A message on the topic of drought in geography. Drought - consequences of climate change? Drought control
Introduction
1. Formation of droughts
2. Types of drought
3. Known droughts
4. Fight 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 moisture reserves in the soil dry out (through evaporation and transpiration) and unfavorable conditions are created for the normal development of plants, and the yield of field crops is reduced or perishes.
1. Formation of droughts
As a rule, droughts are accompanied by hot weather, extremely dry air, and sometimes by strong burning winds, which create all the conditions favorable for increased evaporation of soil moisture. The soil dries up first from the surface, then, thanks to the cracks that appear, deeper and deeper, and the plants growing on it, not being able 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. Thus, in the steppes of southern Russia, where in summer precipitation falls mainly in the form of showers, extremely abundant in terms of the amount of water they bring, but short 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 part of the moisture that has time to soak into the ground does not benefit the plants, because, thanks to the hot weather again, it evaporates very quickly. The onset of drought in many cases depends on a number of other causes, among which, undoubtedly, is the destruction of vast forests.
It is precisely where the presence of forests is most important "as regulators of the life of rivers and springs", in the upper reaches of the rivers and along their slopes, that they turn out to be almost completely reduced (for example, near the upper reaches of the Volga, Don, Dnieper, etc.). As a result of such predatory destruction of forests, strong floods occur in spring. The rivers turn, as it were, 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 to what was previously delayed by forests and fed rivers and springs in the summer. The shallowing of many, formerly many water, rivers (Bityug, Vorskla) and, in general, a decrease in the water surface and, associated with it, air humidity, also depend 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, following the deforestation and drought of the slopes, the mass of inconvenient land increases.
The strength and impetuousness of the dry wind is so great that it blows away crops, blows out the surface layer of 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 northeast winds. Terrible blizzards, sometimes lasting for a whole week, are not rare in southern Russia. From the high steppe, snow is carried by these winds into ravines and gullies, leaving the 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 the plowing of steep slopes. The essence of drought is the lack of moisture in the soil during the period of plant growth, which always adversely affects their development and is often the main cause of crop failure, and sometimes complete crop failure of grain and grass.
Droughts with adverse effects on crops are observed especially in the steppe zone, less often in the forest-steppe and in the south of the forest zone. On the ETC for 65 years 3. crops were harmed 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 result, soil drought, i.e. desiccation of the soil, resulting in insufficient provision of plants with water.
The atmospheric regime during drought is due to the predominance of stable anticyclones, in which the air warms up strongly in clear weather and moves away from the saturation state.
The beginning of a drought is usually associated with the establishment of an anticyclone. The abundance of solar heat and dry air create increased evaporation (atmospheric drought), and soil moisture reserves are depleted without replenishment by rains (soil drought).
During drought, the flow of water into plants through the root systems is hindered, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of tissues decreases, and the normal conditions for photosynthesis and carbon nutrition are violated.
2. Types of drought
soil drought- drying of the soil associated with atmospheric drought, i.e. with certain weather conditions during the growing season, and leading to insufficient supply of vegetation, primarily crops, with water, to its oppression and reduction or death of the crop.
Physiological drought- a phenomenon when, at high daytime temperatures in spring, the transpiration of tree species increases, and the supply of water by roots due to low soil temperature is not provided. The plant begins to starve, despite the presence in the soil of a sufficient amount of water and mineral compounds.
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, a spring drought turns into a summer one, or a summer drought turns into an autumn one, or a drought that begins in spring continues until late autumn.
spring drought most harmfully affects the first period of growth of spring crops. This drought is characterized by low relative air humidity, but low temperatures and cold dry winds. Often, prolonged winds cause dust storms that exacerbate 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 winter seedlings.
Particularly harmful is the prolonged spring drought, which developed against the background of insufficient soil moistening by precipitation in the autumn-winter period with small reserves of soil moisture. Under such conditions, plants develop very poorly, and even the onset of rainy weather will not be able to completely eliminate the effects of drought: the crop will turn out to be reduced.
For example, in 2002–2003, summer in the Republic of Adygea came on time close to the 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° below the long-term average. One decade was within the normal range. The highest temperatures (35–37°) were observed in the first decade of July, the third of August and the first of 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 long-term average value.
