As a result, floods occur. Flood - types and causes

History remembers several of the most terrible floods; such natural disasters also occurred in Russia, including in St. Petersburg. Several devastating floods occurred in the 20th century.

The worst floods in history

In historical chronicles you can read about many severe floods that claimed several hundred thousand human lives. Because natural disasters like these happen unexpectedly, people are left unprepared for them.

Some floods occur due to river overflows, dam failures, incessant rainfall, ocean earthquakes and tsunamis. We know about floods that were deliberately caused by people.

Flood of St. Mary Magdalene

One of the most destructive floods occurred in 1342. It is considered the largest in Central Europe. Several rivers overflowed their banks at once: the Rhine, Weser, Main, Moselle, Werra, Elbe, etc. Having flooded the surrounding lands, the water harmed such large European cities as Cologne, Passau, Vienna, Regensburg, Frankfurt am Main.

The reason was heavy rains that had been falling for several days. The exact number of those who drowned is unknown; we can say that there were several thousand people. This natural disaster was called the St. Mary Magdalene Flood.

Burchardi flood

More than eight thousand people were killed by a flood that occurred in 1634 in Denmark and Germany. Due to hurricane winds, a storm surge of water began, leading to a dam failure in several places along the North Sea coast.

The communities of North Frisia and many coastal towns were flooded. This flood is called the Burchardi flood.

Floods on the Yellow River

As you know, the Yellow River is one of the most capricious rivers in China. She is famous frequent floods, and more than once its waters have claimed many human lives. The largest Yellow River spills occurred in 1887 and 1938.

In 1887, after prolonged rains, multiple dam breaks occurred. Due to the flooding, almost two million people lost their homes and nine hundred thousand people died. In 1938, the flood was provoked by the Nationalist government, thus wanting to stop the advance of Japanese troops into China. Many villages and thousands of hectares of agricultural land were destroyed, almost five hundred thousand people drowned, and millions became refugees.

The worst floods of the 20th century

In the 20th century, unfortunately, there were also floods. One of them happened in China in 1931 on a river called the Yangtze. It is estimated that about four million people died. This flood is considered the most severe after the Great Flood. Four million houses were demolished, three hundred thousand square kilometers were covered in water.

In 1970, severe flooding occurred in the Ganges Delta in India. It claimed the lives of five hundred thousand people. It was caused by the waters of the Kosi River and heavy monsoon rains. Having broken the dam, the waters of the Kosi changed their course and flooded a huge region that had never before been subject to flooding.

In 1927, a flood called the “Great” occurred in America. The waters of the Mississippi overflowed their banks due to heavy rains. Flooding affected the territory of ten states, reaching ten meters in depth in some places. In order to avoid flooding New Orleans, it was decided to blow up a dam near the city. As a result, other areas were flooded. About five hundred thousand people died.

At the end of April 1991, the devastating cyclone Marian raised a nine-meter wave off the coast of Bangladesh. The flood resulted in the death of one hundred and forty thousand people. The lands flooded with salt water became unsuitable for agriculture for many years.

Floods in St. Petersburg

St. Petersburg suffered from floods quite often. The city was flooded at least three hundred and thirty times. In different areas you can see memorial plaques on houses showing the water level. There are about twenty such tablets.

In 1691, even before the founding of St. Petersburg, when the territory of the city was under the Swedes, it was also flooded by the waters of the Neva. This is evidenced by Swedish chronicles, according to which the water level in the river rose to seven hundred and sixty-two centimeters.

The worst flood occurred in 1824. According to various estimates, from two hundred to six hundred thousand citizens died as a result. It is known that the water level in the Neva has risen by more than four meters. Many houses were destroyed and flooded. Before the flood, heavy rain began, followed by a sharp rise in water.

The worst flood in the world - the Great Flood: myth or reality

Not only the Bible tells about the Great Flood; many peoples living in almost all parts of the planet have similar descriptions of the terrible flood. You can read about the flood in the myths of the Indians of California, it is described in ancient Mexican manuscripts, and the myths of the Canadian Indians. It is known about the Japanese “variant” of the flood. Quite rarely, it is reported by manuscripts found in the interior regions of Africa and Asia, which are located at a considerable distance from the oceans and seas.

We can conclude that many legends about the flood are associated with certain local phenomena that led to a sharp rise in water levels. Scientists have expressed several versions of the occurrence of a powerful flood. Most likely, the so-called Great Flood occurred in different parts of the Earth, was different in each region and had its own causes on different continents.

Floods also bring with them giant waves. .
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After the Great Flood inundated the entire surface of our planet, floods are considered one of the most dangerous natural disasters in the world. While they may not look as grandiose and impressive as a sudden tornado or typhoon, and often give people time to leave the dangerous area, the consequences of floods are no less dire.

Thus, the largest documented flood in the world occurred in China in the thirties of the last century, when the longest and deepest river in the country, the Yangtze, together with the neighboring Yellow River, after prolonged rains, overflowed their banks, destroying dams and flooding more than 300 thousand hectares of fertile land ( in some areas the water did not drain for about six months). When the river waters calmed down, the consequences of the flood were so catastrophic that the world shook: according to official data alone, the death toll exceeded 3.7 million people.

A flood is the inundation of large areas, which was caused by a rise in water levels in lakes, rivers, seas after heavy rainfall, snow melting, or a dam breaking, which led to the release of water far beyond the borders. coastline.

Despite the fact that in most cases the population can be warned about the approach of a natural disaster, warnings are often ignored due to the fact that local residents refuse to leave their homes in the hope that the disaster will bypass them. And it’s completely in vain: the advancing water spares no one and not only destroys buildings (especially buildings with a shallow foundation and constructed of wood), but often leads to human casualties.

Speaking about the causes of floods, hydrologists identify the following factors:

• Long rains - this type of flood occurs only in humid areas, which are characterized by a large number of precipitation. For example, numerous downpours, which often fall in the summer on the Abyssinian Highlands, supplying the Nile with water, lead to the river annually flooding the entire valley of the mouth. Despite the fact that the soil here is ideal for the development of agriculture, it is impossible to delay harvesting, otherwise it will be destroyed by the rising waters.
• Melting snow - the cause of flooding is the intense melting of the snow cover, when the water entering the ground is quickly directed to nearby rivers, sharply increasing the amount of water in them, as a result of which even a very small river increases in size many times over.
• Tsunamis - floods that bring with them tsunamis most often become catastrophic, often flooding the entire coast and going deep up to four kilometers. A tsunami is formed in the ocean as a result of the shift of lithospheric plates, and huge waves can also form in lakes and bays after large landslides fall into them from a height.
• Raising the bottom - over time, any river accumulates sediment in places where it bends, which causes flooding. The depth of the river in these places decreases, but the flow expands, flooding the coastal strip.
• A reservoir breakthrough is an extremely destructive element, since the flow of water that breaks through is extremely strong, and therefore is not inferior in strength to a tsunami: it demolishes everything that is in its path, regardless of the weight of the object.

