What is the main characteristic of a flood. Classification of flood situations

UDC 614.8.084

E.V. Arefieva Ph.D., V.I. Mukhin (AGZ EMERCOM of Russia), E.G. Mirmovich Ph.D. (FGU VNII GOChS) FLOODING AS A POTENTIAL SOURCE OF EMERGENCIES

E. Arefeva, V. Mukhin, E. Mirmovich SUBMERGENCE AS A POTENTIAL SOURCE OF EC

One of the partial risks of a potential source of destruction of buildings and structures is the long-term impact of flooding.

Does not contain such a potential source of buildings and constructions destruction long-lasting drowning influence.

IN AND. Mukhin

E.G. Mirmavich

The topic of the article refers to the specialty "Safety in emergency situations", although it is located at the interdisciplinary interface of hydro- and engineering geology, soil science and land hydrology; geoecology and even permafrost. Why?

Fighting the very fact of flooding or another type of excessive moisture is meaningless in itself ("Nature does not have bad weather"). And for the occurrence of an emergency, necessary and sufficient conditions are needed. The necessary conditions for this type of emergency are the presence of people, critical facilities, economic facilities located in flooded areas. One condition is enough

The critical relationship between the external influence and the protective properties of the object. In this case, potentially dangerous objects can play both one (passive) and another (active) role.

Among the disaster risk maps created recently, the risk of disaster from the impact of flooding is replaced by the probability of flooding from climatic and meteorological factors (Fig. 1).

Most of the consequences of emergencies of any origin are associated with collapses, partial or complete destruction of buildings and structures due to their insufficient reliability and protection from dangerous techno-natural impacts. To paraphrase a well-known expression, we can say that for such impacts as sources of emergencies, almost "all roads lead to collapses."

Potential sources of such types of damage include sources with small and even zero (earthquakes, tornadoes, transport and industrial accidents, etc.) and with large delays between cause and effect, impact and emergency response to them.

Among the latter, it is worth highlighting flooding, which leads to moistening and liquefaction of soils, a decrease in their bearing capacity, flooding of basements and underground utilities. Flooding often causes activation of existing landslides, karst processes, subsidence of loess and swelling of clay soils, frost heaving processes, and even changes in the microseismic characteristics of the territory.

The damage from flooding is up to 5-6 billion dollars a year. Subsidence of loess massifs cause deformations, and sometimes complete destruction of buildings and structures, underground utilities, pipelines, and transport systems. The subsidence of loess rocks as a result of flooding and excessive moisture is experienced by more than 560 cities in Russia. Thus, in Volgodonsk, as of 2003, out of 907 residential buildings, 732 did not have guaranteed operational reliability due to deformation of the foundations as a result of subsidence of flooded loess soils. In some cities of the North Caucasus, the subsidence reaches up to 1.0-1.5 m. The threatening dynamics of flooding is reflected in the fact that in 1986 733 cities (70%) of Russia were covered by flooding, and in 2006 - already 93% of cities. The main reason for the flooding of urban areas is leakage from water-carrying communications (about 70%).

Scientific and technical developments

Rice. 1. An example of partial risk maps associated with flooding, in which the probability of occurrence of flooding itself replaces the risk of emergency from flooding

The number of objects that are threatened by landslides during flooding of territories in Russia has increased from 3-4 thousand to 12 thousand, the volume of karst voids has tripled. In some cities (Volgograd, Volgodonsk, Nizhny Novgorod, etc.), groundwater rose from 9-12 m to 3 m above the earth's surface.

In recent decades, the process of flooding of developed territories has become almost universal in Russia. Currently, about 9 million hectares of land for various economic purposes have been flooded, including 5 million hectares of agricultural land and 0.8 million hectares of built-up urban areas. Out of 1064 cities in Russia, flooding is observed in ~ 800 (~75%), out of 2065 workers' settlements

In 460 (> 20%), as well as in more than 760 settlements. Many of the largest cities in the country are flooded, such as Astrakhan, Volgograd, Irkutsk, Moscow, Nizhny Novgorod, Novosibirsk, Omsk, Rostov-on-Don, St. Petersburg, Tomsk, Tyumen, Khabarovsk and others.

Currently, in Russia, the physical deterioration of housing and communal services (pipelines, etc.) is 55-75%. 30% of water supply capacities require urgent modernization, and the number of accidents over 10 years (from 1990 to 2000) has increased five times and amounted to 70 accidents for every 100 km of water supply networks per year. According to this trend, by 2010 the increase may be up to 350 accidents for every 100 km of networks. The number of accidents in heat supply systems reaches up to 100 thousand per year, and in water supply systems up to 200 thousand accidents per year. Water losses in water-carrying communication systems exceed the permissible level of losses in Russia by 2.5-3 times and exceed the permissible water losses in Europe by 4-6 times. Given this deterioration of residential buildings, the trend of an increase in the number of accidents and building collapses will naturally continue. Dilapidated housing is practically unable to resist negative natural and natural-technogenic processes.

Can research in this area be directed to their practical application? It would seem that cleaning, replacing existing drainage and outflow

systems (which, by the way, are obviously not enough), the organization of drying after floods, as was the case after catastrophic floods in Europe at the beginning of this century - that's the whole system for combating this source of emergency situations.

However, intensive pumping of groundwater and a change in the established hydrodynamic regime in built-up areas composed of structurally unstable soils, affected by ancient karst, landslide processes, can cause a violation of their stability and the development of so-called karst-suffusion processes, leading to the formation of sinkholes of man-made natural origin. Often there is a response "drainage effect", activating suffusion and subsidence processes. In some areas, these processes are developing so rapidly that they become dangerous not only for buildings and structures, but also for people.

Flooding enhances the activation of dangerous engineering and geological processes. Thus, over the past 30 years, 42 karst-suffusion sinkholes have formed in the northwestern part of Moscow. The craters had a diameter of several to 40 m, a depth of 1.5 to 5-8 m. As a result, three five-story buildings were damaged, the inhabitants of which had to be relocated and the buildings dismantled. Over the past 65 years, more than 80 karst-suffusion sinkholes have been registered in the Ufa region. This process is even more widespread in the area of the city of Dzerzhinsk (Perm Region), where it affects about 30% of the city's territory.

Of the 100% of the territory of the Russian Federation, where nuclear, hydro- and thermal power plants and other objects of increased environmental danger are operated, up to 50% is located in zones of dangerous flooding processes.

