More often at elevated temperatures and low air humidity, as a result of which the moisture reserves in the soil dry up, which leads to a decrease or death of the crop.
The onset of drought is usually associated with the establishment of an anticyclone. The abundance of solar heat and dry air create increased evaporation (atmospheric drought), and the reserves of soil moisture are depleted without replenishment by rains (soil drought).
During drought, the flow of water into plants through the root systems becomes difficult, the consumption of moisture for transpiration (evaporation of water by the plant) begins to exceed its inflow from the soil, the water saturation of tissues decreases, and the normal conditions of photosynthesis and carbon nutrition are violated.
Depending on the season, a distinction is made between spring, summer and autumn droughts. Spring droughts are especially dangerous for early crops; summer crops cause severe damage to both early and late cereals and other annual crops, as well as fruit plants; autumn is dangerous for winter seedlings. The most destructive are spring-summer and summer-autumn droughts.
Most often, droughts are observed in the steppe zone, less often in the forest-steppe, 2-3 times a century droughts occur even in the forest zone.
The concept of "drought" is inapplicable to areas with rainless summer and extremely low rainfall, where agriculture is possible only with artificial irrigation (for example, the Sahara, Gobi, etc.).
It is possible to determine in advance the likelihood of drought only by individual factors. For example, the autumn moisture reserves in a meter layer of soil less than 50% of the average long-term data indicate an impending shortage of soil moisture. If the height of the snow cover and the moisture reserves in it make up no more than half of the average annual indicators, then the probability of drought in the coming spring period is also very significant.
To combat drought, a complex of agrotechnical and reclamation measures is used to enhance the water-absorbing and water-retaining properties of the soil, to retain snow in the fields.
Of the agrotechnical control measures, the most effective is the main deep plowing, especially soils with a highly compacted sub-arable horizon (chestnut, solonetz, etc.). On soils located on slopes, special soil cultivation techniques should be carried out to regulate surface runoff: plowing across the slope; contour plowing (horizontal); techniques that change the microrelief of arable land surface.
To reduce moisture evaporation, the soil on fallows and wide-row crops must be kept in a loose state, preventing the formation of a soil crust. For this purpose, harrowing, trailing, cultivation, processing of row spacings, etc. are used.
Techniques for the destruction of weeds, regulation of snow melting, fertilization, pre-sowing soil preparation and sowing in the shortest possible time are also of great importance.
It is effective to combine sowing winter crops that make good use of autumn precipitation and are resistant to spring-summer droughts, with sowing early spring crops that need precipitation in the first half of summer, as well as sowing corn, millet, sorghum and other late crops that use precipitation in the second half. summer and relatively easily tolerated spring drought. In drylands, the introduction of drought-resistant crop varieties is important.
Among other agrotechnical measures in the fight against droughts, the development of correct crop rotations with clean fallow in arid and occupied fallow in better humid regions has a positive value. Pure steam (with curtains) in arid regions is equivalent to fields with water-charging irrigation (irrigation to create reserves (charge) water in the soil).
Of the reclamation control measures, field-protective afforestation, preservation and expansion of water-protective forests are of great importance.
The material was prepared on the basis of information from open sources
Introduction
1. Formation of droughts
2. Types of drought
3. Known droughts
4. Combating drought
5. Deserts
Literature
Introduction
Drought - a significant (compared to the norm) lack of precipitation for a long time in spring and summer, at elevated air temperatures, as a result of which the moisture reserves in the soil dry up (by evaporation and transpiration) and unfavorable conditions are created for the normal development of plants, and the yield of field crops decreases or dies.
1. Formation of droughts
As a rule, droughts are accompanied by hot weather, extremely dry air, and sometimes strong burning winds, which creates all the conditions conducive to increased evaporation of soil moisture. The soil dries out first from the surface, then, thanks to the emerging cracks, deeper and deeper, and the plants growing on it, unable to get the water they need, die. But it happens that even with a sufficient amount of rain, plants suffer from a lack of water. So, in the steppes of southern Russia, where in summer precipitation falls mainly in the form of showers, extremely plentiful in terms of the amount of water they bring, but short-term and rare, drought is a frequent phenomenon.
The dried earth does not have time to take in even a tenth of the fallen water, as the rest of its mass quickly falls into ravines and gullies. But even that fraction of moisture that manages to be absorbed into the ground does not benefit the plants, since, thanks to the coming hot weather again, it evaporates very quickly. The onset of drought in many cases depends on a number of other factors, among which, undoubtedly, is the destruction of forests on an enormous scale.
It is where the presence of forests is most important "as regulators of the life of rivers and springs", in the upper reaches of rivers and on their slopes, that they are almost completely reduced (for example, at the upper reaches of the Volga, Don, Dnieper, etc.). As a result of such predatory destruction of forests, there are strong floods in spring. Rivers turn into drainpipes, through which a huge mass of water, instead of being distributed over several weeks, rushes in 3-4 days.
At the same time, up to 60% of it is lost, compared with what was previously retained by forests and fed rivers and springs in the summer. The shallowing of many, previously many water, rivers (Bityug, Vorskla) and, in general, a decrease in the water surface and, associated with it, air humidity, depends on such a rapid passage of spring waters. Thus, the destruction of forests causes undoubted harm, especially to agriculture, both because the regulators of the elements of the weather (humidity, wind, temperature) are destroyed through this, and because after deforestation and drought of slopes, the mass of uncomfortable land increases.