What are floods like?

Naturally, not all types of floods lead to catastrophic consequences. Those that occur most frequently are not as destructive as those that occur once every few decades, but the effects of such floods are felt over a significant period. Therefore, hydrologists, focusing on the consequences of floods, classified the elements into four groups and gave them a description.

Small floods created by lowland rivers cover small coastal areas, occur once every five to ten years, and the population easily copes with the consequences of floods of this type.

Floods classified as “Dangerous” are much more serious. They happen less frequently, once every 20-25 years. Covering quite a large land located in river valleys, cause significant material damage, flooding from 10 to 20% of crops. In some cases, partial evacuation of the population is even required.

Floods, which hydrologists call “Particularly Dangerous,” occur once every fifty to hundred years. Having overflowed its banks, the river waters completely fill the river basins, destroying from 50 to 70% of crops, and in some cases, populated areas. As a result, all agricultural activities and the life of the region are paralyzed, and the way of life of local residents is sharply disrupted, especially considering the fact that during particularly dangerous floods, mass evacuation of the inhabitants of a dangerous area is required.

The most dangerous types Floods in the world are classified as “Catastrophic” (this is the type of flood that befell China in the thirties of the last century). They flood the area of ​​one or more water systems, destroying almost all agricultural land, settlements (including cities), and causing mass death of people. The country usually copes poorly with the consequences of floods of this scale and requires international assistance, since disasters often cause a humanitarian catastrophe.

In addition to the classification according to the consequences of flooding, there are the following types of floods, based on the description of this phenomenon:

1. High water. This type of flood on the plains inundates low-lying areas and occurs in the spring during snowmelt or after rain. Usually refers to small floods, but in some cases, if the soil was very saturated with moisture in the fall and was very frozen in winter, the consequences of the floods can be catastrophic.
2. Flood. A rapid but short-term rise in water levels in rivers is called a leash. This type of flood can occur several times a year, as its occurrence is primarily influenced by heavy rainfall and, in some cases, rapid melting of snow during thaws.
3. Congestion. Jams form in early spring due to blockage of rivers by a stationary ice block or several ice floes, which slow down the river flow and cause water to rise above the ice. Floods of this type are characterized by a high but short rise in the water level in the river.
4. Gluttony. Ice flooding occurs due to an ice plug, which is a concentration of loose ice in narrowing areas of the river. During this flood, the water does not rise as much as during jams, but at the same time this flood lasts longer.
5. Wind surge. This flood is characterized by a large rise in water and is caused by wind. Since for this to happen, air flows need to properly disperse the wave, wind surge is usually recorded on the sea coast, at the mouth of a river, on large lakes, and reservoirs. Predicting this flood is not easy, since it is characterized by a lack of periodicity and short duration.
6. Break in the reservoir. Floods of this type are formed due to the failure of a reservoir, dam, or dam. Despite their short duration, these floods are dangerous due to their suddenness and unpredictability, as a result of which a significant area is under water, and many objects that are in the path of the water are destroyed.

What to do in case of floods

To reduce the risk of occurrence and minimize the consequences of floods, flood protection is created in reservoirs - shallows are poured, riffles are deepened, and to regulate river flow, protective dams are built on the seashore, and reservoirs are built on rivers that level out the flow of the river flow, increasing it in summer and decreasing it in the spring.

Unlike other natural disasters, scientists predict the likelihood of a flood quite accurately (unless, of course, they are the result of events that are not easy to predict, such as a tsunami or a dam failure). Once warned of an impending disaster, people have time to put in place the necessary flood protection.

If a catastrophe of enormous proportions is coming, special services they begin to evacuate the population (however, these actions are not always successful, since many refuse to leave their homes).

People living in areas prone to floods must know the rules of behavior during floods in order to correctly calculate their actions in emergency situations. To do this, it is necessary to study in advance the boundaries of possible flooding, and also take into account all the hills and places that will be least affected by the elements, and where it will be possible to wait out the flood. It is also worth finding out in advance where boats, rafts or building materials are located so that in the event of a disaster you can make them into a floating craft.

The danger zone should be left as soon as information about flooding appears. It is also worth taking with you a pre-prepared backpack with documents, medicines, valuables, warm clothes and a two-day supply of food. Before leaving the house, you need to turn off the electricity, turn off the gas, extinguish the fire in the stoves, it is advisable to secure light objects outside the room so that they do not float away. Window and door openings should be locked, and if possible, the outside should be covered with boards or shields.

If you can’t leave the house, you need to get out onto the roof and attach a banner so that rescuers know where to look for you. If it is night outside, you need to signal your location with a torch or flashlight. When rescuers approach, you need to calmly, without sudden movements go to the rescue boat and then listen to their instructions.

If there is no help, and the water remains and threatens to flood the shelter, you need to take a raft or object that can be used instead of a floating device and swim in the right side, remembering to send distress signals. If people are found in the water along the way, everything must be done to save them. To do this, you need to calm the drowning person down and then throw him a rope. If a person is in a state of panic and does not understand anything, you need to swim up to him from behind and tow him by the hair so that he cannot drown the rescuer.

Returning after a flood, before going home, you need to make sure that the building is strong and will not collapse, and then ventilate the room. Before turning on electrical appliances, or even lighting a match, be sure to check the gas pipeline, electrical wiring, as well as water supply and sewerage for serviceability (it is advisable to do these actions with specialists). After making sure that everything is in order, you need to pump out water from the basements, dry the rooms, and clean the wells from dirt.

People have long built cities near rivers, seas and other large bodies of water. They served as transport, a source of fish, and natural protection. Modern settlements have been preserved in place of old ones. But at the same time, some of them have become areas of flooding that occur on a regular basis. Why is this happening and what does it mean?

Essence

Most people probably know the biblical story about the Great Flood, in which almost all of humanity perished. Perhaps this in itself is an indicator that flooding is extremely dangerous phenomenon, bringing destruction, chaos and death to all living things. They may not look as impressive as earthquakes or typhoons, but their power should not be underestimated.

Flood is essentially the inundation of large areas due to various reasons. They can be either quite rapid or occur gradually. In other words, huge volumes of water end up where they shouldn't be - on land. There are several classifications of floods, both according to the criterion of danger or scale, and according to the consequences.

