In primitive agriculture, the fate of plant crops depends too much on a random combination of favorable factors, in particular, the timing of rain and a not too dry summer. People quickly grasped the cause-and-effect relationship between lack of water and poor harvests. Most likely, this happened at the gathering stage, before attempts to grow edible plants on their own.
Before full-fledged irrigation systems appeared, people made attempts to deliver water for irrigation by the most in a simple way: Pour into a container and bring it in your hands. Even this method makes it possible to slightly increase crop yields, although its effectiveness is questionable.
So, what is irrigation and how does it differ from banal watering by hand from a bucket or watering can? It was not in vain that humanity decided this problem, after all, precisely due to artificial irrigation the opportunity arose to significantly increase the volume of agricultural products grown.
First irrigation systems
Primitive hand irrigation is still used in the poorest regions of the planet. In most cases, women go to the water source and bear a huge burden. This should be enough for drinking, cooking, household needs and watering plants. It is not surprising that in such conditions there is no question of growing crops in industrial scale. The profitability of such irrigation tends to zero.
What is irrigation in the absence of developed technologies? First of all, these are artificial canals, ditches, which divert part of the water from natural sources to the field. In essence, the same manual watering system is maintained, just without constant human intervention.
Development of land irrigation techniques
Horse-drawn transport and pack animals only partly solve the problem of water delivery. Yes, a horse can bring a large barrel, but this also requires some effort. At one time, the crown of engineering was aqueducts, which supplied water to the place of need from natural sources located on a hill. The appearance of these engineering structures raised irrigation systems to a fundamentally new level.
In fact, this is a prototype of a modern water supply system, only instead of pumps, natural gravity is used - water flows independently from a source located above. At the same time, an artificial river is protected from external pollution better than an open canal.
Simple mechanization
With the advent of all kinds mechanical devices irrigation systems received a new impetus for development. For example, windmills can not only turn millstones to grind grain into flour: wind energy can also be successfully used to raise water to a certain height, so that from there it can flow freely through irrigation canals. The rotation of the mechanism can be entrusted to the wind or human hands (for example, a well gate). Now, by the way, electric pumps of various capacities are increasingly used for this purpose.
Natural water sources
The leader still remains natural sources of fresh water, which, to the best of their ability, fit into irrigation systems. Symbiosis is often used in principle different approaches. For example, partial selection is still actively used fresh water from rivers to be delivered to the fields through a canal system. There, along a narrow canal, they set up irrigation equipment with sprayers - the machine, using powerful pumps, simulates rainfall, moving across the field, evenly moistening the cultivated land. The disadvantage of this method is the large loss of water due to evaporation, but this problem has only recently begun to be solved.
Accumulation and transformation of water resources
The supply of clean fresh water on the planet is not endless. Ecologists have been saying for years that further irresponsible attitude towards resources will lead humanity to disaster. Part of the problem is solved by irrigation systems with reservoirs, where excess water from heavy rains is discharged - this can significantly reduce the risk of rivers overflowing their banks, while replenishing reserves intended for irrigation.
In the absence of precipitation, people turn to underground sources. For a long time artesian wells were considered ideal option water supply But it is worth considering that not only irrigation systems need fresh water. Consume huge amounts of resources industrial enterprises, and large cities only make the situation worse. Consumers are not accustomed to saving water, so enthusiasts are looking for new irrigation methods, for example, desalination sea water, develop agricultural practices that help reduce evaporation and reduce pollution groundwater.
Farming optimization
Traditional cultivation of agricultural crops is gradually losing ground, so the construction of irrigation systems will sooner or later take a different path. For example, good results shows hydroponics as a smart and high-tech alternative to conventional gardening. In this way you can get a record high yields comparatively small area, and much less water is required.
Primitive watering of plants involves huge losses of moisture due to evaporation. Open canals and reservoirs lose millions of tons of fresh water - it literally evaporates into the atmosphere. At the same time, the root drip irrigation plants can significantly reduce water losses, and this must be used, because even the cost of delivering fresh water is steadily increasing.
On the Chengdu Plain in Sichuan Province, the unique and oldest surviving irrigation system, Dujiangyan, built more than 2,200 years ago, still operates. This project outlived all the other great ancient irrigation systems and was the largest irrigation and drainage project of its era.
Dujiangyan is 55 km away. from Chengdu. This is the oldest irrigation system in the world, which is still in use today. In ancient times, every summer the Minjiang River (a tributary of the Yangtze River) drowned the lands of the Sichuan Basin. And in winter it was covered with ice. Therefore, the governor of Sichuan, Li Bin, decided to correct the existing situation and began construction of an irrigation system in 256 BC. The river was divided down the middle by a long embankment. Inner part began to be used for irrigation. Downstream, on one side of the inland river, there is a narrow strait between two hills. It was called the Precious Cork channel.