The strength and impetuosity of the dry wind is so great that it carries away crops, blows out the surface layer of the soil and covers fertile fields with sand. Its activity does not stop even in winter, but at this time of the year it acts in conjunction with the northeasterly winds. Terrible blizzards, sometimes lasting a whole week, in southern Russia are not rare. These winds carry snow from the high steppe into ravines and gullies, leaving fields bare and depriving them of spring moisture. Thus, the onset of drought depends not only on the meteorological conditions of a given year, but is also prepared by the owners themselves through the destruction of forests and plowing of steep slopes. The essence of drought consists in a lack of moisture in the soil during the growing period of plants, which always has a harmful effect on their development and is often the main cause of crop failure, and sometimes a complete failure of crops and grasses.
Droughts with unfavorable consequences for the harvest are observed especially in the steppe zone, less often in the forest-steppe and in the south of the forest zone. At ETC for 65 years 3. Harmed crops in the lower Volga region 21 times, in the east of Ukraine and in the Central Chernozem regions 15–20 times, in the west of Ukraine 10–15 times, in the Kuban 5 times, in the Moscow and Ivanovo regions 1–2 times ... In dry years (1924 and 1946), the number of consecutive days without rain in a large area was 60–70.
Distinguish between atmospheric drought, i.e. the state of the atmosphere, characterized by insufficient precipitation, high temperature and low humidity, and, as a consequence, soil drought, i.e. desiccation of the soil, entailing an insufficient supply of plants with water.
The atmospheric regime during drought is due to the predominance of stable anticyclones, in which the air in clear weather warms up strongly and moves away from the saturation state.
The onset of drought is usually associated with the establishment of an anticyclone. The abundance of solar heat and dry air create increased evaporation (atmospheric drought), and the reserves of soil moisture are depleted without replenishment by rains (soil drought).
During drought, the flow of water into plants through the root systems becomes difficult, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of the tissues decreases, and the normal conditions of photosynthesis and carbon nutrition are disturbed.
2. Types of drought
Soil drought- soil drying associated with atmospheric drought, that is, with certain weather conditions during the growing season, and leading to insufficient provision of vegetation, especially agricultural crops, with water, to its oppression and to a decrease or death of the crop.
Physiological drought- the phenomenon when, at high daytime temperatures in spring, the transpiration of tree species increases, and the supply of water by the roots is not ensured due to the low temperature of the soil. The plant begins to starve, despite the presence of a sufficient amount of water and mineral compounds in the soil.
Droughts on the territory of Russia according to the seasons of the year can be spring, summer and autumn. In the driest years, droughts cover two or even three seasons, that is, spring drought turns into summer, or summer drought turns into autumn, or drought that began in spring continues until late autumn.
Spring drought has the most harmful effect on the first period of growth of spring crops. This drought is characterized by low relative humidity, but low temperatures and cold, dry winds. Often, prolonged winds cause dust storms, exacerbating the harmful effects of spring droughts.
Summer cause severe damage to both early and late cereals and other annual crops, as well as fruit plants;
Autumn dangerous for seedlings of winter crops.
Prolonged spring drought, which developed against the background of insufficient soil moisture by precipitation in the autumn-winter period with small reserves of soil moisture, is especially harmful. In such conditions, plants develop very poorly, and even the onset of rainy weather will not be able to completely eliminate the consequences of drought: the yield will be reduced.
For example, for 2002–2003, summer in the Republic of Adygea came on a date close to usual (May 1–2). Summer was characterized by hot, dry weather at the beginning of the period and moderately warm, rainy at the end.
Out of 15 summer decades, 7 decades of air temperature had positive deviations by 1–5 ° and 7– by 1–2 ° lower than the long-term average. One decade was within normal limits. The highest temperatures (35–37 °) were recorded in the first ten days of July, third August and first September. The number of days with a maximum air temperature of 30 ° was 29–47 days.
The sum of effective temperatures above 10 ° for the summer period was 1565-1820, which is 60-180 ° higher than the average long-term value.
3. Known droughts
In Russia, its southern and southeastern outskirts, drought is a common phenomenon, repeating at more or less prolonged intervals. The history of our fatherland has preserved many memories of the years in which the population suffered not only from hunger, but even from pestilence. The probable cause of such disasters was drought ("hunger from a crop failure, a bad harvest from a bucket"), although exact information about the causes of such crop failures and their size has not been preserved. Only about 1833 and 1840. it is known that crop yield in these years depended mainly on drought. In terms of the size of the area covered by a bad harvest, the greatest bad harvest was in 1891, when 21 provinces suffered from drought, and the crop failure was determined, in comparison with the normal average crop failure, at 80 million quarters.
A severe drought has been going on in Cyprus for several months. The temperature in the winter months exceeded + 30 ° C, local reservoirs are almost empty. Since the beginning of the year, the water supply deficit on the island amounted to more than 17 million cubic meters of water. Strong cuts in water supplies began in the country last week.
The drought that plagued the United States, Southern Europe and Southwest Asia in 1998–2002 was associated with water temperatures in the tropical Pacific and Indian Oceans. For four years now, parts of the northern hemisphere have received less than half of the annual rainfall. This drains farms, empties water bodies, lowers the water table. And it is not yet clear when this drought will end.