Quite often, floods accompany other natural disasters. Thus, an earthquake may be accompanied by a tsunami and subsequent flooding of coastal areas. After Hurricane Katrina, New Orleans also experienced flooding, leaving hundreds of thousands of people homeless.

Causes of floods

They can occur as a result of various events, and this affects their character. If we talk about more or less general causes of floods, they can be as follows:

• Prolonged precipitation. Heavy and prolonged rains in low-lying areas create a situation where moisture simply has nowhere to go. If she doesn’t have time to leave, flooding results.
• Rapid melting of snow. Sometimes in spring the temperature rises very quickly and sharply. At this time, all the snow that fell during the winter begins to melt. If its volume is large, there is a danger of both local and fairly extensive flooding.
• Raising the bottom of reservoirs. In any river or lake, over time, some sediment appears in the form of remains of dead organisms and plants, silt, and sometimes even garbage. This can cause the seabed to rise and, accordingly, change the coastline, sometimes with flooding of areas that were previously out of danger.
• Reservoir breakthrough. Any engineering structures built by man have their own safety margin. Sometimes dams fail due to some event, and then we can expect a destructive, but rather short-lived flood.
• Tsunami. A wave formed in the ocean after strong tremors quite regularly devastates coastal areas, for example, in the countries of Southeast Asia.

An additional contributing factor to flooding can be clogged drains in the city's sewer system, which can result in consequences that are much more devastating than they otherwise would be. What could they be like?

Consequences

Flooding, as has already become clear, is no joke. It has some damaging factors. As you know, water is a universal solvent. With prolonged exposure to some materials, it can completely destroy them. Cracks appear in the walls of houses and agricultural crops are destroyed. Another serious danger is the wave itself, if the flood is fast enough. It literally demolishes the walls of buildings, leaving behind rubble, under which people remain. There is a special classification indicating the scale and danger of each specific flood:

• Small or low. They are observed when large rivers flood in low-lying, flat areas. They are characterized by a relatively small scale and practically do not affect the rhythm of life of the population.
• Dangerous. Cover up to 20% of agricultural land and quite large areas. Often lead to partial evacuation.
• Particularly dangerous. They disrupt the usual way of life and paralyze Agriculture, covering up to 70% of crops. Lead to mass evacuation.
• Catastrophic. They cause enormous moral and material damage, one or more populated areas are flooded, and there are casualties. Hundreds of thousands of people are being evacuated, and a humanitarian and environmental catastrophe is occurring.

Yes, a flood is not a sudden earthquake; you can often protect yourself from it. But it’s hard to argue with the fact that this is still an extremely dangerous phenomenon.

High Risk Areas

Low-lying areas, near which there are large bodies of water, are the first to be hit. For example, Venice is regularly flooded, despite any countermeasures. The same can be said about the Netherlands. The capital of this country, Amsterdam, has been battling the elements for a long time, fighting the sea for every meter of land. There are also areas in Egypt where the Nile overflows especially abundantly, but this happens regularly and naturally.

There are cities located at the mouths of large rivers or simply along their beds. Their residents also may not always feel safe.

Countermeasures

Fortunately, in most cases, scientists can more or less accurately predict flooding. In this case, the number of victims and casualties is significantly reduced, since it is usually possible to begin evacuation in time. If flooding is regular and not too large-scale, it makes sense to build special buildings: dams and sluices that can protect the city from rising water levels. When flooding has already happened, all that remains is to clear the rubble and save people while waiting for the moisture to subside.

People who are aware of the increased risk of flooding in their area should also be familiar with what to do in the event of a disaster. First of all, it is worth studying the location of the hills and the safest places nearby. If there is information about a disaster, you must follow everything recommended by local authorities. If they tell you to stay at home, you should do so. If evacuation is organized, instructions must be followed. Before leaving the house, you need to turn off all communications as much as possible and secure light items.

Floods in Russia

The areas in the Russian Federation where flooding occurs most often are St. Petersburg and the Krasnodar Territory. In the latter region, this natural disaster occurs almost every year. The last major one happened in 2012, when the city of Krymsk suffered the most from the disaster, which was almost completely destroyed.

In 2013, a large-scale natural disaster was observed in Far East. It was due to the fact that in about a month more than the annual norm of precipitation fell over the territory, as a result of which the rivers overflowed their banks. The situation was aggravated by the fact that the previous winter was very snowy, and spring came late, so the hydraulic systems were already saturated. Despite the enormous scale of the flood, no deaths were reported in Russia, while in China the number of victims and missing people was almost 200.

In St. Petersburg, hydrologists have been closely monitoring the behavior of rivers and canals for many years, tracking the slightest rise in water levels. Fortunately, in last years no serious problems were observed.

Types of flood	Causes	Charactermanifestations
High water	Spring melting of snow on the plains or spring-summer melting of snow and rainfall in the mountains	Repeat periodically in the same season. Significant and prolonged rise in water levels
	Intense rains and melting snow during winter thaws	There is no clearly defined periodicity. Intense and relatively short-term rise in water level
Congestion, gluttony (congestion, gluttony)	Large resistance water flow, formed in certain sections of the river bed, arising from the accumulation of ice material in narrowings or bends of the river during freeze-up (jazzhi) or during ice drift (jam)	Mash - at the end of winter or spring. A high and relatively short-term rise in the water level in the river. Gluttonous - at the beginning of winter. Significant (no less than during a jam) rise in the water level and a longer duration compared to jams
Surge	Wind surges of water in sea estuaries and windward areas of the coast of seas, large lakes, and reservoirs	In any season. Lack of periodicity and significant rise in water level
Flooding due to dam failure	An outflow of water from a reservoir or reservoir, resulting from a breakthrough of pressure front structures (dams, dikes, etc.), during an emergency release of water from a reservoir, during a breakthrough of a natural dam created by nature during earthquakes, landslides, landslides, and glacier movement	Formation of a breakthrough wave leading to flooding large territories and to the destruction or damage of objects encountered along the way (buildings and structures, etc.)

In the territory Russian Federation The first two types of floods predominate (about 70-80% of all cases). They are found on lowland, foothill and mountain rivers, in the northern and southern, western and eastern regions of the country. The remaining three types of floods have a local distribution.

Factors influencing the maximum rise in water level at various types floods are given in table. 2.2.

