Natural fires: types and classification. Definition and characteristics of natural fire
| Parameter name | Meaning |
| Article topic: | Wildfires |
| Rubric (thematic category) | Population |
Fires - This is an uncontrolled combustion process that leads to the death of people and the destruction of material assets.
Most forest, peat and field fires occur near populated areas and off roads due to careless handling of fire, from unextinguished fires, from sparks flying from the exhaust pipes of cars, tractors and other equipment, violation of fire safety rules, spontaneous combustion of dry vegetation and peat, as well as from such natural phenomena as lightning. It is known that 90% of fires are caused by humans and only 7-8% by lightning.
Coniferous forests, dry peat bogs, ripened grain, and dry grass have the greatest fire potential.
The main types of fires as natural disasters, covering, as a rule, vast territories of several hundred, thousand and even millions of hectares, are landscape fires - forest and steppe (field).
Rice. 2.9 forest fire
Forest fires– uncontrolled burning of vegetation spreading over the forest area (Fig. 2.9).
Forest fires are divided according to the intensity of burning into weak, medium and strong, and according to the nature of burning - into ground fires and crown fires (fluent and stable).
Forest ground fires are characterized by burning of forest litter, ground cover and undergrowth without capturing tree crowns (Fig. 2.10). The speed of movement of the surface fire front ranges from 0.3 - I m/min. (in case of a weak fire), up to 15 m/min - I km/h (in case of a strong fire), flame height - 1-2 m , the maximum temperature at the edge of the fire reaches 900°C.
Forest crown fires develop, as a rule, from ground fires and are characterized by burning of tree crowns (Fig. 2.11). In a runaway crown fire, the flame spreads mainly from the crown at high speed, reaching 8-25 km/h, sometimes leaving entire areas of forest untouched by fire. In a stable crown fire, not only the crowns, but also the tree trunks are engulfed in fire. The flame spreads at a speed of 5-8 km/h, covering the entire forest from the soil cover to the tops of the trees.
Rice. 2.10 Forest ground fire Rice. 2.11 Forest crown fire
Underground fires arise as a continuation of ground or crown forest fires and spread through the peat layer located in the ground to a depth of 50 cm or more. Combustion occurs slowly, almost without air access, at a speed of 0.1-0.5 m/min with the release of a large amount of smoke and the formation of burnt-out voids (burnouts). For this reason, you need to approach the source of an underground fire with great caution, constantly probing the soil with a pole or probe. Burning can continue for a long time even in winter under a layer of snow.
Steppe (field) fires occur in open areas in the presence of dry grass or ripened grains (Fig. 2.12). Οʜᴎ are seasonal and occur more often in the summer as the herbs (bread) ripen, less often in the spring and are practically absent in the winter. The speed of their spread can reach 20-30 km/h.
Rice. 2.12 steppe fire
The main damaging factors of natural fires are fire, high temperature, and secondary damage factors.
Massive natural fires have a destructive effect on forest resources, destroy flora and fauna, cause damage to the organic layer of soil and its erosion, and pollute the atmosphere with combustion products. Plantations weakened by fires become sources of plant diseases, and the environmental protection, water protection and other beneficial properties of the forest are reduced.
Forest fires can lead to massive fires in rural settlements, holiday villages, failure of communication and power lines, bridges and agricultural land. Fires often lead to damage to people, causing their death, burns, injuries, and cause the death of agricultural and other animals.
At the core of wildfire prevention efforts is strengthening fire protection measures.
To prevent the occurrence of fires, it is prohibited to light fires in forests, especially coniferous ones, on peat bogs, in thickets of reeds and reeds, and near grain crops. It is prohibited to leave broken glass and bottles in a sunny forest clearing. It is not allowed to smoke in the forest (except for specially equipped areas), near windrows of mown bread, or while working on combines, tractors, pick-ups, or cars. All machines must be equipped with spark arrestors.
During the fire season, a temporary cessation of access to the forest for the population and transport should be established.
The simplest and yet sufficient effective way to extinguish fires- overflowing the edge of the fire. For this, bunches of branches 1–2 m long or small deciduous trees are used. A group of 2 – 5 people can extinguish a fire edge up to 1000 meters long in 30 – 40 minutes. You can cover the edge of the fire with loose soil.
Along the path of the fire, barrier and mineralized strips and ditches are arranged, extinguished with water or solutions of fire-extinguishing chemicals, and a counter fire is started (annealing).
The main method of extinguishing an underground peat fire– digging in the burning peat area with protective ditches. You can flood the burning areas of peat with a powerful stream of water.
