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Irrigation

Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost, suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation.

There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as a small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising the water table to moisten the soil below the root zone of plants.

Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. Irrigation can be supplementary to rainfall, which is common in many parts of the world as rainfed agriculture, or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons.

The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting. Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution. Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage.

Extent
In 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 and Eastern India and Pakistan along the Ganges and Indus rivers; in the Hai He, Huang He and Yangtze basins in China; along the Nile river in Egypt and Sudan; and in the Mississippi-Missouri river basin, the Southern Great Plains, and in parts of California in the United States. Smaller irrigation areas are spread across almost all populated parts of the world.

By 2012, the area of irrigated land had increased to an estimated total of 3,242,917 km2 (801 million acres), which is nearly the size of India. The irrigation of 20% of farming land accounts for the production of 40% of food production.

Global overview
The scale of irrigation increased dramatically over the 20th century. In 1800, 8 million hectares globally were irrigated, in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe includes canals redirecting surface water, groundwater pumping, and diverting water from dams. National governments lead most irrigation schemes within their borders, but private investors and other nations, especially the United States, China, and European countries like the United Kingdom, also fund and organize some schemes within other nations.

By 2021 the global land area equipped for irrigation reached 352 million ha, an increase of 22% from the  289 million ha of 2000 and more than twice the 1960s land area equipped for irrigation. The vast majority is located in Asia (70%), where irrigation was a key component of the green revolution; the Americas account for 16% and Europe for 8% of the world total. India (76 million ha) and China (75 million ha) have the largest equipped area for irrigation, far ahead of the United States o fAmerica (27 million ha). China and India also have the largest net gains in equipped area between 2000 and 2020 (+21 million ha for China and +15 million ha for India). All the regions saw increases in the area equipped for irrigation, with Africa growing the fastest (+29%), followed by Asia (+25%), Oceania (+24%), the Americas (+19%) and Europe (+2%).

Irrigation enables the production of more crops, especially commodity crops in areas which otherwise could not support them. Countries frequently invested in irrigation to increase wheat, rice, or cotton production, often with the overarching goal of increasing self-sufficiency.

Groundwater and surface water

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.

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.

Other sources
Irrigation water can also come from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection.

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 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.

a Glasgow-based startup has helped a farmer in Scotland to establish edible saltmarsh crops irrigated with sea water. An acre of previously marginal land has been put under cultivation to grow samphire, sea blite, and sea aster; these plants yield a higher profit than potatoes. The land is flood irrigated twice a day to simulate tidal flooding; the water is pumped from the sea using wind power. Additional benefits are soil remediation and carbon sequestration.

Competition for water resources
Until the 1960s, there were fewer than half the number of people on the planet as of 2024. 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 humans presently take from rivers. Today, the competition for water resources is much more intense, because there are now more than seven billion people on the planet, increasing the likelihood of overconsumption of food produced by water-thirsty animal agriculture and intensive farming practices. This creates increasing competition for water from industry, urbanisation and biofuel crops. 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.

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.

Irrigation methods
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. Irrigation can also be understood whether it is supplementary to rainfall as happens in many parts of the world, or whether it is 'full irrigation' whereby crops rarely depend on any contribution from rainfall. Full irrigation is less common and only happens in arid landscapes experiencing very low rainfall or when crops are grown in semi-arid areas outside of any rainy seasons.

Surface irrigation

Surface irrigation, also known as gravity 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 agricultural lands, in order to wet it and infiltrate into the soil. Water moves by following gravity or the slope of the land. Surface irrigation can be subdivided into furrow, border strip or basin irrigation. It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land. Historically, surface irrigation is the most common method of irrigating agricultural land across most parts of the world. The water application efficiency of surface irrigation is typically lower than other forms of irrigation, due in part to the lack of control of applied depths. Surface irrigation involves a significantly lower capital cost and energy requirement than pressurised irrigation systems. Hence it is often the irrigation choice for developing nations, for low value crops and for large fields. Where water levels from the irrigation source permit, the levels are controlled by dikes (levees), 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. Surface irrigation is even used to water urban gardens 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.

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.

Micro-irrigation
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 use individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinklers, and mini-bubbler irrigation all belong to this category of irrigation methods.

Drip irrigation

Drip irrigation, also known as microirrigation or trickle irrigation, functions as its name suggests. In this system, water is delivered at or near the root zone of plants, one drop at a time. This method can be the most water-efficient method of irrigation, if managed properly; evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90% 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 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

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 using 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 275 to 900 kPa (40 to 130 psi) and flows of 3 to 76 L/s (50 to 1200 US gal/min), usually with nozzle diameters in the range of 10 to 50 mm (0.5 to 1.9 in). 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 use 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

Center pivot irrigation is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined 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 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.

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 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.

Irrigation by lateral move (side roll, wheel line, wheelmove)
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 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 100 or 130 mm (4 or 5 inch) 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 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
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.

Hose-end sprinklers
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
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 the commercial greenhouse production, usually for potted plants. Water is delivered from below, absorbed by 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. A similar technique is the wicking bed; this too uses capillary action.

Efficiency
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. Water use efficiency in the field can be determined as follows:
 * Field Water Efficiency (%) = (Water Transpired by Crop ÷ Water Applied to Field) x 100

Increased irrigation efficiency has a number of positive outcomes for the farmer, the community and the wider environment. Low application efficiency infers that the amount of water applied to the field is in excess of the crop or field requirements. Increasing the application efficiency means that the amount of crop produced per unit of water increases. Improved efficiency may either be achieved by applying less water to an existing field or by using water more wisely thereby achieving higher yields in the same area of land. In some parts of the world, farmers are charged for irrigation water hence over-application has a direct financial cost to the farmer. Irrigation often requires pumping energy (either electricity or fossil fuel) to deliver water to the field or supply the correct operating pressure. Hence increased efficiency will reduce both the water cost and energy cost per unit of agricultural production. A reduction of water use on one field may mean that the farmer is able to irrigate a larger area of land, increasing total agricultural production. Low efficiency usually means that excess water is lost through seepage or runoff, both of which can result in loss of crop nutrients or pesticides with potential adverse impacts on the surrounding environment.

Improving the efficiency of irrigation is usually achieved in one of two ways, either by improving the system design or by optimising the irrigation management. Improving system design includes conversion from one form of irrigation to another (e.g. from furrow to drip irrigation) and also through small changes in the current system (for example changing flowrates and operating pressures). Irrigation management refers to the scheduling of irrigation events and decisions around how much water is applied.

Environmental impacts
Negative impacts frequently accompany extensive irrigation. Some projects which diverted surface water for irrigation dried up the water sources, which led to a more extreme regional climate. Projects that relied on groundwater and pumped too much from underground aquifers created subsidence and salinization. Salinization of irrigation water in turn damaged the crops and seeped into drinking water. Pests and pathogens also thrived in the irrigation canals or ponds full of still water, which created regional outbreaks of diseases like malaria and schistosomiasis. Governments also used irrigation schemes to encourage migration, especially of more desirable populations into an area. Additionally, some of these large nationwide schemes failed to pay off at all, costing more than any benefit gained from increased crop yields.

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 Plain, the Punjab region in India and Pakistan, and the Great Plains of the US is threatened by this phenomenon.

