After the Great Flood flooded the entire surface of our planet, floods in the world are considered one of the most dangerous natural disasters. Maybe they do not look as grandiose and impressive as a sudden tornado or typhoon, and often give people time to leave dangerous territory, the consequences of floods are no less deplorable.
Thus, the largest documented flood in the world occurred in China in the thirties of the last century, when the longest and deep river countries, the Yangtze, together with the neighboring Huang He, overflowed their banks after prolonged rains, destroying dams and flooding more than 300 thousand hectares of fertile land (in some areas the water did not drain for about six months). When the river waters calmed down, the consequences of the flood were so catastrophic that the world shuddered: only according to official figures, the death toll exceeded 3.7 million people.
Flooding is the flooding of vast areas, which was caused by a rise in the water level in lakes, rivers, seas after heavy rainfall, snowmelt, dam break, which led to water flowing far beyond the coastline.
Although in most cases the population can be warned about the approach of a natural disaster, warnings are often ignored due to the fact that local residents refuse to leave their homes in the hope that the disaster will bypass them. And completely in vain: the advancing water does not spare anyone and not only destroys buildings (especially buildings with a shallow foundation and constructed of wood), but often leads to human casualties.
Speaking about the causes of floods, hydrologists distinguish the following factors:
Naturally, not all types of floods lead to catastrophic consequences. Those that occur most often are not as devastating as those that occur once every few decades, but the effects of such floods are felt for a significant period. Therefore, hydrologists, focusing on the consequences of floods, classified the elements into four groups and gave them a description.
Small floods created by lowland rivers cover small coastal areas, occur once every five to ten years, and the population easily copes with the consequences of floods of this type.
Much more serious floods are classified as "Hazardous". They happen less frequently, once every 20-25 years. Covering rather large land plots located in river valleys, they cause significant material damage, flooding from 10 to 20% of crops. In some cases, even a partial evacuation of the population is required.
Floods, which hydrologists refer to as "Especially dangerous" occur once every fifty to a hundred years. Having overflowed its banks, the waters of the river completely fill the river basins, destroying from 50 to 70% of crops, and in some cases - settlements. As a result, all agricultural activities, the life of the region are paralyzed, the way of life is sharply disrupted. local residents, especially considering the fact that during particularly dangerous floods, mass evacuation of the inhabitants of a dangerous area is required.
The most dangerous types of floods in the world are classified as "Catastrophic" (it was this type of flood that befell China in the thirties of the last century). They flood the area of one or more water systems, destroying almost all agricultural land, settlements (including cities), causing mass death of people. A country usually copes poorly with the consequences of floods of this magnitude and requires international assistance, since disasters often cause a humanitarian catastrophe.
In addition to the classification according to the consequences of the flood, there are the following types of floods, based on the description of this phenomenon:
In order to reduce the risk of occurrence and minimize the consequences of floods, flood protection is created in reservoirs - shallows are poured, rifts are deepened, and to regulate river flow, protective dams are built on the seashore, and reservoirs are built on rivers that equalize the flow of river flow, increasing it in summer, and reducing it. spring.
Unlike other natural disasters, scientists predict the likelihood of a flood quite accurately (unless, of course, they are the consequences of phenomena that are not easy to predict, such as a tsunami or a dam break). By being warned of an impending disaster, people have time to put in place the necessary flood protection.
If a catastrophe of enormous proportions is coming, special services begin to evacuate the population (although these actions are far from always successful, since many refuse to leave their homes).
People living in areas prone to floods should definitely know the rules of behavior in case of floods in order to correctly calculate their actions in emergency situations. To do this, it is necessary to study in advance the boundaries of possible flooding, as well as take into account all the hills and places that are least affected by the elements, and where it will be possible to wait out the flood. It is also worth finding out in advance where boats, rafts or building materials are located so that in case of a disaster you can make a floating vehicle out of them.
The danger zone should be left as soon as there is information about the flood. It is also worth taking a backpack prepared in advance with documents, medicines, valuable things, warm clothes and a two-day supply of food. Before leaving the house, you need to turn off the electricity, turn off the gas, put out the fire in the stoves, light objects outside the room so that they do not float away, it is advisable to fix them. Window and door openings must be locked, and if possible, boarded up from the outside with boards or shields.
If you can’t leave the house, you need to get to the roof and attach a banner so that the rescuers know where to look for you. If it is night outside, you need to signal your location with a torch or flashlight. When approaching rescuers, you need to calmly, without sudden movements, go to the rescue boat, and then listen to their instructions.
If there is no help, and the water remains and threatens to flood the shelter, you need to take a raft or an object that can be used instead of a floating facility and sail in the right direction, not forgetting to give distress signals. If people in the water are found along the way, everything must be done to save them. For this drowning person, you need to calm him down, and then throw him a rope. If a person is in a panic state and does not understand anything, you need to swim up to him from behind and tow him by the hair so that he cannot drown the rescuer.
Returning after the flood, before entering the house, you need to make sure that the building stands firmly and does not collapse, and then ventilate the room. Before turning on electrical appliances, or even lighting a match, be sure to check the gas pipeline, electrical wiring, as well as water supply and sewerage for serviceability (it is advisable to do these actions with specialists). After making sure that everything is in order, you need to pump out water from the basements, dry the rooms, clean the wells from dirt.
Mankind has been familiar with floods since ancient times. We have received information about catastrophic spills on (in 2297 BC) and on the Nile River (about 3000 years ago). Previously, these natural disasters were quite rare, but in recent centuries their frequency and the extent of their damage have increased rapidly. If we take the period BC, then the most dangerous floods, the causes of which will be discussed below, happened about once every 50 years (for example, in China). Now such disasters occur several times a year. At the most "fruitful" time, these disasters happen with a frequency of 2-3 days, which is immediately reported to us by the media. Maybe that's why the topic "Flood" is relevant for many people. And interest in it is constantly growing.