In cases where the fire is approaching a populated area located in the forest, it may be extremely important to evacuate people. The withdrawal or removal of people is carried out in a direction perpendicular to the direction of the wind (fire). It is extremely important to move not only on roads, but also along rivers and streams. It is advisable to cover the mouth and nose with a damp cotton-gauze bandage.
To reduce the possibility of fires, every citizen is obliged to strictly follow the established rules for their prevention in residential buildings and enterprises, in forests and peatlands, in fields and other places. Malicious violators who are responsible for fires that cause significant material damage are brought to criminal liability.
Natural fires - concept and types. Classification and features of the category "Natural fires" 2014, 2015.
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Faculty FEF
Department environmental and economic policy
Essay
on the topic of: “General information about wildfires. Classification, damaging factors, criteria"
Is done by a student __ 1 ___ course
___11_ __groups
Speciality Accounting, analysis and audit
Ab-Ganeeva Asiya Rinatovna
(last name, first name, patronymic of the student)
«_ 11 _»___ December_____ 2010
(student's signature)
Reviewer Associate Professor Rogozin V.F.(position, surname of acting teacher)
Introduction. 3
General information about wildfires. 4
Classification of natural fires. 7
Damaging factors of fires. 13
Fire criteria. 14
Conclusion. 15
Used Books. 16
Introduction.
Today, in the age of technological progress, the development of science and technology, many different types of accidents and disasters occur in the world, which are certainly associated with the death of people, with the destruction of material assets, with the occurrence of serious environmental violations, etc.
The topic of natural emergencies is becoming increasingly relevant. The number of floods, earthquakes, and volcanic eruptions increases every year, killing more and more people.
Natural emergencies include natural fires. Forest fires are one of the most serious problems of Russian forests. Recently, the total forest area has been decreasing disproportionately. And one of the reasons for this reduction is forest and peat fires. Currently, many forest fires occur every year, and catastrophic outbreaks of forest and peat fires are increasing. The harm they cause to humanity is enormous, especially if we take into account not only direct, but also indirect damage. Fire is a spontaneous (uncontrollable) burning that has spread to a forest area surrounded by unburned territory. The forest area through which the fire spreads also includes open forest spaces. One fire includes the entire area covered by the fire, surrounded by territory that is not currently burning.
General information about wildfires.
A fire that occurs in the natural environment is called natural.
The concept of natural fires includes forest fires, fires of steppe and grain massifs, peat and underground fires of fossil fuels. The most common natural phenomena that lead to the destruction of forests and other material assets, and sometimes loss of life, are forest fires. Statistics show that they arise spontaneously in 8 - 10% of cases, and in 90% of cases due to human fault.
In Russia, on average, from 30 to 50 thousand hectares of forests burn out annually. Depending on the nature of the fire and the composition of the forest, fires are divided into ground fires, crown fires, and soil fires. Almost all of them at the beginning of their development have a grassroots character and, if certain conditions are created, they turn into upland and soil ones.
The most important characteristics are the speed of spread of ground and crown fires and the depth of underground burning. Fires are divided into weak, medium and strong. Based on the speed of fire spread, ground and top fires are divided into stable and fugitive. The speed of spread of a weak ground fire does not exceed 1 m/min, a medium one - from 1 to 3 m/min, a strong one - over 3 m/min... A weak top fire has a speed of up to 3 m/min., an average one - up to 100 m/min., and a strong one - over 100 m/min... A weak underground fire is considered to be one in which the burning depth does not exceed 25 cm, medium - from 25 to 50 cm, strong - more than 50 cm...
Natural fires are among the most dangerous and frequently recurring emergencies. They lead to the destruction of forests, death of animals and plants, disruption of the heat balance in the fire zone, atmospheric pollution by combustion products, and soil erosion. Natural fires often cause injury, illness, and death.
Causes of fires
The source of natural fires can be natural causes: lightning, spontaneous combustion, friction of trees. In the vast majority of cases, natural fires are the result of human violation of fire safety requirements. Approximately 60-70% of natural fires occur within a radius of 5 kilometers from populated areas. In this zone, people most often spend time “in nature.”
The main causes of natural fires: an unextinguished cigarette, a burning match, a smoldering wad after a shot, oily rags or rags, a glass bottle refracting the rays of sunlight, sparks from a vehicle muffler, burning old grass, stubble, garbage near a forest or peat bog, clearing using fire in forest areas for agricultural use or development of forest pastures. One of the main potential sources of wildfires is fire. In some cases, natural fires are the result of deliberate arson, man-made accident or catastrophe.