4. Combating drought
Drastic measures to counter drought should consist in increasing the flow of water in the area, increasing groundwater and preserving moisture reserves. This can be achieved mainly with the help of continuous afforestation, especially in the upper reaches of rivers along their slopes, and the cultivation of forest edges and hedges along the passes. Only under such conditions is it possible to correctly distribute the snow cover, which would provide moisture in the soil. Both the government (since 1813) and private individuals work in this direction, mainly in the steppe zone. Another means of dealing with drought is artificial irrigation of fields and meadows. It is borrowed from mountainous areas where high-water rivers flow, which, moreover, have a large drop. Water from such rivers is diverted by canals to the fields and distributed over their surface using furrows, or they are completely flooded directly. In areas that are flat and low-water, such as our steppes, they use winter moisture reserves. Melt water is collected by drainage canals in ponds, usually arranged in the upper reaches of the ravines, and the valley and the slopes of this ravine or ravine are irrigated with water from such reservoirs. Another method, which is called watering, is also possible. Along the slope, parallel to its ridge, several rows of dams or ridges are arranged. Spring water, held by them, as the upper areas become wet, descends lower and lower. In the Semirechensk region, huge glaciers are made from snow on the passes, they are covered with earth or straw to protect them from rapid melting, and gradually they use such a supply of water, leading it in small grooves to the fields. In addition to these measures, the farmer still has many means to prevent drought.
Obviously, a field littered with wild vegetation, and, moreover, untimely and shallowly plowed field contains many conditions for the useless waste of soil moisture, and in favorable weather causes a struggle for moisture between plants. When this is joined by prolonged hot weather and winds, the cultivated plants are powerless and die. The best and available to every farmer to combat drought is possible early and deep plowing of the hearth, especially black fallow. Dense soil does not absorb moisture well and, at the same time, quickly evaporates it, thanks to the mass of hair canals in such soil, which raise moisture from the lower milks to the upper ones. By loosening the top layer of the soil, the network of capillaries is destroyed, and more favorable conditions are created for the penetration of moisture into the ground.
With deep autumn plowing, it is possible to delay most of the autumn and winter atmospheric precipitation in the fields with this technique. Only during further processing is it necessary to loosen the top layer to destroy capillary vessels and weeds. This kind of plowing, especially if it is combined with the destruction of weeds and loosening the top layer of the soil, is the best available to any farmer, a means to accumulate and preserve moisture in the soil, and, consequently, to ensure the economy from drought.
5. Deserts
Deserts cover about one fifth of the Earth's surface and are found in areas where rainfall is less than 50 cm / year. While most deserts such as the Sahara Desert in North Africa and the southwestern deserts of the United States, Mexico, and Australia are found in southern latitudes, another type of desert, cold deserts, is found in the basins and ridges of Utah and Nevada and parts of western Asia.
Most deserts have a significant amount of unique vegetation, as well as vertebrates and spineless animals. Soils often have an abundance of nutrients because they only need water to become very useful and have little organic matter that may not be available. Disturbances usually occur due to accidental fires or cold weather, and sudden, infrequent but intense rainfall resulting in flooding.
Because desert is an uncertain term, the use of the meaning of “dry land” and its subdivisions into hyperarid, arid, semi-arid, dry-sub-humid and cold are used in some contexts, and are endorsed by the United Nations.
There are deserts: Atacama, Gobi, Kalahari, Mojave, Namib, Negev, Patagonia, Sahara, Sechura, Simpson, Sonora.
Arabian Desert Is a vast wilderness area that stretches from Yemen to the Persian Gulf and Oman to Jordan and Iraq. It covers most of the Arabian Peninsula with an area of 2,330,000 square kilometers (900,000 mi). At its center lies the Rubal Kali, one of the largest continuous sand massifs in the world.
Gazelles, oryxes, sand cats and rumptail lizards are just a few of the desert-adapted animal species that survive in this extreme environment.
This ecological region contains a small variety of life forms, although some native plants get along well here. Many species such as the striped hyena, jackal and badger have become extinct in this area due to hunting, human invasion and habitat destruction. Other species have been successfully reintroduced to the area, such as the white oryx and sandy gazelle, which are protected on numerous reservations. Overgrazing by livestock, driving off-road vehicles, and destruction of habitats are the main threats to the ecoregion of this desert.
Desert temperatures range from 40-50 ° C in summer, average winter temperatures are 5-15 ° C, although it can drop as low as 0 ° C. Daily extremes are very significant.
Gobi Desert Is a large desert region in China and southern Mongolia. The basins of the Gobi Desert are bounded by the Altai Mountains and fields and steppes of Mongolia in the north, the Tibetan Plateau in the southwest, and the North China Plain in the southeast. The Gobi is made up of several distinct ecological and geographic regions based on climate change and topography. This desert is the largest in Asia.
Most of the Gobi is not sandy, but covered with bare stones.
The Gobi Desert is a cold desert, and it is not uncommon to see frost and sometimes snow on its dunes. In addition, on the north side, it is about 900 meters (2,953 feet) above sea level, which further contributes to its low temperatures. The average annual rainfall is approximately 194 millimeters (7.6 inches) of precipitation, which falls annually in the Gobi.
The Gobi climate is one of the big extremes, with rapid temperature changes, not only throughout the year, but even over 24 hours (up to 32 ° C or 58 ° F).
Kalahari Desert Is a large arid sandy area in southern Kgalagadi in Africa, extending over 900,000 sq. km (562,500 sq mi), covering most of Botswana and part of Namibia in South Africa. It is a semi-desert with huge tracts that make excellent pastures after good rains. The Kalahari supports the life of some animals and plants, because most of it is not a real desert. There is little rainfall in the desert and summer temperatures are usually very high. The Kalahari usually receives 5-10 inches of rain annually.