Li Bin, in turn, was deified by local residents, who raised funds on their own and built the “Temple of Father and Son” in honor of the official’s merits. The temple stands on a steep bank of the river, and the main entrance is reached by a high staircase passing through several colorful gates. Climbing the stairs you can admire the best architectural fragments of the ensemble. On the territory of the complex there is a small stage where performances are held.
Upon completion of construction, the floods stopped, and the fields of Sichuan Province began to bear abundant harvests. This enabled the rulers of the Qin kingdom to maintain a large army. Later, King Qin Shihuang took advantage of this and became the emperor of all China. It was under him that such wonderful monuments of China as the Terracotta Army in Xi'an and the Great Wall of China were created. Through this canal, water from the river enters the irrigation network. Just above the canal, two canals run windingly, connecting to the outer part of the river. This ensures that there is enough water in the interior even during the dry season. During a flood, excess water returns to the river flow. Minjiang. The flow of water in the canal is balanced by a dam.
The system consists of three parts. The first part is a dam called Yuzui (Fish Mouth). It was built right in the middle of the river. The second part of the system is a canal passing through the mountain. To destroy the rock, the ancient builders heated it and then poured water on it. The narrow neck of the channel made it possible to regulate the amount of water in the system. It took 8 years to build a 20 meter wide canal. The third part is the spillway structure.
The Dujiangyan Irrigation System in Sichuan Province demonstrates the highest level of development of science and technology in Ancient China. It became a milestone in the world history of irrigation. The Dujiangyan system was built without a dam. It still supplies water to numerous canals covering an area of 670,000 hectares in Sichuan province. Thanks to the construction of an irrigation system, even in ancient times these lands became a real granary of China.
Listed World Heritage UNESCO as the largest engineering project in Eurasia at that time, among those known today.
Chapter Eight ALONG THE BEDS OF ANCIENT CHANNELS
Under the wing of the plane, sand stretches endlessly, right to the horizon. From here, from above, the dunes seem like small ripples on the surface of a giant sand sea. Ahead you can see the sharp bends of a small ancient channel. Its shores are either completely lost in the sand, or again clearly appear on a bare, covered island. Not far from the riverbed are the ruins of an ancient fortress. Square towers at the corners and in the middle of the walls, two towers in front of the entrance: the large fortress had powerful defenses.
But what is that down there?
A thin dark thread stretches next to the riverbed. Short webs extend from it towards the desert. And not far from the fortress there is a large rectangle: something similar to huge beds. All this is blocked by moving sands, and only by individual pieces, making up something like a dotted outline, can the entire image be traced. From the ground, you probably won’t even notice half of it.
As usual, there is nothing mysterious about this, all this is the work of human hands. From the plane you can see the remains of a main canal with branches and traces of fields.
We have already said that the history of the population of Khorezm is the history of the struggle for water. If there is no water, then the sun is man's worst enemy. The earth dries up and becomes covered with deep cracks. The wind brings sand. The desert tenaciously grabs onto every piece of burnt land, crowding people. The poor desert vegetation attracts only wandering flocks of sheep.
But then water appears, and the sun turns from an enemy into a faithful ally. Fertilized with precious Amu Darya silt, the land here is unusually fertile. Several years pass, and this generous land blossoms. The fields are turning green, fruit trees are blooming, and slender poplars line the roads and canals in rows.
But the water doesn’t come on its own, and digging main canals requires enormous work. But that is not all. The Amu Darya water flows through canals and ditches, and part of the huge amount of silt and sand that it carries is gradually deposited at their bottom. If you don’t take care of them, clean them and deepen them periodically, they will fill with sediments just like the ancient Amu Darya deltas.
The history of ancient Khorezmian irrigation has long been and now still remains one of the main scientific topics of the team of Khorezmian archaeologists.
A special archaeological and topographical detachment has been working as part of the Khorezm expedition for more than ten years. It is led by expedition member B.V. Andrianov. Perhaps this is one of the most mobile, most restless groups. He almost never stays long in one place and almost never excavates. But he discovered many dozens of new archaeological sites in various regions of Khorezm.
An archaeologist nowadays cannot do without a map. We are not talking about an ordinary small-scale map, but about a special, archaeological one. Drawing up an archaeological map is a very complex and labor-intensive task: such maps currently exist only for certain regions of the Soviet Union. The map sums up the results of many years of archaeological work - exploration and excavations. Only then can it be sufficiently complete for this stage of research. At the same time, it is the basis for further research of the territory.
Archaeological maps come in several types and serve different purposes. The main one is an overview map, which shows all the archaeological sites of all times.
