adj.
That can be irrigated: irrigable desert.
irrigable
Dictionary:
ir·ri·ga·ble (ĭr'ĭ-gə-bəl)  |
| 5min Related Video: irrigable |
| Britannica Concise Encyclopedia: irrigation |
For more information on irrigation, visit Britannica.com.
| Sci-Tech Encyclopedia: Irrigation |
The artificial application of water to the soil to produce plant growth. Irrigation also cools the soil and atmosphere, making the environment favorable for plant growth. Water is applied to crops by surface, subsurface, sprinkler, and drip irrigation.
Surface irrigation includes furrow and flood methods. The furrow method is used for row crops. Corrugations or rills are small furrows used on close-growing crops. The flow, carried in furrows, percolates into the soil. Flow to the furrow is usually supplied by siphon tubes, spiles, gated pipe, or valves from buried pipe. In the flood method, controlled flooding is done with border strips, contour or bench borders, and basins.
Subirrigation is a type of irrigation accomplished by raising the water table to the root zone of the crop or by carrying moisture to the root zone by perforated underground pipe. Either method requires special soil conditions for successful operation.
A sprinkler system consists of pipelines which carry water under pressure from a pump or elevated source to lateral lines along which sprinkler heads are spaced at appropriate intervals. Laterals are moved from one location to another by hand or tractor, or they are moved automatically. The side-roll wheel system, which utilizes the lateral as an axle (see illustration), is very popular as a labor-saving method.
A side-roll sprinkler system which uses the main supply line (often more than 1000 ft, or 300 m, long) to carry the sprinkler heads and as the axle for wheels.
Drip irrigation is a method of providing water to plants almost continuously through small-diameter tubes and emitters. It has the advantage of maintaining high moisture levels at relatively low capital costs. It can be used on very steep, sandy, and rocky areas and can utilize saline waters better than most other systems. The system has been most popular in orchards and vineyards, but is also used for vegetables, ornamentals, and for landscape plantings. See also Land drainage (agriculture).
| Modern Science: irrigable |
irrigation
Artificial provision of water to sustain growing plants.
• Irrigation accounts for the greatest part of water usage in the western United States.
| Dental Dictionary: irrigation |
(ir'igā'shən)
n
n
The technique of using a solution to wash or flush debris from the root canal or from a wound.
| Geography Dictionary: irrigation |
The supply of water to the land by means of channels, streams, and sprinklers in order to permit the growth of crops. Without irrigation arable farming is not possible where annual rainfall is 250 mm or less and it is advisable in areas of up to 500 mm annual rainfall. To some extent, irrigation can free farmers from the vagaries of rainfall and, to that end, may be used in areas of seemingly sufficient rainfall because irrigation can supply the right amount of water at the right time.
Within Europe, it is in the Mediterranean regions where irrigation is vital; in 1990, Greece and Italy had 24% of crop land irrigated, Portugal 18%, and Spain 15%. However, 26% of Dutch farmland is irrigated—a reminder that intensive farming systems will use irrigation in seemingly well-watered regions. The UK figure was 2%.
Large-scale irrigation schemes may encounter difficulties if they cross national boundaries; the Punjab irrigation scheme of north-west India and Pakistan is a source of conflict between the two nations since the original scheme was set up before partition. Even within a nation there may be disputes about water supply; Arizona and California both use the water of the Colorado which acts as a frontier between the two states.
In its simplest form, irrigation is achieved by devices such as the sakia and the shaduf to lift water but, increasingly, modern pumps are used. Irrigation is not suited to saline soils since the salt will move to the surface and be so concentrated there as to inhibit the growth of most plants. Similarly, the use of brackish water for irrigation is unwise since the salts remain in the soil after the water has been lost through evapotranspiration.
Irrigated lands show regular and intricate systems of intensively cultivated fields dependent on water through canals, cuts, and irrigation channels.
| US History Encyclopedia: Irrigation |
Irrigation, the delivery of water to grow crops, has been a factor in North American society and agriculture since long before the existence of the United States. Mostly practiced in the arid western regions of the country, its expansion in the twentieth century dramatically altered the national landscape and food production.
Possibly as early as A.D. 300, the Hohokam erected the first large-scale irrigation systems in the area that later became the southwestern United States. Although their rawhide and basket tools were simple and their dams small by modern standards, these indigenous societies maintained thousands of acres under irrigation for centuries. The Papago and Pueblo nations later practiced similar techniques, though they generally irrigated only smaller fields near arroyo mouths and seasonal stream-beds. The coordinated efforts to construct and maintain this sophisticated infrastructure required these early irrigators to develop political institutions and tribal affiliations larger than those of their hunter-gatherer neighbors.