However, the Kalahari is not a real desert. Parts of the Kalahari receive over 250mm of chaotic rainfall annually and are quite well watered. It is truly arid only in the southwest (receiving less than 175 mm of rain annually), where it turns into a rocky desert. Summer temperatures in the Kalahari range from 20 to 40 ° C. In winter, the Kalahari has a dry, cold climate with frosty nights. The coldest winter temperatures can average below 0 ° C. The Kalahari Desert is a harsh place and has 2 seasons - a dry season and a rainy season.
Animals that live in this area include brown hyenas, lions, mercats, several species of antelope (including the oryx or gemsbock), and many species of birds and reptiles. The vegetation in the Kalahari consists mainly of grasses and acacias, but there are also over 400 identified plant species (including wild watermelon or Tsamma melon).
Climate sahara desert has undergone a huge change between wet and dry over the past several thousand years. During the last ice age, the Sahara Desert was larger than it is today, expanding south beyond its present boundaries. The end of the Ice Age brought wetter times to the Sahara Desert, from about 8000 BC to about 8000 BC. to 6000 BC, possibly due to the low pressure areas of the crumbling ice sheet to the sheets in the north. Once the ice sheet was gone, the northern part of the Sahara Desert dried up.
The Sahara Desert has one of the harshest climates in the world. There are many strong winds that blow from the northeast. Occasionally, in the border regions of the north and south, the desert receives approximately 25 cm (10 inches) of rain per year. Showers are very rare, but if they do, they are usually heavy. This occurs after long dry periods that can last for many years. Daytime temperatures can reach 58 ° C (136 ° F), but low temperatures are not uncommon at night, reaching -6 ° C (22 ° F).
Cold deserts- this is a type of desert in which sparse vegetation is determined by initially low temperatures, and not by an arid climate. Cold deserts are icy and alpine. Cold deserts are contrasted with arid deserts.
These deserts are characterized by cold winters with snowfalls and fairly heavy rainfall during the winter and sometimes summer. These deserts are located in Antarctica, Greenland and the non-Arctic region. Deserts have short, damp and moderately warm summers and rather long, cold winters. The average winter temperature ranges from -2 to + 4 ° C, and the average summer temperature ranges from 21 to 26 ° C.
In winter, there is quite a bit of snowfall. The average rainfall is 15-26 cm. Average annual precipitation reached a maximum of 46 cm and a minimum of 9 cm. The strongest spring showers usually occur in April or May. In some areas, the rain can be heavy in the fall.
The soil in these deserts is hard, silty and salty. It contains a fan of alluvial deposits where the soil is porous enough and the drainage is good enough that almost all the salt is washed away.
Plants are widely dispersed. Leafy areas cover about 10 percent of the land, but in some areas wormwood shrubs reach 85 percent. The height of the plants varies between 15 and 122 cm. The main plants are deciduous, most of them with thorny leaves. Common animals include American hares, marsupials, marsupials, grasshoppers, baggy jumpers, and antelope gophers.
Literature
1. P.F. Barakov, "On possible measures to combat drought."
2. A.S. Ermolov, "Crop failure and national disaster".
3. Annenkov, "On measures to reduce drought."
4. A. Shishkin, "On the issue of reducing the harmful effects of drought on vegetation."
5.P.A. Kostychev, "On the fight against drought in the black earth region of Russia".
6. Rudnev G.V. Agrometeorology. - L .: Gidrometeoizdat, 1973.
7. “Strategic forecast of climate change in the Russian Federation for the period up to 2010–2015. and their impact on the sectors of the Russian economy ”Moscow, Roshydromet, 2005.
8. "Climate of the Rostov region: yesterday, today, tomorrow" V.D. Panov, P.M. Lurie, Yu.A. Larionov, Rostov-on-Don, 2006.
What is drought? Most people think of a drought as a period of unusually dry and hot weather that persists long enough to cause crop water problems. But drought is caused not only by lack of rainfall and high temperatures, but also by overspending and overpopulation. One difficulty is that drought means different things in different regions. Thus, drought is a multifactorial phenomenon that develops for various reasons, so many definitions of drought can be found.
In the 1980s, two researchers documented more than 150 published definitions of drought, which they presented in the journal Water International. In an effort to systematize the information found, scientists grouped the definitions into four main categories: meteorological, hydrological, agricultural and socio-economic. The first three categories of definitions reflect drought as a physical phenomenon. The latter category presents drought as a supply and demand problem and a problem of the consequences of water scarcity.
These definitions typically indicate the onset, end, and severity of drought by comparing precipitation over a fixed period of time with historical averages.
Here is a description of the four main categories of definitions of drought:
Meteorological drought differs from region to region depending on the average annual rainfall in that area. A decrease in the amount of precipitation in comparison with the indicators for this area in the past will qualify as a meteorological drought.
Agricultural drought takes into account the water requirements of crops at different stages of cultivation. For example, insufficient moisture during planting can inhibit germination, resulting in reduced plant numbers and reduced yields.
Hydrological drought is associated with a decrease in the amount of water in streams, rivers and reservoirs. Human activities that reduce water bodies can exacerbate hydrological drought. Hydrological drought is often associated with meteorological drought.
Socioeconomic drought occurs when the demand for water exceeds supply. Examples of such droughts are over-irrigation or when a decline in river water levels causes hydropower operators to reduce energy production.
Drought causes
Drought usually occurs when changing weather conditions disrupt the water cycle. A change in the direction of the winds can significantly affect the amount of precipitation that falls in the region. But lack of rain does not necessarily lead to drought. Drought is the result of a combination of many factors.