Technical challenges
Irrigation schemes involve solving numerous engineering and economic problems while minimizing negative environmental consequences. Such problems include:
 * 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.
 * 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 requiring watertable control by some form of subsurface land drainage. For example in Australia, over-abstraction of fresh water for intensive irrigation activities has caused 33% of the land area to be at risk of salination.
 * Drainage front instability, also known as viscous fingering, where an unstable drainage front results in a pattern of fingers and viscous entrapped saturated zones.
 * Irrigation with saline or high-sodium water may damage soil structure owing to the formation of alkaline soil.
 * Clogging of filters: algae can clog filters, drip installations, and nozzles. Chlorination, algaecide, UV and ultrasonic methods can be used for algae control in irrigation systems.
 * Complications in accurately measuring irrigation performance which changes over time and space using measures such as productivity, efficiency, equity and adequacy.
 * Macro-irrigation, typical in intensive agriculture, where also are used agrochemicals, often causes eutrophication.

Social aspects

 * Competition for surface water rights and territory defense.
 * Assisting smallholders in sustainably and collectively managing irrigation technology and changes in technology.

Ancient history

Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture. Some of the earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of Iran. The site of Choga Mami, in present-day Iraq on the border with Iran, is believed to be the earliest to show the first canal irrigation in operation at about 6000 BCE.

Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of which is estimated to have begun around 4500 BCE and drastically increased the size and prosperity of their agricultural settlements. The Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, and an early canal irrigation system from c. 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation.

Farmers in the Mesopotamian plain used irrigation from at least the third millennium BCE. They developed perennial irrigation, regularly watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field. Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots which had been surrounded by dikes. The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. 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 dry seasons. The lake swelled annually from the flooding of the Nile. The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia some time between the third and second millennia BCE. It largely depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan.

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

Evidence of terrace irrigation occurs in pre-Columbian America, early Syria, India, and China. In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE. These canals provide 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.

Ancient Persia (modern day Iran) used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall. The Qanats, developed in ancient Persia 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 of steep hills to tap groundwater. 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), first came into use at about this time among 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.

Sri Lanka
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. These reservoirs and canal systems were used primarily to irrigate paddy fields, which require a lot of water to cultivate. 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).

China
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 Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan 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. By the 2nd century CE, during the Han dynasty, the Chinese also used chain pumps which lifted water from a lower elevation to a higher one. These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. The water was used for public works, providing water for urban residential quarters and palace gardens, but mostly for irrigation of farmland canals and channels in the fields.

Korea
Korea, Jang Yeong-sil, a Korean engineer of the Joseon dynasty, under the active direction of the king, Sejong the Great, invented the world's first rain gauge, uryanggye in 1441. 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.

North America
The earliest agricultural irrigation canal system known in the area of the present-day United States dates to between 1200 BCE and 800 BCE and was discovered by Desert Archaeology, Inc. in Marana, Arizona (adjacent to Tucson) in 2009. The irrigation-canal system predates the Hohokam culture by two thousand years and belongs to an unidentified culture. In North America, the 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 CE 1300. The Hohokam constructed an assortment of simple canals combined with weirs in their various agricultural pursuits. Between the 7th and 14th centuries they 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 cultivated varieties of cotton, tobacco, maize, beans and squash, as well as harvesting an assortment of wild plants. Late in the 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.

South America
The oldest known irrigation canals in the Americas are in the desert of northern Peru in the Zaña valley near the hamlet of Nanchoc. The canals have been radiocarbon dated to at least 3400 BCE and possibly as old as 4700 BCE. The canals at that time irrigated crops such as peanuts, squash, manioc, chenopods, a relative of Quinoa, and later maize.

Modern history
The scale of irrigation increased dramatically over the 20th century. In 1800, 8 million hectares globally were irrigated, in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe included canals redirecting surface water,  groundwater pumping, and diverting water from dams. National governments led most irrigation schemes within their borders, but private investors and other nations, especially the United States, China, and European countries like the United Kingdom,  funded and organized some schemes within other nations. Irrigation enabled the production of more crops, especially commodity crops in areas which otherwise could not support them. Countries frequently invested in irrigation to increase wheat, rice, or cotton production, often with the overarching goal of increasing self-sufficiency. In the 20th century, global anxiety specifically about the American cotton monopoly fueled many empirical irrigation projects: Britain began developing irrigation in India, the Ottomans in Egypt, the French in Algeria, the Portuguese in Angola, the Germans in Togo, and Soviets in Central Asia.

Negative impacts frequently accompanied extensive irrigation. Some projects which diverted surface water for irrigation dried up the water sources, which led to a more extreme regional climate. Projects that relied on groundwater and pumped too much from underground aquifers created subsidence and salinization. Salinization of irrigation water in turn damaged the crops and seeped into drinking water. Pests and pathogens also thrived in the irrigation canals or ponds full of still water, which created regional outbreaks of diseases like malaria and schistosomiasis. Governments also used irrigation schemes to encourage migration, especially of more desirable populations into an area. Additionally, some of these large nationwide schemes failed to pay off at all, costing more than any benefit gained from increased crop yields.

American West
Irrigated land in the United States increased from 300,000 acres in 1880 to 4.1 million in 1890, then to 7.3 million in 1900. Two thirds of this irrigation sources from groundwater or small ponds and reservoirs, while the other one third comes from large dams. One of the main attractions of irrigation in the West was its increased dependability compared to rainfall-watered agriculture in the East. Proponents argued that farmers with a dependable water supply could more easily get loans from bankers interested in this more predictable farming model. Most irrigation in the Great Plains region derived from underground aquifers. Euro-American farmers who colonized the region in the 19th century tried to grow the commodity crops that they were used to, like wheat, corn, and alfalfa, but rainfall stifled their growing capacity. Between the late 1800s and the 1930s, farmers used wind-powered pumps to draw groundwater. These windpumps had limited power, but the development of gas-powered pumps in the mid-1930s pushed wells deep into the Ogallala Aquifer. Farmers irrigated fields by laying pipes across the field with sprinklers at intervals, a labor-intensive process, until the advent of the center-pivot sprinkler after WWII, which made irrigation significantly easier. By the 1970s farmers drained the aquifer ten times faster than it could recharge, and by 1993 they had removed half of the accessible water.

Large-scale federal funding and intervention pushed through the majority of irrigation projects in the West, especially in California, Colorado, Arizona, and Nevada. At first, plans to increase irrigated farmland, largely by giving land to farmers and asking them to find water, failed across the board. Congress passed the Desert Land Act in 1877 and the Carey Act in 1894, which only marginally increased irrigation. Only in 1902 Congress passed the National Reclamation Act, which channeled money from the sale of western public lands, in parcels up to 160 acres large, into irrigation projects on public or private land in the arid West. The Congressmen who passed the law, as well as their wealthy supporters, supported Western irrigation because it would increase American exports, ‘reclaim’ the West, and push the Eastern poor out West in search of a better life.

While the National Reclamation Act was the most successful piece of federal irrigation legislation, the implementation of the act did not go as planned. The Reclamation Service chose to push most of the Act's money toward construction rather than settlement, so the Service overwhelmingly prioritized building large dams like the Hoover Dam. Over the 20th century Congress and state governments grew more frustrated with the Reclamation Service and the irrigation schemes. Frederick Newell, head of the Reclamation Service, proving uncompromising and difficult to work with, falling crop prices, resistance to delay debt payments, and refusal to begin new projects until the completion of old ones all contributed. The Reclamation Extension Act of 1914, transferring a significant amount of irrigation decision-making power regarding irrigation projects from the Reclamation Service to Congress, was in many ways a result of an increasing political unpopularity of the Reclamation Service.