Spanish and Mexican settlers in New Mexico created similar irrigation systems to support their own agriculture. Many of their villages and fields were actually built around an acequia madre or "mother ditch," and they boasted well-articulated lines of command and labor expectations to maintain the ditch. This social and physical system still existed in some of these villages at the end of the twentieth century.
The Mormon settlers arriving in the Salt Lake area in the 1840s drew on these precedents in the erection of their own irrigation networks. Using the cooperative religious institutions that characterized their society, by 1850 they grew such diverse crops as potatoes, wheat, hay, and oats on more than sixteen thousand irrigated acres.
The westward expansion of the United States in the nineteenth century brought the regions where irrigation was needed to practice extensive agriculture under American control. At first, however, migrating Americans were slow to recognize the challenge that aridity posed to their traditional agricultural practices. At less than twenty inches a year, the average rainfall west of the one-hundredth meridian—roughly the line that runs north and south through the middle of the states of Texas, Oklahoma, Kansas, Nebraska, and the Dakotas—is just below the amount needed to grow wheat, and ten inches less than that needed by corn.
The enormous challenge of the arid West was initially difficult to recognize. During the 1880s, when thousands of farmers settled on the Great Plains, rainfall was significantly above average, in some cases twice as heavy as the long-term pattern. Farmers and policymakers were thus lulled into a false sense of security. One theory even held that the plowing of so much virgin territory had in fact fundamentally changed the natural patterns of rainfall, increasing precipitation to facilitate the conquest of the continent.
Private efforts to irrigate the arid regions of the West met with very limited success. Irrigation was generally outside the reach of individual farmers for the simple reason that it required the control of large stretches of rivers and streams and the erection of sizable dams for storage. In the 1870s and 1880s, private land companies entered the irrigation business, constructing dams, building extensive canal systems, and then selling nearby lands to farmers who would remain dependent on the companies for their water. High capital costs, however, constrained these efforts. Only the most opportune sites were irrigated, the total acres under irrigation soon stagnated, and by 1900 nearly nine out of ten of these irrigation companies were in financial jeopardy.
The Federal Role
The failure of private efforts created an opening for those who thought that the federal government should build massive irrigation works. John Wesley Powell, a pioneering scientist and ethnographer who headed the United States Geological Survey, had made the most radical proposals in this regard. Surveying the lands of the arid West in the 1870s, Powell came to the conclusion that the country's model for the settlement of newly acquired territory was deeply flawed. Extinguishing the public domain by giving settlers 160-acre tracts (under the provisions of the Homestead Act) might work where enough rain fell to grow crops, but the development of the West hinged on water rather than land. Since very little of the West could be farmed in the traditional way, the government, Powell believed, should divide the region by watershed. Much like the Mormons—whose communal irrigation made quite an impression on Powell—settlers should govern themselves by watershed, forming a cooperative to raise the capital for the necessary irrigation network. Irrigated farms, more productive and labor intensive, would be smaller than farms back east, probably about 80 acres. Unirrigated lands, which he thought would always comprise the vast majority of the West, would be reserved for ranching in large tracts of 2,500 or more acres.
Powell's vision was at once too radical and too modest to gain the political support it needed to be implemented. Western boosters were enraged by his assumption that little of the region's land was fit for agriculture, and even fewer were willing to accept the drastic revision in territorial laws for which his watershed proposal called. After the failure of private irrigation in the West, the form that federal intervention took was much more modest. The 1902 Newlands Reclamation Act created the Bureau of Reclamation, a federal agency charged with building dams, reservoirs, and irrigation canals for the benefit of private farmers. The West, in other words, was meant to resemble the East, with a little more help from the federal government.
The Newlands Act married conservation's technical expertise with its emphasis on antimonopoly. Farmers were to repay the construction costs through annual charges for their water. Individuals could buy water for a maximum of only 160 acres. The Newlands Act thus extended the provisions of the Homestead Act, seeking to create egalitarian farming communities with dispersed land ownership.
