Natural emergency - the situation in a certain territory or water area that has developed as a result of the occurrence of a source of a natural emergency that may cause or has caused human casualties, damage to human health and (or) the natural environment, significant material losses and violation of people's living conditions.
Natural emergencies are distinguished by the scale and nature of the source of occurrence, they are characterized by significant damage and death of people, as well as the destruction material assets.
Earthquakes, floods, forest and peat fires, mudflows and landslides, storms, hurricanes, tornadoes, snow drifts and icing - all these are natural emergencies, and they will always be companions of human life.
In natural disasters, accidents and catastrophes, a person's life is in great danger and requires the concentration of all his spiritual and physical strength, meaningful and cold-blooded application of knowledge and skills for action in a particular emergency.
Landslide.
A landslide is a separation and sliding displacement of a mass of earthen, rocks downwards under the action of its own weight. Landslides occur most often along the banks of rivers, reservoirs and on mountain slopes.
Landslides can occur on all slopes, but on clay soils they occur much more often, for this, excessive moisture of the rocks is sufficient, so they mostly disappear in the spring and summer.
The natural cause of the formation of landslides is an increase in the steepness of the slopes, washing away their bases with river waters, excessive moisture of various rocks, seismic shocks and a number of other factors.
Mudflow (mudflow)
Mudflow (mudflow) is a rapid stream of great destructive power, consisting of a mixture of water, sand and stones, which suddenly appears in mountain river basins as a result of intense rains or rapid snowmelt. glaciers, breakthrough of reservoirs, earthquakes and volcanic eruptions, as well as the collapse of a large amount of loose soil into the riverbed. Mudflows pose a threat to settlements, railways and roads and other structures located on their way. Having a large mass and high speed of movement, mudflows destroy buildings, roads, hydraulic and other structures, disable communication and power lines, destroy gardens, flood arable land, and lead to the death of people and animals. All this lasts 1-3 hours. The time from the occurrence of a mudflow in the mountains to the moment it reaches the foothills is often estimated at 20-30 minutes.
Collapse (mountain collapse)
Collapse (mountain collapse) - separation and catastrophic fall of large masses of rocks, their overturning, crushing and rolling on steep and steep slopes.
Landslides of natural origin are observed in the mountains, on the seashores and cliffs of river valleys. They occur as a result of the weakening of the coherence of rocks under the influence of the processes of weathering, washing, dissolution and the action of gravity. Contribute to the formation of landslides geological structure terrain, the presence of cracks and zones of crushing of rocks on the slopes.
Most often (up to 80%), modern collapses are formed during improper work, during construction and mining.
People living in hazardous areas should know the outbreaks, the possible directions of movement of flows and the possible strength of these dangerous phenomena. If there is a threat of a landslide, mudflow or collapse, and if there is time, an early evacuation of the population, farm animals and property from threatening zones to safe places is organized. 
Avalanche (snow avalanche)
An avalanche (snow avalanche) is a rapid, sudden movement of snow and (or) ice down the steep slopes of mountains under the influence of gravity and posing a threat to life and health of people, causing damage to economic and environment. Snow avalanches are a type of landslide. When an avalanche forms, the snow first slides off the slope. Then the snow mass quickly picks up speed, capturing more and more snow masses, stones and other objects along the way, growing into a powerful stream that rushes down at high speed, sweeping away everything in its path. The movement of the avalanche continues to more gentle sections of the slope or to the bottom of the valley, where the avalanche then stops.
Earthquake
An earthquake is an earth tremor and vibration of the earth's surface resulting from sudden displacements and ruptures in the earth's crust or the upper part of the Earth's mantle and transmitted over long distances in the form elastic vibrations. According to statistics, earthquakes rank first in terms of economic damage and one of the first places in terms of the number of human casualties.
During earthquakes, the nature of the damage to people depends on the type and density of the building of the settlement, as well as on the time of the earthquake (day or night).
At night, the number of victims is much higher, because. most people are at home and resting. During the day, the number of the affected population fluctuates depending on which day the earthquake occurred - on a working day or on a weekend.
With brick and stone buildings, the following character of people's damage prevails: injuries of the head, spine and limbs, squeezing chest, soft tissue compression syndrome, as well as injuries of the chest and abdomen with damage to internal organs.
Volcano
A volcano is a geological formation that occurs above channels or cracks in the earth's crust, through which red-hot lava, ash, hot gases, water vapor, and rock fragments erupt onto the Earth's surface and into the atmosphere.
Most often, volcanoes form at the junction of the Earth's tectonic plates. Volcanoes are extinct, dormant, active. In total, there are almost 1,000 dormant and 522 active volcanoes on land.
About 7% of the world's population lives dangerously close to active volcanoes. More than 40,000 people died as a result of volcanic eruptions in the 20th century.
The main damaging factors during a volcanic eruption are red-hot lava, gases, smoke, steam, hot water, ash, rock fragments, a blast wave and mud-stone flows.
Lava is a hot liquid or very viscous mass that erupts onto the surface of the Earth during volcanic eruptions. The temperature of the lava can reach 1200°C or more. Together with lava, gases and volcanic ash are ejected to a height of 15-20 km. and up to 40 km. and more. A characteristic feature of volcanoes is their repeated multiple eruptions.
