Mankind has been familiar with floods since ancient times. Information has come down to us about the catastrophic spills on the Yellow River (in 2297 BC) and on the Nile River (about 3, 000 years ago). Previously, these natural disasters were quite rare, but in recent centuries, their frequency and the size of the damage they cause has increased rapidly. If we take the period BC, the most dangerous floods, the causes of which will be discussed below, occurred about once every 50 years (for example, in China). Now, such disasters occur several times a year. At the most “fruitful” time, these catastrophes happen with a frequency of 2-3 days, as the media immediately informs us. Maybe that's why the topic "Flood" is relevant for many people. And interest in her is constantly growing.
Water problems
It is well known that the development of human society depends on the quality of water resources. Many politicians and experts are sure that the water problem is on the first place in the list of common tasks 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 flow regime does not meet the economic and social requirements of the population, and when there is an excess of moisture in habitable territories suffering from for this from the floods. On a global scale, the first three problems were caused by the past century, and the fourth has haunted humanity since ancient times. And although people understood what a flood was, and took measures to protect it from it, they could not succeed in this. And with every century, the damage from this disaster continues to increase. Only in the second half of the twentieth century, the damage done increased 10 times.
History
You can find out the estimated flood date using a hydrological forecast. It is a study aimed at the scientific justification of the scale and nature of this disaster. 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 extent of floods depend on their duration, the nature of the soil, the season, the topography, the speed of the stream, the height of the water and other factors. Everyone heard the legend of the Flood. Many researchers, who know what floods are, believe that the stories about the flood are really based on catastrophes that actually happened 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 Euphrates and Tigris valleys seemed to the whole world to people. Therefore, grandiose floods with a large number of victims were associated with a global flood. Now archaeologists, historians and other specialists have done a great job of researching the legends of the Great Flood. Based on the list of these legends, major floods occurred in almost all areas of the Earth. And this list is very impressive. It includes the tales of the flood on all continents of the planet.
Major floods
With population growth, destruction of forests, and other harmful human activities, floods began to occur much more often. At the beginning of the article, we mentioned two catastrophic floods. Now let's talk about a few more.
1. Flooding in Europe. It covered the territory of Germany, Great Britain and the Netherlands in 1953. In a strong gale, huge waves covered the north coast. This caused a sharp rise in water (3-4 meters) in the estuaries of Scheldt, Maas, the Rhine and other rivers. The Netherlands suffered more than the rest of the countries. 8% of the territory was flooded. Killed about 2000 people.
2. Flooding in the Ganges Delta. It happened in 1970. A 10 meter wave covered the sacred river and reversed the course. It was flooded approximately 20, 000 square meters. km Destroyed hundreds of villages and dozens of cities. About 1.5 million people died. Since the flood destroyed almost all the wells, an acute shortage of drinking water was formed. Hundreds of thousands of people died from starvation and the outbreak of typhoid and cholera.
3. The Amur flood. It happened on the territory of the Russian Federation in July 2013. Total damage exceeded 3 billion rubles. Destroyed 29 bridges. Blurred almost 300 kilometers of roads. Agriculture was hit hard. There were more than ten settlements in the flood zone.
Causes and types of floods
For a deeper understanding of the topic, we will define this natural disaster. After all, not everyone knows what a flood is. Let's fix this omission. The simplest definition is water flooding of significant land areas. Now we list the causes of this disaster.
Causes
1. Melting snow.
2. The tsunami waves.
3. Long rains.
4. Anthropogenic causes.
There are direct reasons related to the destruction of dams and hydraulic engineering measures, and indirect ones are housing and industrial development, drainage of swamps, and deforestation. All this changes the hydrological regime of rivers due to an increase in the surface component of runoff. Deforestation of all forests will increase the maximum runoff to 300%.
Now consider the main types of floods. We are sure that this topic will be very interesting to our readers.
Kinds
1. High water. It occurs during spring snowmelt on the plains or in the mountains. It has a seasonal frequency. It is characterized by a significant rise in water level.