3. Known droughts
In Russia, its southern and southeastern outskirts, drought is a common phenomenon, repeating itself at more or less long intervals. The history of our fatherland retained 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 ("famine from crop failure, crop failure from a bucket"), although exact information about the causes that gave rise to such crop failures and their size has not been preserved. Only about 1833 and 1840. it is known that crop failure in these years depended mainly on drought. In terms of the size of the area covered by crop failure, the largest crop failure in 1891, when 21 provinces suffered from drought, and the shortage of grain 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 during the winter months exceeded +30°C, local reservoirs were almost empty. Since the beginning of the year, the shortage of water supply on the island has amounted to more than 17 million cubic meters of water. Last week, the country began severe cuts in water supply.
The drought that affected the United States, Southern Europe, and Southwest Asia from 1998–2002 was linked to water temperatures in the tropical Pacific and Indian Oceans. For four years now, some areas in the northern hemisphere have received less than half of the annual rainfall. It dries up farms, empties reservoirs, lowers the water table. And it is not yet clear when this drought will end.
4. Fight drought
Fundamental measures to counteract drought should consist in increasing running water in a given area, increasing ground water and maintaining moisture reserves. This can be achieved mainly by dense afforestation, especially in the upper reaches of the rivers and along their slopes, and by planting forest edges and hedges along the passes. Only under such conditions is it possible to correctly distribute the snow cover, which would provide moisture to the soil. Both the government (since 1813) and private individuals are working in this direction, mainly in the steppe zone. Another means to combat drought is the artificial irrigation of fields and meadows. It is borrowed from the mountainous areas, where the high-water rivers flow, which, moreover, have a large fall. Water from such rivers is diverted by canals to the fields and distributed over their surface with the help of furrows, or they are directly flooded completely. In flat and shallow areas, such as, for example, our steppes, winter moisture reserves are used. Melt water is collected by drainage channels into ponds, usually arranged in the upper reaches of the beams, and the valley and slopes of this beam or ravine are irrigated with water from such reservoirs. Another method is also possible, which is called flooding. Along the slope, parallel to its ridge, several rows of dams or ridges are arranged. The spring water held by them, as the upper areas are moistened, descends lower and lower. In the Semirechensk region, huge glaciers are made of snow on the passes, they are covered with earth or straw to protect them from rapid melting, and gradually they use this supply of water, conducting it in small grooves to the fields. In addition to these measures, the farmer has many more means at his disposal to prevent drought.
Obviously, a field littered with wild vegetation, and, moreover, untimely and finely plowed field contains many conditions for the useless waste of soil moisture, and in favorable weather causes a struggle for moisture between plants. When prolonged hot weather and winds join this, the cultivated plants are powerless and die. The best means available to every farmer to combat drought is early and deep plowing, and especially black fallow. Dense soil poorly absorbs moisture and, at the same time, quickly evaporates it, due to the mass of hair channels in such soil, raising moisture from the lower to the upper. Loosening the top layer of soil destroys the network of capillaries, and creates more favorable conditions for the penetration of moisture into the ground.
With deep autumn plowing, it is possible to delay most of the autumn and winter precipitation in the fields in this way. Only with 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 of the top layer of soil, is the best means available to any farmer for the accumulation and preservation of moisture in the soil, and, consequently, for ensuring the economy from drought.
5. Deserts
Deserts cover approximately one-fifth of the Earth's surface and are found in areas where rainfall is less than 50 cm/year. Although 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, the cold desert, is found in the Utah and Nevada basins and ranges and in 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 be very useful and have little or no organic matter. Disturbances usually occur due to occasional fires or cold weather, and sudden, infrequent but intense rainfall leading to flooding.
Because desert is an ambiguous term, the use of the meaning "dryland" and its divisions into hyper-arid, 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 that stretches from Yemen to the Persian Gulf and Oman to Jordan and Iraq. It occupies most of the Arabian Peninsula with an area of 2,330,000 square kilometers (900,000 miles). At its center is Rubal-Kali, one of the largest continuous sand massifs in the world.
Gazelles, oryxes, sand cats and thorntail lizards are just some 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 do well here. Many species such as the striped hyena, jackal and badger have become extinct in this area due to hunting, human encroachment and habitat destruction. Other species have been successfully reintroduced into the area, such as the white oryx and sand gazelle, which are protected on numerous reserves. Overgrazing by livestock, off-road driving, and habitat destruction are the main threats to this desert ecoregion.