Continuous archaeological research of the territory (ancient Khorezm and adjacent areas and, ultimately, drawing up a complete archaeological map is one of the main tasks of the Khorezm archaeological and ethnographic expedition. The archaeological and topographical detachment plays a significant role in this. Often it acts independently, sometimes together with others reconnaissance archaeologists under the leadership of S.P. Tolstov.
Punctually, kilometer by kilometer, with short marches, the detachment combs the desert. Neither massifs of sand and impassability, nor bad weather will delay him. Where a car cannot go, the archaeologist goes on foot. Dozens of adventures, dangerous and funny episodes, interesting discoveries are recorded in the diaries of the detachment.
IN last years The main goal of the detachment was to study the monuments of ancient irrigation. The main result of these studies will be the most detailed maps of ancient irrigation for each period of Khorezm history, now being prepared for publication under the leadership of S.P. Tolstov and B.V. Andrianov.
The vast expanses of land cultivated in ancient times and the degree of preservation of ancient water-irrigation structures made it almost impossible to use traditional methods of archaeological exploration in their study.
In the Khorezm expedition, a new technique was developed and successfully applied. Its main principle is the combination of extensive aerial reconnaissance and aerial photography with detailed ground research.
Just a few days ago, a flight of these small machines - blunt-nosed AN-2 biplanes - was working on pollination in one of the Karakalpak collective farms. Today, a group of people are installing something above a hatch cut into the bottom of the plane. A few hours later the plane takes off from the Nukus airfield and heads east. The strip of cultivated land is quickly ending. Desert under your wing.
The small plane does not need a special landing pad, and it lands on the takyr next to the archaeologists’ tent city. Above the lower hatch there is a large aerial photography camera, into which an expedition member, engineer-geodesist N.I. Igonin, places a roll of wide photographic film. Early in the morning the plane takes off. On low altitude, according to pre-planned landmarks, the plane will “iron” a large piece of desert. In the evening work will begin again.
Takyr near the shawl town of archaeologists is an excellent landing site
Aerial photography is a very responsible business. But no more painstaking work than working with aerial photographs. Once the film is developed, thousands of pictures are printed from it. N.I. Igonin sits for weeks over a large drawing board, comparing prints, “adjusting” them one to another - along the lines of canals, massifs of sand ridges. The result is large tablets - photographic diagrams. Of course, it is impossible to stitch together all the footage; individual, most interesting areas are selected, the importance of which for further work is either known in advance or becomes clear in the process of viewing the prints. A non-specialist will find little of interest in hundreds of seemingly similar photographs. They can tell a specialist a lot. The process of studying images obtained by aerial photography is called interpretation.
In order for the photographic sketches to be more expressive, so that in the photographs all objects of interest to archaeologists appear with maximum clarity, the most favorable time for filming is selected. Thus, when interpreting aerial photographs, it was found that monuments that are not expressed or very weakly expressed in the relief with heavily destroyed ground structures are best photographed in spring or autumn. At this time, the walls of settlements and fortresses, canal lines, and mounds, destroyed to the ground, unmask themselves either with vegetation (after short rains, the desert vegetation turns lushly green) or with color.
On the other hand, it has been established that the best time for filming during the day is, firstly, the morning, from 7 to 10, and, secondly, the evening, from 5 to 8 o'clock. During these hours, the sun's rays fall on the ground at a slight angle, and with oblique lighting, the layout of ancient monuments, even if their structures rise above the surface by only a few centimeters, is clearly visible.
An archaeologist can walk through a burial ground with several dozen burial mounds or through a primitive settlement with the remains of half-dugout houses, not noticing anything except scattered shards of pottery. The assistance of aerial reconnaissance and aerial photography is especially important in such cases.
It goes without saying what a huge help aerial photography is in the study of ancient irrigation. After all, its monuments are almost completely invisible from the ground. Even the once huge coastal ramparts of powerful main canals are often almost completely invisible in the relief. And their channels are visible on the takyr as an intermittent stripe, differing only in the color of the surface. There is no need to talk about ancient fields: traces of them on the ground can only be detected by an experienced, trained eye.
A photographic map is a kind of geographical map, so detailed that every sand ridge, every takyr island is visible on it. It helps the scouts move in the sea of sands without losing the thin thread of the ancient canal and its branches. One after another, icons with a serial number appear on the diagram - “dots”: here archaeologists stopped, examined and recorded in diaries, on drawings and film the remains of the canal, collected ceramics and other finds. If you decipher them, and the key to deciphering is in diaries, drawings and photographic film, then the history of an ancient complex of irrigation structures emerges. Together with other archaeological monuments of the work area, these materials will tell when the canals were dug here and the fields were built, how long they existed, what was the nature of agriculture and what was the level of irrigation technology.
