| Hydrodynamic accidents

Basics of life safety
8th grade

Lesson 26
Hydrodynamic accidents

Presentations for the lesson

What to do in case of hydrodynamic accidents

HYDRODYNAMIC ACCIDENT is an emergency event associated with the failure (destruction) of a hydraulic structure or part of it, and the uncontrolled movement of large masses of water, causing destruction and flooding of vast areas. The main potentially dangerous hydraulic structures include dams, water intake and drainage structures (sluices).

Destruction (breakthrough) of hydraulic structures occurs as a result of natural forces (earthquakes, hurricanes, dam washouts) or human influence (strikes with nuclear or conventional weapons on hydraulic structures, large natural dams, acts of sabotage), as well as due to design defects or errors design.

The consequences of hydrodynamic accidents are:

damage and destruction of waterworks and short-term or long-term cessation of their functions;
defeat of people and destruction of structures by a breakthrough wave formed as a result of the destruction of a hydraulic structure, having a height of 2 to 12 m and a movement speed of 3 to 25 km/h (for mountainous areas - up to 100 km/h);
catastrophic flooding of vast areas with a layer of water from 0.5 to 10 m or more.

PREVENTIONAL MEASURES

If you live in an area adjacent to a hydroelectric complex, check whether it falls within the zone of impact of a breakthrough wave and possible catastrophic flooding. Find out if there are hills near your place of residence, and what are the shortest routes to them.

Study for yourself and familiarize your family members with the rules of behavior when exposed to a wave of breakthrough and flooding of the area, with the procedure for general and private evacuation. Specify in advance the gathering place for evacuees, make a list of documents and property to be removed during evacuation.

Remember the locations of boats, rafts, other watercraft and available materials for their manufacture.

HOW TO ACTION IN THE THREAT OF A HYDRODYNAMIC ACCIDENT

When receiving information about the threat of flooding and evacuation, immediately, in the prescribed manner, leave the danger zone to a designated safe area or to elevated areas. Take with you documents, valuables, essentials and food supplies for 2-3 days. Some of the property that needs to be preserved from flooding, but cannot be taken with you, should be moved to the attic, upper floors of the building, trees, etc.

Before leaving home, turn off the electricity and gas, and tightly close windows, doors, ventilation and other openings.

HOW TO ACT IN FLOODING CONDITIONS IN HYDRODYNAMIC ACCIDENTS

In case of sudden flooding, to escape from the impact of a breakthrough wave, urgently take the nearest elevated place, climb a large tree or the top floor of a stable building. If you are in the water, when a breakout wave approaches, dive into the depths at the base of the wave.

Once in the water, swim or use improvised means to get out to a dry place, preferably to a road or dam along which you can get to a non-flooded area.

If your house is flooded, turn off its power supply, signal that there are people in the house (apartment) by hanging a flag made of bright fabric from the window during the day, and a lantern at night. To receive information, use a self-powered radio. Move your most valuable possessions to the upper floors and attics. Organize the accounting of food and drinking water, their protection from the effects of rising water and their economical use.

When preparing for a possible evacuation by water, take documents, essential items, clothes and shoes with water-repellent properties, and available life-saving equipment (inflatable mattresses, pillows).

Do not attempt to evacuate on your own. This is possible only if there is visibility of a non-flooded area, the threat of worsening the situation, the need to receive medical care, the consumption of food and the lack of prospects for receiving outside help.

If you find yourself in a flood zone, remain on the upper floors and roofs of buildings, trees and other elevated places until help arrives. Self-evacuation can only be carried out in the event of a real threat to your life (flooding of the location).

Do not eat food that has been in the water or use untested water for drinking. Wells with drinking water can be used after preliminary drying (complete water purification).

Before entering a building, make sure that there is no danger of further destruction.

When entering a room, do not use matches or other open flames as a light source, but use battery-powered flashlights. Do not use electrical sources until the electrical network has been checked. Open all doors and windows to dry out the building, remove debris and allow floors and walls to dry.

HOW TO ACTION AFTER A HYDRODYNAMIC ACCIDENT

After the water level drops, as a rule, people rush to return home.

In this case, you should remember the following precautions:

You should beware of torn and sagging electrical wires.

Damage and destruction of water, sewer and gas mains must be immediately reported to the appropriate life support services.