The link between climate change, Arctic ice loss and extreme weather events is currently an area of active research in the scientific community. However, it is clear that there are natural weather cycles that lead to drier and wetter periods.
El Niño and La Niña
Scientists have found a link between some climatic events and drought. El Niño is a meteorological phenomenon associated with an increase in surface water temperature in the Pacific Ocean along the central South American coast. This phenomenon leads to droughts in Indonesia, Australia and northeastern South America.
La Niña is the “opposite” of El Niño, where surface waters in the Pacific Ocean are cooled along the coast of South America. Chilled waters affect hurricanes, contributing to harsher-than-normal conditions in the Americas. El Niño and La Niña usually last for about a year. The impact of La Niña on weather conditions is often more complex than El Niño. Two of the most damaging droughts in United States history - the dusty bowl of the 1930s and the 1988 Midwest drought - are linked to the La Niña effects.
There is still a lot of discussion about the link between drought and global warming, the current period of climate change. A 2013 NASA study predicts that warmer temperatures around the world will mean more rainfall in some parts of the world and less rainfall in others, leading to more flooding and more drought around the world. Other scientists doubt that there will be more droughts, and believe that global warming, on the contrary, will contribute to a humid climate around the world.
Although drought is a natural phenomenon, human activities can make it worse. For example, drought can worsen if it comes to an area with high water demand and where water management is poor. But even when there is no rainfall, drought may not occur and can be prevented if sufficient water is available (eg in reservoirs) and water consumption is managed wisely.
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Deforestation is one of the environmental problems in Russia
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Drought - a significant, compared to the norm, lack of precipitation for a long time in spring and summer, at elevated air temperatures, as a result of which the moisture reserves in the soil dry up (by evaporation and transpiration) and unfavorable conditions are created for the normal development of plants, and the yield of field crops decreases or dies.
Droughts
As a rule, droughts are accompanied by hot weather, extremely dry air, and sometimes strong burning winds, which creates all the conditions conducive to increased evaporation of soil moisture. The soil dries out first from the surface, then, thanks to the emerging cracks, deeper and deeper, and the plants growing on it, unable to get the water they need, die. But it happens that even with a sufficient amount of rain, plants suffer from a lack of water. So, in the steppes of southern Russia, where in summer precipitation falls mainly in the form of showers, extremely plentiful in terms of the amount of water they bring, but short-term and rare, drought is a frequent phenomenon.
The dried earth does not have time to take in even a tenth of the fallen water, as the rest of its mass quickly falls into ravines and gullies. But even that fraction of moisture that manages to be absorbed into the ground does not benefit the plants, since, thanks to the coming hot weather again, it evaporates very quickly. The onset of drought in many cases depends on a number of other factors, among which, undoubtedly, is the destruction of forests on an enormous scale.
It is where the presence of forests is most important "as regulators of the life of rivers and springs", in the upper reaches of rivers and on their slopes, that they are almost completely reduced (for example, at the upper reaches of the Volga, Don, Dnieper, etc.). As a result of such predatory destruction of forests, there are strong floods in spring. Rivers turn into drainpipes, through which a huge mass of water, instead of being distributed over several weeks, rushes in 3-4 days.
At the same time, up to 60% of it is lost, compared with what was previously retained by forests and fed rivers and springs in the summer. The shallowing of many, previously many water, rivers (Bityug, Vorskla) and, in general, a decrease in the water surface and, associated with it, air humidity, depends on such a rapid passage of spring waters. Thus, the destruction of forests causes undoubted harm, especially to agriculture, both because the regulators of the elements of the weather (humidity, wind, temperature) are destroyed through this, and because after deforestation and drought of slopes, the mass of uncomfortable land increases.
The strength and impetuosity of the dry wind is so great that it carries away crops, blows out the surface layer of the soil and covers fertile fields with sand. Its activity does not stop even in winter, but at this time of the year it acts in conjunction with the northeasterly winds. Terrible blizzards, sometimes lasting a whole week, in southern Russia are not rare. These winds carry snow from the high steppe into ravines and gullies, leaving fields bare and depriving them of spring moisture. Thus, the onset of drought depends not only on the meteorological conditions of a given year, but is also prepared by the owners themselves through the destruction of forests and plowing of steep slopes. The essence of drought consists in a lack of moisture in the soil during the growing period of plants, which always has a harmful effect on their development and is often the main cause of crop failure, and sometimes a complete failure of crops and grasses.
Droughts with unfavorable consequences for the harvest are observed especially in the steppe zone, less often in the forest-steppe and in the south of the forest zone. At ETC for 65 years 3. Harmed crops in the lower Volga region 21 times, in the east of Ukraine and in the Central Chernozem regions 15–20 times, in the west of Ukraine 10–15 times, in the Kuban 5 times, in the Moscow and Ivanovo regions 1–2 times ... In dry years (1924 and 1946), the number of consecutive days without rain in a large area was 60–70.
Distinguish between atmospheric drought, i.e. the state of the atmosphere, characterized by insufficient precipitation, high temperature and low humidity, and, as a consequence, soil drought, i.e. desiccation of the soil, entailing an insufficient supply of plants with water.
The atmospheric regime during drought is due to the predominance of stable anticyclones, in which the air in clear weather warms up strongly and moves away from the saturation state.
The onset of drought is usually associated with the establishment of an anticyclone. The abundance of solar heat and dry air create increased evaporation (atmospheric drought), and the reserves of soil moisture are depleted without replenishment by rains (soil drought).