Hurricane
A hurricane is a wind of destructive force and considerable duration. A hurricane occurs suddenly in areas with a sharp drop in atmospheric pressure. The speed of a hurricane reaches 30 m/s or more. In terms of its harmful effects, a hurricane can be compared with an earthquake. This is explained by the fact that hurricanes carry colossal energy, its amount released by an average hurricane in one hour can be compared with the energy of a nuclear explosion.
The hurricane wind destroys strong and demolishes light structures, devastates sown fields, breaks wires and knocks down power transmission and communication poles, damages highways and bridges, breaks and uproots trees, damages and sinks ships, and causes accidents on utility and energy networks.
A storm is a type of hurricane. The wind speed during a storm is not much less than the speed of a hurricane (up to 25-30 m/s). Losses and destruction from storms are significantly less than from hurricanes. Sometimes a strong storm is called a storm.
A tornado is a strong small-scale atmospheric vortex with a diameter of up to 1000 m, in which the air rotates at a speed of up to 100 m/s, which has great destructive power (in the USA it is called a tornado). In the internal cavity of the tornado, the pressure is always reduced, so any objects that are in its path are sucked into it. average speed the movement of the tornado is 50-60 km / h, when it approaches, a deafening rumble is heard.
Thunderstorm
A thunderstorm is an atmospheric phenomenon associated with the development of powerful cumulonimbus clouds, which is accompanied by multiple electrical discharges between the clouds and the earth's surface, thunder, heavy rain, and often hail. According to statistics, 40,000 thunderstorms occur daily in the world, 117 lightning flashes every second.
Thunderstorms often go against the wind. Just before the start of a thunderstorm, there is usually a calm or the wind changes direction, sharp squalls fly in, after which it starts to rain. However, the greatest danger is "dry", that is, not accompanied by precipitation, thunderstorms.
blizzard
A snow storm is one of the varieties of a hurricane, characterized by significant wind speeds, which contributes to the movement of huge masses of snow through the air, and has a relatively narrow band of action (up to several tens of kilometers). During a storm, visibility deteriorates sharply, and transport communication, both intracity and intercity, may be interrupted. The duration of the storm varies from several hours to several days.
Blizzard, blizzard, blizzard are accompanied by sharp temperature changes and snowfall with strong gusts of wind. The temperature difference, snowfall with rain at low temperatures and strong winds, creates conditions for icing. Power lines, communication lines, roofs of buildings, various supports and structures, roads and bridges are covered with ice or sleet, which often causes their destruction. Ice formations on the roads make it difficult, and sometimes completely hinder the operation of road transport. Pedestrian movement will be difficult.
The main damaging factor of such natural disasters is the impact of low temperature on the human body, causing frostbite, and sometimes freezing.
floods
Floods are significant flooding of an area resulting from a rise in the water level in a river, reservoir or lake. The causes of floods are heavy rainfall, intensive snowmelt, breakthrough or destruction of dams and dams. Floods are accompanied by human casualties and significant material damage.
In terms of frequency and area of distribution, floods rank first among natural disasters, in terms of the number of human casualties and material damage, floods rank second after earthquakes.
high water- a phase of the water regime of the river, which can be repeated many times in different seasons of the year, characterized by an intense, usually short-term increase in water flow and levels, and caused by rain or snowmelt during thaws. Floods following one after another can cause floods. Significant flooding can cause flooding.
catastrophic flood- a significant flood that occurs as a result of intensive melting of snow, glaciers, as well as heavy rains, forming a severe flood, as a result of which there was a mass death of the population, agricultural animals and plants, damage or destruction of property, and also caused damage to the environment. The term catastrophic flood is also applied to floods that cause the same consequences.
Tsunami- gigantic sea waves, resulting from the up or down shift of extended sections of the seabed during strong underwater and coastal earthquakes.
The most important characteristic of a forest fire is the speed of its spread, which is determined by the speed of its edge advance, i.e. streaks of burning along the contour of the fire.
Forest fires, depending on the scope of the spread of fire, are divided into ground, crown and underground (peat).
A ground fire is a fire that spreads along the ground and through the lower tiers of forest vegetation. The temperature of the fire in the fire zone is 400-900 °C. Ground fires are the most frequent and account for up to 98% of the total number of fires.
Horse fire is the most dangerous. It starts with a strong wind and covers the crowns of trees. The temperature in the fire zone rises to 1100°C.
An underground (peat) fire is a fire in which the peat layer of waterlogged and swampy soils burns. Peat fires are characterized by the fact that they are very difficult to extinguish.
The causes of fires in the steppe and grain massifs can be thunderstorms, accidents of ground and air transport, accidents in grain harvesting equipment, terrorist attacks and careless handling of open fire. The most fire-hazardous situation develops in late spring and early summer, when the weather is dry and hot.
emergency natural character inherent in the subject of the Russian Federation. Possible consequences of their occurrence
1. general characteristics natural emergencies
Natural emergencies include:
1. Geophysical hazards: earthquakes; volcanic eruptions.
2. Geological hazards: landslides, landslides, talus, avalanches; sat down, prone to flushes; subsidence of loess rocks and the earth's surface as a result of karst; abrasion, erosion; dust storms.
3. Meteorological and agrometeorological hazards: 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 vibrations; strong draft in ports; early ice cover or fast ice; ice pressure, intense ice drift.