Products that have fallen into water should not be used as food without boiling.

Water supplies should be tested before use, and existing drinking water wells should be drained by pumping out contaminated water.

It is necessary to ensure that the structure of the buildings has not undergone obvious damage.

Before entering the building, make sure there is no significant damage to the ceilings or walls. Ventilate the building to remove accumulated gases. Do not use open flame sources until the room is fully ventilated and the gas supply system is checked to ensure proper operation. Check the serviceability of electrical wiring, gas supply pipes, water supply and sewerage. They are allowed to be used only after the conclusion of specialists about their serviceability and suitability for work. Dry the room by opening all doors and windows. Remove dirt from the floor and walls, pump out water from basements. Do not eat food that has been in contact with water.

Compliance with these rules helps reduce damage and save lives.

QUESTIONS and TASKS
1. What types of hydrodynamic accidents do you know?
2. Name hydrodynamically dangerous objects.
3. Name the main damaging factors of hydrodynamic accidents.
4. What dangers do natural dams pose?
5. Explain what a hydrodynamically dangerous object is and what its danger is.
6. Name the causes of hydrodynamic accidents.
7. Explain the concept of “catastrophic flood zone”.
8. Tell us about the consequences of hydrodynamic accidents.
9. Name the secondary damaging factors of hydrodynamic accidents.
10. What protective measures are carried out in advance at the places of operation of hydraulic structures of the pressure front? Name the main measures to protect the population.
11. What should be done when notified of the danger of dam failure?
12. What should not be done after the water has receded?
13. What should you do when returning to the building after the water has receded?
14. Name the safest places where you can hide from flooding.

Task 25. Among the listed causes of accidents, select those that are typical for hydrodynamic accidents:
a) improper operation;
b) sudden stop of turbines at hydroelectric power plants;
c) destruction of the foundation of hydraulic structures;
d) lack of special instruments indicating an increase in water pressure;
e) military actions;
f) insufficient spillways.

Check your answer with the one given at the end of the textbook. What causes of accidents at hydraulic structures are not listed among those listed? Name them and give their characteristics. Check the correctness of your answers in the text of the textbook.

Task 26. Imagine that the settlement in which you live is located 10 km from the dam on the bank of the river. At night you were awakened by the sound of sirens and horns. Turning on the radio, you heard a message from the Civil Defense Department about the overflow of water over the crest of the dam and the possible flooding of some settlements, including yours. The population is advised to leave their homes and urgently go to safe places.
Define:
a) the procedure for your family when notified of flooding;
b) a list of things that need to be taken when evacuating from home;
c) safe places where you can wait out the flooding.

Check the correctness of your answers in the text of the textbook.

Task 27. From the listed damaging factors, select those that are characteristic of a breakthrough wave:
a) the damaging effect of various objects involved in movement;
b) reduced oxygen concentration in the air;
c) increased ambient temperature;
d) direct dynamic impact on the human body;
e) traumatic effect of building debris;
e) shock air wave.

Check your answer with the one at the end of the textbook.

Fundamentals of life safety. 8th grade : textbook for general education. institutions
/ S. N. Vangorodsky, M. I. Kuznetsov, V. N. Latchuk, V. V. Markov.
- 5th ed., revised. - M.: Bustard, 2005. - 254, p. : ill.

Water is one of the most dangerous and unpredictable natural phenomena. In order to protect their settlements and at the same time have the necessary supply of water, people have to build special hydraulic structures. They create differences in hydraulic levels. Before the structure there is an upper pool (high water level), and after it there is a lower one.

Hoover Dam

Dams are among the most common. You can also find dams and. All of them are potentially dangerous and require constant monitoring by the relevant organizations.

As a result of their destruction or breakdown, a large uncontrolled release of water occurs, resulting in an emergency situation involving the death of people, animals and numerous destructions. This is called (definition and presentation in the encyclopedia website).

What to do in such a situation, what consequences you need to be prepared for and whether it can be prevented, we will consider in this article.

Causes

The failure of a dam or dike can occur due to natural causes or due to human activity. Natural forces that can cause a breakthrough in a hydraulic structure include: earthquakes, floods, heavy and prolonged downpours, hurricanes, and landslides. Natural corrosion of concrete structures can also lead to an accident, but now soil dams are most common.