Table 2.2

Factors influencing the extent of flooding

Type of flood	Factors influencing the value maximum rise in water levels
High water	The reserve of water in the snow cover before the onset of spring melting; precipitation during snowmelt and flood periods; autumn-winter soil moisture by the beginning of spring snowmelt; ice crust on the soil; snowmelt intensity; combination of flood waves of large tributaries of the river basin; lacustrine, swampy and forested areas of the basin; relief of the pool
	The amount of precipitation, its intensity, duration, coverage area, previous precipitation, soil moisture and permeability, basin topography, river slopes, presence and depth of permafrost
Congestion, glutton	Surface speed of water flow, the presence in the channel of narrowings, bends, shoals, sharp turns, islands and other channel obstacles, air temperature during freeze-up (in case of a jam) or during ice drift (in case of a jam), terrain
	Wind speed, direction and duration, coincidence in time with high tide or low tide, slope of the water surface and river depth, distance from the sea coast, average depth and configuration of the reservoir, terrain
Flooding due to dam failures	The magnitude of the water level drop at the dam site: the volume filled with water in the reservoir at the time of the breakthrough; slope of the reservoir and river bottom; size and time of formation of the hole; distance from the dam, terrain

According to the initial causes, floods are divided into surges, storm (rain), floods (associated with the melting of snow and glaciers), gluttonous and mash-filled, obstructive and breakthrough.

Floods passing along rivers are divided by height:

♦ low or small (low floodplains are flooded);

♦ medium (high floodplains, partially populated, are flooded);

♦ strong, or outstanding (cities and communications are partially flooded, evacuation of the population is required);

♦ catastrophic (cities are significantly flooded, major rescue operations, mass evacuation are required).

Floods (not counting surges that accompany hurricanes) rank first in the world in the number of emergencies they create (about 40% of all emergencies), and second or third in the number of victims (7.5 thousand per year in 1947-1970). ), place in the top three in terms of long-term average and maximum one-time magnitude of direct economic damage.

With surge, storm and dam-burst floods in populated areas of southern Asia, Central and South America Various legends about the global flood are associated, behind which are hidden actual events that determined the fate of entire ethnic groups.

Surge floods occur in coastal areas during the passage of deep cyclones, especially hurricanes (typhoons).

Surge water is a rise in its level caused by the influence of wind on the water surface. Surges leading to floods occur at the mouths of large rivers, as well as on large lakes and reservoirs.

The surge occurs on the windward shore of the reservoir due to shear stress at the water-air interface. The surface layers of water, drawn by the wind towards the windward coast, experience only the resistance of the lower layers of water. With the formation of a slope of the water surface under the influence of gravity, the lower layers begin to move in the opposite direction, already experiencing much greater resistance to the roughness of the bottom. Due to the inequality of water flows moving in opposite directions, a rise in level occurs at the windward shore of the reservoir and a decline at the leeward shore.

Wind surge just like flood, flood, jam, ice jam, is an extraordinary, especially dangerous hydrological phenomenon. The main condition for the occurrence of surge floods is strong and prolonged wind.

The main characteristic by which the magnitude of the surge can be judged is the surge rise in water level, usually measured in meters.

Other quantities characterizing the surge are the depth of propagation of the surge wave, the area and duration of flooding.

The magnitude of the surge level in sea estuaries is influenced by wind speed and direction. For each area prone to surge floods, it is possible to determine the direction of the wind over the reservoir at which surge phenomena will be maximum.

A common feature of marine estuaries is that the surge may coincide in time with high or low tide; accordingly, it will be either slightly larger or smaller. The surge wave travels further up the river, the lower the slope and the greater the depth of the river. The duration of flooding usually ranges from several hours to several days.

The magnitude of the rise in the surge water level of large reservoirs is influenced by: wind speed and direction; length of wind acceleration over a body of water; average depth of the reservoir along the length of the acceleration; size and configuration of the reservoir.

The larger the reservoir, the shallower its depth, the closer its configuration to a circle or ellipse, the larger the size of the surges and surges of water.

The main characteristics of the consequences of surge floods are almost the same as those of flash floods.

In emergency situations associated with mid-latitude and tropical hurricanes (strong winds, heavy precipitation, snow drifts, surge floods (accompanied by hurricanes), sea storms, outbreaks of seashore abrasion, soil salinization in flooded areas), the main threat is floods. They account for 90% of the victims and the lion's share of economic losses.

Surge floods (Japanese - takashio) are caused by: pressure rise in sea level (usually up to 1 m, rarely up to 2.5 m); long waves due to the surge itself (height up to 8-12m); wind short waves. As a result, the water level may rise above normal for a long time: by 4-5 m on the Okhotsk coast; at 6-8 m on the Atlantic coast of North America; at 8-10 m in Japan, the Philippines, the Hawaiian Islands; at 11-12 m in the Ganges delta, Bangladesh, at 12-13 m in Australia.

In Russia, the main threat in the Far East is created by extreme precipitation, snow drifts, and flash floods, the zone of which extends to the Baikal region.

Flash floods– the most common type of flood. They are possible everywhere (even in deserts), except for the Arctic and Antarctic, but are most frequent and strong in areas with a monsoon climate - between 40° N. w. and 40° S. w.

Flash floods are created by heavy rainfall and vary in nature depending on weather and runoff conditions. A particularly sharp (up to a hundredfold) increase in maximum flow rates relative to the average annual flow occurs in arid regions (since the average annual flow rate is small) and in areas with low water absorption capacity of soils - in mountains with a large proportion of rocky surfaces, in areas of permafrost, in paved cities. A particularly rapid increase in costs occurs during relatively short thunderstorms, when the monthly norm of precipitation is poured out in a few hours. But they cover relatively small watersheds (area up to 1000 km2) and are mainly dangerous for cities.

Floods caused by prolonged intense frontal rains are more common. The “record” for the number of victims from such floods belongs to China, where a monsoon climate and flat, flat terrain are combined, and some of the rivers in the lower reaches flow along a bed raised above the developed floodplain, for example, the bed of the river. The Yellow River is elevated to a height of 12–15 m, although the level rise in it can reach 30 m. Catastrophic floods in China occur on average once every 50 years. They are intensified by the breaking of dams protecting rivers, threatening the lives of tens of millions of people, hundreds of thousands of square kilometers of territory, thousands of settlements, and last for 2–4 months. The 1959 flood set a world “record” for the number of victims - 2 million people.

In the United States, 6% of the country's area is prone to floods. Among emergency situations, they rank fifth in terms of the number of victims (in 1913–1986 - an average of 130 per year) and first in terms of direct economic damage. At the same time, 70% of the damage occurs from long-term floods, and 80% of casualties occur from short-term, rapidly developing flash floods. Floods that occur when rain coincides with prolonged flooding are especially dangerous. In this case, the water level in the upper reaches of the river. The Missouri-Mississippi River may rise to 17 m and flooding will become outstanding or catastrophic.