It is well known that the development of human society depends on quality. Many politicians and experts are sure that the problem of water is at the top of the list of common problems of the last decades. “Water issues” can arise in four cases: in the absence or insufficient amount of life-giving moisture, when the regime of water bodies does not correspond to the optimal functioning of ecosystems, when the supply regime does not meet the economic and social requirements of the population, and when there is excess moisture in inhabited areas suffering from behind it from floods. On a global scale, the first three problems were generated by the past century, and the fourth has haunted mankind since ancient times. And although people understood what a flood was and took measures to protect against it, they could not succeed in this. And with each century, the damage from this disaster continues to increase. Only in the second half of the twentieth century, the damage done increased 10 times.
You can find out the estimated date of the flood using a hydrological forecast. It is a study aimed at scientific substantiation of the scale and nature of this catastrophe. Forecasts are divided into ultra-long-term (more than 1 quarter), long-term (up to 3 weeks), short-term (10-12 days), territorial and local. The consequences and scale of floods depend on their duration, the nature of the soil, the season, the terrain, the speed of the flow, the height of the water rise and other factors. Everyone has heard the legend of the Flood. Many researchers who know what a flood is believe that the legends about the flood are based on catastrophes that actually occurred in different parts of the Earth. Ethnographers, historians, geographers and archaeologists have established that in the 3rd and 4th millennium BC, these natural disasters occurred in Mesopotamia. The inhabited areas in the valley of the Euphrates and the Tigris seemed to people the whole world. Therefore, they associated grandiose floods with a large number of victims with flood. Now archaeologists, historians and other specialists have done a great job of researching the legends about the Great Flood. Based on the list of these legends, major floods occurred in almost all regions of the Earth. And this list is quite impressive. It includes legends about the flood on all continents of the planet.
With population growth, deforestation and other destructive human activities, floods have become much more frequent. At the beginning of the article, we mentioned two catastrophic floods. Now let's talk about a few more.
1. Flooding in Europe. Covered the territory of Germany, Great Britain and the Netherlands in 1953. With a strong storm wind, huge waves covered the northern coast. This caused a sharp rise in water (3-4 meters) in the estuaries of the Scheldt, Meuse, Rhine and other rivers. The Netherlands was hit the hardest. 8% of the territory was flooded. About 2000 people died.
2. Flooding in the Ganges Delta. Happened in 1970. A 10-meter wave covered the sacred river and turned the current back. Approximately 20,000 sq. km. Hundreds of villages and dozens of cities were destroyed. About 1.5 million people died. Since the flood destroyed almost all the wells, there was an acute shortage drinking water. Hundreds of thousands of people died from starvation and outbreaks of typhus and cholera.
3. Amur flood. It happened on the territory of the Russian Federation in July 2013. The total damage exceeded 3 billion rubles. 29 bridges destroyed. Almost 300 kilometers of roads were washed out. hit hard Agriculture. More than ten settlements turned out to be in the flood zone.
For a deeper understanding of the topic, let's define this natural disaster. After all, not everyone knows what a flood is. Let's correct this omission. The simplest definition is the flooding of significant areas of land with water. Now let's list the causes of this disaster.
1. Melting snow.
2. Tsunami waves.
3. Long rains.
4. Anthropogenic causes.
There are direct causes associated with the destruction of dams and the implementation of hydrotechnical measures, and indirect ones - housing and industrial development, drainage of swamps, deforestation. All this changes the hydrological by increasing the surface component of the runoff. The reduction of all forests will increase the maximum flow to 300%.
Now consider the main types of floods. We are sure that our readers will be very interested in this topic.
1. High water. Occurs during the spring melting of snow on the plains or in the mountains. It has a seasonal frequency. It is characterized by a significant rise in the water level.
2. Flood. Occurs during winter thaws due to melting snow or intense rains. It does not have a clearly defined periodicity. It is characterized by a fairly short-term and intense rise in the water level.
3. Jam and jam floods. Occur when in certain zones of the riverbed there is resistance to the water flow. It occurs due to the accumulation of ice floes in the narrowing of the channel during ice drift (jamming) or freezing (jamming). A river jam flood occurs in early spring or late winter. It has a relatively short-term high rise in water level. Zazhorny flooding occurs at the beginning of winter. It is characterized by a significant rise in the water level and a significant duration of the disaster.
4. Surge floods. They arise as a result of water in the mouths of rivers, as well as in rather windy areas of reservoirs, large lakes and the sea coast. Can happen at any time of the year. They do not have a periodicity. The rise in water level is significant.
5. Floods as a result of breaking dams. During a disaster, water is poured out of a reservoir or reservoir due to a breakthrough of a pressure structure (dam, dam, etc.) or an emergency discharge of water. Another reason is the natural dam break due to natural factors, etc.). During the catastrophe, a breakthrough wave is formed, flooding vast territories and damaging or destroying objects (structures, buildings, etc.) encountered in the path of its movement.
So, we found out the causes and types of floods, but we must not forget that these natural disasters are also divided into classes. The main principles for separating these disasters are the period of recurrence and the scale of distribution.
1. Low. They usually do minor damage. They cover small coastal areas. Agricultural lands are flooded by less than 10%. Almost do not knock out the population from the current rhythm of life. Repeatability - 5-10 years.
2. High. Apply substantial and material). They cover large areas of river valleys. They flood about 10-15% of the land. Violate both household and economic way of life of the population. Partial evacuation of people is very likely. Periodicity - 20-25 years.
3. Outstanding. They cause great material damage, covering river basins. Approximately 50-70% of agricultural land, as well as a certain part of settlements, is under water. Outstanding floods not only disrupt the way of life, but also paralyze economic activity. It is necessary to evacuate material assets and the population from the disaster zone and protect the main objects of economic importance. Repeatability - 50-100 years.
4. Catastrophic. They cause huge material damage, spreading over vast territories within one or more river systems. Lead to human casualties. More than 70% of the land is flooded, many settlements, utilities and industrial enterprises. Industrial and economic activity is completely paralyzed, and the way of life of the population is changing. Periodicity - 100-200 years.
The main features of the situation that arises during such natural disasters are: the rapid increase in the strength of damaging factors, the difficulty of access to the victims, the destructive nature of the situation, the low survival rates of the victims, as well as the presence of difficult weather conditions (mudflows, ice drift, heavy rains, etc.). ).