Various inaccuracies in design, errors in the construction of objects, material defects or low quality, explosions, sabotage, military operations near hydrodynamic structures are among the reasons that are associated with human activity.

If even the slightest risk of a dam break is detected, actions are taken to strengthen it and prevent a break. During spring floods, water is regularly discharged from the facility.

Streams of water

Depending on the volume and force of the released water, the following types of hydrodynamic accidents are distinguished:

Breakthrough of a structure with the occurrence of strong waves leading to flooding of vast areas
A dam or levee breaks, resulting in a breakthrough flood (a short-term but intense rise in the water level in a watercourse).
An accident leading to the deposition of river sediments over a large area and the destruction of the fertile soil layer.

In most cases, the decline in water level in flooded areas occurs after 4 hours, in some cases it is necessary to wait a couple of days.

Consequences and damaging factors

As a result of a hydrodynamic accident, flooding of the area occurs, often comparable to a catastrophe. The resulting wave quickly hits the area located in the lowland.

The main damaging factors in such situations include:

flow force;
emerging wave;
as well as calm waters that have a destructive effect on agricultural facilities.

The force of the wave when a structure breaks through can be compared to the shock air wave from an explosion. However, not every flood is catastrophic. To obtain the status of an emergency, its duration, depth, boundaries of the zone of possible flooding are taken into account, as well as the height of the wave and the flow speed should be maximum.

The primary consequences of hydrodynamic accidents include:

mass death and numerous losses of animals and people;
destruction of buildings and important public utilities;
power outages;
cessation of the functioning of irrigation or other water management systems (as well as pond fisheries facilities);
destruction or flooding of populated areas and industrial enterprises;
disruption of communications and other infrastructure elements;
death of crops and livestock;
removal of agricultural land from economic use;
disruption of the life of the population and the production and economic activities of enterprises;
loss of material, cultural and historical values;
damage to the natural environment (including as a result of landscape changes);
death of people.

Subsequent, secondary consequences can be called:

and areas with substances from destroyed (flooded) storage facilities of industrial and agricultural enterprises, leading to the development of infections and epidemics among the population;
mass diseases of people and farm animals;
accidents on highways;
landslides and collapses.

Frequent fires may occur in the disaster area due to broken and damaged power lines. Landslides and landslides also become a consequence of an accident as a result of severe erosion of the soil layer.

There are also residual phenomena of a breakthrough of a hydraulic structure of a long-term nature. This is a change in the landscape, ecology, and a decrease in soil fertility.

How to behave in an emergency zone

In areas with a risk of dam failure, a pre-warning system is provided in advance, and an evacuation plan is created indicating collection points. For notification, sirens, horns, loudspeakers, as well as media (radio, television) are used.

Residents living downstream should familiarize themselves in advance with the most convenient one. Most often, they are laid to the nearest elevated points in a given area. In every home, for such an emergency, a backpack with the necessary minimum set of things should be prepared; for people in uniform, such a kit is called an “emergency suitcase”, you can read about it in our article.

How should you behave if you hear a warning that a dam has broken and a flood of water is approaching?

It is necessary to adhere to the following recommendations clearly and without panic:

We go around the house and turn off the water supply completely, shut off the gas and electricity supplies.
We make (we didn’t prepare in advance) a supply of clean water and food. Pack everything in airtight packaging.
On the lower floors, doors and windows should be strengthened, or better yet, nailed.
Move all valuable items to a higher place (attic, 2nd floor)
Take your documents, first aid kit, and things and go to the designated collection point for your area for mass evacuation.

If a disaster takes you by surprise, then try to hide from the oncoming wave. Any elevated location (tree, top floor of a building, roof of a house) is quite suitable for this.

Be sure to pay attention to the building itself. It must be stable and without destruction, able to withstand the impact of water. Once in the water, try to stay on the surface using floating objects. Beware of sharp, glass objects.

Signal Threat of catastrophic flooding

In a situation where your home is flooded, go up to the roof and constantly signal your presence in your home. You can hang bright fabric. At night, a flashlight or phone screen will do.

Closely control your supplies of drinking water and food. Remember that help can only come to you after 1-2 days. Do not eat food that has been flooded. They can cause poisoning.