Prohibitions to prevent fire in the natural environment:
Throwing burning matches, cigarette butts, smoldering rags into the forest;
Make a fire in dense thickets and young coniferous trees, under low-hanging tree crowns, next to timber and peat warehouses, in close proximity to mature crops;
Leave spontaneously combustible materials in the forest: rags and rags soaked in oil, gasoline, glassware, which in sunny weather can focus the sun's ray and ignite dry vegetation;
Burn dry grass in forest clearings, gardens, fields, under trees;
Set fire to reeds;
Make a fire in windy weather and leave it unattended;
Leave the fire burning after leaving the campsite.
If a natural fire is detected, try to eliminate the source of fire on your own; If this fails, quickly leave the danger zone, be sure to report the location of the fire to the forest guard, administration, police, and Rescue Service.
Classification of natural fires.
Natural fires include forest, steppe, peat, underground, and possible combinations thereof.
Forest fires
A forest fire is an uncontrolled burning of vegetation that spreads spontaneously throughout a forest area. The phenomenon is very fast and frequent. Such disasters and emergencies arising in connection with them occur in various regions of the country every year and largely depend on the behavior of people in the forest. Forest fires destroy trees and shrubs, forest products, buildings and structures. Plantings weakened by fires become hotbeds of harmful diseases, which leads to the death of not only those affected by fire, but also the plantings adjacent to them. As a result of fires, the protective, water-protective and other beneficial properties of the forest are reduced, valuable fauna is destroyed, the planned management of agricultural activities and the use of forest resources are disrupted. Up to 80% of fires occur due to the population’s violation of fire safety measures when handling fire in places of work and recreation, as well as as a result of the use of faulty equipment in the forest. In logging areas, forest fires occur mainly in the spring when clearing cutting areas using fire methods - burning logging residues. Forest fires may be the result of an insufficiently established forest monitoring service and untimely notification of the relevant authorities about fires that have arisen in the forest and their transformation into mass ones.
Depending on the elements of the forest where the fire spreads, fires are divided into:
The classification of forest fires is shown in Figure 1.
Ground fires are most often observed - about 90% of their total number. In this case, the fire spreads only along the ground cover, covering the lower parts of tree trunks and roots protruding to the surface.
Ground fires are divided into fugitive and stable. during a ground fire, living and dead ground cover, self-seeded leaves, fallen leaves and needles burn, the bark of the lower part of trees and exposed roots, coniferous undergrowth and undergrowth burn. Such a fire spreads at high speed, bypassing places with high humidity, so part of the area remains unaffected by the fire. Runaway fires most often occur in the spring, when only the very top layer of small combustible materials dries out.
In a sustained ground fire, the litter burns out, the roots and bark of trees are severely burned, and the undergrowth and undergrowth are completely burned. Typically, sustainable fires begin in mid-summer, when the litter dries out.
In a low-level, fluent fire, the flaming type of combustion predominates; in a stable fire, the flameless type predominates.
There are high stable fires and high fluent fires. Roof fires cause especially great damage when the crowns of the trees in the upper tier burn. Runaway crown fires are typical for both the first and second half of summer.
Analyzing the causes and development of forest fires, it is easy to notice that the fire danger in forests significantly depends on weather conditions, for which there are currently quite advanced methods for predicting them. The greatest probability of forest fires occurs during the fire season (April-November). The greatest influence on fire danger in a forest is exerted by: precipitation, air temperature and humidity, wind and cloudiness.
Peat fires.
Under the influence of temperature, environmental humidity, the biological structure of peat-forming plants and a number of other reasons, peat gradually decomposes. The higher the degree of decomposition of peat, the more susceptible it is to fire. because Such peat has lower humidity, higher average density and heat capacity. The burnout rate of peat in calm weather or low winds is 0.18 kg/sq.m.
When the wind speed is 3 m/sec or more, burning peat particles are often scattered in the wind over considerable distances. Sparks falling on a layer of dried peat located on the surface ignite this layer and form new sources of combustion. The fire spreads in the direction of the wind.
The movement of fire along the surface in a continuous line, without taking into account the fires formed by sparks scattered by the wind, is usually called the speed of fire movement, and the speed of fire movement, taking into account the fires formed from sparks, is the speed of fire spread.
Depending on the speed of fire progression, there are 4 peat fire fronts:
Head (main), moving in the direction of the wind at the highest speed;
Two lateral (flank) ones, moving to the sides from the head front and at a lower speed;
Rear, moving in the direction opposite to the direction of the wind (towards the wind), and at the lowest speed.
The development of peat fires is greatly influenced by the time of year and day, as well as meteorological factors. At night, the fire develops more slowly, because... the surface temperature of the peat is lower than the temperature of the deposit, and as a result, moisture rises to its upper layers. In addition, the wind usually subsides at night and dew falls.
The development of peat fires can be divided into three periods.