2. The flood. Occurs during winter thaws due to melting snow or heavy rains. It does not have a clearly defined periodicity. It is characterized by a rather short-term and intense rise in water level.
3. Shock and mash floods. They occur when resistance to water flow is created in certain areas of the riverbed. It arises due to the accumulation of ice in the narrowing of the channel during ice drift (congestion) or freeze-up (jam). Mash flood of the river occurs in early spring or late winter. It has a relatively short high rise in water level. Pompous flooding occurs at the beginning of winter. It is characterized by a significant rise in water level and a significant duration of the disaster.
4. Flood surges. They arise as a result of wind surges in the mouths of rivers, as well as in rather windy sections of reservoirs, large lakes and the sea coast. May occur at any time of the year. They do not have periodicity. The rise in water level is significant.
5. Floods as a result of breaking dams. In a disaster, water spills from a reservoir or reservoir due to a breakdown of a pressure structure (dam, dam, etc.) or an emergency discharge of water. Another reason is the natural breakthrough of the dam due to natural factors (landslides, landslides, etc.). During the catastrophe, a breakthrough wave is formed, flooding vast territories and damaging or destroying objects (structures, buildings, etc.) that are encountered along its path.
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 the separation of these disasters are the period of recurrence and the scale of the spread.
Flood Classes
1. Low. As a rule, they cause minor damage. Cover coastal areas of small size. Agricultural land is flooded by less than 10%. Almost do not knock the population out of the current rhythm of life. Repeatability - 5-10 years.
2. High. Cause significant damage (moral and material). Cover large areas of river valleys. Inundate about 10-15% of the land. They violate both the household and the economic structure of the population. Partial evacuation of people is very likely. Frequency - 20-25 years.
3. Outstanding. Cause heavy material damage, spanning river basins. About 50-70% of farmland, 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 is 50-100 years.
4. Catastrophic. They cause huge material damage, spreading to vast territories within the framework of one or more river systems. Lead to human sacrifice. Over 70% of the land is flooded, many settlements, utilities and industrial enterprises. Production and economic activities are completely paralyzed, and the way of life of the population is also changing. Frequency - 100-200 years.
Flood consequences
The main features of the situation arising from such natural disasters are: the rapid increase in the power of damaging factors, the difficulty of access to the victims, the destructive nature of the situation, the small numbers of survivors of the victims, as well as the presence of difficult weather conditions (mudflows, ice drift, heavy rains, etc.)
Characteristics of water flow as a damaging factor
1. The highest water level.
2. The highest water consumption.
3. The speed of the current.
4. Flooding area.
5. Repeatability of the magnitude of the highest water level.
6. Duration of flooding.
7. Water temperature.
8. Security of the highest water level.
9. The time of the onset of the disaster.
10. The rate of rise of the water level for the entire time of the flood.
11. The depth of the flooding of the territory in the area.
Impact Characteristics
1. The population in the disaster area (victims, victims, etc.).
2. The number of objects of economic sectors affected by natural disasters.
3. The number of settlements in the disaster area.
4. The length of roads (railways and automobiles), communication lines and power lines caught 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 farmland affected by the disaster, etc.
Rescue work
The main goal of emergency rescue operations is the search and rescue of people who find themselves in the flood zone. It is necessary to help them as soon as possible and ensure their survival in the current situation. Success during rescue operations is achieved through a series of actions.
1. Conducting early and systematic training of commanders, soldiers of civil defense units who know exactly what floods are, as well as members of search and rescue services for rescue operations.
2. A quick response to a disaster, alerting and providing the necessary forces and means.
3. Organization of operational intelligence and deployment of the control system.
4. The use of effective technologies for the search for victims and their salvation, as well as ways to protect economic facilities and the population.
What does emergency emergency work include?
1. The construction of enclosing shafts and dams.
2. The construction of drainage channels.
3. Equipment of moorings 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 factors of damage.