These ancient canals and traces of fields are not easy to spot from the ground
These materials, summarized for the entire territory of Khorezm, for the entire Aral region, acquired particular expressiveness and strength. They told the story of the gradual improvement of the techniques and methods of irrigation, irrigated agriculture, a story filled with dramatic episodes of the struggle for water and with the elements of water. Periods of successful struggle of people with the forces of nature were followed by long years of devastation and desolation and new searches and discoveries of Khorezm irrigators, who gropingly knew the laws of nature, learned to control the elements, to put them at the service of man.
We have already talked in different places in the book about the most ancient artificially irrigated areas, and about the grandiose irrigation of ancient and medieval times.
Agriculture, which arose during the Bronze Age in the most ancient parts of the Akcha-Daryinsjoy delta, was initially based on the use of moist low-lying areas. Then people learned to regulate and retain excess flood waters in the dying channels of the delta. Later, in the Bronze Age, the simplest irrigation structures of several types appeared. Farmers of this time not only used dammed and artificially buried dying channels, but also learned to build small ditches, for which the dammed channels played the role of main canals.
The canals and irrigated fields of the Amirabad period are described in some detail in the first chapter. A large main canal with branches in the lower part and an irrigation system with an area of 200 hectares are already harbingers of the powerful irrigation systems of ancient Khorezm.
The ancient ancient canals, built by the hands of slaves, amaze with their enormous size. Their width (between the bank shafts) in the archaic period reaches 40 m. The canals stretch along the ancient riverbed, therefore they have branches only on one side. It is curious that most of the branches extend from the canal at right angles.
The enormous size, and in particular the very large width of the main canals, testified not only to the strength of the slave state, but also to the still low level of scientific knowledge and practice in the construction of irrigation structures. Canals of the archaic type - very wide and shallow - are not very economical, since a significant amount of water does not reach the fields, but either evaporates or goes (filtered) into the soil. Therefore, in the future there is a gradual transition to narrower and deeper channels.
Already the Kangyu and Kushan channels have a width from 6 - 8 to 18 - 20 m, and the huge shafts - about 10 m wide and up to 4 m high - indicate their significantly greater depth, compared to archaic ones. They no longer walk along the riverbed and next to it, but cut through the takyr layer in the space between two riverbeds. Naturally, the branches, which now usually extend at an acute angle, are present not on one side, but on both sides. The canals from the heyday of Khorezm antiquity no longer originate from the delta channels, but directly from the Amu Darya; they were more reliable, since they did not depend on the attenuated and frequently changing flow of the ducts.
The ancient period in the history of Khorezm is a time when artificially irrigated lands occupied the maximum area. Even in the Middle Ages, during the period of a new heyday of irrigation agriculture (XII - XIV centuries), the area of irrigated land barely reached 2/3 of the ancient one. However, the structures of this time were more advanced: the transition to economical, narrow and deep canals ended, and irrigation systems with numerous branches took the form of branched trees. The most important innovation of this period was the use of chigir - a water-lifting structure in the form of a wheel with vessels tied to it. Archaeologists date its appearance in Khorezm to the 9th - 10th centuries; At this time, the archaeological material began to contain large quantities of fragments of chigir pots - specially made ceramic vessels necessary for constructing chigirs.
Another important improvement in agriculture was the use of fertilizers. They began to artificially fertilize the land in Khorezm, apparently, at the beginning of the Afrigid period, in the 5th - 6th centuries; from IX - X centuries. This innovation has already become more widespread. The fertilizer was quite peculiar - the remains of old adobe buildings containing a lot of saltpeter. It is possible that in this regard, archaeologists will miss many monuments of ancient times.
Oh more high level The development of agricultural culture in the Middle Ages is evidenced by a wider range of cultivated crops than in ancient times. At this time, according to archaeological excavations, farmers grew not only grain crops - millet, wheat and barley, but also apricots, peaches, grapes, plums, pears, melons, watermelons, pumpkins, cucumbers, carrots, beans and mung beans, cotton and sesame.
A detailed study of the monuments of ancient Khorezm irrigation made it possible to resolve another important issue. Scientists have long been interested in the reasons why vast areas of once flourishing lands fell into desolation and were captured by the desert. According to calculations by S.P. Tolstov and B.V. Andrianov, during the heyday of Khorezm antiquity in the Aral Sea region (in the lower reaches of the Amu Darya and Syr Darya), the area occupied by irrigation occupied 3.5 - 3.8 million hectares, that is, four times more than now (It should, however, be taken into account that at that time the lands covered by irrigation structures were used for agriculture many times less intensively than now. The size of the cultivated plots was relatively small and interspersed with huge uncultivated lands. In ancient times, only 10% of the land suitable for irrigation was used, while now in the territory of Karakalpakia 30 - 40% is cultivated, in southern Khorezm - 50 - 60%). In the Middle Ages, in the XII - XIV centuries, in the same territories only 2.4 million hectares were covered by irrigation. Within the cultural oases, the irrigated area was close to modern in size.