The temperature range of the desert is 40-50°C in summer, the average temperature in winter is 5-15°C, although it can drop to 0°C. Daily extremes are very significant.
Gobi Desert is a large desert area in China and southern Mongolia. The Gobi Desert basins are bounded by the Altai Mountains and the fields and steppes of Mongolia to the north, the Tibetan Plateau to the southwest, and the North China Plain to the southeast. The Gobi consists of several distinct ecological and geographic regions based on changes in climate 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 occasional 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 rainfall annually in the Gobi.
The climate of the Gobi is one of the great extremes, with rapid temperature changes, not only throughout the year, but even within 24 hours (up to 32°C or 58°F).
Kalahari Desert- a large arid sandy area in southern Kgalagadi in Africa, extending over 900,000 square meters. km (562,500 sq mi), covering most of Botswana and parts of Namibia in South Africa. It is a semi-desert with huge tracts that become excellent pastures after good rains. The Kalahari supports some animal and plant life because most of it is not a true desert. The desert receives little rain and summer temperatures are usually very high. The Kalahari usually receives 5-10 inches of rain annually.
However, the Kalahari is not a true desert. Parts of the Kalahari receive over 250 mm of chaotic rainfall annually and are quite well watered. It is truly arid only in the southwest (receiving less than 175mm of rain annually), where it transitions into rocky desert. Summer temperatures in the Kalahari range from 20 to 40°C. During the winter, the Kalahari has a dry, cold climate with frost at night. The lowest winter temperatures can average below 0°C. The Kalahari Desert is a harsh place and has 2 seasons - the dry season and the rainy season.
Animals that live in this area include brown hyenas, lions, merkats, several varieties of antelope (including the oryx or gemsbok), and many varieties of birds and reptiles. 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 few 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 around 8000 BC. before 6000 BC, possibly due to low pressure areas of the collapsing ice sheet to the north. Once the ice sheet was gone, the northern part of the Sahara dried up.
The Sahara desert has one of the harshest climates in the world. There are many strong winds that blow from the northeast. Sometimes in the border regions of the north and south, the desert receives approximately 25 cm (10 inches) of rain per year. Showers happen very rarely, but if they fall out, they are usually plentiful. This happens after long dry spells 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 opposed to arid deserts.
These deserts are characterized by cold winters with snowfalls and fairly heavy rainfall during winter and sometimes summer. These deserts are located in Antarctica, on the island of Greenland and the non-Arctic region. Deserts have short, damp and moderately warm summers and fairly long, cold winters. The average winter temperature ranges from -2 to +4°C, and the average summer temperature ranges from 21 to 26°C.
Quite a bit of snow falls in winter. The average precipitation rate is 15-26 cm. The average annual precipitation reached a maximum of 46 cm and a minimum of 9 cm. The heaviest spring showers usually occur in April or May. In some areas the rains 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 sufficiently porous and the drainage is so good that almost all the salt has been washed away.
Plants are widely scattered. Leafy areas cover about 10 percent of the land, but in some areas sagebrush reaches 85 percent. The height of the plants varies between 15 and 122 cm. The main plants are deciduous, most of them have thorny leaves. Widely distributed animals are American hares, marsupial rats, marsupial mice, grasshopper mice, sac jumpers and antelope ground squirrel.
Literature
1. P.F. Barakov, "On possible measures to combat drought."
2. A.S. Yermolov, 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 combating 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 influence on the sectors of the Russian economy” Moscow, Roshydromet, 2005.
8. "The climate of the Rostov region: yesterday, today, tomorrow" V.D. Panov, P.M. Lurie, Yu.A. Larionov, Rostov-on-Don, 2006.
Introduction
1. Formation of droughts
2. Types of drought
3. Known droughts
4. Fight 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 moisture reserves in the soil dry out (through evaporation and transpiration) and unfavorable conditions are created for the normal development of plants, and the yield of field crops is reduced or perishes.