1. The highest water level.
2. The highest water consumption.
3. The speed of the current.
4. Area of flooding.
5. Repeatability of the value of the highest water level.
6. Duration of flooding.
7. Water temperature.
8. Security of the highest water level.
9. Time of start of the disaster.
10. The rate of rise in the water level during the entire time of the flood.
11. The depth of flooding of the territory in the area under consideration.
1. Population in the disaster area (victims, injured, etc.).
2. The number of objects of economic sectors affected by natural disasters.
3. The number of settlements that fell into the disaster zone.
4. The length of roads (rail and road), communication and power lines that are in the flood zone.
5. The number of tunnels, bridges and residential buildings damaged, destroyed and flooded as a result of the disaster.
6. The number of dead animals previously involved in the agricultural sector.
7. The area of agricultural lands affected by the disaster, etc.
The main goal of emergency rescue operations is the search and rescue of people who find themselves in a flood zone. It is necessary to help them as soon as possible and ensure their survival in the current situation. Success during rescue work is achieved by a number of actions.
1. Carrying out advance and systematic training of commanders, soldiers of civil defense units who know exactly what a flood is, as well as members of search and rescue services for rescue operations.
2. Rapid response to a disaster, alerting and providing the necessary forces and means.
3. Organization of operational intelligence and deployment of a control system.
4. Application effective technologies search for victims and their rescue, as well as ways to protect economic facilities and the population.
1. Construction of protecting shafts and dams.
2. Construction of drainage channels.
3. Equipment of berths for special equipment.
4. Elimination of blockages and congestion.
5. Restoration of power supply.
6. Restoration and protection of road structures.
7. Localization of foci of secondary damage factors.
1. Determination of the area of flooding.
2. Managing the dynamics of disaster development.
3. Identification of places where people and farm animals in need of help are located.
4. Detection of material assets that are subject to removal from the disaster site.
5. Search and equipment of sites for landing helicopters in the disaster area.
6. Search and selection of routes for the evacuation of material assets, people and animals using watercraft. If necessary, the equipment of berths.
Rescue work is carried out by units of the Civil Defense Army, search and rescue services and reinforced special-purpose special means of crossing and landing. For the implementation of other urgent work, taking into account its nature, engineering and technical and road formations are appointed. When searching for victims in flooded areas, rescuers must use aviation equipment (helicopters and airplanes).
And the last. Do not forget that the threat of flooding is always there. Therefore, prepare in advance for a meeting with this natural phenomenon.
If the risk was great, a person either refused to use floodplain lands or tried to reduce the danger by building simple protective structures. Sooner or later, these protective measures were not enough and the person again faced the need to make a choice. Human activities leading to floods. Man has struggled with floods throughout his existence, and in his long history there have been many such natural disasters.
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Plan:
Introduction…………………………………………………………………..3
1. Types and causes of floods…………………………………………….4
2. Examples of floods in Russia and the world………………………………..8
3. Problems of floods and safety of hydraulic structures.12
Conclusion…………………………………………………………………14
List of used literature…………………………………………………………15
Introduction.
It is well known that the state, development and vital activity of the biosphere and human society is directly dependent on the state water resources, but water does not always play a positive role in the functioning of all living things. Unfortunately, sometimes it becomes a powerful element that can destroy everything in its path.
For many centuries, humanity, making incredible efforts to protect against floods, can not succeed in this matter. On the contrary, with every century the damage from floods continues to grow. Catastrophic floods and floods quite often occur on the rivers of our country. Huge areas of agricultural land, towns and cities are flooded. Livestock and crops are dying, transport arteries and bridges, residential buildings and industrial facilities are being destroyed. Sometimes people die.
Severe floods occur almost every year. Some arise as a result of the rapid melting of heavy snows that covered vast catchment areas, others due to heavy and prolonged heavy rains, and others as a result of surge winds that prevent rivers from flowing into the final basins.
Catastrophic floods on rivers are perhaps the most significant natural hazard. For centuries and millennia, people intuitively assessed the risk of floods - they compared the benefits from the development of coastal territories with the potential consequences of their flooding. If the risk was great, a person either refused to use floodplain lands, or tried to reduce the danger by building simple protective structures. Sooner or later, these protective measures were not enough, and a person again faced the need to choose.
1. Types and causes of floods.
Nowadays, rivers have gained importance as a source of energy, irrigation, industrial water supply, sewage receiver, as well as a place of mass recreation, tourism and sports. Flooding is an intense flooding of a large area with water above annual levels, one of the natural disasters. It is noted during high waters, floods, breakthroughs of dams and dams.
High water is a relatively prolonged rise in the water level in rivers; which is repeated annually in the same season and is accompanied by a high and prolonged rise of water, usually its exit from the channel to the floodplain. During floods, structures in floodplains are damaged, banks are eroded, and valuable agricultural land is sometimes covered with sand. The greatest floods lead to floods, are considered natural disasters.
Flood - an intense relatively short-term rise in the water level in the river, caused by heavy rains, downpours, sometimes rapid snow melting during thaws. Unlike floods, floods can occur several times a year. A particular threat is the so-called flash floods associated with short-term, but very intense downpours, which also occur in winter due to thaws.
Natural causes of floods include:
A) Spring-summer melting of snow and glaciers in catchment areas. Such floods are amenable to forecasting by seasons, and based on snow reserves - approximately also in height and duration. It should be borne in mind that the correlation between snow reserves and the height of the flood is not so high. With relatively small snow reserves, a friendly spring can lead to a large flood. The condition of the underlying rocks (frozen or not) on which the snow cover. And vice versa, with large snow reserves, but not frozen soils and extended spring, when frosts alternate with thaws, the snow on the watersheds "rots" to a large extent, not giving runoff.
B) torrential rains. Here, in the sense of the forecast, we can only talk about the flood season, and in the order of a short-term warning - about calendar dates, approximately - about the duration and height of the expected rise in the level. In the climatic conditions of Russia, such level rises are widespread in monsoons. Far East, in the south-west of the European territory of the country, along the rivers of the Black Sea coast of the Caucasus, etc. It should be noted the peculiarity of the Caucasian rivers, high floods on which can be observed at any time of the year. In mountainous mudflow-prone areas, floods can be accompanied by the movement of water erosion products, as well as bottom sediments, along river valleys.