The areas captured by the desert - they are called lands of ancient irrigation - occupy, as can be seen from the figures given, several hundred thousand hectares.
Significant changes (“drying out”) of the climate of the plains of Central Asia, changes in the flow of rivers, the advance of sand, salinization of soils - these and many other reasons tried to explain the desolation of vast territories in various countries of Western and Central Asia. However, even in the first generalizing works on the history of Khorezm, S.P. Tolstov showed the fallacy of this point of view. “The reasons,” he wrote, “are rooted in the processes social history. The transition from the ancient to the feudal system and the accompanying barbarian conquests with subsequent feudal strife and the invasion of nomads - this is the brilliant solution to this problem indicated by Marx and now documented. And what is destroyed by man can be recreated by him. And a clear evidence of this is the history of Khorezm today.”
Research carried out by the Khorezm expedition under the leadership of S.P. Tolstov in recent years has provided many more new materials to confirm this point of view.
But most importantly, it is confirmed by the practice of national economic development.
Long ago, in the process of studying the lands of ancient irrigation, the question arose: is it possible to bring these vast, once flourishing, but now deserted areas back to life? Couldn't they be included in an extensive program of irrigation construction to water the lands of dry areas?
In order to imagine the scale of which we're talking about, it is necessary to provide a few more figures.
Areas of ancient irrigation lands:
1. In the lower reaches of the Syr Darya (the left bank part of the Kzyl-Orda region of the Kazakh SSR and the Kara-Kalpak Autonomous Soviet Socialist Republic) - 2.5 - 2.8 million hectares.
2. In the lower reaches of the Amu Darya: in the Kara-Kalpak Autonomous Soviet Socialist Republic - 800 thousand hectares, in the Sarykamysh delta (Ta-Shauz region of the Turkmen SSR) over 1 million hectares. The total area of ancient irrigation lands in the Aral Sea region is almost 5 million hectares.
As you can see, the numbers are quite impressive. But in addition to these areas, archaeologists have identified huge tracts of ancient irrigation lands suitable for irrigated agriculture in the Caspian region and some other now arid regions (The area of “ancient irrigation lands” throughout Central Asia reaches 6 - 8 million hectares; in the USSR - 9 -10 million hectares).
Schematic map of ancient irrigation lands in the lower reaches of the Amu Darya and Syr Darya
Archaeologists, studying together with geographers the lands of ancient irrigation of the Aral Sea region, came to the conclusion that the development of these lands, which is now happening very slowly and on an insignificant scale, can be sharply accelerated. Calculations have shown that the required water rise (only 2 - 3 m) can be provided by existing and designed hydraulic structures.
There is an opportunity to transform the lower interfluve of the Amu and Syr Darya from an area of extensive transhumance cattle breeding into an area of intensive irrigated agriculture and stable cattle breeding. New millions of hectares of the most fertile lands can be introduced into the national economy of the country in a relatively short period of time.
In the summer of 1962, at a meeting of the Presidium of the USSR Academy of Sciences, the head of the Khorezm expedition, corresponding member of the USSR Academy of Sciences, Professor S.P. Tolstov, presented a report on the results of many years of research into ancient irrigation lands and proposals for their new development. Numerous maps, diagrams, photographs and calculations were offered to the attention of the most prominent Soviet scientists, reflecting the work of archaeologists and geographers in the Aral deltas. Summing up the discussion of the report, the Presidium of the USSR Academy of Sciences noted in its decision that the work of the Khorezm expedition “allows us to make adjustments towards increasing the areas currently projected for priority development for irrigation at the expense of ancient irrigation lands.
The materials collected by archaeologists deeply interested specialists involved in the problems of irrigation in Central Asia. They were and are now used in the design and construction of irrigation systems in the lower reaches of the Amu Darya, in the lower and middle Syr Darya, on Zeravshan, along the South Turkmen Canal. The day is not far off when fields and gardens will appear in the vastness of the present desert instead of sand and sparse thorny grass.
It was famous already in ancient times for agricultural progress achieved through systematic irrigation. Since time immemorial, there have been examples of irrigation structures in countries ancient culture: in China, India and Egypt, and in the New World - in the regions of the disappeared kingdom of the Aztecs. The Egyptians were not content with periodic floods of the Nile to fertilize their fields; and the waters carried it, with the help of an extensive system of canals, throughout its fertile region to the edge of the desert. Subsequently, they switched to water-scooping wheels, which raised the water to a height.
In Europe, the oldest masters of irrigation are the Etruscans. The huge remains of the canals between the Adige and the Po still testify to the gigantic structures carried out by these people solely for the purpose of watering the fields. They passed on their art to the Romans. The latter highly valued water, and their hydraulic structures are still amazing today: elevated pools, water canals, artificial ponds and lakes, excellent decoration of springs and other perfect devices for delivering good water.