In the lower Colorado Basin of Arizona, Colorado, and Nevada, the states derive irrigation water largely from rivers, especially the Colorado River, which irrigates more than 4.5 million acres of land, with a less significant amount coming from groundwater. In the 1952 case Arizona v. California, Arizona sued California for increased access to the Colorado, under the grounds that their groundwater supply could not sustain their almost entirely irrigation-based agricultural economy, which they won. California, which began irrigating in earnest in the 1870s in San Joaquin Valley, had passed the Wright Act of 1887 permitting agricultural communities to construct and operate needed irrigation works. The Colorado also irrigates large fields in California's Imperial Valley, fed by the National Reclamation Act-built All-American Canal.

Soviet Central Asia
When the Bolsheviks conquered Central Asia in 1917, the native Kazakhs, Uzbeks, and Turkmens used minimal irrigation. The Slavic immigrants pushed into the area by the Tsarist government brought their own irrigation methods, including waterwheels, the use of rice paddies to restore salted land, and underground irrigation channels. Russians dismissed these techniques as crude and inefficient. Despite this, in absence of other solutions, tsarist officials maintained these systems through the late 19th century.

Before conquering the area, the Russian government accepted a 1911 American proposal to send hydraulic experts to Central Asia to investigate the potential for large-scale irrigation. A 1918 decree by Lenin then encouraged irrigation development in the region, and development began in the 1930s. When it did, Stalin and other Soviet leaders prioritized large-scale, ambitious hydraulic projects, especially along the Volga River. The Soviet irrigation push stemmed largely from their late 19th century fears of the American cotton monopoly and subsequent desire to achieve cotton self-sufficiency. They had built up their textile manufacturing industry in the 19th century, requiring increased cotton and irrigation, as the region did not receive enough rainfall to support cotton farming.

The Russians built dams on the Don and Kuban Rivers for irrigation, removing freshwater flow from the Sea of Azov and making it much saltier. Depletion and salinization scourged other areas of the Russian irrigation project. In the 1950s Soviet officials began also diverting the Syr Darya and the Amu Darya, which fed the Aral Sea. Before diversion, the rivers delivered 55km3 of water to the Aral Sea per year, but after they only delivered 6km3 to the Sea. Because of its reduced inflow, the Aral Sea covered less than half of its original seabed, which made the regional climate more extreme and created airborne salinization, lowering nearby crop yields.

By 1975, the USSR used eight times as much water as they had in 1913, mostly for irrigation. Russia's expansion of irrigation began to decrease in the late 1980s, and irrigated hectares in Central Asia capped out at 7 million. Mikhail Gorbachev killed a proposed plan to reverse the Ob and Yenisei for irrigation in 1986, and the breakup of the USSR in 1991 ended Russian investment in Central Asian cotton irrigation.

Africa
Different irrigation schemes with a variety of goals and success rates have been implemented across Africa in the 20th century, but have all been influenced by colonial forces. The Tana River Irrigation Scheme in eastern Kenya, completed between 1948 and 1963, opened up new lands for agriculture, and the Kenyan government attempted to resettle the area with detainees from the Mau Mau uprising. Libya's underground water resources were discovered by Italian oil drillers during the Italian colonization of Libya. This water lay dormant until 1969, when Muammar al-Gaddafi and American Armand Hammer built the Great Man-Made River to deliver the Saharan water to the coast. The water largely contributed to irrigation but cost four to ten times more than the crops it produced were worth.

In 1912, the Union of South Africa created an irrigation department and began investing in water storage infrastructure and irrigation. The government used irrigation and dam-building to further social goals like poverty relief, both by creating construction jobs for poor whites and by creating irrigation schemes to increase white farming. One of their first major irrigation projects was the Hartbeespoort Dam, begun in 1916 as a mechanism to elevate the living conditions of the ‘poor whites’ in the region and eventually completed as a ‘whites only’ employment opportunity. The Pretoria irrigation scheme, Kammanassie project, and Buchuberg irrigation scheme on the Orange River all followed in the same vein in the 1920s and 30s.

In Egypt, modern irrigation began with Muhammad Ali Pasha in the mid-1800s, who sought to achieve Egyptian independence from the Ottomans through increased trade with Europe—specifically cotton exportation. His administration proposed replacing the traditional Nile basin irrigation, which took advantage of the annual ebb and flow of the Nile, with irrigation barrages in the lower Nile which better suited cotton production. Egypt devoted 105,000 ha to cotton in 1861, which increased fivefold by 1865. The majority of their exports were shipped to England, and the United-States-Civil-War-induced cotton scarcity in the 1860s cemented Egypt as England's cotton producer. As the Egyptian economy became more dependent on cotton in the 20th century, it became more important to control even small Nile floods. Cotton production was more at risk of destruction than more common crops like barley or wheat. After the British occupation of Egypt in 1882, the British intensified the conversion to perennial irrigation with the construction of the Delta Barrage, the Assiut Barrage, and the first Aswan Dam. Perennial irrigation decreased local control over water and made traditional subsistence farming or the farming of other crops incredibly difficult, eventually contributing to widespread peasant bankruptcy and the 1879-1882 ‘Urabi revolt.

title: Irrigation


text:
Victor Davis Hanson

Victor Davis Hanson (born September 5, 1953) is an American classicist, military historian, and conservative political commentator. He has been a commentator on modern and ancient warfare and contemporary politics for The New York Times, Wall Street Journal, National Review, The Washington Times, and other media outlets.

He is a professor emeritus of Classics at California State University, Fresno, the Martin and Illie Anderson Senior Fellow in classics and military history at the Hoover Institution, and visiting professor at Hillsdale College. Hanson was awarded the National Humanities Medal in 2007 by President George W. Bush and was a presidential appointee in 2007–2008 on the American Battle Monuments Commission.

Early life and education
Hanson grew up in Selma, California, in the San Joaquin Valley, and has worked there most of his life. He is of Swedish and Welsh ancestry, and his father's cousin, for whom he was named, was killed in the Battle of Okinawa.

Hanson received a B.A. in classics and general Cowell College honors from the University of California, Santa Cruz, in 1975 and his PhD in classics from Stanford University in 1980.

Academic career: 1985–2004
In 1985, he was hired at California State University, Fresno, to launch a classical studies program. In 1991, Hanson was awarded the American Philological Association's Excellence in Teaching Award, given annually to the nation's top undergraduate teachers of Greek and Latin. He was named distinguished alumnus of the year for 2006 at University of California, Santa Cruz. He has been a visiting professor of classics at Stanford University in California (1991–1992) and a National Endowment for the Humanities fellow at the Center for Advanced Studies in the Behavioral Sciences, Stanford, California (1992–1993), received an Alexander Onassis traveling fellowship to Greece (1999) and a Nimitz Fellow at University of California, Berkeley (2006), and held the visiting Shifrin Chair of Military History at the U.S. Naval Academy, Annapolis, Maryland (2002–2003).

In 2004, he took early retirement to focus on his political writing and popular history. Hanson has held a series of positions in ideologically-oriented institutions and private foundations He was appointed Fellow in California Studies at the Claremont Institute, a conservative think-tank in California, in 2002. Hanson was appointed Senior Fellow at the Hoover Institution, another conservative think-tank in California. He was often the William Simon visiting professor at the School of Public Policy at Pepperdine University, a private Christian institution in California (2009–15), and was awarded in 2015 an Honorary Doctorate of Laws from the graduate school at Pepperdine. He gave the Wriston Lecture in 2004 for the Manhattan Institute whose mission is to "develop and disseminate new ideas that foster greater economic choice and individual responsibility." He became a board member of the Bradley Foundation in 2015 and served on the HF Guggenheim Foundation board for over a decade.