C) wind surges of water. They appear on the coasts of reservoirs and in the lower reaches of the rivers flowing into these reservoirs. In terms of timing, they are not amenable to foreseeing; in some cases, one can speak of seasons when surges are generally observed more often and have a greater height. In general, we can only talk about a probabilistic description of the height and duration of surge waters, which can vary greatly in different parts of the coast. On the coasts of the marginal seas, one has to reckon with the joint manifestation of surge and tidal level rises.
D) congestion. Congestion - clogging of the channel by a fixed ice cover and a heap of ice floes during spring ice drift in narrowings and on the bends of the river channel, restricting the flow and causing a rise in the water level in the place of ice accumulation and above it. Jam floods are formed in late winter or early spring, and occur due to the non-simultaneous opening of large rivers flowing from south to north. Opened southern sections of the river in its course spring up accumulation of ice in the northern regions, which often causes a significant increase in water levels. Jam floods are characterized by a high and relatively short-term rise in the water level in the river.
D) congestion. Zazhor - ice plug, accumulation of in-water, loose ice during winter freezing in the narrowings and bends of the channel, causing the rise of water in some areas above the level of the main river channel. Jam floods form at the beginning of winter and are characterized by a significant, but less than during a jam, rise in the water level and a longer duration of the flood.
E) The deposition of sediments at the exit of rivers from the foothills to the plains with a decrease in the speed of the flow and the transporting capacity of the flow; the channel at the same time grows, being higher than the surrounding area and from time to time "falling" to the side.
G) Fluctuations in the level of drainless water bodies as a result of disturbances in the water balance under the influence of the variability of its components, as is the case, for example, in the Caspian Sea, where the amplitude of the corresponding long-term level fluctuations exceeds 3 m.
The causes of floods are diverse, and each cause or group of causes has its own type of flood. Below we indicate four groups of types of floods.
1. Floods associated with the passage of a very large flow of water for a given river. Such floods occur during the period of spring snowmelt, with heavy rainfall and rainfall, in the event of a collapse of dams and breakthroughs of dammed lakes.
2. Floods, mainly caused by the great resistance that the water flow meets in the river. This usually occurs at the beginning and at the end of winter with ice jams and ice jams.
3. Floods due to both the passage of large water flows and significant resistance to water flow. These include mudflows on mountain rivers and water-snow flows in gullies, ravines and hollows.
4. Floods created by wind surges of water on large lakes and reservoirs, and direct causes - are associated with the implementation of various hydraulic engineering measures and the destruction of dams. Indirect - deforestation, drainage of swamps, industrial and residential development, this leads to a change in the hydrological regime of rivers due to an increase in the surface component of runoff. The total evaporation is reduced due to the cessation of precipitation interception by forest litter and tree crowns. If all forests are reduced, then the maximum runoff can increase up to 300%. There is a decrease in infiltration due to the growth of waterproof coatings and buildings. The growth of water-resistant coatings in an urbanized area increases floods by 3 times.
Human activities leading to floods:
1. Restriction of the free section of the flow by roads, dams, bridge crossings, which reduces the throughput of the channel and raises the water level.
2. Violation of the natural regime of flow rates and water levels.
It should be emphasized that for a particular water body floods are usually caused by several reasons, and therefore, to determine the design characteristics of possible flooding, it is necessary to carry out a complex analysis and perform a composition of the probability distribution laws that are characteristic of individual types of floods.
2. Examples of floods in Russia and the world.
Man has struggled with floods throughout his existence, and in his long history there have been many such natural disasters. In Russia, from 40 to 68 crisis floods occur annually.
Floods with catastrophic consequences in the territory of modern Russia over the past 20 years have occurred:
In 1994 in Bashkiria, the dam of the Tirlyanskoye reservoir burst and an abnormal discharge of 8.6 million cubic meters of water occurred. 29 people died, 786 were left homeless. 4 settlements turned out to be in the flood zone, 85 residential buildings were completely destroyed;
In 1998 near the city of Lensk in Yakutia, two ice jams on the Lena River caused a rise in water by 11 m. 97 thousand people ended up in the flood zone, 15 died;
In 2001 Lensk was again almost completely flooded due to the flood, which led to the death of 8 people. 5 thousand 162 houses were flooded, in total, more than 43 thousand people suffered from the flood in Yakutia;
In 2001 in Irkutsk region due to heavy rains, a number of rivers burst their banks and flooded 7 cities and 13 districts (a total of 63 settlements). The city of Sayansk was especially affected. 8 people died, 300 thousand people were injured, 4,635 houses were flooded;
In 2001 a flood occurred in the Primorsky Territory of the Russian Federation, as a result of which 11 people died, more than 80 thousand were injured. 625 sq. kilometers of territory. 7 cities and 7 districts of the region were in the disaster zone, 260 km of roads and 40 bridges were destroyed;
In 2002 As a result of severe flooding in the Southern Federal District of the Russian Federation, 114 people died, of which 59 - in the Stavropol Territory, 8 - in Karachay-Cherkessia, 36 - in the Krasnodar Territory. In total, more than 330 thousand people were affected. 377 settlements were in the flood zone. 8,000 residential buildings were destroyed, 45,000 buildings, 350 km of a gas pipeline, 406 bridges, 1,700 km of roads, about 6 km of railways, over 1,000 were damaged. km of power lines, more than 520 km of water supply and 154 water intakes;
In 2002 on the Black Sea coast The Krasnodar Territory was hit by a tornado and heavy rains. 15 settlements were flooded, including Krymsk, Abrau-Dyurso, Tuapse. Novorossiysk and the village of Shirokaya Balka suffered the greatest destruction. The element claimed the lives of 62 people. Nearly 8,000 residential buildings were damaged;
In 2004 as a result of floods in the southern regions of Khakassia, 24 settlements were flooded (a total of 1077 houses). 9 people died;
In 2010 in the Krasnodar Territory there was a major flood caused by powerful heavy rains. 30 settlements were flooded in the Tuapse, Apsheron regions and in the Sochi region. 17 people died, 7.5 thousand people were injured. As a result of the natural disaster, almost 1.5 thousand households were destroyed, of which 250 were completely destroyed;
In 2012 heavy rains led to the most devastating flood in the history of the Krasnodar Territory. 10 settlements were affected, including the cities of Gelendzhik, Novorossiysk, Krymsk, the villages of Divnomorskoye, Nizhnebakanskaya, Neberdzhaevskaya and Kabardinka. The main blow of the elements fell on the Crimean region and directly on Krymsk. As a result of the flood, 168 people died, of which 153 people - in Krymsk, three - in Novorossiysk, 12 - in Gelendzhik. 53,000 people were recognized as victims of the disaster, of which 29,000 completely lost their property. Were flooded 7.2 thousand. residential buildings, of which over 1.65 thousand households were completely destroyed.