Actions after an accident

When you return home, you should be extremely careful and attentive. Before entering your home, inspect the outside of the walls and roof for severe damage or destruction. Open doors and windows to ventilate the room.

First of all, check the gas equipment for serviceability. Do not use open fire until you are sure that there is no gas leak, you can read about it in our article. All utility systems (electrical wiring, plumbing, sewerage) should also be thoroughly inspected. It is better if a specialist does this.

Water should be pumped out gradually. Don't forget about the basement and well. Before you start cleaning, the home should be dried.

In order for such accidents to occur as rarely as possible, it is necessary to ensure their high quality and reliability during the construction of water-retaining facilities. To this end, in 1997 it was adopted, which establishes the responsibility of authorized persons and regulates all issues regarding the safety of these structures.

The most basic preventive measure for hydrodynamic accidents is constant monitoring of the condition of the dams, as well as close cooperation with meteorological services.

Causes of hydrodynamic accidents

Destruction (breakthrough) of hydraulic structures occurs as a result of the action of natural forces or human influence.

Natural causes of hydrodynamic accidents:

earthquakes
hurricanes,
collapses, landslides,
floods, etc.

Causes related to human activities:

design errors;
structural defects of hydraulic structures;
violation of operating rules;
insufficient spillway and overflow of water over the dam;
acts of sabotage;
striking hydraulic structures with nuclear or conventional weapons.

Damaging factors of hydrodynamic accidents

The main damaging factors of hydrodynamic accidents associated with the destruction of hydraulic structures:

breakthrough wave,

flooding of the area.

The damaging effect of a breakthrough wave manifests itself in the form of the impact on people and structures of a mass of water moving at high speed, and the fragments of destroyed buildings and structures and other objects it moves.

Flooding- This is the covering of an area with water.

Catastrophic flood zone

Emergencies in a flood zone are often accompanied by secondary damaging factors:

fires due to breaks and short circuits of electrical cables and wires,

landslides and landslides as a result of soil erosion,

infectious diseases due to contamination of drinking water and a sharp deterioration in the sanitary and epidemiological condition in the flood zone and near it, especially in the summer.

Consequences of hydrodynamic accidents

The consequences of catastrophic flooding can be aggravated by accidents at potentially hazardous facilities falling within its zone.

In areas of catastrophic flooding, water supply systems, sewerage systems, drainage communications, garbage collection sites and other waste may be destroyed (eroded). As a result, sewage, garbage and waste pollute flood zones and spread downstream. The danger of the emergence and spread of infectious diseases is increasing.

Rules for safe behavior in case of hydrodynamic accidents

Cities and other communities located downstream from dams are at risk of flooding. Therefore, people living in them must know the rules of safe behavior and the procedure for action in case of hydrodynamic accidents.

Basic Rule: Provide in advance several possible evacuation routes to elevated areas.

Actions in the event of a threat of hydrodynamic accident

When receiving information about the threat of flooding and evacuation:

immediately leave (drive) from the danger zone to a safe area or to elevated areas;

take with you documents, money, essential items and a supply of food for 2-3 days;

Before leaving, turn off the electricity and gas, tightly close windows, doors, ventilation and other openings.

Actions in the event of a sudden hydrodynamic accident

In case of sudden flooding, to escape from the impact of a breakthrough wave, urgently take the nearest elevated place or climb to the top floor of a stable building.

Organize accounting and protection of food and drinking water. Do not eat food that has been in the water or use untested water for drinking.

If you find yourself in the water

push away dangerous objects with sharp edges,

hold on to floating objects,

try to tie a raft from floating objects and climb onto it.

Actions after a hydrodynamic accident

Before entering a building, make sure that there is no danger of further destruction. When entering a room, do not use matches or other open flames; use battery-powered flashlights. Open all doors and windows to remove accumulated gases and dry out the room. Do not use electrical sources until the electrical network has been checked.

Hydrodynamic accident- this is an emergency situation associated with the failure (destruction) of a hydraulic structure (dam, dike, locks) or part of it. For a hydrodynamic accident it is typical uncontrolled movement of large masses of water, causing destruction and flooding of vast areas.

