Flood as an emergency - abstract. Floods Flood as an emergency

Natural emergencies inherent in a constituent entity of the Russian Federation. Possible consequences of their occurrence

1. General characteristics of natural emergencies

Natural emergencies include:

1. Geophysical hazards: earthquakes; volcanic eruptions.

2. Geological hazards: landslides, landslides, screes, avalanches; mudflows, prone to washouts; subsidence of loess rocks and the earth's surface as a result of karst; abrasion, erosion; dust storms.

3. Meteorological and agrometeorological hazardous phenomena: storms, hurricanes, tornadoes, squalls, whirlwinds; large hail, heavy rain, snowfall, blizzard, fog; drought, dry wind, frost.

4. Marine hydrological hazards: tropical cyclones (typhoons); tsunami, strong sea fluctuations; strong pull in ports; early ice cover or fast ice; ice pressure, intense ice drift.

5. Hydrological hazards: high water levels (floods, rain floods, congestion, ice jams, wind surges); low water level; early freeze-up and the appearance of ice on navigable reservoirs and rivers; rising groundwater levels (flooding).

6. Natural (landscape) fires: forest fires; fires of steppe and grain massifs; peat fires.

7. Infectious diseases of people: single and group cases of exotic and especially dangerous infectious diseases; epidemic outbreak of dangerous infectious diseases; epidemic, pandemic; infectious diseases of people of unknown etiology.

8. Infectious morbidity in farm animals: isolated cases of exotic and especially dangerous infectious diseases; exotics, epizootics, panzootics; infectious diseases of farm animals of unknown etiology.

9. Damage to agricultural plants by diseases and pests: progressive epiphytopia; panphytotia; plant diseases of unknown etiology; massive spread of plant pests.

2. Causes and consequences of natural emergencies. Earthquake.

Earthquake- These are tremors and vibrations of the earth's surface, caused mainly by geophysical reasons.

Vibrations of the earth's surface during earthquakes are of a wave nature. Ground vibrations excite vibrations of buildings and structures, causing inertial forces in them. If their strength (seismic resistance) is insufficient, they will collapse. Seismic hazard during earthquakes is determined not only by ground vibrations, but also by possible secondary factors, which include avalanches, landslides, landslides, subsidence (subsidence) and distortions of the earth's surface, soil destruction, floods due to the destruction and breakthrough of dams and protective dams, as well as fires.

The most common cause of earthquakes is the occurrence of excessive internal stresses and rock failures. The potential energy accumulated during elastic deformation of the rock, upon destruction (fault), is converted into the kinetic energy of an air seismic wave in the soil. An earthquake of this kind is called tectonic.

Earthquakes are classified according to their magnitude and power using a magnitude scale. The magnitude (M) of an earthquake is a measure of the total amount of energy emitted by a seismic shock in the form of elastic waves.

The occurrence of an earthquake in certain areas is called seismicity. Seismicity is quantitatively characterized by both magnitude and intensity. The intensity of an earthquake characterizes the strength of the earthquake, which depends on the distance, decreasing from the epicenter to the periphery. The intensity of an earthquake on the earth's surface is assessed on a 12-point scale. In the range from 6 to 9 points on the IPE scale (Institute of Earth Physics), recommended by the Bureau of the Interdepartmental Council on Seismology and Seismic Construction (MCSSS) of the Russian Academy of Sciences, the intensity of an earthquake is determined by the parameters of vibrations on the earth's surface.

Based on the intensity of earthquakes, seismic zoning is carried out, which consists in dividing seismically dangerous areas into zones with the same seismic impact. Based on this zoning, maps of seismic zoning and a list of settlements in the Russian Federation located in seismic areas have been developed, indicating the seismicity scores accepted for them and the frequency of earthquakes.

Along with tectonic processes, earthquakes can also occur for other reasons. One of these reasons is volcanoes. The eruption of lava from the crater is accompanied by the release of energy and gives rise to volcanic earthquakes. Compared to tectonic phenomena, seismic tremors caused by volcanic activity are a less dangerous natural phenomenon, since most of the energy is discharged into the atmosphere.

Another category is formed by landslide earthquakes, when the roof of mines or underground voids collapse, causing waves in the ground. These earthquakes are classified as weak.

Floods

Flood refers to the inundation of water in an area adjacent to a river, lake or reservoir, which causes property damage, harm to public health or leads to death. Flooding of an area that is not accompanied by material damage is considered to be a flood of a river, lake or reservoir.

The main natural and geographical conditions for the occurrence of floods are: precipitation during rain, melting of snow and ice, tsunamis, typhoons, emptying of reservoirs. The most frequent floods occur when there is heavy precipitation in the form of rain, heavy melting of snow and the formation of ice jams. Floods associated with the destruction of hydraulic structures (hydroelectric power plants, dams, dams) are very dangerous.

Depending on the causes of floods, as a rule, five groups of floods are distinguished:

1st group - floods associated mainly with maximum runoff from spring melting of snow. Such floods are characterized by a significant and rather prolonged rise in the water level in the river and are usually called floods.

Group 2 - floods formed by intense rains, sometimes by melting snow during winter thaws. They are characterized by intense, relatively short-term rises in water levels and are called floods.

Group 3 - floods, caused mainly by the large resistance that the water flow encounters in the river. This usually happens at the beginning and end of winter due to ice jams and jams.

Group 4 - floods created by wind surges of water on large lakes and reservoirs, as well as in sea estuaries.

5th group - floods created by the breakthrough or destruction of hydraulic structures.