It is known that the destructive effect of earthquakes depends on the deformation of soils during the passage of seismic waves. The intensity of such deformations is different in dry and water-saturated soils. In sandy, sandy-clayey, loess

soils when moistened, structural bonds are broken. Wet sands under the influence of vibration begin to liquefy, which leads to a large draft, a list of buildings built on such soils. The liquefaction of soils on slopes prone to landslides is especially dangerous. So, one of the largest landslides associated with seismic liquefaction of soils caused a disaster at the Vaiont reservoir in Italy. On water-saturated sandy, clayey soils, the intensity of the seismic impact (seismic intensity) increases by 1-2 points, and on loess soils it can reach up to 3 points, while the deformation modulus decreases, the resistance of soils to shear decreases. This is significant, given that during a 6-point earthquake, brick houses remain intact and experience little damage, then with an 8-point earthquake, their destruction is also possible, depending on their foundation.

Thus, the work noted the relationship between the density of distribution of damage to buildings and GWL after the earthquake on September 21, 2004 in Kaliningrad (6-7 points on the Richter scale): 1146 buildings were damaged in the flooded microdistricts of the city, of which 1061 were a residential building, 46 social and cultural facilities , 39 other objects.

In water-saturated soils during earthquakes, additional soil settlement up to 1 m occurs, associated with additional soil compaction. Considering that the dilapidation of buildings and houses in a number of cities of the country has reached significant percentages, it is necessary to immediately carry out water drainage measures in flooded areas, thereby preventing possible emergencies associated with even minor earthquakes, the devastating consequences of which will be enhanced by the negative effects of flooding.

The process of reckless closure of unprofitable mines continues with large negative irreversible consequences for the territory:

There is a rapid increase in the groundwater level (GWL), which is many times higher than the level in comparison with the period before the closure of the mines;

There is pollution and flooding of the territory, the destruction of regional aquifers;

Local earthquakes occur as a result of the development of hydromechanical stresses;

There are subsidence phenomena, a decrease in the mechanical strength properties of rocks;

There is a high probability of groundwater intrusion into open working mines.

Mine waters are saturated with salts of heavy metals, they are aggressive towards concrete and cement. More than 2.62 million tons of various salts are carried out in the Donbass with mine waters annually, therefore, when mines are flooded, dangerous processes are activated due to flooding of the territory: karst, landslides, etc.

In a number of works, it is noted that the substantiated methodological recommendations for managing the GWL regime and for ensuring environmental safety during the liquidation of mines have not been sufficiently worked out.

The main measures to prevent accidental consequences during the closure of mines are:

Early assessment of the impact of mine closure on the ecological state of the environment;

Identification of areas of flooding, geochemical pollution of the territory;

Creation of predictive models of environmental change,

improvement of methods of regulation and management; improvement of monitoring systems at the local and regional levels; hydrogeological situation during the closure of mines.

Information about some emergencies associated with flooding at a number of mines in Russia is given in Table. one .

It should be noted that the increased

Table 1

Mine name, location Social, environmental and economic damage

“Deep”, OJSC “Rostovugol” Collapse of the hanging rock, death of people (2 people)

Rostov region, Novoshakhtinsk, “Zapadnaya”, “Capital” mine, 2003, October The walls of the mine broke through at a depth of 54.5 m; 30 million m3 of water broke through; the same thing happened in February, at a depth of 300 m, the rate of water inflow was 10,000 m3 per hour; the threat of flooding 17 thousand houses in the city

"Pionerka", Kuzbass Flooding of the territory, the village of Triangle in the city of Belovo, closing of the mine, flooded 570 residential buildings

Mine them. Dmitrova, Novokuznetsk Threat of flooding of 99 houses and facilities of the Kuznetsk Iron and Steel Works

Mine “Capital” No. 5, Primorye Flooded village Tavrichanka

Capital mine, Osinnikovsky district of Kuzbass Flooding of mine workings, activation of landslides, the need to relocate

S. Belozerskoye, Belozerskaya mine, 1999. Due to closure, 20 houses were flooded, in an unacceptable state, 5% are not used due to unsuitability, 397 apartments are not used, destruction of the foundation masonry due to high groundwater level

Mine “Novaya”, Zhovtiye Vody Emergency situation due to the rise of GWL, given that uranium mining is underway at the mine, the threat of radioactive contamination of the territory

Scientific and technical developments

Cultural monuments of urban planning and architectural nature are more exposed to the risks of drowning than other buildings. In the papers, this problem is analyzed with proposals for its resolution.

High-risk areas also include places with constant flooding, structurally unstable soils and karst voids, coinciding in megacities with the so-called. zones of "elite construction", which is considered as such for some incomprehensible reason instead of high-rise and, therefore, more dangerous. The solution of the housing problem in the long term with this approach can turn into a re-version of the new "khrushchev", which today have to be demolished throughout the country.

And for a number of cases, sparing drainage measures are recommended with monitoring the safety of the moistened state of foundation foundations, for which water is a kind of preservative. These are, first of all, architectural monuments, monuments of wooden architecture, houses located on a wooden foundation in northern Russian cities, etc. Thus, the most effective technology against the negative effects of flooding is the optimal control of the GWL regime, which, due to the inhomogeneities of the environment, the significant unpredictability of processes and phenomena in the underground hydrosphere, should be an ergatic control system.

In a series of works on the problems of forecasting emergencies (for example,) it is argued that a real-life forecast can only be on a deterministic basis, and not on a stochastic basis (a system of equations with leading and lagging arguments).

At the same time, the scientific and practical task in this area is to increase the lead time of the forecast from the side of science and reduce the readiness time of the response system

From the rescue services of the Ministry of Emergency Situations of Russia and RSChS.

The presence of a large time lag (delay) between the beginning of the process of flooding of territories and their emergency state, which is fraught with the occurrence of emergencies of various levels, has not only a negative aspect, but at the same time provides an opportunity to take preventive, anticipatory measures to prevent them, as well as to prevent them through automated management of ground water.

The coordinate representation of the non-linear

linear parabolic equation of the type of the heat equation:

AND b = (k(x,y) b)x + (k(x,y) bu)y + ™(x, y, 1), where b(, bx, bu are the rates of change in the groundwater level over time and space, k(x, y) - variable coefficient of groundwater filtration, depending on the characteristics of soils in Cartesian-orthogonal directions, and w(x, y, t) - empirically given coefficients of water loss and infiltration recharge.

Numerical modeling and calculations for generating a control action (CC) were carried out within the framework of standard boundary conditions of the first, second and third kind in an iterative recurrent cycle of direct-inverse-direct problem.

The control program for the GWL mode is carried out relative to some reference level for a given object Lk.

The real state of diagnostics, the analysis of existing monitoring systems by VSEGIN-GEO, the nomenclature and content of regulatory documents still do not meet the threatening situation on this problem. In the safety passports of buildings and territories, including KVO and POO, it is not cultivated taking into account the state of the foundations. The same applies to acts of commissions for emergencies, in which the causes of emergencies in the form of flooding are not indicated. Due to the insufficiency of hydrogeological control and observation points in built-up areas, it is not possible to have reliable maps of potential and actual flooding, databases for analyzing the accident rate of buildings and structures.