Writing
Since 2004, Hanson has written a weekly column syndicated by Tribune Content Agency, as well as a weekly column for National Review Online since 2001. He was awarded the National Humanities Medal (2007) by President George W. Bush, as well as the Eric Breindel Prize for opinion journalism (2002), and the Bradley Prize from the Lynde and Harry Bradley Foundation in 2008.

Hanson's Warfare and Agriculture (Giardini 1983), his PhD thesis, argued that Greek warfare could not be understood apart from agrarian life in general and suggested that the modern assumption that agriculture was irrevocably harmed during classical wars was vastly overestimated. The Western Way of War (Alfred Knopf 1989) explored the combatants' experiences of ancient Greek battle and detailed the Hellenic foundations of later Western military practice.

The Other Greeks (The Free Press 1995) argued that the emergence of a unique middling agrarian class explains the ascendance of the Greek city-state and its singular values of consensual government, sanctity of private property, civic militarism, and individualism. In Fields Without Dreams (The Free Press 1996, winner of the Bay Area Book Reviewers Award) and The Land Was Everything (The Free Press 2000, a Los Angeles Times notable book of the year), Hanson lamented the decline of family farming and rural communities and the loss of agrarian voices in American democracy. The Soul of Battle (The Free Press 1999) traced the careers of Epaminondas, the Theban liberator, William Tecumseh Sherman, and George S. Patton in arguing that democratic warfare's strengths are best illustrated in short, intense, and spirited marches to promote consensual rule but bog down otherwise during long occupations or more conventional static battle.

In Mexifornia (Encounter 2003), a personal memoir about growing up in rural California and an account of immigration from Mexico, Hanson predicted that illegal immigration would soon reach crisis proportions unless legal, measured, and diverse immigration was restored, as well as the traditional melting-pot values of integration, assimilation, and intermarriage.

Ripples of Battle (Doubleday 2003) chronicled how the cauldron of battle affects combatants' later literary and artistic work, as its larger influence ripples for generations, affecting art, literature, culture, and government. In A War Like No Other (Random House 2005, a New York Times notable book of the year), a history of the Peloponnesian War, Hanson offered an alternative history, arranged by methods of fighting (triremes, hoplites, cavalry, sieges, etc.) in concluding that the conflict marked a brutal watershed event for the Greek city-states. The Savior Generals (Bloomsbury 2013) followed the careers of five great generals (Themistocles, Belisaurius, Sherman, Ridgway, Petraeus) and argued that rare qualities in leadership emerge during hopeless predicaments that only rare individuals can salvage.

The End of Sparta (Bloomsbury 2011) is a novel about a small community of Thespian farmers who join the great march of Epaminondas (369/370 BC) to the heart of the Peloponnese to destroy Spartan hegemony, free the Messenian helots, and spread democracy in the Peloponnese.

Hanson has edited several collections of essays, including (Hoplites, Routledge 1991), Bonfire of the Humanities (with B. Thornton and J. Heath, ISI 2001), and Makers of Ancient Strategy (Princeton 2010), as well as a number of his own collected articles, such as An Autumn of War [2002 Anchor], Between War and Peace [Anchor 2004], and The Father of Us All [Bloomsbury 2010]. He has written chapters for works such as the Cambridge History of War, and the Cambridge History of Ancient Warfare.

Carnage and Culture
Hanson wrote the 2001 book Carnage and Culture (Doubleday), published in Great Britain and the Commonwealth countries as Why the West Has Won, in which he argued that the military dominance of Western civilization, beginning with the ancient Greeks, results from certain fundamental aspects of Western culture, such as consensual government, a tradition of self-critique, secular rationalism, religious tolerance, individual freedom, free expression, free markets, and individualism. Hanson's emphasis on cultural exception rejects racial explanations for Western military preeminence and disagrees with the environmental or geographical determinist explanations such as those put forth by Jared Diamond in Guns, Germs, and Steel (1997).

The American military officer Robert L. Bateman, in a 2007 article on the Media Matters for America website, criticized Hanson's thesis and argued that Hanson's point about Western armies preferring to seek out a decisive battle of annihilation is rebutted by the Second Punic War in which Roman attempts to annihilate the Carthaginians instead led to the Carthaginians annihilating the Romans at the Battle of Cannae. Bateman argued that Hanson was wrong about Western armies' common preferences in seeking out a battle of annihilation and argued that the Romans defeated the Carthaginians only via the Fabian strategy of keeping their armies in being and not engaging Hannibal in battle. In a response published on his personal website, Hanson argued that Bateman had misunderstood and misrepresented his thesis. Hanson stated that in the Second Punic War, the Romans initially sought out decisive battles but were reluctantly forced to resort to a Fabian strategy after several defeats at the hands of a tactical genius until they had rebuilt their military capacity, when they ultimately defeated Hannibal in decisive battles. He also said that since the Carthaginians themselves had adopted many "Western" methods of warfare from the Greeks, Hannibal, too, was keen to seek decisive battles.

United States education and classical studies
Hanson co-authored the book Who Killed Homer? The Demise of Classical Education and the Recovery of Greek Wisdom with John Heath in 1998. The book explores the issue of how classical education has declined in the US and what might be done to restore it to its former prominence. That is important, according to Hanson and Heath, because knowledge of classical Greece and Rome is necessary for a full understanding of Western culture. To begin a discussion along those lines, the authors state, "The answer to why the world is becoming Westernized goes all the way back to the wisdom of the Greeks—reason enough why we must not abandon the study of our heritage."

The political scientist Francis Fukuyama reviewed Who Killed Homer? favorably in Foreign Affairs and wrote that, "The great thinkers of the Western tradition—from Hobbes, Burke, and Hegel to Weber and Nietzsche (who was trained as a classical philologist)—were so thoroughly steeped in Greek thought that they scarcely needed to refer back to original texts for quotations. This tradition has come under fire from two camps, one postmodernist that seeks to deconstruct the classics on the grounds of gender, race, and class, and the other pragmatic and career-minded that asks what value the classics have in a computer-driven society. The authors' defense of a traditionalist approach to the classics is worthy."

The classicists Victoria Cech and Joy Connolly found Who Killed Homer? to have considerable pitfalls. Reviews of the book have noted several problems with the authors' perception of classical culture. According to Cech, "One example is the relation of the individual to the state and the 'freedom' of belief or of inquiry in each. Socrates and Jesus were put to death by their respective states for articulating inconvenient doctrines. In Sparta, where the population of citizens (male) were carefully socialized in a military system, no one seems to have differed from the majority enough to merit the death penalty. But these differences are not sorted out by the authors, for their mission is to build an ideal structure of classical attitudes by which to reveal our comparative flaws, and their point is more what is wrong with us than what was right with Athens. I contend that Hanson and Heath are actually comparing modern academia not to the ancient seminal cultures but to the myth that arose about them over the last couple of millennia." According to Connolly, Professor of Classics at New York University, "Throughout history, the authors say, women have never enjoyed equal rights and responsibilities. At least in Greece, 'the veiled, mutilated, and secluded were not the norm' (p. 57). Why waste time, then, as feminist scholarship does, 'merely demarcating the exact nature of the sexism of the Greeks and the West' (p. 102)? From their point of view, in fact, the real legacy of feminism is the destruction of the values of family and community."

