What is a flood? Causes and types of floods

Mankind has been familiar with floods since ancient times. We got information about catastrophic spills on the Yellow River (in 2297 BC) and on the Nile River (about 3000 years ago). Previously, these natural disasters were rare, but in recent centuries their frequency and the magnitude of the damage caused by them have skyrocketed. If we take the period before our era, the most dangerous floods, the causes of which will be discussed below, happened about every 50 years (for example, in China). Now such disasters occur several times a year. At the most "harvest" time, these disasters happen with a periodicity 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.

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 problem of water 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 inadequate quantity of life-giving moisture, when the regime of water bodies does not correspond to the optimal functioning of ecosystems, under a feeding regime that does not meet the economic and social requirements of the population, and with an excess of moisture in the habitable territories, For this from floods. On a global scale, the first three problems were born by a bygone century, and the fourth has been haunted by mankind since ancient times. And although people understood what a flood was, and took measures to protect against it, they could not succeed in it. And with every century the damage from this disaster continues to increase. Only in the second half of the twentieth century the damage dealt increased by 10 times.

History

You can find out the estimated date of the flood by using a hydrological forecast. It is a study aimed at the scientific substantiation of the scale and nature of this catastrophe. Forecasts are divided into long-term (more than 1 quarter), long-term (up to 3 weeks), short-term (10-12 days), territorial and local. The consequences and magnitude of floods depend on their duration, the nature of the soil, the season, the terrain, the flow velocity, 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 tragedies of the flood are based on the catastrophes that really 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 settled areas in the Euphrates and Tigris valley seemed to the people to be a whole world. Therefore, grand floods with a large number of victims were associated with a worldwide flood. Now archaeologists, historians and other specialists have done a great job of researching the traditions of the Great Flood. Based on the list of these legends, major floods occurred almost in all areas of the Earth. And this list is very impressive. It includes stories about the flood on all continents of the planet.

Major floods

With the growth of the population, the destruction of forests and other kinds of human activities harmful to nature, floods began to occur much more often. At the beginning of the article, we mentioned two catastrophic floods. Now tell about a few more.

1. Flooding in Europe. Covered the territory of Germany, Britain and the Netherlands in 1953. With a strong stormy wind, the northern coast covered huge waves. This caused a sharp rise in water (3-4 meters) in the estuaries of Scheldt, Maas, the Rhine and other rivers. More than the rest of the countries, the Netherlands suffered. 8% of the territory was flooded. About 2000 people died.

2. Flooding in the Ganges delta. Happened in 1970. 10 meter wave covered the sacred river and turned the current back. It was flooded approximately 20,000 square meters. Km. Hundreds of villages and dozens of cities have been destroyed. About 1.5 million people died. Since the flood destroyed virtually all the wells, there was an acute shortage of drinking water. Hundreds of thousands of people died from hunger and outbreaks of typhus and cholera epidemics.

3. Amur flood. Occurred on the territory of the Russian Federation in July 2013. The total damage exceeded 3 billion rubles. 29 bridges were destroyed. Blurred almost 300 kilometers of roads. Agriculture has suffered greatly. There were more than ten settlements in the flood zone.

Causes and types of floods

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 essential land areas with water. Now let us list the causes of this disaster.

Causes

1. The melting of the snow.

2. Waves of tsunami.

3. Long rains.

4. Anthropogenic causes.

There are direct causes associated with the destruction of dams and the implementation of hydrotechnical measures, and indirect - housing and industrial development, draining swamps, reducing forests. All this changes the hydrological regime of rivers by increasing the surface component of the runoff. The reduction 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 for our readers.

Kinds

1. Flood. It arises when snow melts in the spring on plains or in the mountains. It has a seasonal periodicity. Characterized by a significant rise in water level.

2. Flooding. Occurs during winter thaws due to melting snow or heavy rains. Does not have a clearly expressed periodicity. It is characterized by a fairly short and intensive rise in the water level.