For Moscow, for example, in addition to the existing drainage points, it is necessary to deploy at least several automated HC stations for optimal reverse control of the HCW (for example, Fig. 2).

Rice. 2. Map of flooding of the territory of Moscow

In conclusion, it should be noted that the subsystem within the framework of the RSChS, which contributes to co-prevention of emergencies in case of flooding, should be formed by various structures and departments in this matter.

Literature

1. Dzektser E.S. Patterns of formation of flooding of built-up areas, principles of forecasting and engineering protection. - M., 1987. - 77 p.

2. Mirmovich E.G. Forecasting emergency situations and risks as a scientific and practical task // Problems of safety in emergency situations. - M.: VINITI. - 2003. Issue 1. - S. 142-146.

3. Mirmovich E.G. Forecast as a scientific and practical task and forecasting of emergencies in the region // Sat. Materials of the International Symposium "Integrated Security of Russia: - Research, Management, Experience". - M.: IITs VNII GOChS, 2002. - S. 190-192.

4. Mirmovich E.G. Use of electromagnetic effects of earthquakes in forecasting emergency situations of a seismic nature. Risk Management. - M.: "Ankil". - 2004. - No. 3. - S. 25-30.

5. Arefieva E.V. Flooding of economic objects as a potential source of engineering-geological hazards and emergencies / Ed. d.v.s., prof. IN AND. Mukhin. - M.: AGZ EMERCOM of Russia, 2007. - 117 p.

6. Ershov I.A., Popova E.V. On the influence of soil watering on the intensity of seismic impact. Epicentral zone of earthquakes // Issues of engineering seismology. - M.: Science. - 1978.

Issue 19. - S. 199-221.

7. Kotlov V.F., Chesnokov I.V. Assessment of geological risk factors during an earthquake (on the example of the Kaliningrad earthquake of September 21, 2004) // Assessment and management of natural risks. Materials of the All-Russian conference "RISK-2006". - M.: RUDN, 2006. - S. 207-209.

8. Project "Concepts for the development of water supply and sewerage in the new economic conditions." GFGP "Soyuzvodokanalproekt". - M., 2002.

9. Arefieva E.V. Mathematical methods for preventing emergency situations in case of flooding of objects and territories. - M.: AGZ, 2006. - 87 p.

10. Arefieva E.V., Dzektser E.S. The system of optimal management of groundwater in a built-up area // Water resources. - 1994. - No. 3. - S. 290-296.

11. Mukhin V.I. Study of control systems. - M.: Exam, 2002. - 384 p.

12. Mirmovich E.G. Tourism and cultural monuments as objects of security in the system of civil protection // Actual problems of civil protection. Proceedings of the XI International Scientific and Practical Conference on the Problems of Protecting the Population and Territories from Emergency Situations. Moscow, April 18-20, 2006 EMERCOM of Russia. - N. Novgorod: Vector-TiS, 2006. - S. 318-324.

13. Arefieva E.V. Protection of architectural monuments from flooding (on the example of the Novgorod Kremlin) // Zhilishchnoe stroitel'stvo. - M. - 2003. - No. 2. - S. 25-29.

14. Bulgakov S.N. Liquidation of the housing crisis as the first stage of the implementation of the national project "Affordable and comfortable housing for the citizens of Russia" // Sustainable development of cities and innovations in housing and communal services: Abstracts of the Fifth International Scientific and Practical Conference. - M.: MIKHiS, 2007. - S. 121.

15. Arefieva E.V. Influence of flooding on the safety of construction sites // Zhilishchnoe stroitel'stvo. - M.: - 2005. - No. 3. - S. 23-26.

5.1. Flood - this is a temporary flooding of a vast territory as a result of a rise in the water level in a river, lake, or sea. Floods occur as a result of intense melting of snow (glaciers), heavy rainfall, traffic jams and ice dams, destruction of hydraulic structures, and tsunamis.

Congestion- this is the accumulation of ice in the riverbed, limiting its flow, as a result, the water rises and spills. The jam is formed during ice drift and consists of large and small ice floes.

Zazhor- this is the clogging of the riverbed with internal ice under a fixed ice cover and the formation of an ice plug. Ice dams form in rivers during the formation of the ice cover.

high water- a relatively long-term increase in the water content of rivers, which is repeated annually in the same season, accompanied by an increase in the water level. May cause flooding.

high water- relatively short-term and non-periodic water level rise. Floods following one after another can lead to floods.

Surge floods arise under the influence of powerful cyclones, when the wind reaches high speed and creates a huge surge wave that blocks the flow of rivers and the natural discharge of water into the sea. Encountering such an obstacle, the water in the river rises sharply and can flood a significant area of the adjacent territory. Surge floods often occur in St. Petersburg, Holland, and England.

Flooding is the most common natural hazard, the damage from which annually amounts to hundreds of millions of rubles in Russia.

Today, most floods are predictable, which allows timely preparatory work. The main methods of flood control are the construction of enclosing dams and reservoirs, the diversion of water into the channels of other rivers and reservoirs, and the carrying out of bank- and dredging works.

Those who live in areas prone to frequent flooding should:

build houses on high foundations;

have a floating facility (boat, raft);

store documents and valuables in an accessible and safe place;

stock up on food and medicine.

Actions during a flood:

Before leaving the house, everything that water can spoil should be transferred to the upper floors or other non-flooded places; turn off gas and electricity. Then, taking with you the documents, the most necessary things, a small supply of food and water, arrive at the collection point.

Evacuation is carried out to large settlements that are outside the flood zones.

About the sudden onset of flooding, for example, during the destruction of a hydraulic structure, the population is warned by all available technical means. You should go up to the upper floors, and if the house is one-story, take the attic or go to the roof. The evacuation of the population in this case will be carried out on boats, boats, rafts and other floating facilities. During landing on them, strict discipline must be observed. One should go down into the boat one at a time, stepping on the middle of the flooring, and sit down only at the direction of the elder. During the movement of the boat, you can not change places, get on board; The bow of the boat should be kept perpendicular to the wave. After mooring, one of the passengers must go ashore and hold the boat until all people are on land.

If the flood caught you in a field, in a forest, take the most elevated place: climb a tree, etc.

Remember: the search for people in the flooded area is organized immediately. A drowning person is approached in a boat against the current, and lifted from the stern.

Actions after the flood:

° After the water subsides, keep away from torn and sagging electrical wires, damaged gas lines.