5. Hydrological hazards: high levels waters (high water, rain floods, traffic jams, ice jams, wind surges); low water level; early freezing 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 of farm animals: isolated cases of exotic and especially dangerous infectious diseases; exooty, epizooty, panzooty; infectious diseases of farm animals of unknown etiology.
9. Damage to agricultural plants by diseases and pests: progressive epiphytopy; panphytotia; plant diseases of unknown etiology; mass distribution 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 causes.
Fluctuations 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. With insufficient strength (seismic resistance), their destruction occurs. 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 during the destruction and breakthrough of dams and protective dams, as well as fires.
The most common cause of earthquakes is the appearance of excessive internal stresses and destruction of rocks. Potential energy, accumulated during elastic deformations of the rock, upon destruction (fault) passes into the kinetic energy of an air seismic wave in the soil. An earthquake of this kind is called tectonic.
The classification of earthquakes according to their magnitude and power is carried out on a scale of magnitudes. 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 manifestation of an earthquake in certain areas is called seismicity. Quantitatively, seismicity is characterized by both magnitude and intensity. The intensity of the 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 estimated on a 12-point scale. Within the range of 6 to 9 points on the IPE (Institute of Earth Physics) scale recommended by the Bureau of the Interdepartmental Council for Seismology and Seismic Engineering (MCSS) of the Russian Academy of Sciences, the intensity of an earthquake is determined by the parameters of vibrations on the earth's surface.
According to the intensity of earthquakes, seismic zoning is carried out, which consists in the fact that seismically dangerous areas are divided into zones with the same seismic impact. Based on this zoning, maps of seismic zoning and a list of settlements of the Russian Federation located in seismic regions were developed, indicating the seismicity accepted for them in points and the frequency of earthquakes.
Along with tectonic processes, earthquakes can also occur for other reasons. One such reason is volcanoes. The eruption of lava from the crater is accompanied by the release of energy and generates volcanic earthquakes. Compared to tectonic events, seismic shocks 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 collapses, causing waves in the ground. These earthquakes are classified as weak.
floods
Flooding is understood as the flooding of the area adjacent to a river, lake or reservoir, which causes material damage, damages the health of the population or leads to loss of life. Flooding of the area, 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 with heavy precipitation in the form of rain, heavy snowmelt and the formation of congestion during ice drift. Floods associated with the destruction of hydraulic structures (hydroelectric power stations, 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 the maximum runoff from spring snowmelt. Such floods are characterized by a significant and rather long rise in the water level in the river and are usually called high water.
2nd group - floods formed by intense rains, sometimes by melting snow during winter thaws. They are characterized by intense, relatively short-term rises in the water level and are called floods.
3rd group - floods caused mainly by high resistance, which water flow meets in the river. This usually occurs at the beginning and at the end of winter during traffic jams and ice jams.
4th group - floods created by wind surges of water on large lakes and reservoirs, as well as in sea mouths of rivers.
5th group - floods created in the event of a breakthrough or destruction of hydroelectric facilities.
Floods are generally classified into four groups based on their size or scale and the damage they cause:
low (small) floods. They are observed mainly on lowland rivers, cause minor material damage and almost do not disturb the rhythm of the 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 values.
catastrophic floods. They cause flooding of vast areas within one or more river systems. Such floods lead to huge material losses and loss of life.
The most frequent severe flash floods occur in Far East, as well as in the European part of Russia.
The main characteristics of the flood zone, as a rule, include:
the number of people in the flood zone;
the number of settlements that fell into the zone covered by the flood (here we can distinguish cities, urban-type settlements, rural settlements, completely flooded, partially flooded, caught in the flood zone, etc.);
the number of objects of various sectors of the economy that ended up in the zone covered by the flood;
the length of railways and roads, power lines, communication and communication lines that are in the flood zone;
number of bridges and tunnels flooded, destroyed and damaged by flooding;
the area of agricultural land affected by flooding;
the number of dead farm animals.
The qualitative characteristics of the damage caused to the flooded area, as a rule, depends on:
from the height of the rise of water above the level of the river, reservoir, which can vary from 2 to 14 meters;
from the area of flooding, which ranges from 10 to 1000 km 2;
from the area of flooding of the settlement, 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 / s. (With a catchment area of 500 km 2, the maximum water flow ranges from 100 to 400 m - 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, which fluctuates on small rivers from 1 to 3 days, and on large rivers - from 1 to 3 months;
on the flow velocity, which during floods varies from 2 to 5 m/s.
The main parameters of the impact of flood waves (pass waves) on permanent bridge crossings are:
impact of a moving wave front;
long-term hydraulic pressure on the bridge elements (bridge supports, bank abutments, span structures);
erosion of the soil between the supports (general erosion) and undermining of the supports (local), destruction of regulatory structures, earthen embankments (flyovers) on the approaches to the bridge;
slow flooding of the terrain, structures and roads without their significant destruction on the approaches to the bridge crossing;
impacts of massive floating objects and the formation of flow constraints, 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 is soil erosion.
Tsunami
Tsunami - the formation and propagation of sea and ocean waves caused by underwater earthquakes and the eruption of underwater volcanoes. Huge masses of water thrown ashore with these waves create dangerous emergencies associated with flooding of the area. sea water, destruction or damage to buildings, structures in coastal areas of residential and industrial development, port facilities and moorings, ships and other watercraft, power supply and communication lines, roads and bridges, as well as to the death of people and animals.