Irrigation structures developed most widely in Lombardy. The network of irrigation canals in this area, developed and improved since the times of the Romans, covered an area of up to 450,000 hectares by the beginning of the 20th century. The main canals of this network, which included ancient artificial watercourses, were built at the beginning of the Middle Ages partly by monks, partly by the cities of Milan, Cremona and others under the rule of the Visconti, Sforza, Pallavicino, and in the region of Mantua by the Gonzaga dynasty. The oldest canal was built in 1057. Already in 1216, a collection of regulations on the use of water appeared in Milan, which were subsequently improved and served as the basis for the irrigation legislation of 1747. In the 11th century, the monks owned more than 8,000 hectares of irrigated meadows and sold their surplus water. To determine its quantity, special water meters were used, in which water was passed through a certain hole (0.029 m²), at a constant pressure (0.10 m). 2.1835 m³ flows through such a hole per minute, which is called a Milanese ounce. Subsequently, instead of a water ounce, other devices and instruments began to be used to measure flow, called modules since the time of Soldati, the first inventor of such a device in the 16th century.
Basic information[ | ]
Pumping station for water intake for irrigation needs
Irrigation canal
Irrigation pipelines
Mobile irrigation unit
Irrigation refers to hydromelioration, which is a series of measures aimed at long-term improvement of the water regime of the soil in order to increase its productivity. Reclamation is carried out through the construction of engineering hydraulic structures, with the help of which a calculated change or regulation of the water regime of the territory is carried out. If irrigation is required to be carried out in an area poor in water reserves, then the territory must first be irrigated, since constant transportation of the volumes of water required for irrigation would be extremely ineffective and expensive. With the help of watering, the flow of water is ensured naturally, which allows it to be used in the future directly in irrigation systems.
It is effective to use irrigation together with other types of reclamation, for example, agroforestry, which includes the creation of protective forest belts and areas. In this case, it is possible to achieve not only an improvement in soil conditions, but also a change in better side microclimatic conditions, when local moisture circulation as a whole improves. In arid regions, soil moisture alone may not be enough, since dry winds increase evaporation from the surface of plants, and the rate of replenishment from the root system may be insufficient, which leads to wilting. You can also note such types of reclamation as desalination reclamation, which involves removing harmful salts from the soil, and thermal reclamation, when crops are irrigated with warm water.
In general, irrigation is used in a wide variety of areas according to climatic conditions. Obviously, the greatest need for irrigation is observed in regions with a hot, dry climate (arid climate), characterized by low precipitation (200-300 mm per year). The moisture index (the ratio of annual precipitation to potential evaporation) is less than 0.33, and the evaporation deficit (the difference between possible evaporation during the growing season and productively used precipitation) exceeds 5000 cubic meters per hectare. In Russia, such lands include the territory of the Astrakhan region. This climate is typical for the countries of Central Asia, where the main crop grown with the help of irrigation is cotton.
Irrigation is also very effective in subarid areas. For them, the moisture index is less than 0.77, and the evaporation deficit is 2000-5000 m³ per hectare. The climate in such areas is more favorable than in arid climate zones, but dry periods occur here every few years, which can cause great damage to agriculture. Irrigation here plays a slightly different role; it serves not so much to create possibilities growth, how much to even out fluctuations in the volume of products received over the years or more effective use land with the ability to harvest several times a year. The defining crops are forage and grains.
Depending on the local situation, possible different ways carrying out irrigation. Firstly, the entire area of land can be irrigated, which is typical for arid climates, as well as individual areas of certain crops, which is typical for more humid climatic regions. Secondly, irrigation can be carried out once a year (the so-called estuary irrigation), in which the necessary supply of water is created in the soil, used by plants throughout the year, or irrigation can be carried out constantly.
Irrigation mode [ | ]
The task of irrigation includes determining required quantity water required for irrigation work with maximum efficiency. To do this, take into account both local climatic conditions and the type of irrigated plants and the conditions it requires for maximum growth and the amount of water in different periods growth. You should know the phases of development of a particular culture and provide the required conditions for each of the phases. The following growth phases can be distinguished: germination, tillering, flowering and ripening. The most water-intensive phase for cereal crops is the tillering phase, while, for example, for cotton it is the flowering phase.
There is a distinction between irrigation norm - the amount of water required by a crop for one watering, and irrigation norm - the entire volume of water for the irrigation period. The water consumption coefficient is the amount of water consumed by plants per unit of yield.