Before entering the house, make sure it is secure. Then dry it: pump out water from cellars and cellars; open all windows and doors. Heavily damaged houses are being demolished.

You can use gas, electricity, sewerage only after obtaining permission from the utilities. It is better not to touch electrical wires and sockets until they are completely dry.

Organize the cleaning of wells from the applied dirt and remove water from them. Strictly observe the rules of hygiene in order to prevent outbreaks of epidemics associated with the mass death and decomposition of animals. Do not eat food that has been in contact with water.

5.2. Tsunami- these are giant sea waves resulting from the upward or downward displacement of extended sections of the bottom during strong underwater and coastal earthquakes, less often volcanic eruptions (Fig. 2.2).

The height of the waves in the area of their occurrence is 0.1-5 m, near the coast - up to 40 m, in wedge-shaped bays and river valleys - over 50 m. Tsunamis can spread inland up to 3 km. The main area where tsunamis appear is the coasts of the Pacific and Atlantic oceans (80% of cases), less often the Mediterranean Sea.

Possessing great energy, tsunamis lead to flooding of the area, destruction of buildings and structures, power transmission and communication lines, roads, bridges, as well as to the death of people and animals. An air shock wave propagates in front of the water shaft, which acts similarly to a blast wave, destroying buildings and structures.

A natural tsunami warning signal is an earthquake. Before the start of a tsunami, the water recedes far from the coast, exposing the seabed for hundreds of meters or even several kilometers. Low tide can last from a few minutes to half an hour. The movement of the waves is accompanied by thunderous sounds (they are heard before the approach of the tsunami waves). Before the tsunami, the behavior of animals also changes.

Actions during a tsunami:

Leave the room immediately, after turning off the electricity and gas.

In the shortest way, move to an elevated place 30-40 m above sea level or at a distance of 2-3 km from the coast.

If you are driving, drive in a safe direction, picking up running people along the way.

Once in the water, get rid of shoes and wet clothes, try to catch on floating objects (be careful - the wave can carry large objects and their fragments with it).

Before entering the house after the tsunami, check its strength, the safety of the doors, the condition of the electric lighting, and the absence of gas leaks in the room.

There is no reliable protection against a tsunami. Important for the protection of the population from tsunamis are warning services about the approach of waves, based on the advance registration of earthquakes by coastal seismographs. Tsunamis are not dangerous for ships on the high seas.

Introduction

1. Causes of flooding

2. Effects of floods

3. Flood prevention measures, rescue work

Conclusion

Bibliography

Introduction

It is well known that the state and development of both the biosphere and human society is directly dependent on the state of water resources. In recent decades, an increasing number of specialists and politicians among the problems facing humanity, number 1 call the problem of water. Water problems arise in four cases: when there is no water or it is not enough, when the quality of water does not meet social, environmental and economic requirements, when the regime of water bodies does not correspond to the optimal functioning of ecosystems, and the regime of its supply to consumers does not meet the social and economic requirements of the population, and, finally, when the habitable territories suffer from floods from excess water.

In the global aspect, the first three problems were the product of the outgoing century, and the fourth has been accompanying human society since ancient times. And paradoxically, for many centuries, humanity, making incredible efforts to protect against floods, cannot succeed in this event. On the contrary, with every century the damage from floods continues to grow. Especially strong, about 10 times, it has increased over the second half of the past century. According to our calculations, the area of flood-prone areas on the globe is about 3 million square meters. km, which is home to about 1 billion people.

1.Causes of the flood

Flooding - temporary flooding of a significant part of the land with water as a result of the action of natural forces. Depending on the causing causes, they can be divided into groups.

Floods caused by heavy rainfall or heavy melting of snow, glaciers. This leads to a sharp rise in the level of rivers, lakes, and the formation of congestion. The breakthrough of congestion and dams can lead to the formation of a breakthrough wave, characterized by the rapid movement of huge masses of water and a significant height. The flood in August 1989 in Primorye demolished a significant number of bridges and buildings, killing a huge number of livestock, damaging power lines, communications, roads destroyed, and thousands of people were left homeless.

Floods caused by surge winds. They are typical for coastal regions, where there are mouths of large rivers flowing into the sea. The surging wind delays the movement of water into the sea, which sharply raises the water level in the river. The coasts of the Baltic, Caspian and Azov seas are under constant threat of such flooding. So, St. Petersburg has experienced more than 240 such floods during its existence. At the same time, cases of the appearance of heavy ships were observed on the streets, which caused the destruction of urban buildings. In November 1824, the water level in the Neva rose 4 m above the norm; in 1924 - by 3.69 m, when water flooded half of the city; in December 1973 - by 2.29 m; January 1984 - by 2.25 m. And as a result of the floods - huge material losses and victims.

Flooding caused by underwater earthquakes. They are characterized by the appearance of giant waves of great length - tsunamis (in Japanese - "big wave in the harbor"). Tsunami propagation speed up to 1000 km/h. The height of the wave in the area of its origin does not exceed 5 m. But when approaching the shore, the steepness of the tsunami increases sharply, and the waves crash on the coast with great force. At flat coasts, the wave height does not exceed 6 m, and in narrow bays it reaches 50 m (tunnel effect). The duration of a tsunami is up to 3 hours, and the coastline affected by them reaches a length of 1000 km. In 1952, the waves almost washed away Yuzhno-Kurilsk.

The natural causes of floods are well known to readers, and therefore we will only mention them. In most parts of the world, floods are caused by prolonged, intense rain and downpours resulting from the passage of cyclones. Floods on the rivers of the Northern Hemisphere also occur due to the rapid melting of snow, ice jams, ice jams. Foothills and high-mountain valleys are exposed to floods associated with outbursts of intraglacial and dammed lakes. In coastal areas, surge floods are not uncommon during strong winds, and during underwater earthquakes and volcanic eruptions, floods caused by tsunami waves.

In recent centuries, especially in the 20th century, anthropogenic factors have played an increasing role in increasing the frequency and destructive power of floods. Among them, first of all, it is necessary to name deforestation (the maximum surface runoff increases by 250-300%), irrational agriculture (as a result of a decrease in the infiltration properties of soils, according to some calculations, in the central regions of Russia from the 9th to the 20th century, the surface runoff increased by 4 times and the intensity of floods increased sharply). A significant contribution to the increase in the intensity of floods and floods was made by: longitudinal plowing of slopes, overconsolidation of fields when using heavy equipment, overwatering as a result of violation of irrigation norms. The average flood discharge in urban areas has approximately tripled due to the growth of impermeable coatings and development. A significant increase in the maximum flow is associated with the economic development of floodplains, which are natural flow regulators. In addition to the above, several reasons should be mentioned that directly lead to the formation of floods: improper implementation of flood protection measures leading to a breach of embankment dams, destruction of artificial dams, emergency drawdown of reservoirs, etc.