The Bureau of Reclamation was remarkably successful in its goal of irrigating the West. Whereas in 1906, fewer than thirty thousand acres west of the one-hundredth meridian were under irrigation, by 1992 that number had skyrocketed to more than 45 million. The Bureau of Reclamation, the Army Corps of Engineers, and other federal agencies erected more than one thousand dams in the West. These massive structures not only provided water for crops, but also generated much of the electricity that lit the region's cities and towns. For decades, the politics of irrigation proved irresistible. The construction of dams, aqueducts, and canals created numerous jobs, and the lands that they opened up for agriculture benefited real estate speculators and the local tax rolls alike. While the New Deal saw a significant expansion in the scope of these projects, the fact that their ultimate goal was to support private agriculture kept them attractive to more antistate politicians.
In the 1930s, affordable pumps and low-cost electricity opened up a new dimension in irrigation: ground-water pumping. By 1970, such pumping watered more than 40 percent of the nation's irrigated acreage, most of it on the Great Plains. This irrigation differed from federal projects in that it drew upon generally unrenewable aquifers and was easily affordable by individual farmers.
Social and Environmental Issues
Such intensive irrigation, however, generated its own social and environmental effects. From its inception, the Bureau of Reclamation operated much differently than its founders had envisioned. Very few irrigation projects were actually paid for by their beneficiaries, and so these public works quickly became subsidies. The proliferation of modest homesteads that had been so important to justify giving the federal government primary responsibility for irrigation never came to be. Land speculators bought much of the land where they anticipated dams might be built, and the bureau showed little interest in enforcing its 160-acre limit on what came to be some of the most powerful political interests in the West. In most areas served by the bureau's projects, it was actually impossible to purchase small tracts of land. The high productivity and costs of irrigated lands meant that such agriculture tended to be more market-oriented, more mechanized, and to employ more migrant labor than elsewhere. In practice, then, irrigation helped to solidify the dominance of large-scale agribusiness in the West.
Environmental problems have increasingly limited the effectiveness of irrigation and reduced its public support. The damming of most of the West's major rivers has decimated their salmon runs. Natural river flows have been dramatically altered. The Colorado River, for example, once mighty enough to carve the Grand Canyon, was so heavily drawn on for irrigation that it did not reach the Pacific from 1964 to 1983. Proposals to build further dams on the Colorado sparked an environmental backlash as early as the 1950s. The buildup of silt behind reservoir walls quickly became a problem; by 2000, most reservoirs built before 1945 had lost from 7 to 15 percent of their capacity. Salinization, the accretion of salt in perpetually water-logged soil, puts thousands of acres out of production each year. Groundwater pumping on the Great Plains seemed headed for extinction, with the aquifer predicted to dry up within a few decades.
No large federal irrigation projects were approved from the late 1970s to the turn of the century. In part this was because so many of the most feasible dam sites had been taken, but the loss of support for federal irrigation also reflected the growing political power of more environmental-minded urbanites. Nevertheless, irrigation continues to be a decisive force in American agriculture and the landscape of the West.
Bibliography
Hundley, Norris, Jr. The Great Thirst: Californians and Water—A History. Rev. ed. Berkeley: University of California Press, 2001.
Pisani, Donald J. To Reclaim a Divided West: Water, Law, and Public Policy, 1848–1902. Albuquerque: University of New Mexico Press, 1992.
Reisner, Marc. Cadillac Desert: The American West and Its Disappearing Water. Rev. ed. New York: Penguin, 1993.
Walton, John. Western Times and Water Wars: State, Culture, and Rebellion in California. Berkeley: University of California Press, 1992.
Worster, Donald. Rivers of Empire: Water, Aridity, and the Growth of the American West. New York: Pantheon, 1985.