1. Formation of droughts
As a rule, droughts are accompanied by hot weather, extremely dry air, and sometimes by strong burning winds, which create all the conditions favorable for increased evaporation of soil moisture. The soil dries up first from the surface, then, thanks to the cracks that appear, deeper and deeper, and the plants growing on it, not being able 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. Thus, in the steppes of southern Russia, where in summer precipitation falls mainly in the form of showers, extremely abundant in terms of the amount of water they bring, but short 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 part of the moisture that has time to soak into the ground does not benefit the plants, because, thanks to the hot weather again, it evaporates very quickly. The onset of drought in many cases depends on a number of other causes, among which, undoubtedly, is the destruction of vast forests.
It is precisely where the presence of forests is most important "as regulators of the life of rivers and springs", in the upper reaches of the rivers and along their slopes, that they turn out to be almost completely reduced (for example, near the upper reaches of the Volga, Don, Dnieper, etc.). As a result of such predatory destruction of forests, strong floods occur in spring. The rivers turn, as it were, 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 to what was previously delayed by forests and fed rivers and springs in the summer. The shallowing of many, formerly many water, rivers (Bityug, Vorskla) and, in general, a decrease in the water surface and, associated with it, air humidity, also depend 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, following the deforestation and drought of the slopes, the mass of inconvenient land increases.
The strength and impetuousness of the dry wind is so great that it blows away crops, blows out the surface layer of 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 northeast winds. Terrible blizzards, sometimes lasting for a whole week, are not rare in southern Russia. From the high steppe, snow is carried by these winds into ravines and gullies, leaving the 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 the plowing of steep slopes. The essence of drought is the lack of moisture in the soil during the period of plant growth, which always adversely affects their development and is often the main cause of crop failure, and sometimes complete crop failure of grain and grass.
Droughts with adverse effects on crops are observed especially in the steppe zone, less often in the forest-steppe and in the south of the forest zone. On the ETC for 65 years 3. crops were harmed 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 result, soil drought, i.e. desiccation of the soil, resulting in insufficient provision of plants with water.
The atmospheric regime during drought is due to the predominance of stable anticyclones, in which the air warms up strongly in clear weather and moves away from the saturation state.
The beginning of a drought is usually associated with the establishment of an anticyclone. The abundance of solar heat and dry air create increased evaporation (atmospheric drought), and soil moisture reserves are depleted without replenishment by rains (soil drought).
During drought, the flow of water into plants through the root systems is hindered, the consumption of moisture for transpiration begins to exceed its inflow from the soil, the water saturation of tissues decreases, and the normal conditions for photosynthesis and carbon nutrition are violated.
2. Types of drought
soil drought- drying of the soil associated with atmospheric drought, i.e. with certain weather conditions during the growing season, and leading to insufficient supply of vegetation, primarily crops, with water, to its oppression and reduction or death of the crop.
Physiological drought- a phenomenon when, at high daytime temperatures in spring, the transpiration of tree species increases, and the supply of water by roots due to low soil temperature is not provided. The plant begins to starve, despite the presence in the soil of a sufficient amount of water and mineral compounds.
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, a spring drought turns into a summer one, or a summer drought turns into an autumn one, or a drought that begins in spring continues until late autumn.
spring drought most harmfully affects the first period of growth of spring crops. This drought is characterized by low relative air humidity, but low temperatures and cold dry winds. Often, prolonged winds cause dust storms that exacerbate 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 winter seedlings.
Particularly harmful is the prolonged spring drought, which developed against the background of insufficient soil moistening by precipitation in the autumn-winter period with small reserves of soil moisture. Under such conditions, plants develop very poorly, and even the onset of rainy weather will not be able to completely eliminate the effects of drought: the crop will turn out to be reduced.
For example, in 2002–2003, summer in the Republic of Adygea came on time close to the 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° below the long-term average. One decade was within the normal range. The highest temperatures (35–37°) were observed in the first decade of July, the third of August and the first of 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 long-term average value.
3. Known droughts
In Russia, its southern and southeastern outskirts, drought is a common phenomenon, repeating itself at more or less long intervals. The history of our fatherland retained 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 ("famine from crop failure, crop failure from a bucket"), although exact information about the causes that gave rise to such crop failures and their size has not been preserved. Only about 1833 and 1840. it is known that crop failure in these years depended mainly on drought. In terms of the size of the area covered by crop failure, the largest crop failure in 1891, when 21 provinces suffered from drought, and the shortage of grain 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 during the winter months exceeded +30°C, local reservoirs were almost empty. Since the beginning of the year, the shortage of water supply on the island has amounted to more than 17 million cubic meters of water. Last week, the country began severe cuts in water supply.