Political views
Hanson was at one time a registered member of the Democratic Party but is a conservative who voted for George W. Bush in the 2000 and 2004 elections. As of 2020, he is a registered independent. He defended George W. Bush and his policies, especially the Iraq War. He vocally supported Bush's Secretary of Defense Donald Rumsfeld, describing him as "a rare sort of secretary of the caliber of George Marshall" and a "proud and honest-speaking visionary" whose "hard work and insight are bringing us ever closer to victory".

Hanson, a supporter of Donald Trump, wrote a 2019 book called The Case for Trump. Trump praised the book, in which Hanson defends Trump's insults and incendiary language as "uncouth authenticity", and praises Trump for "an uncanny ability to troll and create hysteria among his media and political critics."

Conservative views
He has been described as a conservative by some commentators for his views on the Iraq War and stated, "I came to support neocon approaches first in the wars against the Taliban and Saddam, largely because I saw little alternative." Hanson's 2002 An Autumn of War called for going to war "hard, long, without guilt, apology or respite until our enemies are no more." In the context of the Iraq War, Hanson wrote, "In an era of the greatest affluence and security in the history of civilization, the real question before us remains whether the United States – indeed any Western democracy — still possesses the moral clarity to identify evil as evil, and then the uncontested will to marshal every available resource to fight and eradicate it."

Race relations
In July 2013, Attorney General Eric Holder gave a speech where he mentioned that as a black man, he needed to deliver "the Talk" to his son to instruct him on how to interact with police as a young black man. In response to Holder's speech, Hanson wrote a column, "Facing Facts about Race," in which he offered his own version of "the Talk," the need to inform his children to be careful of young black men when venturing into the inner city, who Hanson argued were statistically more likely to commit violent crimes than young men of other races, and so it was understandable for the police to focus on them. Ta-Nehisi Coates of The Atlantic described Hanson's column as "stupid advice:" "in any other context we would automatically recognize this 'talk' as stupid advice. If I were to tell you that I only employ Asian-Americans to do my taxes because 'Asian-Americans do better on the Math SAT', you would not simply question my sensitivity, but my mental faculties."

The American journalist Arthur Stern called "Facing Facts About Race" an "inflammatory" column based upon crime statistics that Hanson had never cited: "His presentation of this controversial opinion as undeniable fact without exhaustive statistical proof is undeniably racist." The journalist Kelefa Sanneh, in response to "Facing Facts About Race," wrote, "It's strange, then, to read Hanson writing as if the fear of violent crime were mainly a "white or Asian" problem, about which African-Americans might be uninformed, or unconcerned – as if African-American parents weren't already giving their children more detailed and nuanced versions of Hanson's "sermon", sharing his earnest and absurd hope that the right words might keep trouble at bay." Hanson, in response to Sanneh's essay, accused him of a "McCarthyite character assassination" and "infantile, if not racialist, logic."

Obama criticism
Hanson was a critic of President Barack Obama. He criticized the Obama administration for appeasing Iran and Russia, and blamed Obama for the outbreak of the war in Ukraine in 2014. In May 2016, Hanson argued that Obama failed to maintain a credible threat of deterrence and that "the next few months may prove the most dangerous since World War II."

Works

 * Warfare and Agriculture in Classical Greece. University of California Press, 1983. ISBN 0-520-21025-5. Rev. ed. 1998.
 * The Western Way of War: Infantry Battle in Classical Greece. Alfred A. Knopf, 1989. 2nd. ed. 2000. ISBN 0-394-57188-6
 * Hoplites: The Classical Greek Battle Experience, editor, Routledge, 1991. ISBN 0-415-04148-1
 * The Other Greeks: The Family Farm and the Agrarian Roots of Western Civilization, Free Press, 1995. ISBN 0-02-913751-9
 * Fields Without Dreams: Defending the Agrarian Idea, Free Press, 1996. ISBN 0-684-82299-7
 * Who Killed Homer? The Demise of Classical Education and the Recovery of Greek Wisdom, with John Heath, Encounter Books, 1998. ISBN 1-893554-26-0
 * The Soul of Battle: From Ancient Times to the Present Day, How Three Great Liberators Vanquished Tyranny, Free Press, 1999. ISBN 0-684-84502-4
 * The Wars of the Ancient Greeks: And the Invention of Western Military Culture, Cassell, 1999. ISBN 0-304-35222-5
 * The Land Was Everything: Letters from an American Farmer, Free Press, 2000. ISBN 0-684-84501-6
 * Bonfire of the Humanities: Rescuing the Classics in an Impoverished Age, with John Heath and Bruce S. Thornton, ISI Books, 2001. ISBN 1-882926-54-4
 * Carnage and Culture: Landmark Battles in the Rise of Western Power, Doubleday, 2001. ISBN 0-385-50052-1
 * Published in the UK as Why the West Has Won: Carnage and Culture from Salamis to Vietnam, Faber, 2001. ISBN 0-571-20417-1
 * An Autumn of War: What America Learned from September 11 and the War on Terrorism, Anchor Books, 2002. ISBN 1-4000-3113-3 A collection of essays, mostly from National Review, covering events occurring between September 11, 2001, and January 2002
 * Mexifornia: A State of Becoming, Encounter Books, 2003. ISBN 1-893554-73-2
 * Ripples of Battle: How Wars Fought Long Ago Still Determine How We Fight, How We Live, and How We Think, Doubleday, 2003. ISBN 0-385-50400-4
 * Between War and Peace: Lessons from Afghanistan and Iraq, Random House, 2004. ISBN 0-8129-7273-2. A collection of essays, mostly from National Review, covering events occurring between January 2002 and July 2003
 * A War Like No Other: How the Athenians and Spartans Fought the Peloponnesian War, Random House, 2005. ISBN 1-4000-6095-8
 * The Father of Us All: War and History, Ancient and Modern, Bloomsbury Press, 2010. ISBN 978-1-60819-165-9
 * The End of Sparta: A Novel, Bloomsbury Press, 2011. ISBN 978-1-60819-164-2
 * The Savior Generals: How Five Great Commanders Saved Wars That Were Lost – From Ancient Greece to Iraq, Bloomsbury Press, 2013. ISBN 978-1-6081-9163-5
 * The Second World Wars: How the First Global Conflict Was Fought and Won, Basic Books, 2017. ISBN 978-0465066988
 * The Case for Trump, Basic Books, 2019. ISBN 978-1541673540
 * The Dying Citizen: How Progressive Elites, Tribalism, and Globalization Are Destroying the Idea of America, Basic Books, 2021. ISBN 978-1541647534

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Victor Davis Hanson


text:
Talk:Shortest path problem

2007-2002 in approximately random order
Shouldn't there be a section where various practical adaptions and optimizations can be discussed? For instance, finding the shortest path between a pair of vertex by using two dijkstras (forward and backward) simultaneously? rasmusdf 08:30, 14 June 2007 (UTC)

The algorithms doesn't really make clear what the shortest path actually is. Also, do we need f ≥ 0?

The algorithm given is not correct. For instance, if A is connected to B with cost 1 and B connected to C with cost 1 and A connected to C with cost 3, then the algorithm (for n = A and n' = C) will find the "shortest path" A-C with cost 3, even though A-B-C is shorter. AxelBoldt

Right you are :-( Next try JeLuF

Should there be "see also" here for Traveling salesman problem? David 10:48 Aug 9, 2002 (PDT)

The general definition at the top references a set of vertices V, but then chooses nodes n and n' from N. This is inconsistent.

Fixed. (204.50.113.28 22:34, 11 September 2006 (UTC))

Is the Spanish reference really appropriate on the English Wiki? I'm sure there are many decent English references available. 24.7.106.155 07:32, 9 May 2006 (UTC)

single-pair vs. single-source
“It turns out that there are no algorithms for solving the single-pair problem that are asymptotically faster than algorithms that solve the single-source problem.”