In countries Western Europe zones of probable flooding during catastrophic floods occupy up to 4% of the territory, 1–4% of the population live in them. In the 80s, severe flash floods were observed in Portugal, Spain, France, Belgium, Great Britain, Germany, Switzerland, Austria and other countries. Settlements, roads, power lines, and agricultural land were damaged.

In Russia, flash floods are most frequent in the Far East with its monsoon climate and further west to the Chita region, where the influence of Pacific cyclones reaches, as well as in Ukraine, the North Caucasus and Transcaucasia. R level The Amur and other rivers in the Far East can rise by 10 m or more. Crops, pastures, and livestock are dying, roads, power lines, populated areas are damaged, and enterprises are shut down. In July 1990, during a typhoon in Primorye, more than two months of precipitation fell. At the beginning of July 1991, a catastrophic flood in Moldova was caused by heavy rains (three monthly precipitation norms) and the failure of dams in ponds and small reservoirs. The height of the breakthrough wave reached 12.5 m, the storm rise of water in the rivers was more than 3.5 m. More than 3 thousand houses, 18 bridges, etc. were damaged and destroyed.

Floods and floods snow melts are common in areas where there is snow cover on approximately 1/3 of the land area. They are most common in Eurasia and North America– on plains and in mountain-glacial areas. On the plains, floods last 15–20 days on small rivers and up to 2–3 months on large rivers, in the mountains - all summer. Floods – peak floods – last up to 15–35 days. In the northern part temperate zone and in inland areas where heavy rainfall is relatively rare, snowmelt floods can be a major cause of flooding.

In Russia, strong (outstanding) floods of this type occur on average once every 10–25 years. They are possible with a combination of abundant autumn soil moisture and rapid snow melting (tens of millimeters of water layer per day), provided by the arrival of masses of warm air with rain. In this case, the amount of snow must correspond to the amount of incoming heat in such a way that lakes of melt water can appear in the snow cover, bursting together under the influence of rain. Snow-water flows (snow melt mudflows) occur in ravines and hilly areas. The effects of meltwater breakthrough are difficult to predict.

An example is the flood in Bashkiria in April–May 1990. Rapid snowmelt was accompanied by torrential warm rains, the river level rose 9 m higher than usual (in the Belaya River) and 3 m higher than predicted. More than 130 settlements were affected, including the city of Ufa, 90 bridges, 100 livestock farms, etc. were destroyed. 12 people died. Somewhat later, at the end of May, similar events occurred in Evenkia. Water level in the river Nizhny Tunguska rose by 26 m, the city of Tura and a number of villages were partially flooded.

Zhornye and jam floods occur in foothill and lowland areas of rivers covered with ice. These include most of the rivers of Eurasia and North America north of 35° N. w. Jams are accumulations of slush and broken ice that form in winter, while jams are accumulations of ice floes during spring ice drift. In the territory of the former USSR, on 1,100 rivers, there are more than 2,400 ice jams and ice jams. The thickness of jammed ice accumulations on the Angara and Amu Darya reaches 10–15 m, length – 25 km, reduction in the cross-sectional area of ​​the channel – up to 80%. The duration of the gluttons varies depending on the situation - from several days to the entire winter. The depth of the water sometimes increases 4–5 times compared to the open channel. Despite the low water content of rivers in winter, a flood rise in water level can exceed the flood level, i.e., create a threat of flooding. The water level rise reaches 5–6 m on the Northern Dvina, Western Dvina, and Altai rivers; 6–7 m on the Angara and Yenisei; up to 12 m on the river Naryn. As a result of floods, seasonal river ice is created in many areas of Siberia and the mountains of Central Asia - a hindrance to roads.

Congestion is typical for rivers, the opening of which from ice begins from the upper reaches and occurs mechanically. These are all rivers flowing north, primarily the rivers of Siberia and the north of the European part of Russia. In the lower reaches of the Lena, the length of traffic jams reaches 50–100 km. The duration of congestion is up to 12–15 days. The jammed water rise above the maximum flood level often reaches 4–6 m, with a maximum of up to 10 m on many large rivers of Siberia and the Far East, on the Northern Dvina, Pechora, Western Dvina, and in the upper reaches of the Dniester. On the territory of Russia, the maximum height of the rise of the jammed water level above the low-water level was noted on the Lower Tunguska in the narrowings of the valley - up to 35–40 m. For the formation of jams, a large amount of ice and a friendly spring flood are required. On large rivers of Siberia, such conditions are observed almost every year; the frequency of jams is 70–100%. The most famous are jam floods on the Northern Dvina near Arkhangelsk (recurrence on average once every 4 years, water level height up to 10 m); on the Ob and its tributaries, where Tobolsk, Kemerovo and other cities are under constant threat; on the Yenisei and its tributaries, where in the 20th century. There were 6 catastrophic and many outstanding floods in Krasnoyarsk, Yeniseisk and other cities.

An ice jam occurs at the beginning of winter during the formation of ice cover. The surface velocity of water flow (more than 0.4 m/s), as well as the air temperature during the freezing period, are of decisive importance in the formation of a ice jam. The formation of jams is facilitated by various channel obstacles: islands, shallows, boulders, sharp turns and narrowings of the channel, areas in the tailwaters of hydroelectric power plants. Accumulations of slush and other loose ice material, formed in these areas as a result of the continuous process of formation of inland ice and destruction of the ice cover, cause constriction of the water section of the river bed, which results in a rise in the water level upstream. The formation of a continuous ice cover at the site of the jam is delayed.

Similar characteristics of ice jam and ice jam floods are observed for the rivers of Canada and Alaska. Less frequent, therefore unexpected and especially dangerous, are floods of this type on the rivers of Western Europe and the USA. In the United States, damage from floods accounts for approximately 1/4 of total flood damage.

Zavalnye andoutburst floods less regular than previous types of floods. They occur mainly in mountainous areas and are associated with landslides and landslides (mainly seismogenic) and glacial movements. There are also breakthroughs in artificial dams.

Since 1910, such events have occurred around the world on average 10–15 times a year (including the destruction of large dams – once every 2–3 years). In 1987 in Tajikistan, for example, the dam of the Sargazon reservoir was broken.

Of the consequences of rubble in the former USSR, the most famous is Lake Sarez, up to 500 m deep, which arose on the river. Murghab in the Pamirs as a result of the earthquake of 1911. In the USA, a similar lake was formed by a seismogenic landslide in the canyon of the river. Madison (Montana) in 1959, but was artificially lowered. With the formation of a dammed lake on the Armenian Highlands, in the upper reaches of the river basin. Tiger, connected to that part of the legend of the Flood that speaks of Noah's Ark at Mount Ararat.