During drought, the flow of water into plants through the root systems becomes difficult, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of the tissues decreases, and the normal conditions of photosynthesis and carbon nutrition are disturbed.
Drought types
Soil drought - drying out of the soil associated with atmospheric drought, that is, with certain weather conditions during the growing season, and leading to insufficient provision of vegetation, especially agricultural crops, with water, to its oppression and to a decrease or death of the crop.
Physiological drought is a phenomenon when, at high daytime temperatures in spring, the transpiration of tree species increases, and the supply of water by the roots is not ensured due to the low temperature of the soil. The plant begins to starve, despite the presence of a sufficient amount of water and mineral compounds in the soil.
Droughts on the territory of Russia according to the seasons of the year can be spring, summer and autumn. In the driest years, droughts cover two or even three seasons, that is, spring drought turns into summer, or summer drought turns into autumn, or drought that began in spring continues until late autumn.
Spring drought has the most harmful effect on the first period of growth of spring crops. This drought is characterized by low relative humidity, but low temperatures and cold, dry winds. Often, prolonged winds cause dust storms, exacerbating the harmful effects of spring droughts.
Summer crops cause severe damage to both early and late cereals and other annual crops, as well as fruit plants;
Autumn is dangerous for winter seedlings.
Prolonged spring drought, which developed against the background of insufficient soil moisture by precipitation in the autumn-winter period with small reserves of soil moisture, is especially harmful. In such conditions, plants develop very poorly, and even the onset of rainy weather will not be able to completely eliminate the consequences of drought: the yield will be reduced.
For example, for 2002–2003, summer in the Republic of Adygea came on a date close to usual (May 1–2). Summer was characterized by hot, dry weather at the beginning of the period and moderately warm, rainy at the end.
Out of 15 summer decades, 7 decades of air temperature had positive deviations by 1–5 ° and 7– by 1–2 ° lower than the long-term average. One decade was within normal limits. The highest temperatures (35–37 °) were recorded in the first ten days of July, third August and first September. The number of days with a maximum air temperature of 30 ° was 29–47 days.
The sum of effective temperatures above 10 ° for the summer period was 1565-1820, which is 60-180 ° higher than the average long-term value.
Known droughts
In Russia, its southern and southeastern outskirts, drought is a common phenomenon, repeating at more or less prolonged intervals. The history of our fatherland has preserved many memories of the years in which the population suffered not only from hunger, but even from pestilence. The probable cause of such disasters was drought ("hunger from a crop failure, a bad harvest from a bucket"), although exact information about the causes of such crop failures and their size has not been preserved. Only about 1833 and 1840. it is known that crop yield in these years depended mainly on drought. In terms of the size of the area covered by a bad harvest, the greatest bad harvest was in 1891, when 21 provinces suffered from drought, and the crop failure was determined, in comparison with the normal average crop failure, at 80 million quarters.
A severe drought has been going on in Cyprus for several months. The temperature in the winter months exceeded + 30 ° C, local reservoirs are almost empty. Since the beginning of the year, the water supply deficit on the island amounted to more than 17 million cubic meters of water. Strong cuts in water supplies began in the country last week.
The drought that plagued the United States, Southern Europe and Southwest Asia in 1998–2002 was associated with water temperatures in the tropical Pacific and Indian Oceans. For four years now, parts of the northern hemisphere have received less than half of the annual rainfall. This drains farms, empties water bodies, lowers the water table. And it is not yet clear when this drought will end.
Drought management
Drastic measures to counter drought should consist in increasing the flow of water in the area, increasing groundwater and preserving moisture reserves. This can be achieved mainly with the help of continuous afforestation, especially in the upper reaches of rivers along their slopes, and the cultivation of forest edges and hedges along the passes. Only under such conditions is it possible to correctly distribute the snow cover, which would provide moisture in the soil. Both the government (since 1813) and private individuals work in this direction, mainly in the steppe zone. Another means of dealing with drought is artificial irrigation of fields and meadows. It is borrowed from mountainous areas where high-water rivers flow, which, moreover, have a large drop. Water from such rivers is diverted by canals to the fields and distributed over their surface using furrows, or they are completely flooded directly. In areas that are flat and low-water, such as our steppes, they use winter moisture reserves. Melt water is collected by drainage canals in ponds, usually arranged in the upper reaches of the ravines, and the valley and the slopes of this ravine or ravine are irrigated with water from such reservoirs. Another method, which is called watering, is also possible. Along the slope, parallel to its ridge, several rows of dams or ridges are arranged. Spring water, held by them, as the upper areas become wet, descends lower and lower. In the Semirechensk region, huge glaciers are made from snow on the passes, they are covered with earth or straw to protect them from rapid melting, and gradually they use such a supply of water, leading it in small grooves to the fields. In addition to these measures, the farmer still has many means to prevent drought.
Obviously, a field littered with wild vegetation, and, moreover, untimely and shallowly plowed field contains many conditions for the useless waste of soil moisture, and in favorable weather causes a struggle for moisture between plants. When this is joined by prolonged hot weather and winds, the cultivated plants are powerless and die. The best and available to every farmer to combat drought is possible early and deep plowing of the hearth, especially black fallow. Dense soil does not absorb moisture well and, at the same time, quickly evaporates it, thanks to the mass of hair canals in such soil, which raise moisture from the lower milks to the upper ones. By loosening the top layer of the soil, the network of capillaries is destroyed, and more favorable conditions are created for the penetration of moisture into the ground.