The drought that affected the United States, Southern Europe, and Southwest Asia from 1998–2002 was linked to water temperatures in the tropical Pacific and Indian Oceans. For four years now, some areas in the northern hemisphere have received less than half of the annual rainfall. It dries up farms, empties reservoirs, lowers the water table. And it is not yet clear when this drought will end.
4. Fight drought
Fundamental measures to counteract drought should consist in increasing running water in a given area, increasing ground water and maintaining moisture reserves. This can be achieved mainly by dense afforestation, especially in the upper reaches of the rivers and along their slopes, and by planting forest edges and hedges along the passes. Only under such conditions is it possible to correctly distribute the snow cover, which would provide moisture to the soil. Both the government (since 1813) and private individuals are working in this direction, mainly in the steppe zone. Another means to combat drought is the artificial irrigation of fields and meadows. It is borrowed from the mountainous areas, where the high-water rivers flow, which, moreover, have a large fall. Water from such rivers is diverted by canals to the fields and distributed over their surface with the help of furrows, or they are directly flooded completely. In flat and shallow areas, such as, for example, our steppes, winter moisture reserves are used. Melt water is collected by drainage channels into ponds, usually arranged in the upper reaches of the beams, and the valley and slopes of this beam or ravine are irrigated with water from such reservoirs. Another method is also possible, which is called flooding. Along the slope, parallel to its ridge, several rows of dams or ridges are arranged. The spring water held by them, as the upper areas are moistened, descends lower and lower. In the Semirechensk region, huge glaciers are made of snow on the passes, they are covered with earth or straw to protect them from rapid melting, and gradually they use this supply of water, conducting it in small grooves to the fields. In addition to these measures, the farmer has many more means at his disposal to prevent drought.
Our planet, civilizations, mankind for thousands of years have been faced with phenomena that contribute both to their formation and development, and to destruction. Echoes of cataclysms and natural disasters are heard every day even to the most comfortable areas of the Earth for living. One of such phenomena, characteristic of every era and overtaking hundreds of thousands of lives every minute, is drought. This is
Causes of drought
Drought is characterized by a long absence of precipitation and consistently high air temperatures, leading to the disappearance of plants, dehydration, hunger and the death of animals and people. The reasons for such destructive natural processes were identified in the first half of the twentieth century. And the global climatic phenomena themselves are called El Niño and La Niña.
The phenomena that were given such touching names are a prolonged temperature anomaly, the interaction of air and water masses, which, with a frequency of 7-10 years, make different parts of our planet literally shudder from the abundance or lack of moisture.
Threats and consequences
In some areas of the Earth, hurricanes, tornadoes and floods rage, while others die from lack of water. These terrible phenomena with children's names, according to many scientists, destroyed powerful ancient civilizations, for example, the Olmecs; in the life of a number of peoples of the American continent provoked the development of cannibalism, which captured Indian tribes in dry years. Now the prolonged absence of rains and heat lead to mass deaths of people, mainly in Africa, destroy and cause serious damage to the agricultural sector of the North American continent and Europe. Therefore, there is no doubt that drought is a reason for humanity to mobilize all its forces, knowledge and other resources in the fight against a not fully understood, but very formidable natural enemy.
Hot summer
Drought in Russia also remains an actual phenomenon. Every year, in the summer months, in a number of regions, the Ministry of Emergency Situations introduces a regime due to the stable high air temperature, coupled with the almost complete absence of precipitation, which sooner or later provoke fires in vast areas. Russians remember 2010 as a thick smoke screen that stretched for thousands of kilometers. At the same time, forests raged in fifteen regions of the country and destroyed settlements and infrastructure along with trees. The damage to the population and the state as a whole turned out to be colossal. Residents suffocated from smoke, and insurance companies - from fabulous payments.
Agricultural crops were under attack, as well as dairy farming, which faced an acute shortage of feed. It was in 2010 that the drought in Russia marked a new temperature record, set 70 years after such an abnormally hot summer.
Drought in autumn: a threat to winter crops
Drought often takes agriculture by surprise in autumn. It would seem that autumn is a period of rains, the first snow and temperatures that are relatively acceptable for plant life. However, rainfall that does not fall in time often affects the entire crop, the areas of which are large. That is why agricultural workers keep their finger on the pulse even in autumn.