2. Effects of floods

The structure of sanitary losses during floods is dominated by injuries (fractures, damage to the joints, spine, soft tissues). Cases of diseases as a result of hypothermia (pneumonia, acute respiratory infections, rheumatism, worsening of the course of chronic diseases), the appearance of victims from burns (due to flammable liquids spilled and ignited on the surface of the water) have been recorded.

In the structure of sanitary losses, children occupy a significant place, and the most common consequences among the population are psychoneuroses, intestinal infections, malaria, and yellow fever. Human casualties are especially high on the coasts during hurricanes and tsunamis, as well as during the destruction of dams and dams (more than 93% drowned). As an example, the consequences of the 1970 flood in Bangladesh can be cited: on most of the coastal islands, the entire population died; out of 72 thousand fishermen in coastal waters, 46 thousand died. More than half of the dead were children under 10 years old, although they accounted for only 30% of the population of the disaster zone. Mortality among the population older than 50 years, among women and patients was also high.

Frequent companions of floods are large-scale poisoning. Due to the destruction of treatment facilities, warehouses with hazardous chemicals and other harmful substances, drinking water sources are poisoned. The development of extensive fires is not ruled out when flammable liquids spill over the surface of the water (gasoline and other combustible liquids are lighter than water).

3. Flood prevention measures, rescue work.

Floods are successfully predicted, and the relevant services give warnings to dangerous areas, which reduces damage. In places of floods, dams, dams, hydraulic structures are built to regulate the flow of water. In the winding places of the rivers, work is carried out to expand and straighten their channels. During the threatened period, duty and maintenance of readiness of civil defense formations are organized. Early evacuation of the population, cattle theft, and removal of equipment are being carried out.

Rescue work in flooded areas often takes place in difficult weather conditions (rain showers, fogs, squally winds). Work to save people begins with reconnaissance, using boats and helicopters equipped with communications equipment.

Places of congestion of people are established, and funds are sent there to ensure their salvation. Work on hydraulic structures is carried out by the formation of engineering and emergency technical services of the Civil Defense and Emergency Service: this is the strengthening of dams, dams, embankments or their construction.

In case of floods for rescue operations, the following are involved: rescue teams, teams and groups, as well as departmental specialized teams and units equipped with watercraft, sanitary teams and posts, hydrometeorological posts, reconnaissance teams and units, consolidated teams (teams) of mechanization of work, formation of construction, repair and construction organizations, protection of public order.

Rescue operations during floods are aimed at searching for people in a flooded area (landing them on boats, rafts, barges or helicopters) and evacuating them to safe places.

Reconnaissance groups and units operating on high-speed watercraft and helicopters determine the places where people gather in the flooded area, their condition and periodically give sound and light signals. Based on the intelligence data received, the head of the civil defense specifies the tasks for the formations and puts them forward to the objects of rescue operations.

Small groups of people in the water are thrown out lifebuoys, rubber balls, boards, poles, or other floating objects, taking into account the flow of water, wind direction, they are taken to floating craft and evacuated to safe areas. Motor ships, barges, launches, boats and other watercraft are used to rescue and transport a large number of people from the flooded area. Landing people on them is carried out directly from the shore. In this case, they choose and designate places convenient for ships to approach the shore, or equip berths.

When rescuing people who are in a break in the ice, they give the end of the rope, boards, ladders, any other object and pull it out to a safe place. Approaching people in the polynya should be crawling with outstretched arms and legs, leaning on boards or other objects.

To remove people from semi-flooded buildings, structures, trees and local objects or rescue them from the water, all watercraft used to perform rescue operations must be equipped with the necessary equipment and devices.

Medical assistance is provided by rescue units or sanitary teams directly in the flood zone (first aid) and after delivery to the berth (first medical aid).

The situation in the area of flooding can be sharply complicated as a result of the destruction of hydraulic structures. Work in this case is carried out in order to increase the stability of the protective properties of existing dams, dams and embankments; prevention or elimination of water washing of earthworks and increasing their height. The fight against flooding during the period of ice drift is carried out by eliminating congestion and ice jams that form on the rivers.

Carrying out rescue and urgent emergency and restoration work in flood control causes a certain danger to the life of the personnel of the formations. Therefore, the personnel of the formations must be trained in the rules of behavior on the water, methods of rescuing people and using rescue equipment. When carrying out work, it is prohibited to use faulty equipment, overload watercraft, carry out explosive work near power lines, underwater communications, industrial and other facilities without prior approval from the relevant organizations.

Flood prevention measures:

1. In the economic development of flood-prone territories, both in river valleys and on sea coasts, detailed economic and environmental studies should be carried out. Their goal is to identify ways to obtain the maximum possible economic effect from the development of these territories and, at the same time, to minimize possible damage from floods.

2. When developing flood control measures in river valleys, the entire watershed should be considered, and not its individual sections, since local flood control measures that do not take into account the entire flood situation in the river valley can not only not give an economic effect, but also significantly worsen the situation as a whole. and result in more flood damage.

3. It is necessary to skillfully combine engineering protection methods with non-engineering ones. First of all, these include: restriction or complete prohibition of such types of economic activity, as a result of which floods may increase (forest harvesting, etc.), as well as the expansion of measures aimed at creating conditions leading to a decrease in runoff. In addition, in flood-prone areas, only such types of economic activity should be carried out, which, if flooded, will cause the least damage.

4. Engineering structures for the protection of lands and economic facilities must be reliable, and their implementation must be associated with minimal disturbance to the natural environment.

5. A clear zoning and mapping of floodplains should be carried out with drawing the boundaries of floods of various probability. Taking into account the type of economic use of the territory, it is recommended to allocate zones with 20% flood security (for agricultural land), 5% security (for buildings in rural areas), 1% security for urban areas and 0.3% security for railways. It goes without saying that in different natural zones and ecological regions the number of zones and the principles of their allocation may change to some extent.

6. The country should have a well-functioning system for forecasting floods and for notifying the population about the time of the onset of the flood, about the maximum possible levels of its level and duration. Forecasting floods and floods should be carried out on the basis of the development of a wide, well-equipped with modern instruments service for observing the hydrometeorological situation.

7. Great importance should be given to informing the population in advance about the possibility of flooding, explaining its likely consequences and measures to be taken in case of flooding of buildings and structures. To this end, television, radio and other media should be widely used. Flood knowledge should be widely promoted in flood-prone areas. All government agencies, as well as every citizen, must clearly understand what they should do before, during and after the flood.

8. It is very important to develop and further improve methods for calculating both direct and indirect damage from floods.