With deep autumn plowing, it is possible to delay most of the autumn and winter atmospheric precipitation in the fields with this technique. Only during further processing is it necessary to loosen the top layer to destroy capillary vessels and weeds. This kind of plowing, especially if it is combined with the destruction of weeds and loosening the top layer of the soil, is the best available to any farmer, a means to accumulate and preserve moisture in the soil, and, consequently, to ensure the economy from drought.
Explanatory dictionary of the Russian language. D.N. Ushakov
drought
droughts, w. Lack of water in the soil, caused by a prolonged absence of rain with strong heat or dry sultry winds and leading to complete or partial burnout of crops and vegetation. Drought is fought with artificial irrigation and in other ways.
Explanatory dictionary of the Russian language. S.I.Ozhegov, N.Yu.Shvedova.
drought
And, well. Prolonged absence of rain, leading to drying out of the soil and death of vegetation. It is worth z.
New explanatory and derivational dictionary of the Russian language, T. F. Efremova.
drought
f. Prolonged lack of rain in summer, leading to drying out of the soil, impaired growth or death of plants.
Encyclopedic Dictionary, 1998
drought
prolonged and significant lack of precipitation, more often at elevated temperatures and low air humidity. It causes a decrease in moisture reserves in the soil and, as a result, a deterioration in growth, and sometimes death of plants. Control measures: agrotechnical (special tillage) and reclamation (irrigation) measures, field-protective afforestation.
Drought
a long and significant lack of precipitation, more often at elevated temperatures and low air humidity, as a result of which the moisture reserves in the soil dry up, which leads to a decrease or death of the crop. The beginning of the earth is usually associated with the establishment of an anticyclone. The abundance of the sun's heat and dry air create increased evaporation (atmospheric soil), and the reserves of soil moisture are depleted without being replenished by rains (soil earth). With heat, the flow of water into plants through the root systems becomes more difficult, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of the tissues decreases, and the normal conditions of photosynthesis and carbon nutrition are disrupted. Depending on the season, a distinction is made between spring, summer, and autumn winters. Spring winters are especially dangerous for early grain crops; summer crops cause severe damage to both early and late cereals and other annual crops, as well as fruit plants; autumn is dangerous for winter seedlings. The most destructive spring-summer and summer-autumn winters are most often observed in the steppe zone, less often in the forest-steppe zone: 2 to 3 times a century, winters occur even in the forest zone. The concept of land use is inapplicable to areas with rainless summers and extremely low rainfall, where agriculture is possible only with artificial irrigation (for example, the Sahara and Gobi deserts, and others).
The arid climate in the USSR is typical for the southwestern and central parts of Kazakhstan, the Central Asian republics (with the exception of the high mountainous regions), as well as the southeastern part of the European territory of the USSR. It is difficult to establish the boundaries of the periodical appearance of the earth in the USSR, since there are almost no places where it would not be observed. The driest were 1891, 1911, 1921, 1931, 1936, 1946, 1954, 1957, 1967, 1971. Approximately every 3 years, as a result of the zoning, the country receives less than 1.5 billion poods of grain. Z. most often affects the Middle and Lower Volga regions and the river basin. Ural. It is possible to determine in advance the probability of Z. only by individual factors. For example, the autumn moisture reserves in a meter layer of soil less than 50% of the average long-term data indicate an impending shortage of soil moisture. If the depth of the snow cover and the moisture reserves in it amount to no more than half of the average long-term indicators, then the probability of a snowfall in the coming spring period is also very significant.
A complex of agrotechnical and reclamation measures is used to combat zeal, aimed at enhancing the water-absorbing and water-retaining properties of the soil, and at retaining snow in the fields. Of the agrotechnical control measures, the most effective is the main deep plowing, especially soils with a highly compacted sub-arable horizon (chestnut, solonetz, etc.). In Northern Kazakhstan and in the steppe regions of Western Siberia, it is advisable to cultivate the soil with flat-cutting tools while maintaining stubble on the surface of the field. On soils located on slopes, special soil cultivation techniques should be carried out to regulate surface runoff: plowing across the slope; contour plowing (horizontal); techniques that change the microrelief of the surface of arable land (making holes, microlimans, intermittent furrows). To reduce moisture evaporation, the soil on fallows and wide-row crops must be kept in a loose state, preventing the formation of a soil crust. For this purpose, harrowing, trailing, cultivation, processing of row spacings, etc. are used. Techniques for the destruction of weeds, regulation of snow melting, fertilization, pre-sowing soil preparation and sowing in the shortest possible time are also of great importance. It is effective to combine the sowing of winter crops, which make good use of autumn precipitation and are resistant to spring-summer winter, with the sowing of early spring cereals that need precipitation in the first half of summer, as well as with the sowing of corn, millet, sorghum, and other late crops. which use precipitation in the second half of summer and tolerate spring winter relatively easily. In arid regions, the introduction of drought-resistant varieties of agricultural crops plays an important role. plants (see. Drought resistance of plants). Of the other agrotechnical measures in the fight against winter, the development of correct crop rotations with clean fallow in arid and occupied fallow in better humid regions is of positive importance. Pure fallow (with curtains) in arid regions is equated to fields with water-charging irrigation. Of the reclamation control measures, field-protective afforestation, preservation and expansion of water-protective forests are of great importance.