The first one is the initial one – peat combustion. It is characterized by a small hearth area, low burning rate, relatively low temperature and low smoke content in the combustion zone. The duration of the tanning period ranges from several minutes to several hours and depends on the moisture content of the peat, wind speed, temperature and relative humidity.
The second is characterized by intense combustion with an increase in its speed and temperature. The fire area quickly increases, often reaching several thousand square meters. The ambient temperature rises and smoke spreads over a long distance.
Third, the fire spreads most intensively and over a very large area, amounting to several hectares. The fire is characterized by high temperatures in the combustion zone and heavy smoke.
In peat fires, debris appears from burnt, fallen trees and cavities of burnt peat, into which people and equipment can fall.
Underground peat fires themselves spread very slowly and usually arise from ground fires, in which the fire spreads throughout the entire fire in separate pockets. Therefore, the first priority is to extinguish the ground fire. Then they begin to eliminate the sources of the underground fire. To extinguish underground fires, chemical solutions or “wet” water are used, supplied under pressure by injection deep into the peat layer using fire engines or watering machines equipped with hoses with perforated stems - peaks. You can also localize underground fires by creating ditches around them using ditch diggers, trenchers, bulldozers, or explosive methods. The depth of the ditches should reach the groundwater level or reach the mineral soil, going 20 cm deep into it, i.e. it should be equal to:
The outer slope of the ditches is covered with mineral soil. In this case, it is advisable to fill the ditches with water. Considering that the edge of underground fires is not visible everywhere, when extinguishing such fires, care must be taken to avoid people and vehicles falling into burnt-out pits or caverns.
Underground fires.
Underground fires occur in mines, mines, and mineral deposits. They are caused by both external thermal impulses (careless handling of fire, faulty electrical equipment, friction of moving parts of machines and mechanisms), and spontaneous combustion of coal, carbonaceous rocks, and sulfide ores. Underground fires in places where explosive substances accumulate, including methane, coal and sulfide dust, pose a particular danger. Prevention of underground fires and the prevention of their consequences lies in the fact that, along with general fire prevention measures (the use of non-combustible materials for fastening mine workings, low-flammable conveyor belts and electrical cables in non-flammable casings, the installation of an extensive fire water supply network, etc.). the use of special schemes for opening and preparing deposits is envisaged. They allow you to localize an area in the event of a fire and divert fire gases into the general mine outgoing air stream, bypassing other areas where people are located.
Steppe fires.
Steppe fires are the result of ignition of dry grass or mature crops and spread in windy weather at speeds of up to 120 km/h.
Damaging factors of fires.
The main damaging factors include direct exposure to fire (combustion), high temperature and heat radiation, gaseous environment; smoke and gas contamination of premises and territories with toxic combustion products. People in the combustion zone suffer the most, as a rule, from open flames and sparks, elevated ambient temperatures, toxic combustion products, smoke, and low oxygen concentrations.
Open fire. Cases of direct exposure to open fire on people are rare. Most often, damage occurs from radiant streams emitted by the flame.
Ambient temperature. The greatest danger to people is inhalation of heated air, which leads to burns of the upper respiratory tract, suffocation and death. So, at a temperature above 100 ° C, a person loses consciousness and dies within a few minutes. Skin burns are also dangerous.
Loss of visibility due to smoke. The success of evacuating people in case of fire can only be ensured if their movement is unhindered. Evacuees must clearly see emergency exits or exit signs. When visibility is lost, the movement of people becomes chaotic. As a result, the evacuation process becomes difficult and can then become unmanageable.
Reduced oxygen concentration. During a fire, the concentration of oxygen in the air decreases. Meanwhile, a decrease in it even by 3% causes a deterioration in the motor functions of the body. A concentration of less than 14% is considered dangerous; it disrupts brain activity and coordination of movements.
Fire criteria.
According to official statistics, up to 2 million hectares of forest per year are engulfed in fire, and according to unofficial statistics, up to 14 million hectares (this is 140 times the area of Moscow). Why such difference? It’s very simple: approximately a third, that is, 200 of the 600 million hectares of Russian forests are officially (!) outside the fire protection zone, and for this territory there are not even reliable statistics on the number and area of fires. For the rest of the area, data on fires is also not always reliable.
Thus, according to official data, in 2007, one million hectares of Russian forests burned in fires. And the international organization International Forest Fire News, with reference to our AviaLesOkhrana, names a figure ten times (!) higher.
According to official data, about 67% of forest fires and 95% of the forest area covered by fire occurred in 24 constituent entities of the Russian Federation. These are the Chita, Irkutsk, Amur, Belgorod, Ryazan, Voronezh, Arkhangelsk, Volgograd, Rostov, Nizhny Novgorod, Ulyanovsk regions, the Republics of Komi, Tyva, Buryatia, Khakassia, Krasnodar, Stavropol, Krasnoyarsk, Khabarovsk territories, Yamalo-Nenets, Khanty-Mansiysk, Chukotka, Ust-Ordynsky Buryat and Aginsky Buryat autonomous districts.