External signs tsunami waves are:
jerks earth's crust like an earthquake;
a sharp drop in the 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 the consequences and damage in the 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 catastrophic tsunamis can vary from 2-3 meters (near Sakhalin Island) to 10-18 meters (on the Kuril Islands).
The speed of wave movement 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 of wave approach to the coastline for the areas of Sakhalin and the Kuril Islands (after earthquakes with an epicenter at pacific ocean) is between 10 and 40 minutes.
The width of the flood zone of the coast depends on the slope of the terrain 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.
Hydroflow pressure and the degree of destruction of coastal structures depends mainly on the height of the wave, the speed of the wave and the slope of the coast.
Ice jams and ice jams on rivers
An ice jam is an accumulation of ice in a channel that restricts the flow area (flow) and causes a rise in the water level at the place of ice accumulation and in some area above it. Jamming, as a rule, is formed when rivers are opened at flow rates of more than 0.6 m/s.
Congestion sites include:
areas with a change in the slope of the water surface from larger to smaller;
sharp turns of the river;
narrowing of the riverbed;
areas with increased ice thickness.
The most common congestion is hummocking. They are formed during an intensive rise in the water level, when, following the formation of a crack along the coast, the ice cover breaks into separate fields and ice floes. As a result of the collision, some ice floes creep onto others, they are compressed and hummocked.
In areas with significant destruction of the ice cover, at current velocities of more than 1 m/s, diving jams are formed. The surface of the jam is hummocky. The height of the hummocks can reach several meters. The loss of stability and the breakthrough of the congestion occurs under the influence of water pressure and an increase in air temperature. In the event of a break, the speed of the blockage is from 2 to 5 m/s, the thickness of the moving ice accumulation is 3-6 m. The water flow below the broken blockage can go beyond the channel and flood the area, leaving piles of ice more than 3 m high on the banks of the rivers.
Ice blockage is a phenomenon similar to ice blockage. It is also an accumulation of ice material in a riverbed causing water to rise at the location of the accumulation and in some area above it. However, there are differences between congestion and congestion. Firstly, a jam consists of an accumulation of loose ice material (clods of sludge, particles of in-water ice, fragments of icebergs, small ice floes), while a jam is an accumulation of large and small ice floes. Secondly, ice jam occurs at the beginning of winter, while ice jam occurs at the end of winter and in spring.
Various channel obstacles can be attributed to the places of formation of ice jams: islands, shoals, boulders, sharp turns, narrowing of the channel, areas in the downstream of the hydroelectric power station.
The main characteristics of congestion and blockage usually include: structure, size, maximum rise in water level.
There are three characteristic sections in the structure of the congestion:
jam lock - an ice cover covered with cracks or a jumper from ice fields that have jammed the channel;
the head of the jam (the jam itself) is a multi-layered accumulation of chaotically arranged ice floes subjected to intensive 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 level during the jam over the level of the spring flood without jams.
The maximum blockage level characterizes the excess of the level during a blockage over the level during freeze-up without blockage.
According to the values of the maximum rises in 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 jamming water level rise of more than 5 meters - catastrophically powerful jamming;
with a maximum jamming rise in the water level from 3 to 5 meters - a strong jam;
with a maximum jamming rise in the water level from 2 to 3 meters - an average traffic jam;
with a weak jam, the maximum jam level of water rise does not exceed 1-1.5 m.
Mudflows
Mudflow source - a section of a mudflow channel or mudflow basin, which has a significant amount of loose clastic soil or conditions for its accumulation, where mudflows are born under certain conditions of flooding.
Mudflow (debris) is called rapid channel flows, consisting of a mixture of water and rock fragments, suddenly arising in the basins of small mountain rivers.
The immediate causes of mudflows are showers, intense melting of snow and ice, breakthrough of reservoirs, earthquakes, volcanic eruptions. Despite the variety of causes, the mechanisms of mudflow generation have much in common and can be reduced to three main types: erosional, breakthrough, and landslide-landslide.
With the erosion mechanism of origin, the water flow is first saturated with clastic material 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 generation, a water wave, due to intense erosion and involvement of clastic masses in the movement, immediately turns into a mudflow wave, but with a variable saturation.
With the landslide mechanism of origin, when the massif of water-saturated rocks (including snow and ice) is washed away, the saturation of the flow and the mudflow wave are formed simultaneously (the saturation is immediately almost maximum).
Mudflows are: water-stone; water-sandy and water-dusty; mud; mud stone; water-snow-stone.
A water-stone mudflow is a flow in which coarse-grained material predominates. It is formed mainly in the zone of dense rocks.
Water-sand - such a stream in which sandy and silty material predominates. It occurs mainly in the zone of loess-like and sandy soils during heavy rains, washing away a huge amount of fine earth.
The mudflow is close to water-silty. It is formed in the areas of distribution of rocks of predominantly clay composition.
Mud-rock mudflow is characterized by a significant content of clay and silt particles in the solid phase with their clear predominance over the stone component of the flow.
Water-snow-stone 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 due to a certain combination of geological, climatic and geomorphological conditions: the presence of mudflow-forming soils, sources of intensive watering of soils, as well as geological forms that contribute to the formation of rather steep slopes and channels.