3. Zazhornye and mash floods. Occur when in some parts of the river bed there is resistance to the water flow. It arises from the accumulation of ice floes in the narrowings of the riverbed during ice drift (congestion) or ice (zazhory). Mash flooding of the river is formed at the beginning of spring or at the end of winter. Has a relatively short high water level rise. Over-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. Over-flooding. They arise as a result of wind surges in the estuaries of rivers, as well as in fairly windy areas of reservoirs, large lakes and the sea coast. Can occur at any time of the year. They do not have periodicity. The rise in water level is significant.

5. Floods caused by dam breaks. In case of distress, water is spilled from a reservoir or reservoir due to a breakthrough in the pressure structure (dam, dam, etc.) or emergency discharge of water. Another reason is the natural breakthrough of the dam due to natural factors (landslides, landslides, etc.). In the course of the catastrophe, a breakthrough wave forms, flooding huge areas 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 can not Forget that these natural disasters are also divided into classes. The main principles of separating these disasters are the period of occurrence and scale of distribution.

Classes of floods

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 out the population from the current rhythm of life. Repeatability is 5-10 years.

2. High. Inflict significant damage (moral and material). Cover large areas of river valleys. About 10-15% of the land is flooded. They violate both the household and the 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. Under water is about 50-70% of farmland, as well as a certain part of settlements. Outstanding floods not only violate everyday life, but also paralyze economic activity. Evacuation of material values and population from the disaster zone and protection of the main objects of economic importance are necessary. Repeatability is 50-100 years.

4. Catastrophic. They cause enormous material damage, spreading over huge territories within one or several river systems. Lead to human casualties. 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 changing. The periodicity is 100-200 years.

Consequences of floods

The main features of the situation arising from such natural disasters are: a rapid increase in the strength of the damaging factors, the difficulty of access to the victims, the destructive nature of the situation, small numbers of survivors' survival, and the presence of difficult weather conditions (mudflows, ice drifts, heavy rains, ).

Characteristics of water flow as a damaging factor

1. The highest water level.

2. The greatest water flow.

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. Provision of the highest water level.

9. The time of the beginning of the disaster.

10. The rate of water level rise during the entire time of flooding.

11. Depth of flooding in the area.

Characteristics of consequences

1. The population in the disaster zone (victims, victims, etc.).

2. The number of objects in the economic sectors affected by the natural disaster.

3. Number of settlements in the disaster area.

4. The length of roads (railways and roads), communication lines and power transmission, caught in the flood zone.

5. The number of tunnels, bridges and houses, damaged, destroyed and flooded as a result of the disaster.

6. The number of dead animals involved earlier in the agricultural sector.

7. Area of affected farmland, etc.

Rescue work

The main purpose of rescue operations is the search and rescue of people caught in the flood zone. We need to help them as soon as possible and ensure their survival in this situation. Success during rescue operations is achieved by a number of actions.

1. By carrying out advance and systematic training of commanders, soldiers of civil defense units who know exactly what a flood is, and also members of search and rescue services for conducting rescue operations.

2. Rapid response to the disaster, alerting and providing the necessary forces and resources.

3. Organization of operational intelligence and deployment of the management system.

4. The use of effective technologies for searching for victims and their salvation, as well as ways to protect economic facilities and the population.

What do emergency emergency work include?

1. Construction of fencing ramparts and dams.

2. Construction of drainage canals.

3. Equipment of berths for special means.

4. Elimination of gluttons and congestion.

5. Restoration of power supply.

6. Restoration and protection of road structures.

7. Localization of foci of secondary damage factors.

Problems of reconnaissance in case of flood

1. Determination of flooding area.

2. Managing the dynamics of disaster development.

3. Identify places where people in need of assistance and farm animals are located.

4. Discovery of material assets that are to be removed from the disaster site.

5. Search and equipment of grounds for helicopter landing in the disaster area.

6. Search and selection of routes for the evacuation of material values, people and animals with the help of water craft. If necessary, the equipment of the berths.

Rescue and rescue work is carried out by the units of the Civil Defense Army, search and rescue services and reinforced ferry-landing special means. To implement other urgent work, taking into account its nature, engineering and road building units are appointed. When searching for victims in flooded areas, rescuers should use aviation equipment (helicopters and airplanes).

And the last. Do not forget that the threat of floods always exists. Therefore, prepare in advance for a meeting with this spontaneous phenomenon.