Has that been proven, or do they just imply no-one has invented such an algorithm? Roman V. Odaisky 17:39, 24 May 2007 (UTC)
 * The wording seems to vaguely imply a proof ("it turns out" is a phrase rigorous mathematics people often use, and it doesn't use the word "known"), but I'll be damned if I have a source handy. Dcoetzee 07:59, 25 May 2007 (UTC)

TSP wording
I reverted back from this wording "[TSP] is not able to be perfectly solved on large graphs in a reasonable time" to the earlier wording "[TSP] is not known to be efficiently solvable." This version is more correct as it has the uncertainty, and I think the wording is cleaner. Also, I'm not sure we want to get into detail about all the caveats here—approximations and small instances and "reasonable time", plus special cases that are easier, or the average case time, etc.... Leave that all to the articles on the topic. But in the spirit of the revision I reverted, I added another wikilink that will hopefully fill in those details. --Nethgirb 20:21, 9 July 2007 (UTC)

TSP Classification Error
In the article, it is said that TSP is NP-Complete whereas it is "only" NP-Hard which is much worst since it is not even in NP

Cipher1024 (talk) 05:58, 15 May 2008 (UTC)

 * This is not really true. NP-Completeness deals with decision problems (the answer is yes or no), so saying "TSP is NP-Complete" is shorthand for saying "the decision version of TSP is NP-Complete".  This is standard usage and is spelled out explicitly at Travelling salesman problem.  Given that this is not a core issue for this article I think we can stick with the shorthand which is correct and more informative. --Nethgirb (talk) 09:56, 15 May 2008 (UTC)

 * Far from me be the idea of arguing more than is necessary but I'd like learn something if I am to be corrected. So here I would say that the view that TSP is NP-Hard is simpler since it does not refer to the specificities of the NP-Complete class namely that it applies to decision problems.  To put TSP in NP-Complete, one has to introduce the variation of TSP which is a decision problem.  Am I missing something here? Cipher1024 (talk) 03:42, 16 May 2008 (UTC)

 * I could go either way personally. To say "TSP is NP-complete", meaning "the decision version of TSP is NP-complete," implies something additional about the easiness of TSP: that a solution can be verified against a bound in polynomial time. However, seeing as the point here is that "TSP is harder to solve than SPP", the lower-bound "NP-hard" statement seems just as informative and concise. On the other hand, saying that both TSP and LPP are NP-complete allows a more direct comparison of those two problems (after all, the halting problem is NP-hard too, but it's rather more difficult than TSP). Dcoetzee 07:38, 16 May 2008 (UTC)

 * I suppose that for NP-hardness you don't need to know about the decision version of TSP so you could say that the NP-complete statement is more complicated. But let's put this in perspective: when you consider all you need to know to understand NP-hard or NP-complete, the decision-version bit of it is only about 3% of it.  I.e., it's only so very slightly more complicated.  Moreover, essentially everyone who has an idea what NP-hard means will also have an idea what NP-complete means; these are core concepts in computer science and they are essentially always introduced together.
 * So to me the added value of the greater information content vastly outweighs the very slight additional definition that you need to know. Anyway if the reader doesn't know, they can look it up...on wikipedia.... :-)

 * Along the lines of what Dcoetzee said, let me point out that the NP-completeness statement is worth it. Cipher1024 wrote above that it is "only" NP-Hard which is much worst since it is not even in NP. This is exactly the incorrect impression that readers might get if we said only that it was NP-Hard.  The "show me the path" version is, in fact, not much worse than the decision version, because you can easily recover the full path by making a few judicious subroutine calls to the decision version. --Nethgirb (talk) 08:41, 16 May 2008 (UTC)

"The problem of finding the longest path in a graph is also NP-complete." can we have a citation for this? —Preceding unsigned comment added by 219.88.197.233 (talk) 11:07, 13 June 2008 (UTC)

Caption on the pic
"A graph with 6 vertices and 7 edges" But the graph actually has 14 edges since the distance between two vertices need not be commutative. Is this nit worth picking? Dmforcier (talk) 18:22, 8 August 2010 (UTC)

 * I don't understand your objection. The graph pictured has 7 edges.  Counting the number of edges in a graph doesn't really have anything to do with distance.  Are you talking about directed graphs?  Meaning that a single undirected edge is really two directed edges?  All of the graph theory books and papers I've ever read would count the number of edges in that graph as 7.  —Preceding unsigned comment added by 131.136.242.1 (talk) 18:42, 26 August 2010 (UTC)

sloppy addition
the following recent addition removed from the article.
 * Actually, there isn't an algorithm to directly solve the single-pair shortest path problem on general graph. Finding single-pair shortest path would be done by solving single-source shortest path problem. However, there are algorithms to solve single-pair shortest path on special graphs, such as tree, linear graph and cycle graph.

It has several issues. As you maight have noticed, these staements reqire citaitions. Please provide them and re-add accoringly into the article. - Altenmann >t 05:01, 18 November 2012 (UTC)
 * The corrected first statement would be something like this: "All known algorithms for single-pair shortest path in general graphs are in fact algorithms for single-source shortest path problem, which can be stopped once the destination vertex is reached."
 * The correct second statement might be: However there are dedicated single-pair algorithms for some special graph classes, such as such as trees, linear graphs and cycle graphs.
 * The first statement is not true. See e.g. bidirectional search. Perhaps what is meant is that there is no known single-pair shortest path algorithm whose worst case running time is better than that of the known single-source shortest path algorithms. —David Eppstein (talk) 07:27, 18 November 2012 (UTC)
 * Well, it is not exactly not true. While I admit I forgot to mention the runtime issue, the bidirrectional search is nothing but a heuristic in which two searches stop a bit earlier. Here again, which bidir search will be worst-case better than the Dijkstra-based one? - Altenmann >t 05:18, 19 November 2012 (UTC)

By the way, what's screwed up with the references in the table? And what's the mess with "Roadnetworks"? - Altenmann >t 05:18, 19 November 2012 (UTC)

 * The references in the Shortest path problem table are not in the article; clicking on them seeks an anchor that is not on the page. I added Bellman with ref=harv, so clicking Bellman 1958 now works. Is that your concern? Glrx (talk) 16:25, 20 November 2012 (UTC)

Edit Made to "Perturbation Theory" Section Under Algorithms
Under the "Algorithms" section, perturbation theory is listed and it links to the Wiki article on perturbation theory. However, the wiki page on perturbation theory has absolutely no mention of perturbation theory on graphs for shortest path algorithms, and is devoted to the standard applications of perturbation theory only. Therefore, I am adding a "citation needed", even though the article links to the Wiki page, and I am also questioning whether the link to the Wiki page is even appropriate (but leaving it for now) until someone adds to that article "perturbation theory on graphs" or some other section that is relevant to the shortest path problem. 99.116.177.3 (talk) 08:29, 7 January 2013 (UTC)jp