The most fire-dangerous territories were the Chita region and the Khabarovsk Territory, they accounted for 56% of the territory covered by fire.
Unfortunately, official statistics practically do not take into account fires outside the territories of the state forest fund. In particular, the vast areas covered by grass fires are not taken into account.
Conclusion.
Emergency statistics show that in Russia the share of natural fires and emergencies caused by them is approximately 24% of the total number of natural emergencies. Thus, the problem of natural fires is one of the most serious and requires special attention. To solve this problem, it is necessary to improve the technology and equipment of the Ministry of Emergency Situations for extinguishing natural fires. In densely populated areas of Russia, when planning and maintaining forestry, it is necessary to avoid crops that are especially dangerous in terms of fire. An effective national satellite fire monitoring system must be created, ensuring direct reception of satellite information by all state and independent stations, including public receiving stations.
Used Books.
3. Korovin G.N., Isaev A.S., Protection of forests from fires as the most important element of national security of Russia. "Forest Bulletin", No. 8-9 1998
4. Guidelines for studying the topic “Emergencies associated with fires and explosions” / Comp. CM. Serbia, G.A. Kolupaev. M.: Publishing house Ros. econ. acad., 1999. 34 p.
Test
in the discipline Life Safety
Topic 6: Wildfires
Completed by: student Balandina Elena Vladimirovna
Group: ZIPOB-14-1
Code: 03/44/05
Teacher: Kuvshinova I.A.
Magnitogorsk
By what criteria are natural fires classified?
A fire that occurs in the natural environment is called natural.
The concept of natural fires includes forest fires, fires of steppe and grain massifs, peat and underground fires of fossil fuels. The most common natural phenomena that lead to the destruction of forests and other material assets, and sometimes loss of life, are forest fires. Statistics show that they arise spontaneously in 8 - 10% of cases, and in 90% of cases due to human fault.
In Russia, on average, from 30 to 50 thousand hectares of forests burn out annually. Depending on the nature of the fire and the composition of the forest, fires are divided into ground fires, crown fires, and soil fires. Almost all of them at the beginning of their development have a grassroots character and, if certain conditions are created, they turn into upland and soil ones.
The most important characteristics are the speed of spread of ground and crown fires and the depth of underground burning. Fires are divided into weak, medium and strong. Based on the speed of fire spread, ground and top fires are divided into stable and fugitive. The speed of spread of a weak ground fire does not exceed 1 m/min, a medium one - from 1 to 3 m/min, a strong one - over 3 m/min. A weak top fire has a speed of up to 3 m/min., an average one up to 100 m/min., and a strong one. - over 100 m/min. A weak underground fire is considered to be one in which the burning depth does not exceed 25 cm, medium - from 25 to 50 cm, strong - more than 50 cm.
Natural fires are among the most dangerous and frequently recurring emergencies. They lead to the destruction of forests, death of animals and plants, disruption of the heat balance in the fire zone, atmospheric pollution by combustion products, and soil erosion. Natural fires often cause injury, illness, and death.
Definition and characteristics of natural fire
From the point of view of work related to fire extinguishing,
rescue of people and material assets, classification of fires
produced in three zones:
Individual fires;
Massive and continuous fires;
Extinguishing fires and smoldering in the rubble.
Fires are also divided into forest, peat, steppe, fires in populated areas, gas, gas-oil and oil products.
The zone of individual fires represents areas in the territories
which fires occur in certain areas, in certain areas and production facilities. Such fires are dispersed throughout the region, which makes it possible to quickly organize their mass extinguishing with the involvement of all available forces and means.
The zone of massive and continuous fires is the territory where
there are so many fires and fires that the passage and presence in it
relevant units without localization or extinguishing measures are impossible, and rescue operations are difficult. Such zones arise in conditions of continuous development, compact forests, and the accumulation of large amounts of flammable materials.
A type of continuous fire is a firestorm. He
characterized by the presence of air convergence that occurs in
as a result of the combustion of a large amount of materials, which causes the formation of a convection flow, to which, in turn, air masses rush at a speed of 15 m/s. The conditions for the occurrence of a fire storm are: the presence of buildings or the spreading of flammable material over an area of up to 1000 hectares, low relative humidity (less than 30%), the presence of a certain amount of flammable materials in the corresponding area. In terms of wood - about 200 kg/m2 over an area of 1 km2.