Around the world you can see:
December 1999 - Severe flooding in Venezuela was caused by rain that lasted for a week. A state of emergency was declared in the territory of 5 northwestern states and the capital federal district. The number of deaths, according to Western news agencies, exceeded 10 thousand people;
- February - March 2000 - The largest flood in Mozambique was caused by Cyclone Eline. The element destroyed hundreds of thousands of houses, huge areas of farmland and caused the death of more than 700 people. About 2 million people, more than 10% of the country's population, were left homeless as a result of the floods;
March 2000 - In Hungary, heavy rains and melting snow caused one of the worst floods in years. A state of emergency was declared in the eastern regions of the country. More than 200 thousand hectares of land were under water;
September 2000 - in India, a natural disaster was caused by prolonged and very strong monsoon rains, which caused a ten-meter rise in water in rivers. The number of deaths in Indian states West Bengal and Bihar reached almost 800 people. In total, up to 15 million people fell into the category of victims. About 600 settlements were flooded, crops and food storage facilities were completely destroyed;
October 2000 - Vietnam's emergency was triggered by the worst floods in the country's history. Heavy rains in the south of Vietnam continued for more than 2 months. The water level in the Mekong River within the city of Ho Chi Minh City exceeded the permissible level and reached 1.26 m. According to official figures, 727 people died as a result of the floods, including 239 children. About 45 thousand families were evacuated;
- August 2002 - heavy rains in the summer, in the north and in the center of Europe, caused catastrophic flooding in August. 250,000 people were directly affected;
2005 - Hurricane Katrina in the United States causes extensive flooding in the states of Louisiana, Mississippi and Alabama. The levees around New Orleans, Louisiana were breached and the entire city flooded, most of the city's population was evacuated. 1193 people died;
May 2008 - Myanmar's Irrawaddy Delta flood due to Cyclone Nargis is the largest cyclone ever recorded in the Bay of Bengal. The United Nations reported that 2.4 million people were affected, with about 146,000 dead or missing;
2008 - Haiti. Four tropical cataclysms - Tropical Storm Fey, Hurricanes Gustav, Hanna and Ike, which lasted for 1 month caused flooding, which led to the death of 425 people, crops were destroyed throughout the country, up to 600,000 people need international assistance;
2009 - in the Philippines, after two tropical downpours, mudflows and the most severe flooding are formed within a week. The President declares a nationwide state of emergency. At least 3 million people were affected, more than 540 people died;
2009 - Samoa Islands. An earthquake in the sea, led to the formation of a wave up to 6 m in height, which washed away all the villages up to 1 km inland on the coast of Samoa, American Samoa and Tonga, on the Pacific Islands, more than 189 people died;
July–August 2010 – Approximately 2,000 people were killed in Pakistan. The flood caused a mass exodus of spiders: they escaped from the streams of water on the trees, entangling their crowns with a thick layer of cobwebs, giving the coastal landscapes an ominous look;
July 2011 - January 2012 - Thailand was flooded for six months, entire provinces went under water. The flood claimed the lives of more than 600 people.
3. Problems of floods and safety of hydraulic structures.
Floods are among the most destructive and frequently recurring natural disasters. In the Russian Federation, the area of flood-prone territories is about 400,000 km². Flooding with catastrophic consequences affects an area of about 150,000 km², where more than 7 million hectares of agricultural land are located. The areas most at risk from flooding are Krasnodar region, Volgograd, Astrakhan, Amur and Sakhalin regions, Transbaikalia, Stavropol Territory, Buryatia, Primorsky Territory, Dagestan, Kabardino-Balkaria. In recent years, in the south of Russia, in the Primorsky Territory, the Republic of Sakha (Yakutia), there has been an increase in floods with catastrophic consequences for the population and economic facilities.
The main reasons for the occurrence and increase in the risk of floods are climate change and the manifestation of anomalous weather events, as a result of ice jams in riverbeds, intensive development and development of watersheds and flooded areas, insufficient provision of settlements and agricultural lands, reliable engineering protection. Risk factors are measures to restrict (reduce) the living section of the river flow, the economic development of flood-prone areas in the downstream of hydroelectric facilities, with the placement of residential and utility facilities.
The aggravation of the problem of floods in Russia is directly related to the aging of the main production assets of the country's water management. With deterioration technical condition hydraulic structures, the risk of their destruction during floods and floods increases. Of the total number of hydraulic structures, over 90% are built from earth and stone-soil materials, for which the service life is about 30 years. However, the share of hydraulic structures with a service life of more than 30 years is about 50%. Flood control in the Russian Federation consists mainly of fencing the territory with dams, increasing the capacity of rivers, redistributing runoff, and other engineering measures.
Reservoirs are important to cut off the peaks of floods. For this purpose, the drawdown of reservoirs is provided before the start of the flood, but this is not enough. In the context of increasing anthropogenic pressure, pollution and degradation of land and water sources, and the increasing risk of catastrophic floods, the use of the ecosystem approach to nature management is of decisive importance. It examines environmental, economic and social resources and their interactions. The problem of floods and the safety of hydraulic structures is an environmental, socio-economic and technical problem. Along with engineering measures, in order to solve the problem of floods, it is necessary to analyze the factors, the safety of the operation of hydraulic structures and, at the same time, focus on preventing and reducing the negative consequences of floods, timely ensuring accident-free passage of flood waters, modernizing and improving the safety of hydraulic structures. The fundamental basis for this is system analysis the state of functioning of water bodies and hydraulic structures, spillways and flood-prone areas, the causes of the consequences of floods, taking into account natural, social and economic resources.