Based on the size or scale and damage caused, floods are usually divided into four groups:

low (small) floods. They are observed mainly on lowland rivers, cause minor material damage and almost do not disrupt the rhythm of life of the population.

high floods. They are accompanied by significant flooding, cover relatively large areas of river valleys and sometimes significantly disrupt the economic and everyday life of the population. In densely populated areas, high floods lead to partial evacuation of the population.

outstanding floods. Such floods cover entire river basins. They paralyze economic activity, cause great material damage, and lead to mass evacuation of the population and material assets.

catastrophic floods. They cause flooding of vast areas within one or more river systems. Such floods lead to enormous material losses and loss of life.

Most often, severe flash floods occur in the Far East, as well as in the European part of Russia.

The main characteristics of a flood zone typically include:

the number of people in the flood zone;

the number of settlements caught in the flood zone (here we can distinguish cities, urban-type settlements, rural settlements, completely flooded, partially flooded, caught in the flood zone, etc.);

the number of objects in various sectors of the economy that found themselves in the flood zone;

the length of railways and highways, power lines, communications and communication lines located in the flood zone;

number of bridges and tunnels flooded, destroyed or damaged as a result of flooding;

area of ​​agricultural land affected by flooding;

number of dead farm animals.

The qualitative characteristics of the damage caused to the flooded area, as a rule, depend on:

on the height of water rise above the level of a river or reservoir, which can vary from 2 to 14 meters;

from the flooded area, which ranges from 10 to 1000 km 2;

from the area of ​​flooding of a populated area, which ranges from 20 to 100%;

from the maximum water flow during the flood period, which, depending on the catchment area, ranges from 100 to 4500 m 3 /sec. (with a catchment area of ​​500 km 2, the maximum water flow ranges from 100 to 400 m 3 /sec, 1000 km 2 - 400 - 1500 m 3 /sec., 10000 km 2 - 1500 - 4500 m 3 /sec.).

From the duration of the flood, ranging from 1 to 2 days;

on the duration of the flood, varying on small rivers from 1 to 3 days, and on large rivers - from 1 to 3 months;

on the flow speed, which during floods varies from 2 to 5 m/s.

The main parameters of the impact of flood waves (passage waves) on permanent bridge crossings are:

impact of a moving wave front;

long-term hydraulic pressure on bridge elements (bridge supports, bank abutments, spans);

erosion of the soil between the supports (general erosion) and erosion of the supports (local), destruction of regulatory structures, earthen embankments (overpasses) on the approaches to the bridge;

slow flooding of areas, structures and roads without significant destruction on the approaches to the bridge crossing;

impacts from massive floating objects and the formation of flow restrictions, which causes additional backwater from the upstream side of the bridge.

Analysis of statistical data on the destruction of permanent bridge crossings from flooding shows that the most vulnerable elements of a bridge crossing are the bridge and its protective elements. The main reason for the destruction of all elements of the bridge crossing is soil erosion.

Tsunami

Tsunami is the formation and propagation of sea and ocean waves caused by underwater earthquakes and the eruption of underwater volcanoes. Huge masses of water washed ashore with these waves create dangerous emergency situations associated with flooding of the area with sea water, destruction or damage to buildings, structures in coastal residential and industrial areas, port facilities and berths, ships and other watercraft, power supply and communication lines , roads and bridges, as well as to the death of people and animals.

External signs of the occurrence of tsunami waves are:

tremors of the earth's crust, as during an earthquake;

a sharp drop in water level and exposure of the sea (ocean) bottom;

the appearance of cracks in the ice cover off the coast and the release of large masses of water.

The nature and extent of consequences and damage in areas affected by tsunami waves depend mainly on the height of the waves and the speed of its movement, the time of approach, as well as the width and slope of the terrain in the flood zone. The height of waves splashing onto the shore during a catastrophic tsunami can vary from 2-3 meters (in the area of ​​Sakhalin Island) to 10-18 meters (on the Kuril Islands).

The speed of the wave at the water's edge can reach 6 m/s, and at a distance of 1 km and 2 km from the water's edge - 4 m/s and about 2 m/s, respectively.

The time it takes for a wave to approach the coastline for the areas of Sakhalin and the Kuril Islands (after earthquakes with an epicenter in the Pacific Ocean) ranges from 10 to 40 minutes.

The width of the coastal flood zone depends on the slope of the area and the height of the waves. With a terrain slope of C=0.001 and a tsunami wave height of up to 3 meters, the width of the flood zone can reach 3 km.

The pressure of the hydraulic flow and the degree of destruction of coastal structures depend mainly on the height of the wave, the speed of the wave and the slope of the coast.

Ice jams and jams on rivers

An ice jam is an accumulation of ice in a channel that restricts the living section (current) and causes a rise in the water level in the place where the ice accumulates and in some area above it. Jams, as a rule, form when rivers open up at flow speeds of more than 0.6 m/s.

Places where congestion occurs include:

areas with changes in the slope of the water surface from higher to lower;

sharp turns of the river;

narrowing of the river bed;

areas with increased ice thickness.

The most common jams are hummocking. They are formed during an intense rise in water level, when, following the formation of a crack along the shores, the ice cover breaks into separate fields and ice floes. As a result of the collision, some ice floes creep onto others, compressing and hummocking.

In areas with significant destruction of the ice cover at current speeds of more than 1 m/s, diving jams form. The surface of the mash is hummocky. The height of hummocks can reach several meters. Loss of stability and blockage breakthrough occurs under the influence of water pressure and increased air temperature. When a jam breaks, the speed of the jam is from 2 to 5 m/s, the thickness of the moving ice accumulation is 3-6 m. The water flow below the broken jam can go beyond the channel and flood the area, leaving piles of ice more than 3 m high on the river banks.