The zone of dying fires and smoldering in the rubble is characterized by strong
smoke and prolonged (over two days) burning in the rubble. The actions of the relevant units are limited to the danger to human life due to thermal radiation and the release of toxic combustion products.
Dangerous smoke is considered to be one in which visibility is not
exceeds 10 m. The concentration of carbon monoxide in the air up to 0.2% causes fatal poisoning of people when they stay in the zone for 30-60 minutes, and at a concentration of 0.5-0.7% - within several minutes.
The cause of death may be the high temperature of a smoky environment. Inhalation of combustion products heated to 60°C, even at 0.1% carbon monoxide, is fatal.
Forest fires are uncontrolled burning of vegetation that spreads throughout the forest. Depending on the heights at which the fire spreads, forest fires are divided into ground fires,
underground and above.
Ground forest fires develop as a result of burning of undergrowth
coniferous species, the above-ground layer of litter (fallen needles, leaves, bark,
dead wood, stumps) and living vegetation (moss, lichens, grasses, shrubs). The front of a surface fire in strong winds moves at a speed of up to 1 km/h, at a height of 1.5-2 m.
Ground fires can be fleeting and common. Flash fires are characterized by rapidly moving flames and light gray smoke. Conventional ground fires spread relatively slowly. They are distinguished by the complete combustion of living and dead ground cover.
Crown forest fires are the combustion of the ground cover and biomass of the forest stand. Their speed of propagation is 25 km/h. They develop from ground fires when drought is combined with windy weather.
Crown fires can be short-lived or common.
Underground (soil) forest fires are stages of development
ground fires. They occur in areas with peat soils. Fire penetrates underground through cracks in tree trunks. Combustion occurs slowly and flamelessly. After the roots burn, the trees fall, forming rubble.
Peat fires are the result of the ignition of layers of peat on
different depths. They cover large areas. Peat burns slowly, to the depth of its occurrence. Burnt-out areas are dangerous because sections of roads, equipment, people, and houses fall into them.
Steppe fires occur in open areas with dry
vegetation. In strong winds, the speed of fire spread is 25 km/h.
Essay
in the course “Life Safety”
on the topic: “Natural fires”
Content
Introduction
Today, in the age of technological progress, the development of science and technology, many different types of accidents and disasters occur in the world, which are certainly associated with the death of people, with the destruction of material assets, with the occurrence of serious environmental violations, etc.
The topic of natural emergencies is becoming increasingly relevant. The number of floods, earthquakes, and volcanic eruptions increases every year, killing more and more people.
Natural emergencies include natural fires. Forest fires are one of the most serious problems of Russian forests. Recently, the total forest area has been decreasing disproportionately. And one of the reasons for this reduction is forest and peat fires. Currently, many forest fires occur every year, and catastrophic outbreaks of forest and peat fires are increasing. The harm they cause to humanity is enormous, especially if we take into account not only direct, but also indirect damage. Fire is a spontaneous (uncontrollable) burning that has spread to a forest area surrounded by unburned territory. The forest area through which the fire spreads also includes open forest spaces. One fire includes the entire area covered by the fire, surrounded by territory that is not currently burning.
1. The concept of “fire” and “fire safety”
A fire is a combustion outside a special source that is not controlled and can lead to mass casualties and deaths, as well as environmental, material and other damage.
Fire safety is a condition of an object in which the possibility of a fire is excluded, and if it occurs, the necessary measures are taken to eliminate the negative impact of fire hazards on people, structures and material assets
Fire safety can be ensured by fire prevention measures and active fire protection. Fire prevention includes a set of measures aimed at preventing a fire or reducing its consequences. Active fire protection measures that ensure the successful fight against fires or explosive situations.
Fire protection has as its goal finding the most effective, economically feasible and technically sound methods and means of preventing fires and extinguishing them with minimal damage with the most rational use of forces and technical means of extinguishing.
2. General information about natural fires.
A fire that occurs in the natural environment is called natural.
The concept of natural fires includes forest fires, fires of steppe and grain massifs, peat and underground fires of fossil fuels. The most common natural phenomena that lead to the destruction of forests and other material assets, and sometimes loss of life, are forest fires. Statistics show that they arise spontaneously in 8 - 10% of cases, and in 90% of cases due to human fault.
In Russia, on average, from 30 to 50 thousand hectares of forests burn out annually. Depending on the nature of the fire and the composition of the forest, fires are divided into ground fires, crown fires, and soil fires. Almost all of them at the beginning of their development have a grassroots character and, if certain conditions are created, they turn into upland and soil ones.