Mudflows are fed by solid components of glacial moraines with loose filling, loose clastic material of screes, landslides, landslides, washouts, channel blockages and blockages formed by previous mudflows, woody and plant material. Mudflows are supplied with water by rains and showers, glaciers and seasonal snow cover, waters of mountain rivers.
Most often, rain-fed mudflows are formed, the main condition for the formation of which is the amount of precipitation that can cause a washout of the destruction products of rocks and involve them in motion.
The formation of mudflows occurs in mudflow catchment areas, the most common form of which in terms of plan is pear-shaped with a funnel and a fan of hollow and valley channels, passing into the main channel. The mudflow catchment area includes three main zones in which mudflow processes are formed and occur:
the zone of mudflow formation (the supply of mudflows with water and the solid component);
transit zone (debris flow);
unloading zone (massive deposition of debris flows).
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 transition zone ranges from 25°-30° (in the upper part) to 8°-15° (in the lower part). With smaller slopes, the process of deposition of mudflow mass begins. Mudflow movement stops completely at a steepness of 2 ° -5 °.
The result of mudflow impact on various objects depends on its main parameters: density, speed, advancement, height, width, flow rate, volume, duration, inclusion size and viscosity.
The mudflow density depends on the composition and content of the solid component. Usually it is at least 100 kg. in one cubic meter of water, which at a rock density of 2.4-2.6 g/cm 3 leads to a mudflow density of approximately 1.07-1.1 g/cm 3 . As a rule, the mudflow density fluctuates between 1.2-1.9 g/cm 3 .
The speed of the 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. Max speed can exceed the average by 1.5-2 times.
The height of the mudflow varies considerably and can be: for powerful and catastrophic mudflows 3-10 m, for low-power ones - 1-2 m.
The width of the mudflow depends on the width of the channel and in most mountain basins in the transit areas varies from 3-5 m (narrow canyons, necks, deeply incised channels of small basins) to 50-100 m.
The maximum mudflow flow varies from several tens to 1000-1500 m 3 /s.
The volume of mudflow deposits (the volume of loose clastic rock in natural occurrence, taken out of the mudflow source and channel) determines the impact zone 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 small and medium thickness.
The duration of mudflows varies from tens of minutes to several hours. Most of the registered mudflows lasted 1-3 hours. Sometimes mudflows can occur in waves of 10-30 minutes with non-mudflow intervals up to several tens of minutes between them.
The maximum sizes of coarse clastic inclusions are characterized by the size of individual blocks and boulders of hard and semi-rocky rocks, 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) - a snowfall of a mass of snow on mountain slopes that has come into heavy movement. Snow avalanches are a serious hazard. As a result of their gathering, people die, sports and sanatorium-resort complexes, iron and car roads, power lines, mining facilities and other objects of the economy, entire areas are blocked, and floods (including breakthrough ones) with a volume of a dammed reservoir of up to several million cubic meters of water can also be caused. The height of the breakthrough wave in such cases can reach 5-6 meters. Avalanche activity leads to the accumulation of mudflow material, as rock mass, boulders and soft soil are carried along with the snow.
The occurrence of avalanches is 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 with a steepness of 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 settling;
temperature regime of air and snow cover;
blizzard distribution of snow cover.
In the absence of precipitation, avalanches may be the result of intense snow melting under the influence of heat, solar radiation and the process of recrystallization, leading to the destruction of the snow mass (up to the formation of a fine snow mass in the depth of this mass) and weakening the strength and bearing capacity of individual layers.
The formation of avalanches occurs in the avalanche focus, which is a section of the slope and its foot, within which the avalanche moves. The avalanche focus is usually characterized by three zones:
origin zone (avalanche collection);
transit zone (tray);
stop zone (fan) of an avalanche.
Up to 70% of all avalanches are caused by snowfalls. These avalanches come down during snowfalls or within 1-2 days after they stop.
According to the frequency of descent (repeatability), there are:
systematic avalanches (go down every year or once every two years);
sporadic avalanches (go down 1-2 times in 100 years or less, the place of the descent is difficult to determine).
Landslides
A landslide is the displacement to a lower level of part of the rocks that make up the slope, in the form of a sliding movement, mainly without loss of contact between moving and immobile rocks. The movement of a landslide begins as a result of a violation of the equilibrium of the slope and continues until a new state of equilibrium is reached.
Landslides can destroy individual objects and jeopardize entire settlements, destroy agricultural land, create a danger of exploiting quarries, damage communications, tunnels, pipelines, telephone and electrical networks, and threaten water facilities (dams).
Landslides that form on natural slopes and in the slopes of excavations are usually divided into two groups.
1st group. Structural landslides (structure - homogeneous cohesive clay rocks: clays, loams, clay marls).
The main reasons for the formation 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 soles;
moistening of the bottom of the slope.
Typical places (conditions) for the occurrence of landslides can be:
artificial earth structures with steep slopes;
in recesses formed in homogeneous clay soils in the watershed areas of the upland;
in deep sections for open mining of mineral deposits;
in embankments filled with the same rocks during waterlogging of the soil and vegetation cover and clayey rocks occurring near the day surface.
2 group. Contact (sliding, shearing, shearing) - cohesive clay rocks occurring in the form of layers with well-defined bedding planes (clays, loams, marls, loose limestones, weak clay slates, loess, loess-like loams, etc.).