Irrigation systems[ | ]
Irrigation systems generally consist of several components:
- Water source - river, pond, reservoir, well, providing the required volume of water
- Water intake structure - regulates water intake into the system
- Network of linear water supply devices - channels, trays, pipelines
- Irrigation network and devices - direct irrigation strips, furrows, checks, tiers, watering machines and devices
- Drainage and discharge network - for collection and disposal surface runoff from the site
- Drainage network - to regulate the level of groundwater and remove salts
- Auxiliary structures - to regulate the pressure, flow and volume of water, wastewater treatment plants etc.
- Infrastructure - roads, forest belts, energy supply structures, industrial and residential buildings, storage ponds, etc.
Accordingly, several types of irrigation systems can be distinguished depending on the components used. For example, if a water intake structure is used pumping stations, then the system is with mechanical water lift, as opposed to a gravity system. Based on the type of openness, one can distinguish between open systems, where channels and trays are used, and closed systems, where pipelines are used. Systems also differ in the method of irrigation: surface irrigation, sprinkler, rice, estuary, drip or subsurface irrigation.
Soil moisture [ | ]
Studying and predicting the properties of soil moisture is one of the most important tasks in irrigation, since it is precisely for its regulation that irrigation is intended. Soil moisture refers to the moisture contained in top layer land within the vadose zone. The key parameter characterizing soil moisture is its mobility, depending on the value of which soil moisture is divided into crystallization, solid (ice), vapor, tightly bound, loosely bound and free. The task of irrigation is to create a certain humidity that would ensure the maximum yield of the crop sown in a given area. At the same time, several types of soil moisture are distinguished, which allows you to calculate its properties as accurately as possible:
- Maximum hygroscopicity allows you to estimate how much moisture the soil can contain before the absorption process stops
- The smallest moisture capacity shows how much water will remain in the soil after all the gravitational water has drained away
- Total moisture capacity determines the maximum amount of moisture that can be contained in the soil.
- Wilting humidity is the humidity at which the process of absorption of moisture from the soil by a certain plant stops, respectively, this characteristic depends not only on the type of soil, but also on the variety of crop.
The rate of water absorption into the soil can be determined by the formula:
u = α K t α − 1 (\displaystyle u=\alpha Kt^(\alpha -1)),By integrating this expression, we can obtain a layer of absorbed moisture over time t (\displaystyle t):
H = K t α (\displaystyle H=Kt^(\alpha )).In order to prevent the process of irrigation erosion from starting, it is necessary that all incoming moisture be absorbed into the soil.
To assess the water yield properties of certain soils, you can use the water yield coefficient, which is equal to the ratio of the volume of water freely flowing from the soil to the volume of this soil, expressed as a percentage. Fluid loss coefficient values range from 0.01 for clays to 20 for fine-grained sands.
Irrigation methods[ | ]
Pivot irrigation system
on the fields of the GDR (1967)
The main methods of irrigation include:
- watering furrows with water supplied by a pump or from an irrigation canal;
- spraying water from specially laid pipes;
- aerosol irrigation- irrigation with tiny drops of water to regulate the temperature and humidity of the surface layer of the atmosphere;
- subsoil (intrasoil) irrigation- irrigation of land by supplying water directly to the root zone;
- estuary irrigation- deep one-time spring moistening of the soil with local runoff waters.
- sprinkling- irrigation using self-propelled and non-self-propelled systems of a circular or frontal type.
Irrigation in different countries[ | ]
Negative environmental consequences[ | ]
If there are errors in the organization of land reclamation, irrigation agriculture can cause a whole chain of negative environmental consequences. The main ones are:
Secondary salinization is one of the main consequences of land irrigation in an arid climate. It is associated with the rise of mineralized groundwater to the earth's surface. Groundwater containing salts begins to evaporate intensively, as a result of which the soil is saturated with an excess amount of salts. An acute environmental problem in irrigated agriculture is pollution of surface and groundwater. This is the result of watering land and using water for soils. Most rivers whose waters are used for irrigation have a mineralization of 0.2-0.5 g/l. Currently, their mineralization has increased 10 times, which has led to an increase in secondary salinization. The problems of soil and water salinity are aggravated by the use of mineral fertilizers.
Reducing the negative environmental effect to a minimum is possible with proper planning and implementation of irrigation, since most of the shortcomings are not organically inherent in it.
Feasibility study of irrigation[ | ]
The economic efficiency of irrigation measures depends on whether they can additional income, obtained as a result of irrigation activities, exceed the costs of their implementation. Accordingly, it is required to have information about how much money will need to be invested in the construction of the reclamation system, to represent the additional volume of production received, and also to calculate the amount of expenses spent on the production of agricultural products itself.
It should be taken into account that the volume of capital investments in irrigation systems includes not only funds for these systems themselves, but also funds for the creation of appropriate infrastructure, for example, the creation of an on-farm road network, electrification, construction of additional buildings for production needs and accommodation of service personnel etc.