To prevent crisis situations, it is necessary to improve the unified state management system, which implies the presence of the Federal Center, basin, regional, municipal structures and, accordingly, unified information and analytical systems based on the monitoring of water bodies and hydraulic structures. The mechanism for implementing measures to solve the problem of floods and the safety of hydraulic structures includes the use of a set of organizational, legislative, legal, regulatory, methodological and socio-economic measures.
Conclusion.
Floods are inevitable a natural phenomenon. The task of mankind is to study the features of floods in as much detail as possible and learn how to prevent catastrophic consequences.
From history it is clear that a person copes with this problem quite successfully. Scientists-hydrologists carry out the necessary calculations and forecasts, perform work aimed at combating floods - agrotechnical, forest reclamation, field protection. However, the accuracy of calculations and the lead time of the measures taken leave much to be desired. This can be corrected by the widespread introduction into practice of new technical means of collecting and processing information about the state of the natural environment.
Man continues to build up the banks of rivers and lakes, actively develops river valleys, and storms mountains. For these reasons, the scope of work to combat floods is growing. Floods as a natural disaster are becoming more and more unbearable. Scientific, engineering and socio-economic substantiation of flood protection projects are among the most important tasks of specialists in many fields, primarily hydraulic engineers, hydrologists, ecologists and economists.
In the age of technological progress, floods have claimed millions of human lives and caused enormous material damage, which tends to increase.
List of used literature.
1. the federal law"On the protection of the population and territories from natural and man-made emergencies" No. 68-FZ of December 21, 1994 (as amended on July 21, 2014).
2. Vorobyov Yu.L. Catastrophic floods of the early 21st century: lessons and conclusions. Moscow: Deks-Press, 2003.- 352 p.
3. Oleinik T. F. Great natural disasters: floods, earthquakes, volcanoes, tornadoes. - Rostov-on-Don: Phoenix, - 2006. - 254 p.
4. Chumakov B.N. How to survive natural disasters. - Moscow: Eksmo, 2005. - 58 p.
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Flooding is a dangerous natural phenomenon, a possible source of emergency, if the flooding of the area causes material damage, damages the health of the population or leads to the death of people, farm animals and plants.
In terms of frequency, distribution area and total average annual material damage, floods on the territory of the Russian Federation rank first in a number of natural disasters, and in terms of the number of human casualties and specific material damage (per unit of the affected area) - the second place after earthquakes.
Rivers differ from each other in different conditions for the formation of water runoff (water runoff is the amount of water flowing through the closing section of the river for any time interval).
According to the conditions of runoff formation and the occurrence of floods, the rivers of the Russian Federation are divided into four types (Table 1).
Table 1
|
Formation conditions |
Distribution areas |
|
Spring snowmelt on the plains |
European part of the Russian Federation and Western Siberia |
|
Melting mountain snows and glaciers |
North Caucasus |
|
Heavy rainfall |
Far East and Siberia |
|
Combined effect of snowmelt and precipitation |
Northwestern regions of the Russian Federation |
The variety of floods can be reduced to five general groups that combine various floods according to the causes of occurrence and the nature of their manifestation (Table 2).
Within the Russian Federation, floods of the first two types prevail (about 70 - 80% of all cases). They are found on the plains, foothills and mountain rivers, in the northern and southern, western and eastern regions of the country. The remaining three types of floods have a local distribution.
The classification of floods depending on the scale of their distribution and frequency is presented in Table. 3.
table 2
|
Types of floods |
Causes |
The nature of the manifestation |
|
high water |
Spring snowmelt in the plains or spring-summer snowmelt and rainfall in the mountains |
Repeat periodically in the same season. Characterized by a significant and prolonged rise in water levels |
|
high water |
Intense rains and snowmelt during winter thaws |
There is no clearly defined periodicity. It is characterized by an intense and relatively short-term rise in the water level. |
|
Jam, zazhorny floods (jamming, zazhora) |
High resistance to water flow, in certain sections of the river channel, arising from the accumulation of ice material in narrowings or bends of the river during freeze-up (jamming) or ice drift (jamming) |
Jam floods form in late winter or early spring. They are characterized by a high and relatively short-term rise in the water level in the river. Jam floods form at the beginning of winter and are characterized by a significant (but less than during a jam) rise in the water level and a longer duration of the flood. |
|
Surge floods (surges) |
Wind surges of water in sea mouths of rivers and on windy sections of the coast of the seas, large lakes, reservoirs |
Possible at any time of the year. Characterized by the absence of periodicity and a significant rise in the water level |
|
Floods (flooding) formed when dams break |
An outflow of water from a reservoir or reservoir, which is formed when a pressure front structure (dams, dams, etc.) breaks through or during an emergency discharge of water from a reservoir, as well as when a natural dam breaks through, created by nature during earthquakes, landslides, collapses, glacier movement |
Characterized by the formation of a breakthrough wave, leading to flooding large territories and destruction or damage of objects encountered on the way of its movement (buildings, structures, etc.) |
Table 3
|
Classes |
Scale of distribution |
Repeatability |
|
Low (small) |
They do relatively little damage. Covers small coastal areas. Less than 10% of agricultural land is flooded. Almost do not break the rhythm of life of the population. |
5-10 years |
|
High |
They cause significant material and moral damage, cover relatively large areas of river valleys, flood approximately 10-15% of agricultural land. Significantly violate the economic and everyday life of the population. Lead to the partial evacuation of people. |
20-25 years old |
|
Outstanding |
They cause great material damage, covering entire river basins. Flood approximately 50-70% of agricultural land, some settlements. Paralyze economic activity and drastically disrupt the way of life of the population. Lead to the need for mass evacuation of the population and material assets from the flood zone and protection of the most important economic facilities |
50-100 years old |
|
catastrophic |
They cause enormous material damage and lead to death of people, covering vast territories within one or more river systems. More than 70% of agricultural land, many settlements, industrial enterprises and utilities are flooded. Economic and industrial activity is completely paralyzed, the way of life of the population is temporarily changed |
100-200 years |
The main characteristics of the water flow are given in table. 4.