The main reasons for the formation of contact landslides are:
excessive steep fall of layers;
overloading the slope with dumps or various earthworks;
violation of the integrity of rocks on the slope by trenches or upland ditches;
slope cutting;
wetting of bedding planes (contacts) with groundwater.
Typical places (conditions) for the occurrence of landslides 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 uneven distribution of atmospheric pressure on the surface of the earth and the passage of atmospheric fronts separating air masses with different physical properties.
The most important characteristics of hurricanes, storms and storms, which determine the amount of possible destruction and loss, 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 and more.
Table 1.18 shows the Beaufort scale, which defines the characteristics of the wind regime, the magnitude and the 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 regions can vary from 20 to 200 kilometers or more. In mid-latitudes, the width of the zone of action of a hurricane can reach several thousand kilometers. The duration of the hurricane wind can vary from 9 to 12 days or more, and the duration of storms and storms from several hours to several days. The direction of the wind during hurricanes in our latitudes is mainly from West to East. The most frequent hurricanes in the territory Russian Federation occur in August - September.
Very often, hurricanes are accompanied by showers, snowfalls, hail, dust and snow storms.
A hurricane, passing over the sea or ocean, can form powerful clouds that are the source of heavy rains.
Dust (sand) storms occur in plowed steppe regions and are accompanied by the transfer of millions of tons of soil and sand over tens and hundreds of kilometers. Dust storms are observed in summer during the dry season, 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 line Saratov, Ufa, Orenburg and the foothills of Altai.
Snow storms are characterized by the movement of huge masses of snow and a relatively small band of action - from several kilometers to 10-20 km. They occur on the flat territory of the Russian Federation and in the steppe part of Western and Eastern Siberia.
As a result of abundant precipitation accompanying hurricane winds, flooding of the area and snow drifts over a large area may occur. Power supply and communication lines can be destroyed.
The destruction of buildings during hurricane winds and the lashing of wires of power lines contribute to the emergence and rapid spread of massive fires.
TOPIC QUESTIONS AND ANSWERS
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:
Answer options:
1. Tsunami.
3. Hurricane.
Question 3.
What is called "Landslide"?
Answer options.
1. Separation and sliding displacement of the mass of earthen, rocks down under the action of its own weight. Landslides occur most often 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 snowmelt.
3. separation and catastrophic fall of large masses of rocks, their overturning, crushing and rolling on steep and steep slopes.
4. rapid, sudden movement of snow and (or) ice down the steep slopes of mountains under the influence of gravity and posing a threat to human life and health, causing damage to economic facilities and the environment.
Question 4.
The accumulation of ice in the channel, which restricts the living section (flow) and causes a rise in the water level in the place of ice accumulation and in some area above it is called.
Answer options:
1. Ice jam.
2. Ice blockage.
3. Constipation of ice.
Question 5.
What phenomena are hurricanes, storms, storms?
Answer options:
1. To meteorological hazards.
2. To geophysical hazards.
3. To hydrological hazards.
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 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 a global aspect, the first three problems were a product of the outgoing century, and the fourth accompanies human society from ancient times. And, paradoxically, for many centuries, mankind, 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 - " a big wave in the harbour). 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 northern hemisphere also occur in connection with 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 twentieth century, an increasing role in increasing the frequency and destructive power of floods is played by anthropogenic factors. Among them, first of all, we should mention deforestation (the maximum surface runoff increases by 250-300%), irrational management 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, surface runoff increased 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
In structure sanitary losses floods are 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, sources are poisoned drinking water. 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. So personnel 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 forbidden 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 countryside), 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 above-floodplain terraces (the Yellow River, the 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.
Classification of natural emergencies
EMERGENCIES OF NATURAL CHARACTER AND THEIR CLASSIFICATION.
Lecture #3
1. Classification of natural emergencies
2. Floods
3. Earthquakes
Another source of constant danger for a significant part of the population of our country is natural disasters. As already mentioned, they belong to natural emergencies and manifest themselves as powerful and destructive forces beyond the control of man. Natural disasters cause extreme situations, pose a threat to the life and health of people, disrupt the operation of economic facilities, and cause great material damage.
The vast territory of Russia (the area is 17 million km, the length of the borders is 48 thousand km), the variety of climatic, geological and hydrometeorological conditions, the presence of a huge number of large rivers, lakes, reservoirs, seas, oceans, mountainous regions cause a wide variety of various hazardous natural phenomena.
The classification of emergencies of natural origin, characteristic of our country, divides them into six types, each of which, in turn, is divided into several types:
Geophysical hazards:
- earthquakes;
- volcanic eruption.
Geological hazards:
- landslides;
- sat down;
- collapses, talus;
- avalanches;
- slope flush;
- subsidence of loess rocks;
- subsidence (failure) of the earth's surface as a result of karst;
- abrosia (destruction by surf waves), erosion (the process of soil destruction by water flows);
- kurums (accumulation of blocks moving along the slope from weathering);
- dust storms.
Meteorological and agrometeorological hazards:
- storms (9–11 points);
- hurricanes (12–15 points);
- tornadoes, tornadoes;
- squalls;
- large hail;
- strong: rain (rainstorm), snowfall, ice, frost, blizzard;
- heatwave;
- heavy fog;
- drought, dry wind;
- frosts.