An ice jam is a phenomenon similar to an ice jam. It also represents an accumulation of ice material in a river bed, causing water to rise at the point of accumulation and in some area above it. However, there are differences between congestion and jam. Firstly, a jam consists of an accumulation of loose ice material (clumps of slush, particles of inland ice, iceberg fragments, small ice floes), while a jam is an accumulation of large and small broken ice floes. Secondly, ice jams are observed at the beginning of winter, while ice jams occur at the end of winter and spring.

Places where ice jams form include various channel obstacles: islands, shoals, boulders, sharp turns, narrowing of the channel, areas in the downstream of hydroelectric power stations.

The main characteristics of jams and jams usually include: structure, size, maximum rise in water level.

There are three characteristic sections in the structure of the jam:

jam lock - a sheet of ice covered with cracks or a bridge of ice fields that have jammed the riverbed;

the head of a jam (the jam itself) is a multi-layered accumulation of chaotically located ice floes that have undergone intense hummocking;

jam tail - a single-layer accumulation of ice floes adjacent to the jam in the backwater zone.

The maximum jam level characterizes the excess of the jam level above the spring flood level without jams.

The maximum ice jam level characterizes the excess of the level during ice jam over the level during freeze-up without ice jam.

Based on the values ​​of the maximum rises of jam (jam) water levels and large-scale maps, the flood areas and depths in this zone are determined.

According to the values ​​of the maximum jam (jam) water levels, jams and jams can be divided into catastrophically powerful, strong, medium and weak:

with a maximum jam, the water level rises more than 5 meters - a catastrophically powerful jam;

with a maximum jam, the water level rises from 3 to 5 meters - a strong jam;

with a maximum jam, the water level rises from 2 to 3 meters - an average jam;

with weak congestion, the maximum mash level of water rise does not exceed 1-1.5 m.

Mudflows

Mudflow source is a section of a mudflow channel or mudflow basin that has a significant amount of loose clastic soil or conditions for its accumulation, where mudflows originate under certain water conditions.

A mudflow (mudflow) is a name given to rapid channel flows consisting of a mixture of water and rock fragments that suddenly appear in the basins of small mountain rivers.

The immediate causes of mudflows are rainfall, intensive melting of snow and ice, breakthrough of reservoirs, earthquakes, and volcanic eruptions. Despite the variety of causes, the mechanisms of debris flow generation have much in common and can be reduced to three main types: erosion, breakthrough and landslide.

With the erosion mechanism of origin, the water flow is first saturated with debris due to the washout and erosion of the mudflow basin, and then the formation of a mudflow wave in the channel.

With a breakthrough mechanism of origin, a water wave, due to intense erosion and involvement of debris masses in the movement, immediately turns into a mudflow wave, but with variable saturation.

With the landslide-landslide initiation mechanism, when a massif of water-saturated rocks (including snow and ice) is washed away, the flow saturation and the mudslide wave are formed simultaneously (the saturation is immediately almost maximum).

Mudflows are: water-rock; water-sand and water-silt; mud; mud-stone; water-snow-stone.

A water-rock mudflow is a flow in which coarse material predominates. It is formed mainly in the zone of dense rocks.

Water-sand flow is a flow in which sandy and silty material predominates. It occurs mainly in the zone of loess-like and sandy soils during intense rainfalls, washing away a huge amount of fine earth.

Mud mudflow is close to water-silt mudflow. It is formed in areas where rocks of predominantly clayey composition occur.

Mud-stone mudflow is characterized by a significant content of clay and silt particles in the solid phase with their clear predominance over the rock component of the flow.

A water-snow-rock mudflow is a transitional stage between the mudflow itself, in which the transport medium is water, and a snow avalanche.

The formation of mudflows is caused by a certain combination of geological, climatic and geomorphological conditions: the presence of mudflow-forming soils, sources of intensive soil watering, as well as geological forms that contribute to the formation of fairly steep slopes and channels.

The sources of solid components for mudflows are glacial moraines with loose filling, loose clastic material of screes, landslides, landslides, washouts, channel blockages and obstructions formed by previous mudflows, and woody plant material. The sources of water supply for mudflows are rains and downpours, glaciers and seasonal snow cover, and the waters of mountain rivers.

The most common mudflows are rain-fed mudflows, the main condition for the formation of which is the amount of precipitation that can cause the washout of rock destruction products and involve them in movement.

The formation of mudflows occurs in mudflow catchments, the most common form of which in plan is pear-shaped with a drainage funnel and a fan of hollow and valley channels that pass into the main channel. The mudflow catchment includes three main zones in which mudflow processes form and occur:

mudflow formation zone (mudflows fed with water and solid components);

transit zone (mudflow movement);

unloading zone (massive deposition of mudflows).

The areas of mudflow catchment areas range from 0.05 to several tens of square kilometers. The length of the channels ranges from 10-15 m (micro mudflows) to several tens of kilometers, and their steepness in the transit zone ranges from 25 ° -30 ° (in the upper part) to 8 ° -15 ° (in the lower part). At lower slopes, the process of deposition of mudflow mass begins. The movement of the mudflow completely stops at a slope of 2 ° -5 °.

The result of the impact of a debris flow on various objects depends on its main parameters: density, speed, advancement, height, width, flow rate, volume, duration, inclusion size and viscosity.