The most important characteristics are the speed of spread of ground and crown fires and the depth of underground burning. Fires are divided into weak, medium and strong. Based on the speed of fire spread, ground and top fires are divided into stable and fugitive. The speed of spread of a weak ground fire does not exceed 1 m/min, a medium one - from 1 to 3 m/min, a strong one - over 3 m/min. A weak top fire has a speed of up to 3 m/min., an average one up to 100 m/min., and a strong one. - over 100 m/min. A weak underground fire is considered to be one in which the burning depth does not exceed 25 cm, medium - from 25 to 50 cm, strong - more than 50 cm.
Natural fires are among the most dangerous and frequently recurring emergencies. They lead to the destruction of forests, death of animals and plants, disruption of the heat balance in the fire zone, atmospheric pollution by combustion products, and soil erosion. Natural fires often cause injury, illness, and death.
2. Causes of fires
The source of natural fires can be natural causes: lightning, spontaneous combustion, friction of trees. In the vast majority of cases, natural fires are the result of human violation of fire safety requirements. Approximately 60-70% of natural fires occur within a radius of 5 kilometers from populated areas. In this zone, people most often spend time “in nature.”
The main causes of natural fires: an unextinguished cigarette, a burning match, a smoldering wad after a shot, oily rags or rags, a glass bottle refracting the rays of sunlight, sparks from a vehicle muffler, burning old grass, stubble, garbage near a forest or peat bog, clearing using fire in forest areas for agricultural use or development of forest pastures. One of the main potential sources of wildfires is fire. In some cases, natural fires are the result of deliberate arson, man-made accident or catastrophe.
Prohibitions to prevent fire in the natural environment:
Throwing burning matches, cigarette butts, smoldering rags into the forest;
- make a fire in dense thickets and young coniferous trees, under low-hanging tree crowns, next to timber and peat warehouses, in close proximity to mature crops;
- leave spontaneously combustible materials in the forest: rags and rags soaked in oil, gasoline, glassware, which in sunny weather can focus the sun's ray and ignite dry vegetation;
- burn dry grass in forest clearings, gardens, fields, under trees;
- set fire to reeds
- make a fire in windy weather and leave it unattended;
- leave the fire burning after leaving the parking lot.
If a natural fire is detected, try to eliminate the source of fire on your own; If this fails, quickly leave the danger zone, be sure to report the location of the fire to the forest guard, administration, police, and Rescue Service.
3. Classification of natural fires.
Natural fires are divided into:
- Forest fires.
Peat fires.
Steppe fires.
Landscape fires.
Based on the speed of fire spread, ground and crown fires are divided into stable and fluent.
Spread speed:
weak ground fire does not exceed 1 m/min (the height of a weak ground fire is up to 0.5 m);
average from 1 m/min to 3 m/min (average height – up to 1.5 m);
strong over 3 m/min. (The height of the strong one is over 1.5 m).
Crown fire, speed of spread:
weak up to 3 m/min;
average up to 100 m/min;
strong over 100 m/min.
The strength of a soil fire is determined by the depth of burnout:
a weak soil (underground) fire is considered to be one in which the burning depth does not exceed 25 cm;
average – 25–50 cm;
strong – more than 50 cm.
Area Rating:
fire – 0.1–2 hectares are engulfed in fire;
small – 2–20 ha;
medium – 20–200 ha;
large – 200–2000 ha;
catastrophic – more than 2000 hectares.
Ground forest fires develop as a result of the combustion of coniferous undergrowth and the above-ground layer of litter(fallen needles, leaves, bark, dead wood, stumps) and living vegetation(moss, lichens, grasses, shrubs). Crown forest fires are the combustion of the ground cover and biomass of the forest stand. Underground (soil) forest fires are stages of development of ground fires. They occur in areas with peat soils. Fire penetrates underground through cracks in tree trunks. Combustion occurs slowly and flamelessly. After the roots burn, the trees fall, forming rubble.
Peat fires– are the result of ignition of peat layers at different depths. They cover large areas. Peat burns slowly, to the depth of its occurrence.
The development of peat fires is greatly influenced by the time of year and day, as well as meteorological factors. At night, the fire develops more slowly, since the temperature of the peat surface is lower than the temperature of the deposit, and as a result, moisture rises to its upper layers. In addition, the wind usually subsides at night and dew falls.
The development of peat fires can be divided into three periods.
First - initial– combustion of peat. It is characterized by a small hearth area, low burning rate, relatively low temperature and low smoke content in the combustion zone. The duration of the tanning period ranges from several minutes to several hours and depends on the moisture content of the peat, wind speed, temperature and relative humidity.
Second– characterized by intense combustion with an increase in its speed and temperature. The fire area quickly increases, often reaching several thousand square meters. m. The ambient temperature rises, smoke spreads over a long distance.