Marine hydrological hazards:
- tropical cyclones (typhoons);
- tsunami;
- strong fluctuations in sea level;
- icing of ships and port facilities;
- separation of coastal ice.
Hydrological hazards:
- high water levels (floods);
- high water;
- rain floods;
- congestion and ice jams (accumulations of ice in the riverbed during ice drift);
- wind surges;
- low water levels.
Natural fires:
- Forest fires;
- fires of steppe and grain massifs;
- peat fires;
- underground fires of fossil fuels.
Infectious morbidity of people, animals, damage to plants by diseases and pests:
- group cases of dangerous infectious diseases;
- epidemics, pandemics;
- infectious diseases of humans and animals of unknown etiology (causes);
- epizootics (mass infectious diseases of animals);
- epiphototia (mass infectious disease of plants);
- mass distribution of pests.
Emergencies of an ecological nature associated with a change in the state of the land (soil, subsoil, landscape).
Emergencies associated with changes in the composition of the atmosphere:
- abrupt change in weather or climate as a result of anthropogenic activities;
- exceeding the maximum permissible concentrations of harmful impurities in the atmosphere;
- oxygen starvation in cities;
- the formation of an extensive zone of acid precipitation;
- destruction of the ozone layer of the atmosphere.
Emergencies associated with changes in the state of the hydrosphere.
Emergencies associated with changes in the state of the biosphere:
- extinction of animal and plant species;
- destruction of vegetation over a vast area;
- a sharp change in the ability of the biosphere to reproduce renewable resources;
- mass death of animals.
GOST R 22.0.03-95. Safety in emergency situations. NATURAL EMERGENCIES. Terms and Definitions. Introduction date 1996-07-01
The greatest damage in Russia is caused by various floods. The total area of zones of possible catastrophic flooding is more than 72 thousand square kilometers, which include 101 cities, 121 urban-type settlements and 2110 settlements with general population more than 7 million people
Spring floods or prolonged rains create flood zones in which 5.7 million people live.
Potentially dangerous are also zones of possible flooding from 20 largest hydroelectric power plants Russia, on the territory of which 6 million people live. In this regard, it seems extremely important knowledge and the ability to determine the parameters and characteristics of expected floods and the possibility of their timely forecast.
Significant flooding of the area as a result of a rise in the water level in a river, lake, sea or reservoir, caused by various reasons, and causing material damage, causing damage to the health of the population or leading to death of people, is called a flood.
Floods not accompanied by damage are classified as flooding of a river, lake or reservoir.
The territory of Russia is characterized by flooding of the area as a result of rising water levels in rivers. Examples include periodic floods on the Kuma River in the Stavropol Territory, on the Northern Dvina in Arkhangelsk region, on the Terek River in Dagestan, on the Amur in the Far East, floods in the Perm, Sverdlovsk regions, in Bashkiria, etc.
Flood classification.
Depending on the causes, the following classification groups of floods are distinguished:
Associated with maximum runoff from spring snowmelt - floods;
Formed by intense rains or snowmelt during winter thaws - floods;
Caused by the resistance that the water flow meets in the river: blockages, i.e. the formation of an ice plug under the ice at the beginning of winter, and traffic jams during ice drift;
caused by wind surges and
Floods caused by dams and protective dams.
According to the height of the rise in the water level, the size of the areas of flooding and the magnitude of the damage, they distinguish:
· low or small - with flooding of less than 10% of agricultural land, causing minor damage and not disturbing the rhythm of life of the population; occur once a year or 2 years;
high - with flooding of 10-15% of the land (mainly hayfields and pastures); in densely populated areas are accompanied by partial evacuation; cause tangible material and moral damage, violate the economic and everyday life of the population; occur once every 20-25 years;
large or prominent - cover entire river basins, flood up to 50% of land, paralyze economic activity, cause great material and moral damage, occur once every 50 years;
· catastrophic - flooding of huge territories within one or several river systems; up to 75% of land is flooded, settlements, industrial enterprises and engineering communications; such floods lead to huge material losses and loss of life; occur on the territory of the Russian Federation no more than once every 100-200 years.
Flood forecasting.
An important condition for protecting the population, economy and territories from the consequences of floods is the forecast of the timing, nature and parameters of these dangerous phenomena. Gosgidromet, based on data on moisture reserves in snow cover collected by a network of meteorological stations throughout the country, as well as on the basis of weather forecasts, models the process of water passage in a particular river basin and gives a forecast of the parameters of the expected flood.
Depending on the lead time, hydrological forecasts are divided into short-term (up to two weeks) and long-term (long lead times).
Short term forecasts are produced by solving the equations of hydrodynamics and determining the levels and flow rates of water in the lower and intermediate sections with their reference to time.
Long-term hydrological forecasts are used, as a rule, to predict the magnitude of floods. These forecasts are based on the water-balance method, which, based on the data of long-term hydrometeorological observations, establishes empirical relationships between the amount of runoff in the river basin during the flood and such factors as water reserves in the snow cover, expected precipitation, water infiltration into the soil and evaporation from the surface.
According to the results of the forecast, specially authorized state bodies and local authorities the authorities take various protective measures in advance, which should minimize the risk of expected flooding in a certain area.