The density of the mudflow depends on the composition and content of the solid component. Usually it is at least 100 kg. in one cubic meter of water, which with a rock density of 2.4-2.6 g/cm 3 leads to a mud flow density of approximately 1.07-1.1 g/cm 3 . As a rule, the density of a mudflow fluctuates between 1.2-1.9 g/cm 3 .

The speed of movement of a mudflow in transit conditions (depending on the depth of the flow, the slope of the channel and the composition of the mudflow mass) ranges from 2-3 to 7-8 m/s, and sometimes more. The maximum speed can exceed the average by 1.5-2 times.

The height of the mudflow varies widely and can be: for powerful and catastrophic mudflows 3-10 m, for low-power mudflows - 1-2 m.

The width of the mudflow depends on the width of the channel and in most mountain basins in transit areas ranges from 3-5 m (narrow canyons, necks, deeply incised channels of small basins) to 50-100 m.

The maximum mudflow flow ranges from several tens to 1000-1500 m 3 /s.

The volume of mudflow deposits (the volume of loose clastic rock in its natural occurrence, removed from the mudflow source and channel) determines the zone of impact of the mudflow. As a rule, the total volume of debris flow determines the type of debris flow and its destructive effect on the structure. Most mudflow basins in Russia are characterized by mudflows of low and medium thickness.

The duration of mudflows ranges from tens of minutes to several hours. Most of the recorded mudflows lasted 1-3 hours. Sometimes mudflows can occur in waves of 10-30 minutes with non-mudflow intervals between them of up to several tens of minutes.

The maximum sizes of coarse inclusions are characterized by the size of individual blocks and boulders of rock and semi-rock, and can be 3-4 m in diameter. The mass of such blocks can be up to 300 tons.

Snow avalanches

Avalanche (from Late Latin labina - landslide) is a snow collapse of a mass of snow on mountain slopes that has come into intense motion. Snow avalanches pose a serious danger. As a result of their collapse, people die, sports and sanatorium-resort complexes, railways and roads, power lines, mining facilities and other economic facilities are destroyed, entire areas are blocked, and floods (including breakthrough ones) with the volume of a dammed reservoir can be caused up to several million cubic meters of water. The height of the breakthrough wave in such cases can reach 5-6 meters. Avalanche activity leads to the accumulation of mudflow material, since rock mass, boulders and soft soil are carried away along with the snow.

Avalanches are possible in all mountainous areas where snow cover is established. The possibility of avalanches is determined by the presence of a favorable combination of avalanche-forming factors, as well as slopes of steepness from 20 to 50 ° with a snow cover thickness of at least 30-50 cm. Avalanche-forming factors include:

snow depth;

snow density;

snowfall intensity;

snow cover subsidence;

temperature regime of air and snow cover;

snowstorm distribution of snow cover.

In the absence of precipitation, avalanches can be a consequence of intensive melting of snow under the influence of heat, solar radiation and the process of recrystallization, leading to the destruction of the snow layer (up to the formation of a fine snow mass in the depths of this layer) and a weakening of the strength and bearing capacity of individual layers.

The formation of avalanches occurs in an avalanche source, which is a section of the slope and its foot within which the avalanche moves. An avalanche source is usually characterized by three zones:

zone of origin (avalanche collection);

transit zone (tray);

stopping zone (cone) of an avalanche.

Up to 70% of all avalanches are caused by snowfall. These avalanches occur during snowfalls or within 1-2 days after they stop.

According to the frequency of occurrence (repetition) there are:

systematic avalanches (occur every year or once every two years);

sporadic avalanches (occur 1-2 times every 100 years or less, the location of the avalanche is difficult to determine).

Landslides

A landslide is the displacement to a lower level of part of the rocks that make up a slope, in the form of a sliding movement, mainly without loss of contact between the moving and stationary rocks. The movement of a landslide begins as a result of an imbalance in the slope and continues until a new state of equilibrium is reached.

Landslides can destroy individual objects and endanger entire settlements, destroy agricultural land, create a danger for the operation of quarries, damage communications, tunnels, pipelines, telephone and electrical networks, and threaten water management structures (dams).

Landslides that form on natural slopes and in excavation slopes are usually divided into two groups.

1st group. Structural landslides (structure - homogeneous cohesive clayey rocks: clays, loams, clayey marls).

The main causes of landslides are:

excessive steepness of the slope (slope);

overloading the upper part of the slope with various dumps and engineering structures;

violation of the integrity of slope rocks by trenches, upland ditches or ravines;

trimming the slope and its base;

moisturizing the bottom of the slope.

Typical places (conditions) for landslides to occur can be:

artificial earthen structures with steep slopes;

in recesses formed in homogeneous clayey soils in watershed areas of the upland;

in deep cuts for open-pit mining of mineral deposits;

in embankments filled with the same rocks when the soil-vegetation cover and clayey rocks lying near the day surface are waterlogged.

2nd group. Contact (sliding, shearing, shearing) - cohesive clayey rocks occurring in the form of layers with well-defined bedding planes (clays, loams, marls, loose limestones, weak clayey shales, loess, loess-like loams, etc.).

The main reasons for the formation of contact landslides are:

excessively steep fall of layers;

overloading the slope with dumps or various earthen structures;

violation of the integrity of rocks on the slope by trenches or upland ditches;

slope trimming;

wetting of bedding planes (contacts) with groundwater.

Typical places (conditions) for landslides to occur can be: natural slopes of hills and river valleys (on slopes), slopes of excavations consisting of layered rocks, in which the fall of the layers is directed towards the slope or towards the excavation.