Hydrodynamically hazardous objectsare structures or natural formations that create a difference in water levels before (upstream) and after (downstream) them. These include the following hydraulic structures: dams, dams, dikes, water intakes and water intake structures, pressure basins and equalization tanks, waterworks, small hydroelectric power stations and structures that are part of the engineering protection of cities and agricultural land.

Types of hydrodynamic accidents:

breaches of dams (dams, locks, dams, etc.) with the formation of breakthrough waves, leading to catastrophic flooding;
breaches of dams (dams, sluices, dams, etc.), leading to the occurrence of breakthrough floods;
breakthroughs (dams, dikes, sluices, dams, etc.), leading to the washout of fertile soils or the deposition of sediment over large areas.

In the flooded area, four zones of catastrophic flooding are distinguished:

Catastrophic flood zone- a flood zone within which massive losses of people, farm animals and plants occurred, material assets, buildings and other structures were significantly damaged or destroyed.

First zone directly adjacent to the hydraulic structure and extends 6-12 km from it. The wave height here can reach several meters. Characterized by a rapid flow of water with a flow speed of 30 km/h or more. Wave travel time - 30 minutes.

Second zone- fast current zone (15-20 km/h). The length of this zone can be 15-25 km. The wave travel time is 50-60 minutes.

Third zone- middle flow zone (10-15 km/h) with a length of up to 30-50 km. The wave travel time is 2-3 hours.

Fourth zone- zone of weak current (spill). The current speed here can reach 6 -10 km/h. The length of the zone, depending on the terrain, can be 35-70 km.

In our country there are more than 30 thousand reservoirs and several hundred reservoirs for industrial wastewater and waste. There are 60 large reservoirs with a capacity of more than 1 billion m3. Hydraulic structures operated at 200 reservoirs and 56 waste storage facilities are potentially hazardous objects (Fig. 1).

Fig.1. Number of hydrodynamically hazardous facilities by regions of Russia,%

Hydraulic structures are divided into primary and secondary.

TO main include pressure front structures, the breakthrough of which will entail disruption of the normal life of the population of nearby settlements, destruction, damage to residential buildings or national economic facilities. There are about 40 of these structures in Russia.

TO secondary include hydraulic structures of the pressure front, the destruction or damage of which will not entail significant consequences.

Causes of hydrodynamic accidents and their consequences

Destruction (breakthrough) of hydraulic structures occurs as a result of the action of natural forces or human influence.

Natural causes of hydrodynamic accidents:

earthquakes
hurricanes,
collapses, landslides,
impact of floods.

Causes related to human activities:

design errors;
structural defects of hydraulic structures;
violation of operating rules;
insufficient spillway and overflow of water over the dam;
acts of sabotage;
striking hydraulic structures with nuclear or conventional weapons.

Of the 300 dam failures (accompanied by their breakthrough) in various countries over 175 years, in 35% of cases the cause of the accident was a violation of operating rules - exceeding the calculated maximum discharge flow (overflow of water over the dam crest).

Damaging factors of hydrodynamic accidents

1. The main one- action breakthrough waves, in the form of a direct impact on people and structures of a mass of water moving at high speed, and the fragments of destroyed buildings and structures and other objects it moves. This wave is formed in the downstream as a result of the rapid fall of water from the upstream.

The breakthrough wave destroys a large number of buildings and structures. The degree of destruction will depend on their strength, as well as the height and speed of the wave.

2. Catastrophic flooding of the area with the destruction of systems that support life, a threat to the life and health of people (staying in cold water, neuropsychic stress, hypothermia, drowning).

Consequences of hydrodynamic accidents

The consequences of accidents at hydrodynamically hazardous facilities can be difficult to predict.

1. Being located, as a rule, within or upstream of large populated areas and being objects of increased risk, if destroyed, they can lead to catastrophic flooding of vast territories, a significant number of cities and villages, economic facilities, mass loss of life, and a long-term cessation of navigation , agricultural and fishing industries.

Losses of the population located in the zone of influence of the breakthrough wave can reach 90% at night, and 60% during the day.

The greatest danger comes from the destruction of hydraulic structures of the pressure front - dams and dikes of large reservoirs.

When they are destroyed, there is a catastrophic flooding of large areas and the destruction of significant material assets.