| Columbia Encyclopedia: irrigation |
irrigation, in agriculture, artificial watering of the land. Although used chiefly in regions with annual rainfall of less than 20 in. (51 cm), it is also used in wetter areas to grow certain crops, e.g., rice. Estimates of total irrigated land in the world range from 543 to 618 million acres (220 to 250 million hectares), almost half of them in India, Pakistan, and China. The United States had almost 60 million acres (23.8 million hectares) of irrigated farmland in 1991. In many cases irrigation is correlated with drainage to avoid soil salinity, leaching, and waterlogging. Irrigation may also involve preliminary clearing, smoothing, and grading of land. Methods of applying water include free-flooding of entire areas from canals and ditches; check-flooding, in which water flows over strips or checks of land between levees, or ridges; the furrow method, in which water runs between crop or tree rows, penetrating laterally to the roots; the surface-pipe method, in which water flows in movable slip-joint pipes; sprinklers, including large-scale center-pivot and other self-propelled systems; and a variety of water-conserving drip and trickle systems. Since prehistoric times water has been diverted from waterways to fields by ditching. Early improvements for raising water included counterbalanced poles with attached water vessels, and adaptations of the wheel and of a pump called the Archimedes' screw. The use of canals, dams, weirs, and reservoirs for the distribution, control, and storage of water was probably initiated in ancient Egypt. In modern times pumps have facilitated the use of underground as well as surface water. Large-scale 20th-century irrigation projects commonly also include water supply, hydroelectric power, and flood control. Many regions, notably in China, Egypt, Mesopotamia, and India, have been under continuous irrigation from ancient times. Today China, India, the United States, and Pakistan rank highest in irrigated land. In North America, where most of the arid and semiarid land lies west of the 100th meridian, irrigation was first practiced in the Southwest by Native Americans and later by the Spanish, especially in California. As agriculture expanded, early irrigation initiatives by individual farmers or local groups were soon supplemented by commercial projects, until more ambitious water conservation and development schemes involved state and federal governments in vast projects. A drawback to intensive irrigation, especially in areas of high evaporation rates, is that excessive quantities of salts accumulate in the upper layers of the soil as water evaporates from the surface, rendering the soil unfit for crop production.
Bibliography
See J. Keller and R. D. Bliesner, Sprinkle and Trickle Irrigation (1990); B. A. Stewart and D. R. Nelson, Irrigation of Agricultural Crops (1990); W. F. Ritter, ed., Irrigation and Drainage (1991).
| Essay: Irrigation and the rise of civilization |
After the Agricultural Revolution, farmers quickly learned the importance of water and sunlight to crops. Sunlight can be obtained by burning away part of the forest, which is the method used in most places with abundant water to this day. Often, however, broad reaches of land already exist with no forest cover; but this is because the region lacks sufficient water. If a farmer can get water to fields in such sunny lands, the resulting crops are prolific.
Sometimes a river runs through such land. The river obtains its water somewhere that is rainy, usually in high mountains unsuitable for farming. It then carries the water through desert or semidesert as it flows to the sea. Rivers of this type include the Nile, Tigris, Euphrates, Hwang Ho (Yellow River), Indus, and about 50 waterways in Peru that run from the Andes to the Pacific. Merely listing the rivers suggests that there is a connection between rivers running through dry lands and the development of civilization, for these are the rivers of Egypt, Sumer, China, Harappa, and the Chavín, virtually all of the earliest civilizations known.
The connection between rivers in deserts and civilization is thought to be irrigation. The political structure necessary to organize people for canal digging and fair use of river water for farming is also the political structure that supports other types of construction, city planning, state religion, education, and a class with the leisure to pursue mathematics, science, and philosophy. This "theory of the hydraulic society" stems from such thinkers as Friedrich Engels, Karl Marx, Max Weber, and Karl Wittfogel. While not everyone agrees that irrigation caused the state (some think that class divisions started first, enabling irrigation systems), even most critics of the hydraulic theory think that it applies to some degree to the civilizations listed in the previous paragraph. It especially seems to apply to Sumer, which was, after all, the first civilization. Although other civilizations seem to have independent origins, there is a strong possibility that they at least heard rumors that something brand new was taking place in Mesopotamia.
In Mesopotamia streams were at a low level during the fall planting season, requiring very deep ditches for irrigation. When the high water arrived in the spring, it not only irrigated the plants, it also laid down a lot of silt in the canals, so the deep digging needed to be repeated. Both maintaining and building the system required organization and that seemed to mandate state control.
Where the hydraulic theory seems to break down is in civilizations such as the Olmec and early Maya, civilizations that developed in regions where a lot of water falls from the skies on a regular basis. In the past few years, however, aerial studies have shown that the Maya did possess large irrigation systems. Such systems were needed because most of the rain that fell over Maya sites immediately passed deep into the soil and underlying rock. There were no large rivers in Mayaland, but there were sinkholes filled with water and regular rain. Combining these resources required the large irrigation works that are called for in the hydraulic theory.
The Olmec civilization presents a tougher problem. One careful study, by William Rathje, focuses on the lack of hard rock and obsidian in the lowland rain forests of eastern Mexico, where the Olmec civilization began. Rathje has proposed that the state must have arisen there to facilitate long-distance trade, a recognized part of Olmec life.