During flooding, secondary damaging factors may occur: fires (due to breaks and short circuits in electrical cables and wires); collapse of buildings, structures (under the influence of water flow and due to erosion of the base); diseases of people and farm animals (due to contamination of drinking water and food), etc.
Buildings that periodically fall into the flood zone lose their solidity: wood is damaged by rot, plaster falls off, bricks fall out, and corrode metal constructions, due to erosion of the soil under the foundation, uneven settlement of buildings occurs and, as a result, cracks appear.
The number of people who find themselves in a zone prone to floods (here they stand out: the number of victims, the number of victims, the number of people left homeless, etc.);
the number of settlements that fell into the zone covered by the flood (cities, urban-type settlements, rural settlements, completely flooded, partially flooded, caught in the flood zone are distinguished here);
the number of objects of various sectors of the economy that ended up in the zone, floods;
the length of railways and roads, power lines, communication and communications lines that are in the flood zone;
number of bridges and tunnels flooded, destroyed and damaged by flooding;
the number of residential buildings flooded, destroyed and damaged as a result of flooding;
the area of agricultural land covered by the flood;
the number of dead farm animals, etc.
Generalized characteristics of the consequences: the magnitude of the damage caused by the flood.
Table 4
|
Basic |
Characteristics of the main |
Units |
water flow |
Maximum water level during the flood (in the considered section of the river) |
m or cm |
|
Maximum water flow during the flood (in the considered section of the river) |
m 3 / s |
|
|
Current speed (in the considered section of the river) |
m/s |
|
|
Area of flooded area |
km 2 |
|
|
Duration of area flooding |
weeks, days, hours |
|
|
Repeatability of the maximum water level |
years, months |
|
|
Provision of the maximum water level |
||
|
Water temperature during a flood |
degrees Celsius |
|
|
Start time (season) of the flood |
month, date |
|
|
The rate of rise (intensity of rise) of the water level during the flood |
m/h, cm/h |
|
|
Layer (depth) of terrain flooding at the considered point |
m, cm |
The main features of the situation that occurs during floods are: the destructive nature of the emergency, the rapid increase in the parameters of damaging factors, the limited survival time of the victims affected by them; the difficulty of access to the victims, the need to use special floating facilities for this, as well as complex weather(heavy rains, ice drift, mudflows, etc.).
The main goal of emergency rescue and other emergency work in flood conditions is the search, assistance and rescue of people who find themselves in the flood zone, as soon as possible, ensuring their survival in the current situation.
Carrying out systematic, advance preparation of command and control bodies and units of civil defense troops, search and rescue units and services for conducting emergency rescue operations; quick response to the occurrence of a natural disaster, alerting and deploying the necessary forces and means, organizing effective reconnaissance and deploying a command and control system;
the use of effective methods and technologies for searching and rescuing victims, as well as methods for protecting the population and economic facilities;
Search for victims;
ensuring access of rescuers to victims and rescue of victims;
provision of first aid to victims;
evacuation of victims from the danger zone.
Strengthening (construction) of enclosing dams and ramparts;
construction of drainage channels;
elimination of congestion and congestion;
equipment of berths for life-saving equipment;
protection and restoration of road structures;
restoration of power supply;
localization of sources of secondary damaging factors.
The main ways to protect people from the damaging factors of floods are the evacuation of the population from flooded areas, the placement of people in non-flooded parts, undamaged structures and terrain.
Depending on the location of the settlement, the time before the start of its flooding, the state of transport communications and other factors, evacuation can be carried out immediately before receiving a signal about the possible flooding of this area or only with an immediate threat of flooding, on foot or using vehicles. In addition to the evacuation of the population, the export of farm animals, material and cultural values can also be carried out in an organized manner.
The effectiveness of evacuation as a way to protect the population during floods depends mainly on the timely warning of the danger, the degree of preparedness of the population and routes.
To this end, a public warning system is being created in areas of possible flooding, information is provided in advance about the location of settlements regarding a possible danger zone and evacuation routes, training is conducted with the population and evacuation authorities to practice evacuation issues, including independent exit of people to a non-flooded area .
In addition to the direct impact of the water flow, aspiration (inhalation) of water, prolonged stay in cold water, neuropsychic overstrain, as well as flooding (destruction) of systems that ensure the vital activity of the population, especially the failure of water supply and sewerage systems.
With prolonged forced stay of people in water with a low temperature, hypothermia (hypothermia) of the body occurs. If a person enters the water, hypothermia is possible even with relatively high temperature(Table 5).
Placement of people on non-flooded parts, non-destructible structures and terrain is used in cases where high speed the water flow causes its rapid arrival in settlements and (or) the population cannot be evacuated to a safe area. In this case, the implementation of such protective measures, as a rule, requires the further implementation of rescue operations to evacuate people from temporary accommodation in the danger zone. At the same time, it should be borne in mind that the population can also use the upper parts of trees as a place of temporary residence (shelter).
Table 5
|
Water temperature, °C |
Time of safe stay, min |
|
420-540 |
|
|
5-15 |
10-270 |
|
10-15 |
|
|
Up to 2 |
The decision to carry out emergency rescue and other urgent work in case of floods is made on the basis of intelligence data, which is organized during floods to identify the situation in disaster areas in order to minimize damage.
Determining the boundaries of flooding;
control of flood development dynamics;
establishing the locations of people and farm animals in need of help;
identification of material values to be removed from the disaster zone;
selection and reconnaissance of routes for the evacuation of people, animals and material assets by watercraft, equipment of berths;
selection and equipment of landing sites for helicopters in the disaster area.
To carry out emergency rescue operations, units of the civil defense troops, search and rescue teams (services), reinforced with amphibious assault vehicles, are assigned. To perform other urgent work, taking into account their nature, engineering, engineering and technical, road units and formations are assigned.
When searching for and rescuing victims in the water and in flooded areas, aviation technologies using aircraft and helicopters should be widely used.
The use of certain technologies for eliminating ice blockages (blockages) and landslides depends on the scale of floods and the consequences associated with them. Explosives are the main method of destroying the ice cover, eliminating ice blockages (blocks), as well as rock falls. The work is carried out by pyrotechnic units equipped with watercraft and vehicles equipped for the delivery of explosives and explosives. During catastrophic floods, especially on the large rivers of the North and North-East of Russia, flowing from south to north, the destruction of the ice cover, ice jams and ice jams is practiced using bomber aircraft.
