoric numerals Origin of religion

Paleolithic religion Prehistoric religion Spiritual drug use

Prehistoric warfare Symbols

symbolism

Authority control

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