Annual production costs increase with the introduction of irrigation systems. Besides normal costs for fertilizers, sowing, harvesting and transporting crops, etc. there are costs for maintaining the irrigation systems themselves, which may include costs for paying workers, depreciation of equipment, and additional excavation(for example, cleaning canals, cutting temporary irrigation networks), for irrigation.
In this regard, before introducing irrigation systems, a thorough analysis is required, accompanied by economic calculations and technical and economic comparison of several options. This may require data on the types and areas of land proposed for irrigation, assessment of their reclamation status, geodetic work on surveying the area in order to draw up topographic plans and profiles of land, data on physical and chemical composition soils, geological data on soil foundations and groundwater levels.
The creation of large-scale irrigation systems requires the participation of specialized design institutes and scientific support due to both significant costs and a possible dramatic impact on the nature and population of the region. It is possible to derive the maximum benefit from the introduction of land reclamation with the overall development of the agricultural industry, when modern agricultural machinery is introduced, a professional workforce is created, and the social sphere in the countryside is developed.
Regulatory and technical support for irrigation in the Russian Federation[ | ]
Currently, work on the construction, operation and maintenance of irrigation systems is regulated by a set of building codes and regulations (SNiP) with accompanying normative and methodological documents (departmental building codes(VSN), manuals for SNiP, guidelines, most of which have been preserved since the time of state regulation of land reclamation issues. The task is to create new standards that meet both modern requirements and the situation, and are in accordance with the requirements of the International Standardization Associations (ISO). However, the emergence of a unified Russian technical regulation on land reclamation in the near future is unlikely. Currently, work is underway to develop a scientific and methodological basis for the creation of national standards that would regulate irrigation activities as an integral part of land reclamation as a whole.
Irrigation(or in Russian “irrigation”) is a system of measures aimed at increasing the moisture content in soil used in agriculture. Irrigation is the oldest method of increasing productivity, used by man for many millennia. The first irrigation systems in the form of canals running from deep river beds to fields already existed in ancient Egypt, Mesopotamia and China in the 4th millennium BC.
Irrigation– the main condition for successful agricultural activities. And for many dry areas with fertile soils and a completely obligatory and indispensable condition for growing any crops, even drought-resistant ones, along with soil fertilization and the purchase of seed material.
But proper irrigation, which necessarily takes into account its own soil moisture when organizing irrigation, is becoming even more important in our time, when humanity is constantly faced with. This is worth talking about in more detail.
History of irrigation
As we mentioned above, irrigation- one of ancient methods, used by mankind in agriculture. At the same time, we should not forget that irrigation, in turn, is part of the broader concept of land reclamation - the process of improving and protecting agricultural land from adverse weather factors (as a rule, this is especially true today, there is not enough water for irrigation, but there are areas , where it is in abundance - marshy soils and drainage is used there, a process opposite to irrigation, which is also part of land reclamation, as well as anti-mudflow, anti-landslide and anti-corrosion measures).
There are areas where people widely use natural irrigation - flourishing ancient egypt This is largely due to the fact that the twice-yearly floods of the Nile produced just such natural irrigation of the soil, and people just had to not be lazy and, with the help of a canal system, expand the irrigated areas, and then plant and harvest two abundant crops a year. There was no such excellent support in Mesopotamia, so the ancient civilizations that lived there were forced to build a wide system of irrigation canals connecting the two main rivers Tigris and Euphrates. The enormity of the work of the ancients amazes to this day; most of the channels are still in use today.
In Europe, one of the oldest regions where irrigation canals were built is the northern region of Italy - Lombardy, where irrigation structures began to be built back in ancient Roman times, and in the Middle Ages, for the first time in human history, metering devices appeared here - primitive water meters operating on the principle fixed watercourse, the great-great-grandfathers of today's water meters.
Today is Irrigation Day
Irrigation today is one of the most important areas in intensification Agriculture. After all, two of the most pressing problems humanity today are in short supply drinking water and food. And soil irrigation, on the one hand, is an indispensable factor for increasing productivity and increasing agricultural production, but on the other hand, an increase in the need for irrigation inevitably leads to an increase in consumption, of which humanity feels an increasing shortage every year.
This is why it is so important to use water rationally for irrigation. That's why they've become so popular in recent years diverse system automatic watering, which, in addition to convenience for users, primarily serve the purposes of saving water and increasing plant productivity. Having installed such a system on your personal plot or dacha, each of us can make our own contribution to the common cause of caring for the conservation of the resources of our planet!
At the same time, in many parts of Russia and even the Moscow region the main source clean water There are wells for drinking and watering. This unique invention has served people for many thousands of children, subject to mandatory proper care. You can read more about the care and cleaning of wells on the “Old Well” website.