Hurricanes, storms, storms

Hurricanes, storms, storms are meteorological hazards characterized by high wind speeds. These phenomena are caused by the uneven distribution of atmospheric pressure on the surface of the earth and the passage of atmospheric fronts that separate air masses with different physical properties.

The most important characteristics of hurricanes, storms and storms that determine the volume of possible destruction and losses are wind speed, the width of the zone covered by the hurricane, and the duration of its action. Wind speed during hurricanes, storms and storms in the regions of the European part of the Russian Federation varies from 20 to 50 m/s, and in the Far East 60-90 m/s or more.

Table 1.18 shows the Beaufort scale, which defines the characteristics of the wind regime, intensity and range of changes in wind speeds during hurricanes, storms and storms, as well as a visual assessment of the signs of the wind regime. This scale was adopted in 1963 by the World Meteorological Organization.

The width of the zone of catastrophic destruction during hurricane winds in tropical areas can vary from 20 to 200 kilometers or more. In mid-latitudes, the width of a hurricane's impact zone can reach several thousand kilometers. The duration of hurricane winds can vary from 9 to 12 days or more, and storms and storms from several hours to several days. The wind direction during hurricanes in our latitudes is mainly from West to East. Hurricanes most often occur in the Russian Federation in August - September.

Very often, hurricanes are accompanied by downpours, snowfalls, hail, and the occurrence of dust and snow storms.

A hurricane, passing over the sea or ocean, can form powerful clouds that are a source of heavy rain.

Dust (sand) storms occur in plowed steppe areas and are accompanied by the transfer of millions of tons of soil and sand over tens and hundreds of kilometers. Dust storms occur in the dry season in summer, sometimes in spring and in winters with little snow. On the territory of the Russian Federation, dust storms can occur in areas south of the Saratov, Ufa, Orenburg and Altai foothills.

Snow storms are characterized by the movement of huge masses of snow and a relatively small range of action - from several kilometers to 10-20 km. They occur on the flat territory of the Russian Federation and in the steppe parts of Western and Eastern Siberia.

As a result of heavy precipitation accompanying hurricane winds, flooding of the area and snow drifts may occur over a large area. Power and communication lines may be damaged.

The destruction of buildings during hurricane winds and the overlap of power line wires contribute to the emergence and rapid spread of massive fires.

CHECK QUESTIONS AND ANSWERS ON THE TOPIC

Question 1

Which of the following is a natural emergency?

Answer options.

1. Earthquakes, floods, forest and peat fires, mudflows and landslides, storms, hurricanes, tornadoes, snow drifts and icing.

2. Explosions, releases of chemical and radioactive substances.

3. Industrial accidents and disasters.

Question 2.

The formation and propagation of sea and ocean waves caused by underwater earthquakes and the eruption of underwater volcanoes is called:

Possible answers:

1. Tsunami.

3. Hurricane.

Question 3.

What is called a "Landslide"?

Answer options.

1. Separation and sliding displacement of a mass of earthen and rocks downward under the influence of its own weight. Landslides most often occur along the banks of rivers, reservoirs and on mountain slopes.

2. a rapid stream of great destructive power, consisting of a mixture of water, sand and stones, suddenly appearing in mountain river basins as a result of intense rains or rapid melting of snow.

3. separation and catastrophic fall of large masses of rocks, their overturning, crushing and rolling down on steep and steep slopes.

4. rapid, sudden movement of snow and (or) ice down steep mountain slopes under the influence of gravity and posing a threat to human life and health, causing damage to economic facilities and the environment.

Question 4.

An accumulation of ice in a channel that constrains the living section (current) and causes a rise in the water level in the place of ice accumulation and in some area above it is called.

Possible answers:

1. Ice jam.

2. Congestion of ice.

3. Ice constipation.

Question 5.

What phenomena include hurricanes, storms, storms?

Possible answers:

1. To meteorological hazards.

2. To geophysical hazards.

3. To hydrological hazards.

A special type includes floods caused by wind surges of water into river mouths. Floods lead to the destruction of bridges, roads, buildings, structures, cause significant material damage, and at high speeds of water movement (more than 4 m/s) and high heights of water rise (more than 2 m), they cause the death of people and animals. The main cause of destruction is the impact on buildings and structures of hydraulic shocks from a mass of water, ice floes floating at high speed, various debris, watercraft, etc. Floods can occur suddenly and last from several hours to 2 – 3 weeks.

Types of flood

Depending on the cause of occurrence, floods are divided into 5 types:

• flood – flood resulting from melting snow and the release of a reservoir from its natural banks
• flood – flooding associated with heavy rainfall
• floods caused by large accumulations of ice that block a river bed and prevent water from flowing downstream
• surge floods , occurring due to a strong wind that drives water in one direction, most often against the current
• floods resulting from dam break or reservoirs.

Causes of floods:

1. Long rains
2. Snow melting
3. tsunami wave
4. Bottom profile
5. Dam failure
6. Other natural and man-made causes

Flood classification:

River floods are divided into the following types:
1. low (small or floodplain) - low floodplain is flooded;
2. medium - high floodplains are flooded, sometimes inhabited or technogenically cultivated (arable lands, meadows, vegetable gardens, etc.);
3. strong - terraces with buildings, communications, etc. located on them are flooded, often requiring evacuation of the population, at least partially;
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 Flood;
2. continental;
3. national;
4. regional;
5. regional;
6. local.