More or less regular glacier movements are possible in all glacial regions of the world. About 5% of mountain glaciers are classified as pulsating (with an interval of years or decades). When moving, they block watercourses and ensure the accumulation of temporary lakes that break out sooner or later. Long-existing periglacial lakes can also break through if they are dammed by a loose ice-containing moraine ridge. Breakthrough waves pass down the valleys, often taking on the character of mudflows. Floods of this kind occur in mountain valleys on average at least once every 10-20 years, and in each mountainous region as a whole once every 2-5 years.

Over the past 200 years, 35 catastrophic outburst floods have been recorded in the Himalayas.

The fact that floods are intensifying is confirmed by the fact that in the 1980s around the world, flash floods and snowmelt floods in many areas broke records for 100 years or during the observation period, and according to calculations, some of them corresponded to a frequency of once every 300–400 years (storm floods in New Zealand, Great Britain, Portugal, the snowmelt flood mentioned above in Bashkiria). Some experts associate this trend with the onset of anthropogenic climate change. But local reasons can be considered undoubted: anthropogenic changes in the geometry of river channels, surface runoff in river basins, winter temperature regime of watercourses, as well as the local field of precipitation and snowmelt. The growth factor in the number of artificial reservoirs and outburst floods is obvious.

Changes in river channels, increasing the height of floods, occur through their unintentional anthropogenic siltation and shallowing, as well as through improper channel straightening works (excessive narrowing and straightening). Changes in the conditions of surface runoff occur when swamps are drained, forests are cleared, plowed, and, in cities, when large impermeable surfaces are created. When draining swamps, the maximum surface runoff increases by 1.5-2.5 times; when clearing forests and plowing - 2–4 times, and in small catchment areas - even more, which contributes to siltation, first of all, of small rivers.

An increase in the area of ​​impervious coatings in cities leads to the same increase in the flow rate of flash floods and to an even greater reduction in the time it takes for the flood wave to “reach”, which sharply increases the maximum costs.

The temperature regime of rivers in temperate, colder zones changes when reservoirs are created: a polynya is constantly maintained at the river outlet from the reservoir in winter, which sharply increases the frequency of ice jams, and in some cases, the height of ice jam levels in comparison with natural ones (on the downstream of the Krasnoyarsk hydroelectric power station - by 2 .5 m or more). On the upper reaches of reservoirs, there is an increase in ice jams and congestion, and in some places an increase in the level of ice jams above the previous maximum level of the spring flood.

Local changes in precipitation and snowmelt fields occur in large cities. They create torches of dusty and warm air above them, which significantly increases the frequency and intensity of thunderstorms, and in general - an increase in precipitation by up to 20% compared to the surrounding area. Pollution of the snow cover near cities changes the snowmelt regime. All these changes are still awaiting quantification.

Preventive measures in case of threat of flooding of populated areas and territories

Flood protection measures are divided into operational (urgent) and technical (preventive).

Operational measures do not generally solve the problem of flood protection and must be carried out in conjunction with technical measures.

Technical measures include advance design and construction of special structures. These include: regulation of flow in the riverbed; drainage of flood waters; regulation of surface flow on spillways; embankment; river channel straightening and dredging; construction of bank protection structures; backfilling of the built-up area; restriction of construction in areas of possible flooding, etc.

The greatest economic effect and reliable protection of floodplain areas from floods can be achieved by combining active protection methods (drainage regulation) with passive methods (embankment, channel dredging, etc.).

The choice of protection methods depends on a number of factors: the hydraulic regime of the watercourse, the terrain, engineering-geological and hydrogeological conditions, the presence of engineering structures in the riverbed and on the floodplain (dams, dikes, bridges, roads, water intakes, etc.), the location of economic facilities subject to flooding.

The main directions of action of executive authorities in the event of a threat of flooding are:

♦ analysis of the situation, identification of sources and possible timing of flooding;

♦ forecasting types (types), timing and scale of possible flooding;

♦ planning and preparation of a set of standard measures to prevent flooding;

♦ planning and preparation for emergency rescue operations in areas of possible flooding.

At the federal level, the Russian Ministry of Emergency Situations, with the active participation of Roshydromet and the Ministry of Natural Resources of Russia, carries out planning and preparation of events on a national scale. At the regional level, regional centers of the Russian Ministry of Emergency Situations plan and prepare activities within their competence. At the level of the region, territory, republic, events are planned and prepared in their territories. At the same time, a large share of responsibility lies with the divisions of the Ministry of Natural Resources of Russia: basin water management departments and its territorial water management bodies. During the period of threat of flooding, the management bodies of the Civil Defense and Emergency Situations of the constituent entities of the Russian Federation operate on high alert.

During the period of threat of spring floods and floods on rivers, flood control commissions must provide for the determination of:

♦ boundaries and dimensions (area) of flood zones, the number of administrative districts, settlements, economic facilities, area of ​​agricultural land, roads, bridges, communication lines and power lines falling into flood and inundation zones;

♦ the number of victims, as well as those temporarily resettled from the flood zone;

♦ destroyed (emergency) houses, buildings, etc.;

♦ volumes of pumping water from flooded structures;

♦ number of heads of dead farm animals;

♦ location and size of constructed dams, dams, embankments, fastenings of bank slopes, drainage channels, pits (siphons);

♦ preliminary amount of material damage;

♦ the number of forces and assets involved (personnel, equipment, etc.);

♦ measures to protect the population,

During the preparatory period, an important role is played by analyzing the situation and forecasting possible flooding of populated areas.

Analysis of the situation involves identifying possible causes of the threat of flooding of populated areas, which may include high water and high water, as well as factors contributing to the occurrence of flooding and flooding.

At the same time, possible emergency scenarios are identified in which:

♦ the living conditions of people in the administrative districts of a constituent entity of the Russian Federation are significantly disrupted;

♦ human casualties or damage to the health of a large number of people are possible;

♦ there may be significant material losses;

♦ significant damage to the environment is possible.

Identification of the listed emergency situations associated with flooding of territories is carried out on the basis of:

♦ statistical data on floods and long-term observation data for a given territory;

♦ studying action plans for industrial facilities in the event of an emergency;

own assessments of the territorial management bodies of the RSChS.

Based on the identified factors contributing to the occurrence of emergencies, as well as secondary factors that pose a threat to the population and economic facilities, the following is carried out:

♦ assessment of the probability of an emergency;

♦ assessment of the scale of a possible emergency.