The problem of the whole world
Billion-dollar losses, inflation surges, famine, mass death of people and animals. All these are the consequences of the drought. Every day, there are reports in the news about one or another example of abnormal heat without precipitation. So, in 2011, the victims of the drought were the inhabitants of China. The flood, which had harmed more than 3,000 people, was replaced by an unusually unbearable heat. The extreme drop in the water level in the Yangtze River has hampered navigation and, as a result, caused damage to many areas of activity. The failed rice harvest created a crisis situation in the agricultural commodity market.
Most recently, in December 2015, the drought literally changed the geographical characteristics of the whole country - in Bolivia, one of the largest lakes, Poopo, was destroyed by continuous heat. Due to the fact that local residents previously existed due to fishing alone, already in January 2016, a significant outflow of the population was observed in this region.
Climate change has had the most significant impact on the African continent. It is from there that disturbing news and calls for collection are heard with frightening regularity. The difficult situation with the rebels who deny the catastrophe and prevent the transfer of food, further exacerbates the situation. Drought in Africa is a particularly merciless phenomenon. The world community does not leave what is happening without attention, but a huge number of people die from year to year.
Despite the fact that humanity is making huge strides towards its power, nature is still beyond its control, and one has only to put up with its whims, sometimes very cruel. Overtaking the continents one by one, the drought confirms this.
Stable weather, lack of rain, high air temperature with extremely low levels of humidity - all these factors lead to drought.
This period can last from a couple of weeks to two or three months in different areas.
Why does drought occur?
Drought is associated with such a climatic phenomenon as a high anticyclone. In essence, this is the formation of an area of high atmospheric pressure. A high anticyclone is warm, characterized by clear weather, lack of precipitation and wind, and low mobility of air masses.
In temperate latitudes, droughts, as a rule, occur in the steppes, less often in the forest-steppes. According to the observations of scientists, once every two hundred or three hundred years, a drought is recorded even in wooded areas. In the subtropics and the subequatorial zone, droughts occur regularly, since precipitation in such regions occurs only during the rainy season.
Drought types
Depending on where there is an acute lack of moisture, atmospheric and soil drought are distinguished. Atmospheric creates an increased evaporation of moisture due to the abundance of the sun and reduced air humidity. Soil drought refers to the depletion of the soil due to the lack of rain, due to which the groundwater supply could be replenished. 
If this period lasts for a long time, then lakes, ponds, small rivers begin to dry up, and then we can already talk about hydrological drought. Depending on the season, the drought can be spring, summer, autumn.
Why is drought dangerous?
During the period of drought, the flow of water to the root system of plants stops, the consumption of moisture exceeds its inflow, the water saturation of plant tissues decreases critically, and the normal conditions for its growth are violated. Spring drought can kill early crops, summer drought damages fruit plants, early and late crops; autumn drought destroys winter crops.
Drought can lead to fires and prolonged fires in the steppes or forests, as well as to peat fires, resulting in smoke that is extremely dangerous for the body. 
Drought is detrimental to people. According to statistics, more than a million people died in Africa from droughts in forty years. The UN even established World Drought Day on June 17th.
How to deal with drought?
To predict the likelihood of a drought, measurements of moisture reserves in the soil, accurate calculations of the volume of snow cover help. For example, if the moisture reserve in a meter-long layer of soil in autumn does not exceed 50% of the average annual level, or the snow thickness does not reach half of the average values for a long-term measurement period, then the risk of drought is very high. This means that protective measures must be taken.
To prevent drought, a number of actions are taken to keep moisture in the soil and to keep snow in the fields. The land is deeply plowed, transverse plowing is carried out on the slopes, and the microrelief of the arable land surface is changed. It is especially important to do this on soils with high density.
With the help of sanding, harrowing, cultivation, they try to keep the soil in a loose state. It helps to maintain the viability of plants by timely feeding with fertilizers, regulation of snow melting processes, accelerated pre-sowing soil preparation. 
An effective way is to combine crops of different types of crops that need different amounts of rainfall at certain times of the year. For example, winter crops are resistant to summer droughts, but need moisture in autumn; early spring, on the contrary, require special humidity in the first half of summer. Agronomists also grow special drought-resistant varieties of various crops.