Third– the fire spreads most intensively and over a very large area, estimated at several hectares. The fire is characterized by high temperatures in the combustion zone and heavy smoke.
Underground peat fires themselves spread very slowly and usually arise from ground fires, in which the fire spreads throughout the entire fire in separate pockets.
Steppe fires occur in open areas with dry vegetation. In strong winds, the speed of fire spread is 25 km/h. In cities and towns, individual (if a house or group of buildings catches fire), massive (if 25% of buildings catch fire) and continuous (when 90% of structures catch fire) fires are possible. The spread of fires in cities and towns depends on the fire resistance of buildings, building density, the nature of the terrain and weather conditions.
Landscape fire is a spontaneously spreading fire, as a result of which forests, shrubs, peat reserves and various types of vegetation located in its path are destroyed.
The main damaging factors of landscape fires are:
- high temperature, causing fire of everything in the fire area;
smoke in large areas, which has an irritating effect on people and animals, and in some cases poisoning them with carbon monoxide; visibility limitation;
frightening psychological impact on people.
4. Techniques and means of eliminating the consequences of fires
The main methods of combating forest ground fires are:
- overflowing the edge of the fire, filling it with earth,
pouring water (chemicals),
creation of barrier and mineralized strips,
launch of counter fire (annealing).
etc.................
The concept of “natural fires” includes forest fires, fires of steppe and grain massifs, peat and underground fires of fossil fuels. We will focus only on forest fires as the most common phenomenon, causing enormous losses and sometimes leading to casualties.
Forest fires are uncontrolled burning of vegetation that spontaneously spreads throughout the forest area. The phenomenon is not at all rare. Such disasters, unfortunately, occur every year and largely depend on people.
In dry weather and wind, they cover large areas. If during hot weather there is no rain for 15-18 days, the forest becomes so dry that any careless handling of fire causes a fire that quickly spreads throughout the forest area.
A negligible number of fires occur from lightning discharges and spontaneous combustion of peat crumbs. In 90-97 cases out of 100, the culprits of a fire are people who do not show due caution when using fire in places of work and leisure. The share of fires caused by lightning is no more than 2% of the total.
In certain areas of Siberia and the Far East in the spring, the main cause of fires is agricultural burning, which is carried out to destroy last year's dry grass and enrich the soil with ash elements. If poorly controlled, the fire often goes into the forest. In logging areas, fires occur mainly in the spring when clearing cutting areas using the fire method - burning logging residues. In mid-summer, a significant number of fires occur in places where berries and mushrooms are collected.
Forest fires are classified by the nature of the fire, the speed of spread and the size of the area engulfed by fire.
Depending on the nature of the fire and the composition of the forest, fires are divided into ground fires, crown fires, and soil (underground) fires. Almost all fires at the beginning of their development are of a grassroots nature and, if certain conditions are created, turn into crown or soil fires.
The most important characteristics are the speed of spread of ground and crown fires, the depth of underground burning, therefore they are divided into weak, medium and strong. Based on the speed of fire spread, ground and top fires are divided into stable and fugitive. The speed of spread of a weak ground fire does not exceed 1 m/min, a medium one - from 1 to 3 m/min, a strong one - over 3 m/min. A weak crown fire has a speed of up to 3 m/min, a medium one - up to 100 m/min, a strong one - over 100 m/min. A weak underground fire is considered to be one in which the burning depth does not exceed 25 cm, medium - from 25 to 50 cm, strong - more than 50 cm.
The intensity of combustion depends on the state of the supply of combustible materials, the slope of the terrain, the time of day and, especially, the strength of the wind. Therefore, during the same fire, the rate of fire spread in a forest area can vary greatly.
Runaway ground fires are characterized by the rapid advancement of the edge of the fire when dry grass and fallen leaves burn. They occur more often in the spring and predominantly in grassy forests; they usually do not damage mature trees, but often pose a threat to the emergence of the crown. In stable ground fires, the edge moves slowly and a lot of smoke is produced, which indicates the heterogeneous nature of the combustion. They are typical for the second half of summer.
Roof fires cause great damage when the crowns of the upper tier of trees burn. Runaway crown fires occur both in the first and second half of summer.
Underground fires are the result of ground or crown fires. After the burning of the upper ground cover, the fire goes deeper into the peaty horizon. They are usually called peat.
Based on the area covered by fire, forest fires are divided into six classes (Table 5.5).
Table 5.5
Classification of forest fires by area covered by fire
|
Forest fire class |
Area covered by fire, hectares |
|
Sunbathing |
0,1-0,2 |
|
Small fire |
0,2-2,0 |
|
Small fire |
2,1-20 |
|
Medium fire |
21-200 |
|
Major fire |