Underscaleshould be understood: number of deaths; number of victims; the amount of material damage; the volume of evacuation measures and protection associated with the evacuation of the population; costs of emergency response and restoration work; indirect losses (short production, costs of benefits, compensation payments, pensions, etc.), etc.

An assessment of the likelihood of occurrence and scale of emergency situations caused by accidents at industrial facilities, life support systems, etc. due to the influence of secondary factors is carried out by the administration of the relevant facilities.

Forecasting and assessing the scale of emergency situations should be carried out taking into account the requirements of laws, other regulations and methods recommended by the Russian Ministry of Emergency Situations.

In the absence of such documents for individual specific cases, the executive authorities of the constituent entities of the Russian Federation will organize research to assess the likelihood of occurrence and assess the scale of emergency situations by the scientific forces of the constituent entity of the Russian Federation.

The results of identifying factors contributing to the occurrence of emergency situations associated with flooding of territories and populated areas serve as the basis for making decisions on the implementation of priority preventive measures.

Based on an analysis of the situation, flood prevention measures are planned. Planning is regulated by the Federal Law “On the Protection of the Population and Territories from Natural and Technogenic Emergencies”, regulatory legal acts of state authorities of the constituent entities of the Russian Federation and local governments. In this case, it is advisable to distinguish between subject (target) and operational planning.

Subject (target) planning should include organizational, financial, economic and engineering measures to prevent or reduce the risk of flooding.

Operational planning provides for a set of organizational and technical measures to prepare the population, economic facilities and territories for an emergency situation. These measures should be reflected in plans for the socio-economic development of territories, plans for the development of economic sectors, and economic facilities.

Standard procedure for planning emergency prevention measures,caused by flooding,includes:

♦ identification of organizations and institutions that can be involved in organizing and implementing emergency prevention measures;

♦ development and feasibility study of organizational and engineering measures to prevent or reduce the risk of emergency situations;

♦ development and feasibility study of measures to reduce the severity of the consequences of emergency situations on the population, economic facilities and the environment.

The developed plans are coordinated with interested bodies and organizations, approved by the relevant heads of executive authorities and sent to the implementers. Control over the implementation of plans is carried out by the executive power of the territory through the territorial management bodies of the RSChS.

Let us briefly consider the main measures to reduce the consequences of congestion and gluttony.

Congestion cannot be eliminated; it can only be loosened somewhat or moved to another location. When combating ice jam floods, it is necessary to regulate the flow of ice material.

Flood

Flood in Asheville, North Carolina in July 1916

Flood- flooding of the area as a result of rising water levels in rivers, lakes, seas due to rains, rapid snow melting, wind surge of water on the coast and other reasons, which damages people’s health and even leads to their death, and also causes material damage.

Floods are often caused by an increase in the water level in the river due to blockage of the riverbed with ice during ice drift (jam) or due to clogging of the riverbed under a stationary ice cover with accumulations of inland ice and the formation of an ice plug (jag). Floods often occur under the influence of winds, driving water from the sea and causing an increase in the level due to the retention of water brought by the river at the mouth. Floods of this type were observed in Leningrad (1824, 1924), the Netherlands ( 1953 ). On sea ​​coasts and islands, floods can occur as a result of coastal inundation by waves generated by earthquakes or volcanic eruptions in the ocean (see Tsunami). Similar floods are common on the shores of Japan and on other islands Pacific Ocean. Floods can be caused by breaches of dams and protective dams.

Floods occur on many rivers in Western Europe - the Danube, Seine, Rhone, Po and others, as well as on the Yangtze and Yellow Rivers in China, the Mississippi and Ohio in the USA. In the USSR, large floods were observed on the Dnieper () and Volga ( and ) rivers.

Congestion, gluttony floods (congestion, gluttony)

Great resistance to water flow in certain sections of the river bed, which occurs when ice material accumulates in narrowings or bends of the river during freeze-up ( behind and ors) or ice drift ( behind T ors). Behind T ore floods are formed at the end of winter or beginning of spring. They are characterized by a high and relatively short-term rise in the water level in the river. Behind and ore floods are formed at the beginning of winter and are characterized by a significant (but less than during a jam) rise in the water level and a longer duration of the flood.

Surge floods (surges)

Wind surges of water in sea estuaries and on windy areas of the coast of seas, large lakes, and reservoirs. Possible at any time of the year. They are characterized by a lack of periodicity and a significant rise in water levels.

Floods (flooding) resulting from dam failures

An outflow of water from a reservoir or reservoir, formed when a pressure front structure (dam, dike, etc.) breaks through or during an emergency release of water from a reservoir, as well as when a natural dam breaks through, created by nature during earthquakes, landslides, landslides, or glacier movement. Characterized by the formation of a breakthrough wave, leading to flooding of large areas and destruction or damage to objects encountered along the path of its movement (buildings, structures, etc.)

Classification of floods depending on the scale of distribution and frequency

Low (small)

They are observed on lowland rivers. Covers small coastal areas. Less than 10% of agricultural land is flooded. They hardly disturb the rhythm of life of the population. Repeatability 5-10 years. That is, they cause minor damage.

High

They cause significant material and moral damage, cover relatively large areas of land in river valleys, and flood approximately 10-20% of agricultural land. They significantly disrupt the economic and everyday life of the population. Lead to partial evacuation of people. Repeatability 20-25 years.

Outstanding

They cause great material damage, covering entire river basins. Approximately 50-70% of agricultural land and some populated areas are flooded. Paralyze economic activity and sharply disrupt the everyday life of the population. Lead to the need for mass evacuation of the population and material assets from the flood zone and protection of the most important economic facilities. Repeatability 50-100 years.

Catastrophic

They lead to loss of life, irreparable environmental damage, and cause material damage, covering vast territories within one or more water systems. More than 70% of agricultural land, many settlements, industrial enterprises and utilities are flooded. Economic and production activities are completely paralyzed, and the lifestyle of the population is temporarily changed. The evacuation of hundreds of thousands of people, an inevitable humanitarian catastrophe requires the participation of the entire world community, the problem of one country becomes a problem of the whole world.

Types

• Flood is a periodically recurring, rather prolonged rise in water levels in rivers, usually caused by spring melting of snow on the plains or rainfall. Floods low-lying areas.

A flood can become catastrophic if the infiltration properties of the soil have significantly decreased due to its oversaturation with moisture in the fall and deep freezing in the harsh winter. Spring rains can also lead to increased flooding, when its peak coincides with the peak of the flood.