From the first days of the existence of the Soviet state, the Party and the government have carried out important measures to intensify agricultural production. production and land reclamation. After the strongest winter in 1921, VI Lenin signed a special decree "On the fight against drought", which refers to the allocation of forests of water-protective and protective significance, the strengthening of sands, ravines, the construction of snow-collecting strips and hedges, etc. Subsequently, large-scale work on the struggle against the earth was foreseen at the 17th Party Congress (1934), the February Plenum of the Central Committee of the All-Union Communist Party (Bolsheviks) in 1947, in the Directives of the 19th Party Congress on the fifth five-year plan 1951-55, and others. the implementation of measures to combat agriculture, to strengthen the material and technical base of agriculture, to raise the general culture of agriculture, and to develop land reclamation work to obtain high and stable agricultural yields. crops have the decisions of the March (1965), May (1966) plenums of the Central Committee of the CPSU and the 24th Congress of the CPSU (see Water protection forests, Melioration, Protective forest plantations, Irrigation).
Lit .: Timiryazev K.A., Plant fight against drought. Fav. cit., t. 2, M., 1948; Dokuchaev V.V., Our steppes before and now, Izbr. works. M., 1949; Izmail A.A. How our steppe dried up, Izbr. cit., M., 1949; Droughts in the USSR, their origin, frequency and impact on the harvest. [Sat. materials], ed. A.I. Rudenko, L., 1958; The struggle for moisture is the struggle for the harvest. [Sat. materials], ed. P. f. Kotova, Voronezh, 1969; Transformation of nature in the Stone Steppe. [Sat. materials], M., 1970.
I. A. Skachkov.
Wikipedia
Drought
Drought- a long period of stable weather with high air temperatures for a given area and a low amount of precipitation (rain), as a result of which the moisture reserves of the soil decrease and oppression and death of cultivated plants occurs.
The onset of drought is usually associated with the establishment of a sedentary high anticyclone. The abundance of solar heat and gradually decreasing air humidity create increased evaporation ( atmospheric drought), in connection with which the reserves of soil moisture are depleted without their replenishment by rains ( soil drought). Gradually, as the soil drought intensifies, ponds, rivers, lakes, springs dry up, - begins hydrological drought.
During drought, the flow of water into plants through the root systems becomes difficult, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of the tissues decreases, and the normal conditions of photosynthesis and carbon nutrition are disturbed.
Depending on the season, there are spring, summer and autumn drought.
- spring droughts are especially dangerous for early grain crops;
- summer crops cause severe damage to both early and late cereals and other annual crops, as well as fruit plants;
- autumn is dangerous for winter seedlings.
The most destructive are spring-summer and summer-autumn droughts.
In the middle latitudes, droughts are most often observed in the steppe zone, less often in the forest-steppe zone: 2-3 times a century droughts occur even in the forest zone. The concept of drought is inapplicable to regions with rainless summers and extremely low rainfall, where agriculture is possible only with artificial irrigation (for example, the Sahara, Gobi and others).
Droughts are common in the subtropical zone and in the subequatorial zone, where it only rains during the wet season.
In order to raise awareness of the world community, the UN has established a world day to combat desertification and drought.
Examples of the use of the word drought in literature.
The age-old struggle of Russian agronomy forged a wonderful harmonious teaching on the restoration of soil fertility, on the elimination of the catastrophic fall in harvests in the years droughts.
And he will die, fighting not for apartheid and not for the white race, but for these morgen, which he calls his land, where there are droughts and floods, and earthquakes, and deaths of livestock, and snakes, which he considers the same nonsense as mosquitoes.
Finally, there were communities that answered the challenge droughts a change in homeland and way of life, and this rare double reaction meant a dynamic act that, from the disappearing primitive societies of the Afrasian steppe, spawned the ancient Egyptian and Sumerian civilizations.
The peoples of the Afrasian pastures had to answer the challenge droughts while the peoples of the Asian highlands could still shirk the challenge.
Drought followed by a rainy season, a brown river flowed beyond the blue river, and our Bandeira could not reach its goal, moving from the Southern Cross to the North Star.
Dignam, the victim of a stroke, lies in the ground, and after a brutal droughts, praise to the Lord, at last it did awake, the barman brought the peat, having sailed about fifty miles or so, and said that the crops did not sprout, the fields were dry, they looked dejected and smelled superbly, whether in the lowlands or on the hills.
You were not driven from your usual places drought, but pitiful aliens, who are even weaker than big-eyed dwarfs.
In his opinion, the appearance of such a large number of dingoes near the pasture foreshadowed the imminent onset of a large droughts.
If the issue of tree planting and forest protection, it would seem, is so obvious, and then the population of the planet does not take much, then the issues of herbs and plants fighting deserts and droughts, even less often occupy the attention of mankind.
If you think a little, in addition to agricultural products, you can use almost any object, phenomenon, living organisms for homemade retarders: snow, ice, water, sand, salt, sugar, drought, thunderstorm, day, night, the onset of winter, bed bugs, etc.
How in drought ears thirst for rain, so the Italians thirst for reunification with the empire, - admonished Justinian Munda, Belisarius and many commanders subordinate to them.
Of course, the climate in different periods of the Cenozoic could not help but change, and those lands, which are now dominated by a temperate climate, from the beginning of the Cenozoic era were consistently exposed to intense heat, extreme cold and droughts.
Then Turu used the well-known against droughts and crop failure means: sacrifices, spells, bypassing fields with prayers.
Who in droughts, - asked Opivalo, - drinks half a stream, and then walks through all the fields of our village and sprinkles them, while, mind you, with his mouth?
A few minutes later, Paisley approaches, his hair doused with bergamot oil, and he sits on the other side of Mrs. droughts, he and Lumley Chaff's Snout had made a bet on a silver-trimmed saddle to pick the most dead cows.