Gif animation
I've made an animation to show the difference between algorithms: Bellman–Ford and Dijkstra. Do you have any comments for animation? Do you have any objections not to include animation to article? Artyom Kalinin (talk) 06:32, 10 December 2013 (UTC)
 * I find it hard to understand. Basically I think you have to already know the algorithms pretty well just to be able to figure out which of the two is which. In addition: What does a vertex being blue represent, in Bellman-Ford, since that algorithm does not have a concept of a vertex being finished? Why are you illustrating two algorithms neither of which is the best choice for the type of graph you use as an example? (It's a directed acyclic graph, for which a linear time algorithm is possible.) Why does your animation of Bellman-Ford only make one pass through the graph, and why do you think an input for which it gets the correct answer after only one pass is illustrative of how the algorithm works? —David Eppstein (talk) 07:00, 10 December 2013 (UTC)
 * Thanks for the answer. I studied this topic again and agree with you, that this animation is not suitable for Bellman-Ford algorithm.Artyom Kalinin (talk) 16:58, 16 December 2013 (UTC)

algebraic path problem
I should note here that Jungnickel's 4th ed. (2013) also covers the algebraic path problem (p. 97-102) although he uses rather quaint terminology from an algebraic perspective and still adds some restrictions that aren't really needed since Mohri's paper. So I'm not sure I want to cite/recommend Jungnickel's book as source for this particular topic. JMP EAX (talk) 22:31, 18 August 2014 (UTC)

The most recent paper that Jungnickel cites on that topic dates to 1986, which probably explains the issue. JMP EAX (talk) 22:38, 18 August 2014 (UTC)

Not my area, however is this useful or relevant
Faster all-pairs shortest paths via circuit complexity  Probably not but perhaps of interest to someone 92.25.12.77 (talk) 19:01, 16 November 2015 (UTC)
 * It's a theoretical rather than practical advance, but probably worth mentioning in the article (in the tables of results for all pairs, both undirected and directed). —David Eppstein (talk) 19:23, 16 November 2015 (UTC)

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Diagram Scale
The Shortest Path node diagram provided seems to have a scale issue that is misleading in it's purpose when first looking at the objective of the article. The node distances for paths "10" and "11" are clearly not to scale to those marked "3" and "4". This throws off the reader in general, since the first initial observer's solution looking at the shortest distance path, is A-B-D-F, just based on relative scale alone. I think this detracts from the overall objective of the diagram - to demonstrate the optimal shortest path. SquashEngineer (talk) 13:20, 18 April 2019 (UTC)

Display of square roots
The square roots have the wrong format in sections like https://en.wikipedia.org/wiki/Shortest_path_problem#Directed_graphs_with_arbitrary_weights_with_negative_cycles

I think \sqrt should be used instead. Otherwise, the square roots will look off in other themes. Comeza (talk) 12:24, 1 June 2022 (UTC)

Linear programming formulation (Shortest path problem)
@David Eppstein removed the section on the Linear programming formulation citing "unsourced and the wrong way to formulate this as an LP" and "No, it doesn't. Shortest path is just a standard LP. Find distances from start to all vertices minimizing sum of distances such that for each edge x→y, dist(y) ≤ dist(x) + length(x→y). No integer requirements anywhere". However, both these comments seem false to me. The most natural way to convert this problem into an LP is by first formulating it as an ILP (See section 10.2 of Optimization by K. Aardal et al.). This ILP can then be relaxed into an LP which will have the same optimal solution (see sections 10.2.1 and 10.2.2 of Optimization by K. Aardal et al..). The formulation of this LP as I read it at https://en.wikipedia.org/w/index.php?title=Shortest_path_problem&oldid=1126582726 is correct. The following formulations are equivalent to those on https://en.wikipedia.org/w/index.php?title=Shortest_path_problem&oldid=1126582726.

ILP Formulation:

Let (D, s, t, c) be an instance of Shortest Path, with A(D) the arc-set of D and n = |A(D)|. Let A be the node-arc incidence matrix of D where the first row corresponds to s and the last row corresponds to t. Then the corresponding ILP is the following:

$$ \begin{align} \min \sum_{(u, v) \in A(D)} c_{u v} f_{u v} \\ \text { s.t. } \quad A \boldsymbol{f} = \begin{bmatrix} 1 \\ 0 \\ \vdots \\ 0 \\ -1 \\ \end{bmatrix} \\ \boldsymbol{f} \in\{0,1\}^n \\ \end{align} $$

The decision variables are the fuv = f(u,v), which take value 1 if the arc (u, v) is in the shortest path, and 0 otherwise. All these decision variable together form a vector f.

LP formulation:

Let (D, s, t, c) be an instance of Shortest Path. Then the LP relaxation where fuv ∈ {0, 1} is replaced with fuv ≥ 0 has an optimal solution with fuv ∈ {0, 1}. For the proof see

Primal:

$$ \begin{align} \min \sum_{(u, v) \in A(D)} c_{u v} f_{u v} \\ \text { s.t. } \quad A \boldsymbol{f} = \begin{bmatrix} 1 \\ 0 \\ \vdots \\ 0 \\ -1 \\ \end{bmatrix} \\ \boldsymbol{f} \geq \mathbf{0} \\ \end{align} $$

Dual:

$$ \begin{align} \max \pi_s-\pi_t \\ \text { s.t. } \pi^{\top} A \leq \boldsymbol{c} \\ \pi \in \mathbb{R}^m \\ \end{align} $$

The decision variables in the dual are the $$\pi_u$$ for all u ∈ V. The restrictions in the dual make sure that each $$\pi_u - \pi_s$$ is at most the length of the shortest path from s to u. This means that any feasible dual solution essentially consists of an upper bound for the shortest path from s to u for each u ∈ V.

Not familiar with Wikipedia conventions so just putting this out there. BoostBack (talk) 14:43, 2 January 2023 (UTC)
 * The most natural way of formulating shortest paths as an LP is to make a variable for each pairwise distance between distinct vertices, require d(u,v) ≤ length(uv) when uv is an edge and d(u,v) ≤ d(u,x)+length(xv) otherwise, and ask to maximize the sum of the distances. No integer restriction needed. Works for all pairs or single source. —David Eppstein (talk) 17:06, 2 January 2023 (UTC)
 * I see, that seems very similar to this equivalent formulation of the dual to the LP? Where $$ \pi $$ can be interpreted as labels for the distances and $$ l_{uv} $$ the arc lengths.
 * $$ \begin{align} \max \pi_s-\pi_t \\ \text { s.t. } \pi_u - \pi_v \leq l_{uv} \\\pi \in \mathbb{R}^m \\ \end{align} $$
 * Then there, "d(u,v) ≤ length(uv) when uv is an edge" and "d(u,v) ≤ d(u,x)+length(xv) otherwise" follows from complementary slackness with the primal minimization problem like this:
 * $$ \pi_u \leq l_{uv} + \pi_v\text { for each (u,v) } \in A \text{ (using the dual constraints)} $$
 * $$ \pi_u = l_{uv} + \pi_v \text { for each (u,v) } \in A \text{ on the path (CS)} $$
 * So I think this is just comes down to duality? In my opinion, presenting the minimization as the primal seems as a more natural or intuitive start because the problem formulation is in terms of minimization. And in that case, the most intuitive start is using the integer restriction which can later be relaxed.
 * Thank you for your response, I could definitely be very wrong about all of this. BoostBack (talk) 18:08, 2 January 2023 (UTC)
 * Your last sentence suggests that you are trying to work from first principles rather than published sources. That is the wrong way to go about generating content for Wikipedia. —David Eppstein (talk) 19:02, 2 January 2023 (UTC)
 * I see, I shall refrain from editing but want to mention the importance of the entry of the LP formulation. It is referred to on multiple other webpages which now refer to the deleted section:
 * comparison of simplex and shortest path method, https://news.ycombinator.com/item?id=11845095.
 * This missing link is what caused me to investigate why it was gone in the first place. There are many other sources discussing this LP formulation of the shortest path problem, next to those from which I took the dual formulation (Optimization by K. Aardal et al.). However, I don't know how to properly edit the section so leaving this here for reference for further work. BoostBack (talk) 20:30, 2 January 2023 (UTC)