However, if you return to the main early civilizations, it is hard to find any but the Olmec not heavily involved with irrigation right from the start. Even if war, classes, or population growth came first, large-scale irrigation requires record keeping, organization, different classes of workers, central planning, foresight, and so forth -- in short, civilization and the state.
Unfortunately for most civilizations in arid regions, irrigation from a river also contains the seeds of destruction for the civilization (see the essay "Salt and the fall of civilization").
| Wikipedia: Irrigation |
Irrigation is an artificial application of water to the soil. It is usually used to assist in growing crops 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 growing in rice fields[2] and helping in preventing soil consolidation.[3] In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed farming. Irrigation is often studied together with drainage, which is the natural or artificial removal of surface and sub-surface water from a given area.
Irrigation is also a term used in medical/dental fields to refer to flushing and washing out anything with water or another liquid.
History
Archaeological investigation has identified evidence of irrigation in Mesopotamia and Egypt 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.[4]
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.[5] Sophisticated irrigation and storage systems were developed by the Indus Valley Civilization in Pakistan and North India, including the reservoirs at Girnar in 3000 BCE and an early canal irrigation system from circa 2600 BCE.[6][7] Large scale agriculture was practiced and an extensive network of canals was used for the purpose of irrigation.
There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty (about 1800 BCE) using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during the dry seasons, as the lake swelled annually as caused by the annual flooding of the Nile.[8]
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.[9] 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.[10]
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'. Most of these irrigation systems still exist undamaged up to now, in 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 (1153 – 1186 CE).[11]
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.[12] By the 2nd century AD, during the Han Dynasty, the Chinese also used chain pumps that lifted water from lower elevation to higher elevation.[13] These were powered by manual foot pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen.[14] 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.[15]
In fifteenth century Korea the world's first water gauge, uryanggye (Korean:우량계), was discovered in 1441 CE. 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.[16]
Present extent
In the middle of the 20th century, the advent of diesel and electric motors led for the first time to systems that could pump groundwater out of major aquifers faster than it was recharged. 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.
At the global scale 2,788,000 km² (689 million acres) of agricultural land was equipped with irrigation infrastructure around the year 2000. About 68% of the area equipped for irrigation is located in Asia, 17% in America, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found in North India and Pakistan along the rivers Ganges and Indus, 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.[17]
Types of irrigation
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.
Surface irrigation
Main article: Surface irrigation
In surface irrigation systems water moves over and across the land by simple gravity flow in order to wet it and to 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.
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.
Localized irrigation
Localized 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. Drip irrigation, spray or micro-sprinkler irrigation and bubbler irrigation belong to this category of irrigation methods.[18]
Drip Irrigation
Main article: Drip Irrigation
Drip irrigation, also known as trickle irrigation, functions as its name suggests. 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, if managed properly, since evaporation and runoff are minimized.[citation needed] 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 of a duration or if the delivery rate is too high. 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. Both pressure regulation and filtration to remove particles are important. The tubes are usually black (or buried under soil or mulch) to prevent the growth of algae and to protect the polyethylene from degradation due to ultraviolet light. But drip irrigation can also be as low-tech as a porous clay vessel sunk into the soil and occasionally filled from a hose or bucket. Subsurface drip irrigation has been used successfully on lawns, but it is more expensive than a more traditional sprinkler system. Surface drip systems are not cost-effective (or aesthetically pleasing) for lawns and golf courses. In the past one of the main disadvantages of the subsurface drip irrigation (SDI) systems, when used for turf, was the fact of having to install the plastic lines very close to each other in the ground, therefore disrupting the turfgrass area. Recent technology developments on drip installers like the drip installer at New Mexico State University Arrow Head Center, places the line underground and covers the slit leaving no soil exposed.
Sprinkler irrigation
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 may 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. These cable-type travelers are definitely old technology and their use is limited in today's modern irrigation projects.
Center pivot irrigation
Main article: Center pivot irrigation
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. 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 common in parts of the United States where terrain is flat. Newer irrigations have drops as shown in the image that follows.
Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck 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. The crops are 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 (T-L, Reinke, Valley, Zimmatic). Most sprinklers features GPS devices. Reinkes usually have strobe lights and are red. Valleys have a blue label, while Zimmatics' lights are high with either a red or white Zimmatic label.
Lateral move (side roll, wheel line) irrigation
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.
Sub-irrigation
Subirrigation also sometimes called seepage irrigation 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.