• Flood is an intense, relatively short-term rise in the water level in a river, caused by heavy rains, downpours, and sometimes rapid melting of snow during thaws. Unlike floods, floods can occur several times a year. A particular threat is posed by the so-called flash floods associated with short-term but very intense downpours, which also occur in winter due to thaws.
• A jam is a accumulation of ice floes during the spring ice drift in narrowings and bends of the river bed, restricting the flow and causing a rise in the water level in the place where the ice accumulates and above it.

Congestion occurs due to non-simultaneous opening big rivers, flowing from south to north. The exposed southern sections of the river are spring-loaded in their flow by the accumulation of ice in the northern regions, which often causes a significant increase in water levels.

• Zazhor is an accumulation of loose ice during freeze-up (at the beginning of winter) in narrowings and bends of the river bed, causing water to rise in some areas above it.
• Wind surge is a rise in water level caused by the action of wind on the water surface, occurring at the mouths of large rivers, as well as on the windward shores of large lakes, reservoirs and seas.
• Flooding due to a breakthrough of hydraulic structures (hydrodynamic accident) is an incident associated with the failure (destruction) of a hydraulic structure or its parts, followed by the uncontrolled movement of large masses of water.

Causes

Long rains

Flood in Biysk caused by abnormally long rains (more than 72 hours), 2006

Summer rains falling on the Abyssinian Highlands cause the Nile to overflow every year, flooding the entire valley in its lower reaches.

Snow melting

Intensive snow melting, especially when the ground is frozen, leads to flooding of roads.

tsunami wave

On sea coasts and islands, floods can occur as a result of inundation of the coastal strip by waves generated by earthquakes or volcanic eruptions in the ocean. Similar floods are common on the shores of Japan and other Pacific islands.

Bottom profile

One of the causes of floods is rising seabeds. Each river gradually accumulates sediments, in riffles, in mouths and deltas.

Flood Prevention Methods

Most effective method river flood control - regulation of river flow by creating reservoirs. To combat floods on the seashore, protective dams are used.

One of the ways to combat floods is to deepen riffles and other shallows.

History of floods in Russia

Floods in the Krasnodar region

An almost annual natural disaster, the scale of which depends on weather conditions. But the reasons lie in the social sphere, including: the development of the floodplain, water protection zones and the littering of the river bed, which is heavily overgrown in some areas. Catastrophic flood in the Krasnodar region in 2012.

Floods in Moscow

It is known from the history of Moscow that floods on the Moscow River occurred frequently (in the spring, and also happened in the summer) and brought great disasters to the city. Thus, the chronicle speaks of a severe frosty winter, heavy snows and great floods. In July and August, floods occurred as a result of long, continuous rains. In the 17th century Three spring floods were noted: in , (the southern wall of the Kremlin was damaged, many houses were destroyed) and in (4 floating bridges across the river were demolished). In the 18th century six floods are mentioned: , , , , and ; in 1783, the supports of the Bolshoi Kamenny Bridge were damaged by floods. During the floods in 1788, marks were made on the tower of the Novodevichy Convent and the walls of some buildings. One of the largest floods on the Moscow River was in, during which the maximum water flow was 2860 m³/s. The water in the river rose 8.9 m above the permanent summer horizon; on the embankments near the Kremlin its layer reached 2.3 m. The river and the Vodootvodny Canal merged into one channel 1.5 km wide. 16 km² of the city territory was flooded. During the flood, the maximum flow rate was 2140 m³/s, the water rise above the low-water period was 7.3 m. The next and last flood was in (water rise 6.8 m). Nowadays, in the upper part of the Moscow River basin, Istrinskoye, Mozhaiskoye, Ruzskoye and Ozerninskoye reservoirs have been built, which regulate the flow. In addition, the river bed within the city has been widened in places, sharp bends have been straightened, and the banks are reinforced with granite embankment walls. After this, floods within the city passed almost unnoticed.

Floods often occurred on the river. Yauza during spring floods and heavy summer rains. The modern Elektrozavodskaya, Bolshaya Semyonovskaya, Bakuninskaya streets, Preobrazhenskaya, Rusakovskaya, Rubtsovskaya, Semyonovskaya embankments suffered especially often and severely. An additional reason for flooding on the river. The Yauza was served by the presence of bridges in the form of brick vaulted pipes of insufficient cross-section. Large spring floods were observed in (the water at the Glebovsky Bridge rose by 3.28 m), in (by 2.74 m), in (by 2.04 m), in (by 2.25 m). To replace the old bridges, high reinforced concrete bridges were built, along the banks - reinforced concrete walls (with a margin of 0.5 m above the maximum flood horizon).

Most often Moscow suffered from floods on the river. Neglinnaya after its enclosure in a brick pipe (in the first half of the 19th century in the area from the mouth to Samotyochnaya Square, in - above Samotyochnaya Square). The pipes were designed to carry only 13.7 m³/s of water, and almost every year during heavy rainfalls it burst out of the ground and flooded Samotechnaya and Trubnaya Squares and Neglinnaya Street. The water on Neglinnaya Street rose by 1.2 m. After a heavy rain, Neglinnaya Street turned into a seething stream. After a rainstorm on June 25, a lake formed at the intersection of Neglinnaya Street and Rakhmanovsky Lane; The flooded area was 25 hectares. Neglinnaya Street, Trubnaya and Samotyochnaya squares were flooded somewhat less, twice - on June 8 and 22, and on August 7 and 9; this happened in . A new pipe has now been laid, designed to carry a water flow of 66.5 m³/s. However, the increasing intensity of rainfall in Moscow again leads to severe floods: on June 26, 2005 in the area of ​​Neglinnaya Street and on June 9, 2006 on Entuziastov Highway, when the first floors of buildings were flooded with water.

Flooding also occurred on the Khapilovka, Rybinka, Presnya and other rivers, which also occurred due to heavy rainfall and insufficient cross-section of pipes (large cross-section pipes are now installed).

Floods in St. Petersburg

Main article: Floods in St. Petersburg

Floods in St. Petersburg are caused by a number of factors: cyclones arising in the Baltic with a predominance of westerly winds cause a surge wave and its movement towards the mouth of the Neva, where the rise of water intensifies due to shallow water and narrowing of the Neva Bay. Seiches, wind surges and other factors also contribute to flooding.

Literature

• // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional ones). - St. Petersburg. , 1890-1907.

Links

	Flood in Wiktionary
	Flood on Wikimedia Commons
	Flood in Wikinews

• Major Flood Database (in English)
• General information and chronology of floods in St. Petersburg on the Neva River