Anthropogenic causes of floods:

Human activities leading to floods:
1. Restriction of the living cross-section of the flow by along-channel roads, dams, and bridge crossings, which reduces the channel's throughput capacity and increases the water level.
2. Disruption of the natural regime of flows and water levels, as happens in the lower Volga as a result of seasonal regulation of flow by overlying reservoirs: the need for winter energy forced a 2-3-fold increase in water flows in winter, which, in the presence of ice cover, is accompanied by an increase in water levels (winter floods), often above high water levels.
3. Development of territories in the lower reaches of reservoirs for long-term flow regulation. Economic development of floodplains increases the maximum flow.

Flood classes

1. Low. Typically cause minor damage. Covers small coastal areas. Agricultural land is flooded to less than 10%. They hardly dislodge the population from the current rhythm of life. Repeatability – 5-10 years.

2. High. Cause significant damage (moral and material). Cover large areas of river valleys. About 10-15% of the land is flooded. They disrupt both the everyday and economic life of the population. Partial evacuation of people is very likely. Frequency – 20-25 years.

3. Outstanding. They cause great material damage, covering river basins. Approximately 50-70% of farmland is under water, as well as a certain part of populated areas. Major floods not only disrupt everyday 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 enormous material damage, spreading over vast areas within one or more river systems. Lead to human casualties. More than 70% of the land, many settlements, utilities and industrial enterprises are flooded. Production and economic activities are completely paralyzed, and the everyday life of the population is changing. Periodicity – 100-200 years.

Hazards:

Water flow as a damaging factor

Characteristics of water flow as a damaging factor:

1. Highest water level.

2. Highest water consumption.

3. Current speed.

4. Flood area.

5. Repeatability of the highest water level.

6. Duration of flooding.

7. Water temperature.

8. Providing the highest water level.

9. Time of the start of the disaster.

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

11. Depth of flooding of the territory in the area under consideration.

Damaging factors:

Consequences of floods:

The amount of damage depends on:
1. - lifting height;
2. - rate of water level rise;
3. - flood areas;
4. - timeliness of the forecast;
5. - presence and condition of protective structures;
6. - degree of population and agricultural development of the river valley;
7. - duration of standing flood waters;
8. - frequency of recurrence 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 water level rise, but on its value relative to the altitudinal location of populated areas.

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 close proximity to your place of residence, and the shortest routes to them. Familiarize family members with the rules of conduct during organized and individual evacuation, as well as in the event of sudden and violent flooding. Remember the storage locations for boats, rafts and building materials for their manufacture. Make a list of documents, property and medicines to be removed during evacuation in advance. Place valuables, necessary warm clothes, food supplies, water and medicines in a special suitcase or backpack.

HOW TO ACT DURING A FLOOD

Before leaving home, turn off the electricity and gas, turn off the fire in heating stoves, secure all floating objects located outside the building or place them in utility rooms. If time permits, move valuable household items to the upper floors or attic of a residential building. Close the windows and doors, if necessary and if there is time, board the windows and doors of the first floors from the outside with boards (shields). In the absence of organized evacuation, until help arrives or the water subsides, stay on the upper floors and roofs of buildings, on trees or other elevated objects. At the same time, constantly give a distress signal: during the day - by hanging or waving a clearly visible banner attached to the pole, and in the dark - with a light signal and periodically with a voice. When rescuers approach, calmly, without panic or fuss, and taking precautions, get into the swimming craft. At the same time, strictly follow the requirements of rescuers and do not overload the watercraft. While driving, do not leave the designated places, do not board the aircraft, and strictly follow the requirements of the crew. It is recommended to get out of a flooded area on your own only if there are such serious reasons as the need to provide medical assistance to victims, a continuing rise in water levels with the threat of flooding of the upper floors (attic). In this case, it is necessary to have a reliable swimming device and know the direction of movement. During your independent deployment, do not stop sending the distress signal.

Provide assistance to people floating in water and drowning.

IF A PERSON DROWNS

HOW TO ACT AFTER A FLOOD

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

Flood– temporary significant flooding of an area as a result of rising water in a river, lake or sea, as well as the formation of temporary watercourses. Floods, along with wars, epidemics, earthquakes and fires, are considered one of the greatest disasters in the history of many nations.

Catastrophic flooding- flood, resulting in casualties, damage to human health, destruction or destruction of objects and other material assets in a significant amount, as well as causing serious damage to the environment.

Floods occur for the following reasons:

seasonal melting of snow cover;

melting of glaciers and snow cover in the mountains;

intense rains;

congestion and gluttons ( congestion occur in the spring when rivers open up and the ice cover is destroyed, characterized by the accumulation of ice in the river bed, which impedes its flow; gluttons– accumulation of loose spongy sludge and finely broken ice in the river bed is observed at the beginning of winter);

wind surges of water (surge waves);

• pressure waves;

  destruction of dams and other hydraulic structures.

A short-term rise in water level in rivers and other bodies of water, occurring as a result of melting snow, ice, heavy rains, etc., is called flood. Such floods are observed on most rivers of the Russian Federation.

High water- a river flood that occurs at a certain time due to the melting of snow and ice, seasonal rains, congestion, and gluttony. It is characterized by a significant and rather long-term rise in the water level in the river.

Floods caused by seasonal, usually spring, snow melting are periodically observed on most rivers in the European part of the Russian Federation and Siberia. The occurrence of catastrophic flooding is facilitated by congestion, which occur in the spring when rivers open up and the ice cover breaks down. The jam water level on the Yenisei and Tom, for example, can reach 7-10 m, and on the Lower Tunguska - sometimes 20 m.

Floods resulting from heavy rains are typical for Siberia and the Far East.