Since ancient times, floods have been perceived by man as the most terrible natural disaster. It is no coincidence that in the religions of many peoples it acts as a "punishment of the Lord." It is enough to remember the Biblical global flood". In all likelihood, this is due to the fact that the water shell of the Earth (hydrosphere) occupies 71% of its surface. The bulk of water (94% of the volume) is contained in the seas and oceans. The water reserve in the rivers is approximately 1200 km3.
In terms of frequency of occurrence, area of distribution, total average annual damage, floods rank first in Russia among dangerous hydrological phenomena and processes. In terms of the number of human casualties and damage per unit area of damage, they rank second after earthquakes.
The absolute record for the magnitude of the effects of floods belongs to the Chinese rivers Huang He and Yangtze. On the river Huang He in 1887, the water in the river rose by 3 m and flooded thousands of settlements, causing enormous material damage. About 1 million people died, more than 7 million people suffered. The spill of the river Yangtze (1911) led to the death of about 100 thousand people. The largest catastrophic flood in China occurred in June-July 1959: flooding of rivers in the northeast led to the death of 2 million people.
The causes of floods are very diverse: spring snowmelt, precipitation in the mountains, winter thaws, ice accumulation in the narrowing of rivers, wind surges of water in sea mouths of rivers, etc. Of particular danger are floods associated with the outflow of water from a reservoir when a dam breaks (accidents at dangerous hydrodynamic objects).
The leading damaging factors in most floods are thermal and biological.
With prolonged forced stay of people in water with a low temperature, hypothermia (hypothermia) of the body occurs. When a person gets into the water, freezing is possible even at a relatively high temperature: at a water temperature of up to 15 0 C, the safe time spent in water at this temperature is about 3 hours; at a temperature of 2-3 0 C - only 10-15 minutes.
When vast areas are flooded, water supply systems, sewage systems, drain communications of bath and laundry wastewater, garbage and sewage collection sites, etc. can be destroyed. All this leads to a shortage of good quality water, the emergence and spread of infectious diseases. The conditions for the emergence of epidemics, purulent and anaerobic infections are the most favorable.
In addition to the leading damaging factors characteristic of most floods, in case of accidents at hazardous hydrodynamic objects, the importance of mechanical factor due to kinetic energy breakthrough waves. Mechanical damage of varying severity may be the result of:
– direct dynamic impact on the human body of a breakthrough wave;
- the traumatic effect of the fragments of buildings and structures destroyed by a breakthrough wave;
- the damaging effect of various objects involved in the movement of a breakthrough wave.
However, due to flooding, accidents are possible at fire-explosive objects, chemically and radiation hazardous objects, etc. Therefore, exposure of the population to the air shock wave, elevated temperatures, poisoning with AOHV and exposure to ionizing radiation. So, in 1994, in the Egyptian province of Assiut, a flash flood led to a short circuit in a petroleum products warehouse. After a powerful explosion, flaming fuel flooded the village, killing more than 500 people.
Dangerous hydrodynamic object(GOO) is a structure or natural formation that creates a difference in water levels before (upstream) and after (downstream) it. GOOs include artificial and natural dams, hydroelectric facilities, and dams.
The most important feature of the flood during accidents at the GOO is the formation of the above-mentioned breakthrough wave.
A breakthrough wave is a wave formed in the downstream as a result of the rapid fall of water from the upstream during the GOO breakthrough. The breakthrough wave is the main damaging factor of accidents at GOO.
The volume of water and the rate of its fall from the upstream depend on the magnitude of the breakthrough (the location of the damage to the GOO, through which water rushes from the upstream) during the breakthrough of the hydraulic structure. The main parameters of the breakthrough wave (height, width and speed) depend on the size of the breakthrough.
Depending on the height of the wave and the speed of the current in the flooded area, four zones of catastrophic flooding are distinguished:
- the first - the zone of catastrophic flooding is adjacent directly to the hydraulic structure or reservoir, which extends for 6-12 km, the wave height can reach several meters. The wave is characterized by a rapid flow of water with a current speed of 30 or more km/h. The wave passage time is 30 min.
- the second - a zone of fast current (15-20 km / h). The length of this zone can be 15-25 km. The wave passage time is 50-60 minutes.
- the third - the zone of the middle current (10-15 km / h). Length up to 30-50 km. The wave passage time is 2-3 hours.
- the fourth - a zone of weak flow (spill). The speed of the current can reach 6-10 km/h. Its length will depend on the terrain and may be 36-70 km.
Such a conditional division into zones allows rescuers to better navigate the current situation in the disaster area, which, in turn, improves the quality and efficiency of rescue operations.
The total losses of the population located in the zone of action of the breakthrough wave can reach 90% at night, and 60% during the day. Of the total losses, irretrievable losses amount to 75% at night, 40% during the day, and sanitary losses - 25% at night and 60% during the day.
The magnitude and structure of losses among the population during floods can vary depending on the density of the population in the flood zone, time of day, speed and height of the breakthrough wave, water temperature and other factors. An example of large losses from floods as a result of accidents at GOOs can be the destruction of a dam in the state of Idaho (USA) in 1974, which resulted in the death of 150 people. There were 10 cities in the flood zone.
Main characteristics consequences floods are as follows:
- a large number of human casualties and people left homeless;
- flooding of large areas with many settlements;
- in the disaster zone, the functioning of various sectors of the economy ceases;
- in the flood zone are railway tracks, roads, power lines, communications, communications;
- bridges, tunnels are destroyed;
– flood covers large agricultural areas, etc.