Measures to prevent floods and liquidate their consequences are provided for in action plans for the prevention and liquidation of emergency situations, developed at all levels by emergency commissions.
The organization of interaction between the forces of liquidation, the consequences of floods and catastrophic flooding of territories is one of the critical factors that ensure the success of rescue and other urgent operations.
Interaction is organized primarily in the interests of rescue units, the implementation of these works in the shortest possible time.
Accelerate the formation of territorial monitoring systems, laboratory control and forecasting of emergency situations;
to take measures to develop warning systems for the population, paying particular attention to rural areas;
take measures to create and strengthen bank protection structures, repair dams, deepen and clean river beds;
intensify work on the creation of search and rescue units financed from the budgets of the constituent entities of the Russian Federation;
taking into account this experience, rework action plans for the prevention and elimination of emergency situations;
create full reserves of financial and material resources for the elimination of emergency situations;
to consider the issue of the need (expediency) of redistribution of budget funds of the constituent entities of the Russian Federation in the direction of increasing funds for carrying out urgent measures aimed at the safe functioning of the water management complexes of the regions.
The raging and destructive power of the water element is capable of causing irreparable damage to the ecological and economic sectors of any state. One of the frequent cases that operational services have to deal with is an increase in the water level in local reservoirs and its overflowing the coastline.
In such cases, they speak of floods, floods and floods. However, these concepts are often confused, or even completely identified with each other. In this article, we will try to give a precise definition of these phenomena, we will tell you how the flood differs from floods and floods and how you should behave when you find yourself in a similar situation.
Flooding, high water, high water are similar only in that they can, under certain circumstances, lead to significant land flooding. However, flooding is a more general and broad concept that arises for a variety of reasons. Let's consider in more detail:
It is a short-term, but sharp rise in water in rivers and lakes. It is characterized by its suddenness, and is completely independent of the time of year.
May occur several times a year. The reasons are usually associated with external natural circumstances: prolonged and heavy rainfall, a sharp warming with rapid snowmelt. The maximum duration is several days.
Abundant types of floods, following one after another or having a short time interval between them, can lead to flooding.
This is a common natural phenomenon that always occurs at the same time of the year, in spring. It repeats annually, and is characterized by a long and high rise in the water level in reservoirs. In most cases, water comes out of the riverbed, but floods can occur without flooding the coastal area.
The level of the river during this phenomenon can rise by 20-30 m. The decline can last up to 1 month. It is caused by an abundant influx of water into the reservoir due to rain, melting glaciers and snow.
Types of floods associated with excessive snowmelt in mountainous areas are typical for the Caucasian terrain and rivers located in the Alps and Central Asia.
This is always a major natural disaster, with significant land flooding. Floods, floods, and even a human factor, for example, a breakthrough, can lead to it.
The flood carries not only the destruction of vital structures, flooding of houses, but also the death of animals, crops, causing significant economic damage. Depending on the strength of the flood, there may be human casualties.
Floods and floods, as a rule, do not have such consequences. The period of restoration measures after the flood is quite long. Sometimes this can take several years.
The most harmless floods. They occur in rivers located on flat terrain. It has been observed to recur every 5-10 years. They pose no threat to the life of the population.
They are characterized by fairly severe flooding, affecting large areas of land. With this view, it may be necessary to evacuate people from nearby houses. The material damage does not go beyond the average, but is very noticeable. Fields and pastures are often destroyed. Occur rarely - once every 20-25 years.
They are fixed once a century. They cause very great damage, as all agricultural activities are completely stopped. Residents of the entire settlement are evacuated to a safe place.
Such floods rarely do without loss of life. The disaster zone covers the territory of several river systems. The vital activity of a person in an area that has undergone a catastrophic flood is completely blocked. They are observed once every 200 years.
The severity of the consequences depends on many factors: how long the water stays on land, its height of rise, the speed of the falling stream, the area of the flooded territory and population density.
Flooding can be caused by a variety of reasons. For areas with a warm, mild climate, prolonged and heavy rains, which are a frequent occurrence there, can become a threatening factor. In areas where the climate is dry and cool, precipitation is less frequent and the risk of flooding is minimal.
However, in the northern regions there is another danger - glaciers, mountain snow peaks and abundant snow cover. In the event of a sharp warming or early spring, rapid snowmelt will occur, which will lead to a strong rise in water in the lowland rivers. A major flood can lead to flooding.
The accumulation of mineral deposits at the bottom of the river contributes to its uplift. If the channel is not cleaned in time, then disasters in the form of floods, floods or floods cannot be avoided.
The cause of the most catastrophic floods can be tsunamis, which occur abruptly, and bring terrible destruction and numerous victims. They are gigantic waves that crash onto the land one after another, sweeping away everything in their path. Powerful sea waves can form due to hurricanes or strong winds. They are able to splash out on the coastline with force.
Breakthrough of the earth's crust and access to the surface of groundwater is also one of the possible causes floods. Mudflows and landslides lead to the overflow of mountain rivers. They, leaving the channel, with force and a mud stream descend to the plain. This natural disaster has serious consequences.
The human factor in the formation of floods is the improper operation or failure of hydraulic structures, which leads to their destruction and the breakthrough of a large flow of water to settlements. Various man-made disasters can cause flooding of various scales.
In the lowlands or areas that are located within a particular river system, the water regime in local reservoirs is constantly monitored. When signs of a major flood or annual flood are detected, the population is notified in advance by special services.
The basic rules of conduct during floods and floods are as follows:
When an evacuation is declared, follow the instructions. Take a minimum of things and arrive at the check-in point as quickly as possible. Keep a close eye on children and elderly and/or sick relatives.
If you did not have time to evacuate from the disaster area, then climb onto the roof and give signals. To do this, use a flashlight, phone screen. You can tie a bright fabric to some kind of pin or stick.
You can return home only after the permission of the authorized bodies. Be careful on the street. Do not step on broken or damaged wires, do not stand near heavily damaged buildings or structures.