Tsunami waves formed during the eruption of underwater volcanoes and underwater earthquakes . Unlike wind waves, they cover the entire thickness of the water. In the open ocean, the speed of propagation of tsunami waves is about 800 km/h, the height is approximately 0.5 m, but with access to coastal shallow water, their height quickly increases and in some cases reaches 20-30 m, and sometimes more. Tsunami waves are very dangerous. Simultaneously with tsunami waves, an underwater earthquake produces a “shock wave” that travels at the speed of sound (5,400 km/h), that is, 6-7 times faster than a tsunami wave. These phenomena can be recorded by seismographs and hydrophones and warn the population about the danger of a tsunami.

The world's largest tsunamis were recorded: in 1883 on the island of Krakatoa - 36 thousand people died, in 1923 in Japan - 99.3 thousand people died, in 1976 in the Philippine Islands - 65 thousand people died. In Russia, tsunamis are dangerous for all coastal regions. Particularly strong tsunamis were recorded on the coastline of Kamchatka, Sakhalin and the Kuril Islands in 1737, 1780, 1898, 1919, 1923, 1952 and 1963.

Catastrophic flooding may occur during the destruction of dams and other hydraulic structures during earthquakes, prolonged rains and other phenomena. In this case, extensive flood zones arise after the passage of a destructive breakthrough wave.

In terms of frequency of occurrence, area of ​​distribution, and total average annual damage, floods occupy first place in Russia among dangerous hydrological phenomena and processes. By number of casualties and damage, per unit affected area, they occupy second place after earthquakes.

Hydrodynamically dangerous objects include structures or natural formations that create differences in water levels (dams and dams). A feature of flooding during accidents at such facilities is the appearance of a breakthrough, the main damaging factor of the accident, resulting from the rapid fall of water from the upper pool.

In addition to the damaging factors characteristic of other floods (drowning, mechanical injuries, hypothermia), during accidents at hydrodynamically dangerous objects, people are affected by factors caused by the kinetic energy of the breakthrough wave:

direct dynamic impact on the affected person by the breakthrough wave;

the traumatic effect of debris of buildings and structures destroyed by a breakthrough wave;

the damaging effects of various objects involved in the movement of a breakthrough wave.

In case of accidents at such facilities, the total losses of the population located in the zone of influence of the breakthrough wave can be 90% at night, and 60% during the day, while among the total losses, irrecoverable losses can be; at night - 75%, during the day - 40%, and sanitary - 25 and 60%, respectively.

Depending on the extent of flooding, the speed of water movement, the distance of a populated area from a hydraulic structure or a dangerous natural phenomenon, they are classified as 4 catastrophic flood zones:

The first one is directly adjacent to a hydraulic structure, a dangerous natural phenomenon. It extends over a distance of 6-12 km and is characterized by a rapid flow of water with a flow speed of 30 km/h or more.

The second is the fast current zone (15-20 km/h).

Length up to 15-25 km.

The third is the middle flow zone (10-15 km/h), length up to 30-50 km.

The fourth is a zone of weak current (spill), with a current speed of 6-10 km/h. The length of this zone depends on the terrain and can be 35-70 km.
P

This division into zones allows rescuers and medical workers to better navigate the current situation in the disaster area, which in turn improves the quality and efficiency of rescue operations. Magnitude total losses 20-35% in case of sudden flooding it can average on the number of people in the flood zone. IN cold time of year they can increase by 10-20%

depending on the duration of the victims’ stay in the water. IN structure of sanitary losses

Predominantly are victims with symptoms of asphyxia, chills, as well as acute disorders of respiratory and cardiovascular activity, soft tissue injuries, and concussions. Some victims may be in a state of mental disorder. As a result of the flood, a large number of the population finds themselves without shelter, drinking water and food, and is exposed to cold water and wind.

The health consequences of floods are characterized by:

violation of the existing system of health care provision for the population;

the occurrence of mechanical injuries (mainly to the limbs and torso) and stress reactions, cardiovascular, neuropsychiatric diseases or aggravation of their course in part of the population;

disruption of the life support system and the creation of unfavorable conditions leading to the emergence of infectious diseases (a large number of people are left without shelter, drinking water, food, and are exposed to adverse weather conditions);

significant population migration.

In areas of catastrophic flooding, water supply systems, sewerage systems, drainage communications, wastewater, and waste collection sites may be destroyed (eroded) and, therefore, there is a danger of the emergence and spread of infectious diseases. This will also be facilitated by the accumulation of population in a limited area with a significant deterioration in material and living conditions. Patients with traditional intestinal infections - dysentery, colienteritis, dysbacteriosis, salmonellosis - are arriving in large numbers. The incidence of hepatitis is increasing. In children's infectious diseases hospitals, the workload increases due to meningococcal infection. Following this, zoonoses may appear - leptospirosis, tularemia.

In case of catastrophic flooding, irretrievable losses significantly exceed sanitary losses. The magnitude and structure of population losses will vary depending on the following circumstances:

-
extent of flooding;

Population density in the flood zone;

Timely notification;

Distance of the populated area from the place where the flooding began;

Location of medical facilities;

The height of the flooding wave and the time of its passage;

Water and ambient air temperatures;

Time of year, time of day and other features.

A widespread type of damage during a flood is drowning. Conventionally, drowning is divided into aspiration (“true”), asphyxial and syncope (reflex).

In case of true drowning, water enters the respiratory tract and lungs, which, as a rule, leads to respiratory distress and respiratory hypoxia. Respiratory and vascular disorders in this case are aggravated by vasospasm of the pulmonary circulation and the appearance of metabolic and respiratory acidosis. The skin and mucous membranes of “drowned people”, as a rule, have a bluish color (the so-called “blue drowned people”).