9. Regulation of the use of flood-prone areas should be the prerogative of the republics, territories, regions, districts and cities. The state can direct and stimulate their activities only by adopting certain laws on the regulation of land use.

10. The system of flood protection measures should include both state and public organizations, as well as private individuals. The successful operation of such a system should be coordinated and directed by a central authority at the federal level.

11. The best tool for regulating land use in flood prone areas may be a flexible flood insurance program that combines both compulsory and voluntary insurance. The main principle of this program should be as follows: in case of adopting a rational type of use of the territory from the standpoint of flood protection, the insured is paid a significantly larger sum insured than if he ignores the relevant recommendations and norms.

12. A set of measures in flood-prone areas, including forecasting, planning and implementation of work, should be carried out before the onset of a flood, during its passage and after the end of a natural disaster.

A detailed development of the above provisions of the concept is an urgent task for a number of research and design institutes, a number of ministries, and primarily the Ministry of Emergency Situations.

Conclusion

An analysis of floods over the past century, carried out by us in many countries, showed that all over the world, including Russia, there is a tendency for a significant increase in flood damage caused by irrational management in river valleys and increased economic development of flood-prone areas.

It is necessary to study the factors leading to an increase in floods, especially catastrophic ones, in the 21st century: climate change (increased precipitation, melting ice and rising ocean levels, etc.), further growth in the economic development of river valleys due to an increase in population. Special problems should be studied in the valleys of those rivers whose channels are protected by dams and whose bottom sometimes rises many meters above the floodplains and terraces above the floodplains (Huang He, Yangtze, etc.).

Further refinement of the concept of flood protection is needed, taking into account a wide range of environmental, social, technical, cultural, educational and health measures to be implemented in flood-prone areas before, during and after the end of floods.

Among the top-priority tasks in the field of flood studies should also include: the development of a methodology for accounting for damage caused by changes in the natural environment: valley morphology, soil cover, vegetation, wildlife, water quality, as well as a methodology for accounting for damage to human health during and after completion of the floods.

List of used literature:

1. http://intra.rfbr.ru/pub/vestnik/V4 01/3 1.htm

2. Floods // Fundamentals of life safety. - 1999. - N: 3. - S. 60.

3. Avakyan, Artur Borisovich. Floods / Artur B. Avakyan, Alexey A. Polyushkin,. - M.: Knowledge, 1989. - 46 p.

4. Osipov V.I. Natural disasters at the turn of the 21st century / V.I. Osipov // Vestn. RAN. - 2001. - N: 4 - S. 291-302

5. Avakyan A. Natural and anthropogenic causes of floods. / Avakyan A. // Fundamentals of Life Safety. - 2001. - N 9. - S. 22-27.

FLOODING is a significant flooding of the area as a result of a rise in the water level in a river, lake or sea during the period of snowmelt, heavy rains, wind surges of water, during traffic jams, blockages, etc.

Floods caused by wind surge of water in the mouths of rivers are of a special type. Floods lead to the destruction of bridges, roads, buildings, structures, cause significant material damage, and at high water speeds (more than 4 m/s) and high water rise (more than 2 m) cause death of people and animals. The main cause of destruction is the impact on buildings and structures of hydraulic shocks of water masses, ice floes floating at high speed, various debris, watercraft, etc. Floods can occur suddenly and last from a few hours to 2-3 weeks.

Types of flood

Depending on the cause of the flood, they are divided into 5 types:

high water - flooding resulting from the melting of snow and the release of a reservoir from its natural banks
flood - flooding associated with heavy rains
floods caused by large accumulations of ice that clog the riverbed and prevent water from flowing downstream
surge floods , occurring due to strong winds that drive water in one direction, most often against the current
floods resulting from dam break or reservoirs.

high water	high water	Congestion	Zazhor	wind surge
recurring, rather prolonged rise in the water level in rivers, usually caused by spring snowmelt on the plains or rainfall. Floods low terrain.	an intensive relatively short-term rise in the water level in the river, caused by heavy rains, downpours, and sometimes rapid snowmelt during thaws. Unlike floods, floods can occur several times a year. A particular threat is the so-called flash floods associated with short-term, but very intense downpours, which also occur in winter due to thaws.	blockage of the channel by a motionless ice cover and heaping of ice floes during the spring ice drift in the narrowings and on the bends of the river channel, hampering the flow and causing a rise in the water level in the place of ice accumulation and above it. Jam floods are formed in late winter or early spring, and occur due to the non-simultaneous opening of large rivers flowing from south to north. Opened southern sections of the river in its course spring up accumulation of ice in the northern regions, which often causes a significant increase in water levels. Jam floods are characterized by a high and relatively short-term rise in the water level in the river.	ice plug, accumulation of in-water, loose ice during winter freezing in narrowings and on the bends of the channel, causing the rise of water in some areas above the level of the main river channel. Jam floods form 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.	rise in the water level in the sea mouths of large rivers and in windy areas of the coast of the seas, large lakes, reservoirs caused by the impact of strong winds on the water surface. They are characterized by the absence of periodicity, rarity and a significant rise in the water level, as well as, as a rule, short duration. Floods of this type have been observed in Leningrad (1824, 1924), the Netherlands (1953).
periodically for a long time	fast briefly	ice is standing, piling up water can't get out high level briefly	ice plug loose ice low level for a long time	wind from the sea into the riverbed water can't get out high level brevity

Causes of floods:

Long rains
snowmelt
tsunami wave
bottom profile
Dam failure
Other natural and man-made causes

Flood classification:

1. storm (rain);
2. floods and floods (associated with the melting of snow and glaciers);
3. jamming and jamming (associated with ice phenomena);
4. overwhelming and breakthrough;
5. surge (wind on the coasts of the seas);
6. tsunamigenic (on the coasts from underwater earthquakes, eruptions and large coastal landslides).

River floods are divided into the following types:
1. low (small or floodplain) - a low floodplain is flooded;
2. medium - high floodplains are flooded, sometimes inhabited or technogenically processed (arable land, meadows, vegetable gardens, etc.);
3. strong - terraces with buildings located on them, communications, etc. are flooded, evacuation of the population is often required, at least partial;
4. catastrophic - vast areas are significantly flooded, including cities and towns; emergency rescue operations and mass evacuation of the population are required.

According to the scale of manifestation, there are 6 categories of floods:
1. The global flood;
2. continental;
3. national;
4. regional;
5. district;
6. local.

Anthropogenic causes of floods:

Direct causes - are associated with the implementation of various hydraulic engineering measures and the destruction of dams.
Indirect - deforestation, drainage of swamps (draining of swamps - natural runoff accumulators increases runoff up to 130 - 160%), industrial and residential development, this leads to a change in the hydrological regime of rivers due to an increase in the surface component of runoff. The infiltrating capacity of soils decreases and the intensity of their washout increases. The total evaporation is reduced due to the cessation of precipitation interception by forest litter and tree crowns. If all forests are reduced, then the maximum runoff can increase up to 300%.
There is a decrease in infiltration due to the growth of waterproof coatings and buildings. The growth of water-resistant coatings in an urbanized area increases floods by 3 times.