In June 1993, the dam of the Kisilevsky reservoir on the Kakva River broke and there was a severe flood in the city of Serov, Sverdlovsk region. The emergency situation arose as a result of a catastrophic flood resulting from heavy rains and spring floods. With a sharp rise in water in the Kakva River, 60 km were flooded 2 in its floodplain, residential areas of the city of Serov and nine other settlements. The flood affected 6.5 thousand, of which 12 died. 1,772 houses fell into the flood zone, of which 1,250 became uninhabitable. Many industrial and agricultural facilities were damaged.

2. The consequences of catastrophic flooding can be aggravated by accidents at potentially hazardous facilities falling within its zone.

3. In areas of catastrophic flooding, water supply systems, sewerage systems, drainage communications, garbage collection sites and other waste may be destroyed (eroded). As a result, sewage, garbage and waste pollute flood zones and spread downstream. The danger of the emergence and spread of infectious diseases is increasing. This is also facilitated by the accumulation of population in a limited area with a significant deterioration in material and living conditions.

4. Emergencies in a flood zone are often accompanied by secondary damaging factors:

fires due to breaks and short circuits of electrical cables and wires;
landslides and collapses as a result of soil erosion;
infectious diseases due to contamination of drinking water and a sharp deterioration in the sanitary and epidemiological condition in the flood zone and near it, especially in the summer.

Measures to reduce the consequences of accidents at hydrodynamically hazardous facilities

The safety of the population is ensured by the early implementation of measures aimed at preventing or limiting the scale of accidents, namely:

correct choice of location for the dam and settlements;
limiting the construction of residential buildings and economic facilities in places exposed to a possible breakthrough wave;
embankment of populated areas and agricultural lands (system of barrier structures);
creation of reliable drainage systems;
carrying out bank protection works to prevent landslides and collapses;
installation of waterproofing and special fortifications on buildings and structures;
planting low-trunk forests (poplars, alders and birches) that can reduce the speed of the breakthrough wave;
planned release of water from the reservoir during the spring flood in case of danger of a breakthrough of artificial dams;
strengthening the walls of natural reservoir dams if there is a danger of a breakthrough.

Basic measures to protect the population:

timely notification of the population about the threat of catastrophic flooding and taking the necessary measures to protect it;
independent exit of the population from the zone of possible catastrophic flooding before the approach of the breakthrough wave;
organized evacuation of the population to safe areas before the breakthrough wave approaches;
sheltering the population in non-flooded parts of buildings and structures, as well as in elevated areas;
organizing and conducting emergency rescue operations in the flood zone;
providing qualified and specialized assistance to victims;
carrying out urgent work to ensure the livelihoods of the population.

Rules for safe behavior in case of hydrodynamic accidents

Basic rule: provide in advance several possible evacuation routes to elevated areas.

I. Actions in the event of a threat of a hydrodynamic accident

When receiving information about the threat of flooding and evacuation:

immediately leave (drive) from the danger zone to a safe area or to elevated areas;
take with you documents, money, essential items and a supply of food for 2-3 days;
Before leaving, turn off the electricity and gas, tightly close windows, doors, ventilation and other openings.

II. Actions in case of a sudden hydrodynamic accident:

In case of sudden flooding, to escape from the impact of a breakthrough wave, urgently take the nearest elevated place or climb to the top floor of a stable building.
If your house is flooded, turn off its power supply, signal that there are people in the house (apartment) by hanging a flag made of bright fabric from the window during the day, and a lantern at night.
organize accounting and protection of food and drinking water. Do not eat food that has been in the water or use untested water for drinking.

III. If you find yourself in water:

push away dangerous objects with sharp edges;
hold on to floating objects;
try to tie a raft from floating objects and climb onto it.

IV. Actions after a hydrodynamic accident:

before entering the building, make sure that there is no danger of its further destruction;
When entering a room, do not use matches or other open flames, use battery-powered flashlights;
open all doors and windows to remove accumulated gases and dry the room;
Do not use electrical sources until the electrical network has been checked.

The consequences of hydrodynamic accidents are:

damage and destruction of hydraulic structures and hydraulic structures and short-term or long-term cessation of their functions;

defeat of people and destruction of structures by a breakthrough wave;

flooding of vast areas.