Resuscitation measures include cleansing the oral cavity of foreign objects (algae, mud, etc.), removing water from the lungs, performing artificial ventilation, chest compressions and other measures.

During asphyxial drowning, a small amount of water enters the upper respiratory tract, which causes a reflex cessation of breathing and laryngospasm. Breath holding is accompanied by periods of false breaths, which are ineffective due to laryngospasm. The initial period of asphyxial drowning is practically absent, and the agonal period differs little from that of “true” drowning. The bluishness of the skin and mucous membranes is mild.

When providing medical care, the first step is to remove water from the lungs; when carrying out artificial ventilation of the lungs, laryngeal spasm is overcome with the help of a fixed intense exhalation (the use of oropharyngeal air ducts is desirable).

In syncopal drowning, as a rule, there is a reflex cardiac arrest due to psycho-emotional shock, contact with cold water of the skin and upper respiratory tract. In this case, clinical death occurs immediately. Drowned people have pale skin, no pulse in the carotid arteries, and wide pupils. Water does not enter the lungs, and therefore there is no need to waste time trying to remove it; artificial ventilation and chest compressions should be started immediately.

Those rescued during the initial period of drowning retain consciousness, but must be under the control of others, since they may have mental disorders and inadequate reactions to the environment. This is due to the fact that the development of the so-called “secondary” drowning syndrome is possible, when, against the background of relative well-being, a hysterical cough with profuse sputum containing streaks of blood suddenly appears again, breathing and heartbeat become more frequent, hypoxia increases, and cyanosis of the skin occurs. In some cases, such victims may require resuscitation.

Man and his environment form a system consisting of many interacting elements, which is ordered within certain boundaries and has specific properties. Such interaction is determined by many factors and influences both the person himself and his corresponding environment. This influence can be, on the one hand, positive, and on the other hand, it can be negative (negative).

The negative impacts of environmental factors manifest themselves mainly in emergency situations. These situations can be a consequence of both natural disasters and human production activities. In order to localize and eliminate negative impacts that arise in emergency situations, special services are created, legal frameworks are developed and material resources are created for their activities.

Natural emergency- this is an unfavorable situation in a certain territory that has developed as a result of a dangerous natural phenomenon that can lead to human casualties, damage to health, material losses and disruption of the living conditions of the population.

An emergency occurs only when, as a result of a dangerous natural phenomenon, a real threat to human life and the environment arises. Natural emergencies are also called natural disasters.

More than 20 types of dangerous hydrometeorological phenomena occur on the territory of Russia. These are strong winds, squalls, tornadoes, dust storms, downpours and thunderstorms, hail, heavy continuous rains, droughts, frosts, snowfalls, blizzards, ice and frost phenomena, fogs, severe frosts, floods, avalanches, mudflows and others.

In our region, according to various sources, the most common emergency disaster is flooding. I consider it necessary to dwell on the features of this particular disaster.

Flood

Flood - this is a significant flooding of an area as a result of a rise in the water level in a river, lake or sea during snowmelt, rainfall, wind surges, congestion, floods, etc.

Flood classification:

1. storm (rain);

2. floods and floods (associated with melting snow and glaciers);

3. gluttony and congestion (related to ice phenomena);

4. blockage and breakthrough;

5. surge (wind on the coasts of the seas).

The causes of floods are diverse, and each cause or group of causes has its own type of flood. Below we indicate four main groups of types of floods:

1. Floods associated with the passage of very large water flows for a given river. Such floods occur during the period of spring snowmelt, with heavy rainfall and rainfall, in the event of dam failures and dammed lakes breaking out.

2. Floods caused mainly by the great resistance that the water flow encounters in the river. This usually happens at the beginning and end of winter due to jams and ice jams.

3. Floods caused by both the passage of large flows of water and significant resistance to water flow. NT1 includes mudflows on mountain rivers and water-snow flows in ravines, ravines and hollows.

4. Floods created by wind surges of water on large lakes and reservoirs.

However, the direct reasons are related to the implementation of various hydraulic engineering measures and the destruction of dams. Indirect - deforestation, drainage of swamps, 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. Evapotranspiration is reduced due to the cessation of interception of precipitation by the forest floor and tree crowns. If all forests are removed, the maximum flow can increase to 300%.

The consequences of floods are almost always devastating. Floods lead to the destruction of bridges, roads, buildings, structures, cause significant material damage, and at high speeds of water movement (more than 4 m/s) and high heights of water rise (more than 2 m), they cause the death of people and animals. The main cause of destruction is the impact on buildings and structures of hydraulic shocks from a mass of water, ice floes floating at high speed, various debris, watercraft, etc. Floods can occur suddenly and last from a few hours to 2-3 weeks.

One of the largest floods in Kurgan and the Kurgan region was the flood of 1994. For a month, from April 19 to May 19, 1994, Kurgan was in a state of emergency due to flooding, which affected about 60 thousand people. And this is only in the regional center. In the region, about 200 thousand people suffered material damage. Also in the spring of that year, four districts of the region, the cities of Kurgan and Shadrinsk, 114 settlements, over 200 thousand hectares of agricultural land, incl. 140 thousand hectares of arable land. 37 km of highways were damaged, 35 bridges, 183 dams, more than 240 km of power and communication lines, a significant number of residential buildings, and tens of thousands of garden plots were destroyed and demolished. Enormous damage has been caused to the nature of the Trans-Urals.

The scale of damage caused by the flood is enormous. According to the most conservative estimates, they exceed 200 billion rubles.

The official maximum water level in Tobol near Kurgan then was 10 meters 7 cm.