Sub-irrigation is also used in commercial greenhouse production, usually for potted plants. 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-saving through lowered system maintenance and automation. It is similar in principle and action to subsurface drip irrigation.
Manual irrigation using buckets or watering cans
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.
Automatic, non-electric irrigation using buckets and ropes
Besides the common manual watering by bucket, an automated, natural version of this also exist. Using plain polyester ropes combined with a prepared ground mixture can be used to water plants from a vessel filled with water.[19][20][21] 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 you to save expenses as it does not consume any electricity and only little water (unlike sprinklers, water timers, ...). However, it may only be used with certain crops (probably mostly larger crops that do not need a humid environment; perhaps e.g. paprika's).
Irrigation using stones to catch water from humid air
In countries where at night, humid air sweeps the countryside, stones are used to catch water from the humid air by condensation. This is for example practiced in the vineyards at Lanzarote.
Dry terraces for irrigation and water distribution
In subtropical countries as Mali and Senegal, a special type of terracing (without flood irrigation or intent to flatten farming ground) is used. Here, a 'stairs' is made through the use of ground level differences which helps to decrease water evaporation and also distributes the water to all patches (sort of irrigation).
Sources of irrigation water
Sources of irrigation water can be groundwater extracted from springs or by using wells, surface water withdrawn from rivers, lakes or reservoirs or non-conventional sources like treated wastewater, desalinated water or drainage water. 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 (wadi’s) 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 is the collection of runoff water from roofs or unused land and the concentration of this
How an in-ground irrigation system works
Most commercial and residential irrigation systems are "in ground" systems, which means that everything is buried in the ground. With the pipes, sprinklers, 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.
Water source and piping
The beginning of a sprinkler system is the water source. This is usually a tap into an existing (city) water line or a pump that pulls water out of a well or a pond. The water travels through pipes from the water source through the valves to the sprinklers. The pipes from the water source up to the irrigation valves are called "mainlines", and the lines from the valves to the sprinklers are called "lateral lines". Most piping used in irrigation systems today are HDPE and MDPE or PVC or PEX plastic pressure pipes due to their ease of installation and resistance to corrosion. After the water source, the water usually travels through a check valve. This prevents water in the irrigation lines from being pulled back into and contaminating the clean water supply.
Controllers, zones, and valves
Most Irrigation systems are divided into zones. A zone is a single Irrigation Valve and one or a group of sprinklers that are connected by pipes. 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 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 used to describe 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 sensors (water potential or water content), weather station, or a combination of these.
Sprinklers
When a zone comes on, the water flows through the lateral lines and ultimately ends up at the irrigation Sprinkler heads. Most 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.
Problems in irrigation
- Competition for surface water rights.
- Depletion of underground aquifers.
- Ground subsidence (e.g. New Orleans, Louisiana)
- Underirrigation gives poor soil salinity control which leads to increased soil salinity with consequent build up 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.
- Overirrigation because of poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution.
- Deep drainage (from over-irrigation) may result in rising water tables which in some instances will lead to problems of irrigation salinity.
- Irrigation with saline or high-sodium water may damage soil structure.
Academic resources
- Irrigation Science, ISSN: 1432-1319 (electronic) 0342-7188 (paper), Springer
- Journal of Irrigation and Drainage Engineering, ISSN: 0733-9437, ASCE Publications
Irrigation by country
|
See also
References
- ^ 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. ftp://ftp.fao.org/docrep/fao/008/y7223e/y7223e00.pdf.
- ^ 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. http://www.plantsciences.ucdavis.edu/uccerice/WATER/water.htm. Retrieved 2007-03-14.
- ^ Arid environments becoming consolidated
- ^ The History of Technology – Irrigation. Encyclopædia Britannica, 1994 edition.
- ^ 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:. PMID 16284247.
- ^ Rodda, J. C. and Ubertini, Lucio (2004). The Basis of Civilization - Water Science? pg 161. International Association of Hydrological Sciences (International Association of Hydrological Sciences Press 2004).
- ^ "Ancient India Indus Valley Civilization". Minnesota State University "e-museum". http://www.mnsu.edu/emuseum/prehistory/india/indus/elements.html. Retrieved 2007-01-10.
- ^ "Amenemhet III". Britannica Concise. http://concise.britannica.com/ebc/article-9006076/Amenemhet-III. Retrieved 2007-01-10.