The scale of the consequences of hydrodynamic accidents depends on the parameters and technical condition of the hydraulic structure, the nature and size of the destruction, the volume of water reserves in the reservoir, the characteristics of the breakthrough wave, the terrain, the season and time of day of the incident, as well as specific measures and the level of preparation for action and organization in accident conditions for management personnel, personnel of enterprises and organizations, emergency rescue services.

The main damaging factor of hydrodynamic accidents is a destructive breakthrough wave, water flow and calm waters that flood land areas and objects. The impact of a breakthrough wave is in many ways similar to the effect of an air shock wave generated during an explosion.

Due to major hydrodynamic accidents, people die, the supply of electricity to energy systems is interrupted, the functioning of irrigation or other water management systems, as well as pond fisheries facilities, ceases. In addition, settlements and industrial enterprises are destroyed or under water, communications and other elements of infrastructure are destroyed, crops and livestock are destroyed, agricultural land is taken out of economic use, the livelihoods of the population and the production and economic activities of enterprises are disrupted, material, cultural and historical values, great damage is caused to the natural environment, including as a result of landscape changes.

Secondary consequences of hydrodynamic accidents are pollution of water and terrain with substances from destroyed (flooded) storage facilities, industrial and agricultural enterprises, mass diseases of people and animals, accidents on transport highways, landslides and collapses, loss of strength of buildings and structures.

Losses of the population located in the zone of influence of the breakthrough wave can reach 90% at night, and 60% during the day. Of the total population affected, the death toll may be 75% at night and 40% during the day.

The St. Francis Dam in California will forever go down in geological engineering as a tragic example of human carelessness. It was built 70 km from Los Angeles in the San Francisco Canyon with the purpose of storing water for its subsequent distribution through the Los Angeles water supply system.

Filling of the reservoir began in 1972, but the water reached its maximum level only on March 5, 1928. By that time, the seepage of water through the platinum was already causing concern among local residents, but the necessary measures were not taken. Finally, on March 12, 1928, water broke through the thickness of the soil, and under its pressure the dam collapsed. There were no surviving witnesses to the disasters. It was a terrible sight. The water rushed through the canyon like a wall about 40 m high. After 5 minutes, it demolished a power plant located 25 km away. downstream. All living things, all buildings were destroyed. Then the water rushed into the valley. Here its height decreased and its destructive power weakened somewhat, but remained quite dangerous. Few in the upper valley managed to survive. These were people who accidentally escaped in trees or on debris floating in the stream. By the time the flood reaches the coastal plain, it is a muddy wave 3km wide, rolling at the speed of a fast-walking person. Behind the wave, the valley was flooded for 80 km. More than 600 people died during this flood. The collapse of the St. Francis Dam became an example of how not to build hydraulic structures.

In June 1993, the dam of the Kisilevsky reservoir on the Kakva River broke and a severe flood occurred in the city of Serov, Sverdlovsk region. The emergency situation arose as a result of a catastrophic flood resulting from heavy rains and the final phase of the spring flood. With a sharp rise in water in the Kakva River, 60 km 2 of its floodplain, residential areas in the city of Serov and nine other settlements were flooded. The flood affected 6.5 thousand, of which 12 died. 1,772 houses fell into the flood zone, of which 1,250 became uninhabitable. Many industrial and agricultural facilities were damaged.

Assessing the consequences of accidents. In general terms, the consequences of accidents are expressed using indicators of material damage. Losses among the population are estimated by the number of dead, injured, and missing.

Material damage from hydrodynamic accidents is estimated by the number of units of destroyed, damaged, out of order objects and structures, as well as in monetary terms.

TO direct damage include:

damage and destruction of hydraulic structures, residential and industrial buildings, railways and roads, power and communication lines, reclamation systems;

loss of livestock and crops;

destruction and damage to raw materials, fuel, food, feed, fertilizers;

costs for temporary evacuation of the population and transportation of material assets to non-flooded areas;

washing away the fertile soil layer and filling the soil with sand, clay or stones.

TO indirect damage include:

costs of purchasing and delivering food, clothing, medicine, construction materials and equipment, and livestock feed to the affected areas;

reduction in the output of industrial and agricultural products and slowdown in the rate of development of the national economy

deterioration of living conditions of the local population;

impossibility of rational use of the territory located in the zone of possible flooding.

Basics of life safety 8th grade

Lesson 26 Hydrodynamic accidents