title: Talk:Shortest path problem


text:
Talk:Sudovian language

Sudovian is ALIVE
it is very odd to read in here that everybody emphatically declares Sudovian dead. Sounds like the voice from Moscow and Minsk! Sudovian is very alive and spoken as the first language by a lot of folks. However, the Russian/Belorussian speakers and government have tried hard to destroy it by preventing its teaching, its speaking and by declaring it (pre maturely) as dead! In fact, the New York Times in 1992 carried an article on this odd issue. In it, it correctly observed that any child that speaks Sudovian at school will be punished. Some have been declared "mentally impaired" if they persist. Poor kids, they are just speaking what they learn from their mothers until such time they can also speak Russian (oh, yeah, "Belo"Russian). Sudovian language is very common at home in the western one-third of Belarus--the areas that were part of Poland until 1939. Please stop helping Moscow and Minsk in killing off Sudovian by parroting their ridiculous claim that Sudovian is dead. Not only it is alive, but the speakers being largely Protestants, resist death in the hands of Russian/Belo Russians and the Orthodoxy/Catholicism.. — Preceding unsigned comment added by 66.108.184.225 (talk) 22:48, 3 January 2014 (UTC)

 * What was the article called 145.103.60.130 (talk) 11:04, 12 September 2022 (UTC)

Ptolemy's Σουδινοί - Σουδιυοί
It is possible that Ptolemy's Σουδινοί is perhaps a manuscript copy error for Σουδιυοί (Soudivoi). Since his manuscripts survive only thru copies, the possibility of a error must be considered. If Greek "υ" was mistaken for "ν", Σουδιυοί would resemble current Sūduviai. --Sudowite (talk) 15:24, 09 January 2010 (UTC)

Old talk
User:David Parker, you added a Sudovian language, which I did not. I do not know of a seperate Sudauer or Sudovian language, even though Jatwingian is recorded seperately.The Jatwiger-Sudauer inhabitants are recorded in southern Prussia, which reached further than it did in later years. Between circa 1700 and 1900 several Prussian Vocabularies (Woerterbuecher) were written, but I do not believe a seperate Sudovian language article should exist. Wikipedia has separate language articles for High German, Old High German, Low German, Austrian German, Czech, Slovak, etc. The Soudinoi were documented in the 2nd Century up to the 1500's, and their language remains to this day in hydronyms ( Narew, Kirsna rivers), toponyms (Suduva), and in dialects of Polish, Belarus, and Lithuanian. Fortunately, many have escaped the chauvinistic ethnocide that befell the Old Prussian toponyms in the Russian Kaliningrad Oblast, and in Poland. A separate article is at the least historically substantiated.

Wikipedia has a separate language article for the Wichita language. It states there is only one speaker.

Wikipedia has a separate language artcle for the Yuchi language. It states there are 5 speakers.

There are other examples from Wikipedia, but I will respect the expressed concern about conserving bandwidth, which I gather is the crux of the discussion.

Whoever you claim to be (and if you want to engage in discussion or have your "articles" taken seriously you can start by giving a NAME), there is no such word in the English langiage as Sudauer, and this is an-English-language encyclopedia.

Sudauer is perfectly legitimate in German Wikipedia, but has no legitimate existence here as a title. The English word for the German Sudauer is Sodovian or Sudovians.

Jatvingian (no w in English) is considered another name for or a part of a single language or dialect with the more common name Sudovian. It's stupid to put two equivalent names in the title. It's one or the other, with links from the less-used Jatvingian and Yotvongian.

You so far have Sudovian as a dialect of Old Prussian, and as a language in its own right (which means Old Prussian has to be a language group, not a language. Which is it to be? You created a separate article, not me. Think for once before filling Wikipedia with this drivel. User:David Parker

 * Whoever our mystery author is, he/she assumes, David, that you are more familiar with the common English word "Vocabularies" rather than the definitive German word "Woerterbuecher". MichaelTinkler

Hiya folks. Now now. I vote for the merger, as the use of Sudovian alone would mean primarily the Sudovian language in English. To mean something else Sudovian, you would have to have been talking about it previously.

Actually, whether a language is a dialect or a distinct language is a serious qustion in linguistics. It depends on what you mean by dialect. Maybe that should be defined and referenced. The term is somewhat amorphous. The question comes up when languages are close. I've looked at both Prussian Reconstructions and the Verdainas site. Sudovian and Old Prussian are pretty close, but they are not the same. But you know, I'd like to know where the Verdainas gets its Sudovian!

Anyway, I believe the linguists classify the three as West Baltic, a group of languages, as opposed to East Baltic, another such group. I don't know much about Galindian, and there can't be much to know. People use these terms sometimes for hypothetical languages when everyone thinks the language is known. I'd like to know who knows it.

If part of Lithuania is Sudovia, that is because the ancient Sudovians there assimilated to the Lithuanians. It is a common phenomenon. The Alans, for example, were once an Iranian-speaking people. They were pushed into the Caucasus by the Huns. Today about half the Alans speak Caucasian and have their own state, but they descend from the ancestors of the Iranian Alans.

Sudovia fought for the Prussians, and so the Deutchen Orden came after them too, pillaging, burning, killing and expelling. Nobody thinks they behaved too well. As for the double name, the Sudovians got that in deep antiquity. I think they got it from the Goths, who once ruled Prussia. When the ancient sources speak of Gothic or Vandalic territory in the north (same people), they mean Gothic-dominated Baltic territory. It is generally thought that Danzig (Gdansk) was founded by Goths, just as Elbing was founded by Vikings. Either Sudovii or Iotvingi was assigned by the Goths. I'd like to write about it here but I need to research it first. Why don't you do the same?

As for the foreign words, gee, it is hard to avoid them when you are writing about foreign countries. There ought to be a standard but it has to be flexible.

There are plenty of definitive English words, such as "dictionary." Sometimes you like to speak more abstractly.

Sudovians vs. Yotvingans
Please see Talk:Sudovians. mikka (t) 17:06, 24 September 2005 (UTC)

Pogańskie gwary z Narewu
I've removed links to some alleged "reconstructed" Jatvingian dictionary hosted on some public web service from ==External links==. Lithuanian Wikipedia apparently has an article on Narevo pagonių šnektų žodynėlis, quoting some Zinkevičius' works, and this appears to be the only source on the Internet on the preserved Jatvingian dictionary, so if any Lithuanian-speaker could import some of the information from there it would be highly appreciated :D --Ivan Štambuk (talk) 07:34, 29 January 2009 (UTC)
 * Actually there is much more now and I added some text. More to follow. 04:06, 14 December 2016 (UTC)

Балто-славянские исследования. 1985. М., 1987:
 * В.Э. Орел, Е.А. Хелимский. Наблюдения над балтийским языком польско-«ятвяжского» словарика, стр. 121-134.
 * К. Карулис. К ятвяжскому словарику, стр. 134-140.
 * Т.М. Судник. Замечания к польско-ятвяжскому словарику, стр. 140-142.

It looks like there is enough sources for a separate article. Staszek Lem (talk) 04:06, 14 December 2016 (UTC)

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Sudovian Incubator
The Sudovian Incubator test wiki project had been deleted so the link had been removed. --47.156.8.3 (talk) —Preceding undated comment added 21:14, 6 April 2018 (UTC)

title: Talk:Sudovian language