Human activities leading to floods:
1. Constriction of the free section of the flow by along-channel roads, dams, bridge crossings, which reduces the throughput of the channel and raises the water level.
2. Violation of the natural regime of discharges and water levels, as occurs on the lower Volga as a result of seasonal regulation of the flow by overlying reservoirs: the need for winter energy forced a 2-3-fold increase in water discharges in winter, which, in the presence of ice cover, is accompanied by an increase in water level (winter floods), often higher than in high water.
3. Development of territories in the downstream pools of reservoirs of long-term flow regulation. The economic development of the floodplains increases the maximum runoff.

flood classes

1. Low. They usually do minor damage. They cover small coastal areas. Agricultural lands are flooded by less than 10%. Almost do not knock out the population from the current rhythm of life. Repeatability - 5-10 years.

2. High. Cause significant damage (moral and material). They cover large areas of river valleys. They flood about 10-15% of the land. Violate both household and economic way of life of the population. Partial evacuation of people is very likely. Periodicity - 20-25 years.

3. Outstanding. They cause great material damage, covering river basins. Approximately 50-70% of agricultural land, as well as a certain part of settlements, is under water. Outstanding floods not only disrupt the way of life, but also paralyze economic activity. It is necessary to evacuate material assets and the population from the disaster zone and protect the main objects of economic importance. Repeatability - 50-100 years.

4. Catastrophic. They cause huge material damage, spreading over vast territories within one or more river systems. Lead to human casualties. More than 70% of the land is flooded, many settlements, utilities and industrial enterprises. Industrial and economic activity is completely paralyzed, and the way of life of the population is changing. Periodicity - 100-200 years.

Danger factors:

1. height of water level change;
2. the rate of its change;
3. the duration of the rise period;
4. accompanying phenomena (wind, landslides, soil erosion, turbulent streams, destruction of agricultural products, livestock, death of people, etc.).

The flow of water as a damaging factor

Characteristics of the water flow as a damaging factor:

1. The highest water level.

2. The highest water consumption.

3. The speed of the current.

4. Area of flooding.

5. Repeatability of the value of the highest water level.

6. Duration of flooding.

7. Water temperature.

8. Security of the highest water level.

9. Time of start of the disaster.

10. The rate of rise in the water level during the entire time of the flood.

11. The depth of flooding of the territory in the area under consideration.

Damaging factors:

The combined effect of waves, wind, rainfall causes flooding of the area. This is accompanied by a significant erosion of the coast, leads to the destruction of buildings and structures, erosion of railways and roads, accidents on utility networks, destruction of crops and other vegetation, casualties among the population and the death of domestic animals and natural ecosystems. After the water falls, buildings and land sag, landslides and landslides begin.

Flood consequences:

The main features of the situation that arises during such natural disasters are: the rapid increase in the strength of damaging factors, the difficulty of access to the victims, the destructive nature of the situation, the low survival rates of the victims, as well as the presence of difficult weather conditions (mudflows, ice drift, heavy rains, etc.). ).

The amount of damage depends on:
1. - lifting heights;
2. - speed of water level rise;
3. - areas of flooding;
4. - timeliness of the forecast;
5. - availability and condition of protective structures;
6. - the degree of population and agricultural development of the river valley;
7. - the duration of standing flood waters;
8. - the frequency of floods (with repeated rises in the water level, the damage is less than with the initial one).

The passage of floods (flooding of agricultural land) after harvesting leads to less damage than before harvesting.
The severity of emergencies during channel floods depends not so much on the absolute value of the rise in the water level, but on its value relative to the altitude of settlements.

How to prepare for a flood?

If your area often suffers from floods, study and remember the boundaries of possible flooding, as well as elevated, rarely flooded places located in the immediate vicinity of places of residence, the shortest routes to them. Familiarize family members with the rules of conduct during organized and individual evacuations, as well as in the event of a sudden and rapidly developing flood. Remember the places where boats, rafts and building materials for their manufacture are stored. Prepare in advance a list of documents, property and medicines taken out during the evacuation. Put valuables, necessary warm clothes, a supply of food, water and medicines in a special suitcase or backpack.

HOW TO PROCEED DURING A FLOOD

At the warning signal of the threat of flooding and evacuation, immediately, in accordance with the established procedure, leave (leave) the danger zone of possible catastrophic flooding to the designated safe area or to elevated areas of the area, taking with you documents, valuables, necessary things and a two-day supply of non-perishable food. Register at the final evacuation point.

Before leaving the house, turn off the electricity and gas, put out the fire in the heating stoves, secure all floating objects that are outside the buildings, or place them in the back rooms. If time permits, move valuable household items to the upper floors or to the attic of a residential building. Close the windows and doors, if necessary and have time, board the windows and doors of the first floors from the outside with boards (shields). In the absence of an organized evacuation, stay on the upper floors and roofs of buildings, on trees or other towering objects until help arrives or the water subsides. At the same time, constantly give a distress signal: during the day - by hanging or waving a clearly visible panel lined with a pole, and in the dark - by a light signal and periodically by voice. When the rescuers approach, calmly, without panic and fuss, in compliance with the precautionary measures, go to the swimming facility. At the same time, strictly follow the requirements of the rescuers, do not overload the boats. During the movement, do not leave the assigned places, do not board the sides, strictly follow the requirements of the crew. It is recommended to get out of the flooded area on your own only if there are such serious reasons as the need to provide medical assistance to the victims, the continuing rise in the water level with the threat of flooding of the upper floors (attic). In this case, it is necessary to have a reliable swimming facility and know the direction of movement. During self-advance, do not stop giving a distress signal.

Help people who are swimming in the water and drowning.

IF A MAN DROWNS

Throw a floating object to a drowning person, encourage him, call for help. When reaching the victim by swimming, consider the course of the river. If the drowning person does not control his actions, swim up to him from behind and, grabbing him by the hair, tow him to the shore.

HOW TO ACT AFTER A FLOOD

Before entering a building, check to see if it is in danger of collapsing or falling.

Ventilate the building (to remove accumulated gases). Do not turn on electric lighting, do not use open flames, do not light matches until the room is completely ventilated and the gas supply system is checked for proper operation. Check the serviceability of the electrical wiring, gas supply pipelines, water supply and sewerage. Do not use them until you have verified that they are working properly with the help of specialists. To dry the premises, open all doors and windows, remove dirt from the floor and walls, pump out water from the basements. Do not eat food that has been in contact with water. Organize the cleaning of wells from the applied dirt and remove water from them.