- ^ "Qanat Irrigation Systems and Homegardens (Iran)". Globally Important Agriculture Heritage Systems. UN Food and Agriculture Organization. http://www.fao.org/sd/giahs/other_iran1_desc.asp. Retrieved 2007-01-10.
- ^ Encyclopædia Britannica, 1911 and 1989 editions
- ^ de Silva, Sena (1998). "Reservoirs of Sri Lanka and their fisheries". UN Food and Agriculture Organization. http://www.fao.org/docrep/003/T0028E/T0028E03.htm. Retrieved 2007-01-10.
- ^ China – history. Encyclopædia Britannica,1994 edition.
- ^ Needham, Joseph (1986). Science and 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 장영실. Woongjin Wiin Jeon-gi 웅진위인전기 11. Woongjin Publishing Co., Ltd.
- ^ 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. http://www.tropentag.de/2006/abstracts/full/211.pdf. Retrieved 2007-03-14.
- ^ Frenken, K. (2005). "Irrigation in Africa in figures – AQUASTAT Survey – 2005" (PDF). Food and Agriculture Organization of the United Nations. ftp://ftp.fao.org/agl/aglw/docs/wr29_eng.pdf. Retrieved 2007-03-14.
- ^ polyester ropes natural irrigation technique
- ^ Polyester rope natural irrigation technique 2
- ^ DIY instructions for making sel-watering system using ropes
External links
 |
Look up irrigation in Wiktionary, the free dictionary. |
 |
Wikimedia Commons has media related to: Irrigation |
- "Irrigation techniques". USGS. http://ga.water.usgs.gov/edu/irmethods.html. Retrieved December 8 2005.
- "The Irrigation Association". http://www.irrigation.org. Retrieved December 8 2005.
- Royal Engineers Museum 19th century Irrigation in India
- International Commission on Irrigation and Drainage (ICID)
- Irrigation Water Quality Information Center, U.S. Department of Agriculture
- AQUASTAT FAO's global information system on water and agriculture
- Irrigation methods at Appropedia, a wiki for non-Wikipedia content (projects & practical "how tos").
- Equal and Proportionate Distribution of Water in Irrigation Systems - article at Appropedia
- Texas Irrigation
- Guide to Irrigation an article written by Ahmet Korkmaz
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
This article incorporates text from the Encyclopædia Britannica, Eleventh Edition, a publication now in the public domain.
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
| Best of the Web: irrigable |
Some good "irrigable" pages on the web:
 How? home.howstuffworks.com |
Learn More
 | Agriculture |
| Agriculture, American Indian |
| Reclamation |
 | What is perennial irrigation? Read answer... |
| Why do you irrigate land? Read answer... |
| Irrigation in india? Read answer... |
Help us answer these
 | What is the oppositeof irrigation? |
| What is irrigation famine? |
| How do you irrigate teeth? |
Post a question - any question - to the WikiAnswers community:
Copyrights:
 |
 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
 |
| Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved. Read more |
 |
| Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved. Read more |
 |
| Modern Science. The Dictionary of Cultural Literacy, Second Edition, Revised and updated Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 1993 by Houghton Mifflin Company . All rights reserved. Read more |
 |
| Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved. Read more |
 |
| Geography Dictionary. A Dictionary of Geography. Copyright © Susan Mayhew 1992, 1997, 2004. All rights reserved. Read more |
 |
| US History Encyclopedia. © 2006 through a partnership of Answers Corporation. All rights reserved. Read more |
 |
| Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/. Read more |
|
| Essay. History of Science and Technology, edited by Bryan Bunch and Alexander Hellemans. Copyright © 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. Read more |
 |
| Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Irrigation". Read more |
Related answers
- What is flood irrigation?
- What does irrigation mean?
- What are the meathods of irrigation?
- Can farmlands be irrigated?
- Who invented Irrigation?
ADVERTISEMENT
Answer these
- What does irrigent?
- What is irrigated?
- Furrow Irrigation or Drip Irrigation?
- What is irrigated farming?
- Who inventerd irrigation?
Mentioned in
- Keban Dam
- Native American Rights (legal term)
- Toker Dam
- 1878 (chronology)
- 13th century in North American history
- Mukhrani
- Quincy-Columbia Basin Irrigation District
- Guelma Province
- Fryingpan-Arkansas Project
- Charles Palmer (engineer)
- Rice production in the Philippines
- Rancho la Ballona
- Kushtia District
- List of Texas empresarios