Flooding is a significant flooding of the area as a result of a rise in the water level in a river, lake, or reservoir, causing material damage to the economy, social sphere and the natural environment. The causes of floods are systematized in table 1.

Note: the degree of danger (risk) is an integral indicator, including the probability, scale, and prevalence of the phenomenon. To determine it, the method of expert assessments was used.

Sources of flood emergencies fall into two categories: natural and technogenic character.

Table 1 - Classification of sources of flood emergencies in the territory of the Krasnoyarsk Territory.

	natural character				technogenic character
Type	Zazhornye	Snowy	mash	rain	Accidents at GTS	Raise hydroelectric discharges
Causes	Low air temperature during the freezing period	Large snow reserves + intense snowmelt	Nature of ice formation and opening of the river, air temperature	Intensive precipitation in the river basin	Unsatisfactory state of the hydrotechnical system, large flood wave	Reservoir overflow, additional power generation
Period	Autumn	Spring	Spring	Summer, sometimes spring (snow-rain floods)	Spring	Winter, spring, summer
District	Upper part of the Yenisei basin, Angara	Everywhere	Yenisei, Angara Tuba, Chulym, Kan, Taseeva, Podkamennaya Tunguska	Upper part of the Yenisei basin	Central and southern regions	Downstream hydroelectric power station
Degree danger	Malaya	Big	Medium	Malaya	Medium	Malaya

Floods of a natural nature

Depending on the causes natural floods divided into five types:

1. Floods caused by resistance to flow in the riverbed during autumn freeze-up (jammings).

2. Floods formed by snowmelt during winter thaws.

3. Floods caused by flow resistance in the riverbed during opening of rivers (congestion)

4. Floods associated with maximum runoff from spring thaw (high water).

5. Floods formed by prolonged summer rains (floods).

The order in this classification is determined chronologically according to the hydrological year, which starts in September and ends in August of the following year.

Man-made floods

1. Emergencies during the breakthrough of the dams of hydraulic structures. The period of spring snow melting is typical, when the loads on dams and dams increase many times due to the increased water content of reservoirs during this period.

The spillways of dams cannot always let the flow of water through, which leads to a breakthrough of the dam body. In this case, a powerful flood wave is formed, which propagates downstream the watercourse at high speed. Floods subside only in the case of complete (partial) descent of the reservoir.

Poorly fortified dams are subject to erosion during floods, lose their protective properties, and water floods the residential areas of the floodplain. In the region, more than 100 hydraulic structures are in emergency and unsatisfactory condition and are sources of risk.

A general description of the types of hydraulic structures in the Krasnoyarsk Territory is given in Table 2.

Table 2 - Hydraulic structures on the territory of the Krasnoyarsk Territory (for 2002)

p/p	Name	Quantity
	hydroelectric power plants
	Reservoirs with a capacity of more than 1 million cubic meters
	Reservoirs with a capacity of 100 thousand to 1 million cubic meters
	Reservoirs with a capacity of up to 100 thousand cubic meters
	Dam
6	Treatment facilities
	Surface water pollutants
	Ponds - traps for oil products

2. Floods due to increased discharges from HPPs. Since there are no approved Rules for the use of water resources in the reservoirs of HPPs of the Angara-Yenisei cascade so far, these regimes are established by a special interdepartmental working group. Its task is to establish such modes of operation of HPPs, under which the provision of consumers with electricity is achieved in the absence of flooding of settlements and economic facilities in the downstream of HPPs in winter and spring periods.

In 2001, due to an extremely cold winter, a freeze-up edge formed in the Atamanovo-Khudonogovo region, which was observed for the first time since 1970. The period from 01/07/2001 to 02/15/2001, when the air temperature was below -30º C, was the most stressful both in terms of capacity shortage in the Krasnoyarsk energy system and ice conditions. Only thanks to the optimization of HPP discharges, emergency situations were avoided.

In 2002, due to an abnormally warm winter, a situation arose when, by the beginning of the flood, the reservoirs of the HPPs were overfilled due to various reasons, including the limited consumption of electricity for space heating. At the same time, a sharp increase in HPP discharges would lead to ice breaking and winter flooding of settlements in the downstream. Under these conditions, a regime of gradual increase in discharges based on a scientifically based methodology was developed.

3. Catastrophic floods caused by hydroelectric dams. Of particular importance is the threat of catastrophic flooding in the event of the destruction and breakthrough of hydroelectric dams: the Krasnoyarsk hydroelectric power station, the Sayano-Shushenskaya hydroelectric power station, the Bratsk and Ust-Ilimsk hydroelectric power stations. The total area of catastrophic flooding can reach 31.0 thousand square meters. km. This zone will include 7 cities (Divnogorsk, Krasnoyarsk, Sosnovoborsk, Yeniseysk, Lesosibirsk, Minusinsk, Zheleznogorsk), 17 rural areas and up to 145 settlements, with a population of about 1334.9 thousand people, up to 243 economic facilities and up to 813.2 thousand hectares of arable land. The total material damage can reach 300 billion rubles.

In the flood zone with the complete destruction of the dam of the Krasnoyarsk hydroelectric power station, 6 cities and 112 settlements, with a population of 906 thousand people, fall. The total area of flooding will be 6.8 thousand km 2 including 1.3 thousand km 2 of agricultural land.

Some types of floods that take place on the territory of the Russian Federation in the Krasnoyarsk Territory almost never meet for different reasons:

· floods caused by blockage of the riverbed by driftwood (creases) - due to the almost complete cessation of the use of rivers for transporting timber;

· floods caused by underwater earthquakes or underwater volcanic eruptions - due to the remoteness of water areas from seismically active zones;

· floods created by wind surges on the shores of large lakes and reservoirs, in the sea mouths of large rivers. The shores of the Arctic Ocean, the Krasnoyarsk and Sayano-Shushenskoye reservoirs are practically deserted, they are not characterized by strong winds accompanied by surges of water.

A wide range of sources of flood emergencies requires their comprehensive study and the fight against negative consequences. With the coordinating role of the Commission for Emergency Situations and Fire Safety of the Administration of the Territory, a number of organizations of various profiles are engaged in the study of floods and the development of anti-flood measures in the Krasnoyarsk Territory. Among them are the Central Siberian Interregional Territorial Administration for Hydrometeorology and Environmental Monitoring, the Main Directorate of the Ministry of Emergency Situations for the Krasnoyarsk Territory, the Ministry of Natural Resources and Forestry of the Krasnoyarsk Territory, the Yenisei Basin Water Administration, and the administrations of municipalities of the region.