The presentation “Natural natural phenomena of the hydrosphere” is intended to summarize the “Hydrosphere” section in 6th grade geography lessons. The purpose of this presentation is to summarize the material studied. And also show that water has a powerful destructive force. The presentation shows such natural phenomena of the hydrosphere as mudflows, avalanches, tsunamis, floods and sinkholes. Students can assess the damage caused by these natural disasters. This presentation can be demonstrated both in lessons and during discussions within the framework of the decade of geography.
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“Presentation on geography on the topic “Natural natural phenomena of the hydrosphere” (6th grade)”
Spontaneous natural
hydrosphere phenomena
Zaitseva Elena Vladimirovna
geography teacher
MBOU Irkutsk Secondary School No. 73
FLOOD -
this is a significant flooding of an area as a result of rising water levels in a river, lake or sea during snowmelt, rainfall, wind surges, congestion, etc.
Tsunami in Thailand,
Tsunami in Japan,
Heavy rainfall led to a mudflow
in Crimea.
Due to heavy rainfall, the village of St. Lorenz in Austria
was completely swept away by the mudflow.
Due to a sharp rise in water levels due to heavy rains
The village of Arshan was flooded and mudflows occurred.
SNOW AVALANCHE is a mass of snow falling or moving at a speed of 20 - 30 m/s or more.
Northern Norway
Everest
An avalanche occurred on the India-Pakistan border
Sinkhole –
This is a sinkhole of natural origin.
A sinkhole occurs when groundwater erodes soil and rocks, causing the ground to fall into the resulting void.
Dangerous (natural) hydrological phenomena include various fast-moving floods, accompanied by high water levels (during floods, floods, congestion, ice jams, surges, etc.) and slow changes in the level of the ocean and closed lakes, exceeding particularly dangerous (critical) levels water for specific settlements and economic facilities.
Flood is understood as a significant inundation of an area with water as a result of a rise in the water level in a river, lake, reservoir and sea and their spilling above the normal horizon, which causes material damage, harms the health of the population, and leads to the death of people.
Floods occur during floods and freshets, i.e. when the water level rises in the spring from melting snow and in the fall due to heavy rains, from the accumulation of ice during ice drifts that reduce the cross-sectional area of the river, from the intensive melting of glaciers and snow cover located high in the mountains, and also during winds from the sea (surge floods). In addition, flooding can occur as a result of the formation of blockages or bridges on rivers during earthquakes, mountain falls or mudflows, under the influence of gravitational waves from an underwater earthquake, as well as when dams break.
Floods (not counting the surges that accompany hurricanes) rank first in the world in terms of the number of created or natural disasters (40% of all emergencies), second or third place in the number of victims, place in the top three in terms of the long-term average and the maximum one-time value of direct economic damage.
In terms of frequency, area of distribution and total average annual material damage nationwide, floods rank first among natural disasters, and in terms of human casualties and damage per unit of affected area, they rank second after earthquakes.
Let's look at the main characteristics of floods.
The water level is considered to be the height of the water surface in a river (lake) above a conventional horizontal comparison plane, called the zero point of the post. The height of this plane is measured from sea level. In the mouth areas of rivers flowing into the sea, the water level is measured above the ordinary level, that is, above the average long-term level at a given point. The sum of two quantities - the water level at the post and the zero mark of the post - represents the absolute level mark, i.e. the excess of the water surface in the river above the sea surface. In the Baltic height system, heights are calculated from the average level of the Gulf of Finland near the city of Kronstadt.
Water flow is the amount of water (in m3) flowing through the end of a river per second. The graphical relationship between flow and water level is called a flow curve, and the graph of changes in water flow over time is called a runoff hydrograph.
The criterion for natural hydrological phenomena is the maximum water level, which is associated with some other important characteristics of the flood - area, layer, duration and rate of water level rise.
For cities and towns there are concepts of flooding and inundation. When flooding occurs, water penetrates into the basement through the sewer system (if it has outlets into the river), through various kinds of filled-in ditches and trenches (they contain heating, water supply and other networks) or due to groundwater back-up. In the event of flooding, the area is covered with a layer of water of varying heights.
Factors of danger (damage) during flooding are:
the height of the level change, which affects the area of the area being flooded or drained;
rate of change of water level;
the duration of the period of deviation of the water level from the norm;
accompanying phenomena (wind, air temperature, landslides and soil erosion, etc.).
Rivers differ from each other in different conditions for the formation of water flow. According to the conditions for the formation of runoff and, consequently, according to the conditions for the occurrence of floods, the rivers of the Russian Federation are divided into four types (Table 2.12).
Table 2.12 - Distribution of factors influencing the occurrence of floods by region of Russia
The variety of floods can be reduced to five groups based on the reasons for their occurrence and the nature of their manifestation (Table 2.13). On the territory of the Russian Federation, floods of the first two types predominate (70-80% of all cases). They are found on lowland, foothill 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.
Table 2.13 - Types of floods
|
Nature of manifestation |
||
|
High water |
Spring melting of snow on the plains or spring-summer melting of snow and rainfall in the mountains |
Repeat periodically in the same season. Characterized by a significant and prolonged rise in water levels |
|
Intense rains and melting snow during winter thaws |
There is no clearly defined periodicity. Intense and relatively short-term rise in water level |
|
|
Congestion, gluttony (congestion, gluttony) |
Great resistance to water flow, formed in certain sections of the river bed, which occurs when ice material accumulates in narrowings or bends of the river during freeze-up (jars) or during ice drift (jams) |
Mash - at the end of winter or spring. A high and relatively short-term rise in the water level in the river. Gluttonous - at the beginning of winter. Significant (no less than during a jam) rise in the water level and a longer duration compared to jams |
|
Surge floods (surges) |
Wind surges of water in sea estuaries and windward areas of the coast of seas, large lakes, and reservoirs |
In any season. Lack of periodicity and significant rise in water level |
|
Flooding due to dam failure |
An outflow of water from a reservoir or reservoir, resulting from a breakthrough of pressure front structures (dams, dikes, etc.), during an emergency release of water from a reservoir, during a breakthrough of a natural dam created by nature during earthquakes, landslides, landslides, and glacier movement |
Formation of a breakthrough wave, leading to flooding of large areas and to destruction or damage to objects encountered along the way (buildings and structures, etc.) |
Factors influencing the magnitude of the maximum rise in water level during various types of floods are given in Table. 2.14. Based on the initial causes, floods are divided into surge, storm (rain), floods (associated with the melting of snow and glaciers), ice jams and jams, dams and breakthroughs.
Table 2.14 - Factors influencing the scale of flooding
|
floods |
Factors influencing the magnitude of the maximum rise in water levels |
|
High water |
The reserve of water in the snow cover before the onset of spring melting; atmospheric precipitation during snowmelt and flood periods; autumn-winter soil moisture by the beginning of spring snowmelt; ice crust on the soil; snowmelt intensity; combination of flood waves of large tributaries of the river basin; lake content, swampiness and forest cover of the basin; relief of the pool |
|
The amount of precipitation, its intensity, duration, coverage area, previous precipitation, soil moisture and permeability, basin topography, river slopes, presence and depth of permafrost |
|
|
Congestion, glutton |
Surface speed of water flow, the presence in the channel of narrowings, bends, shoals, sharp turns, islands and other channel obstacles, air temperature during freeze-up (in case of a jam) or during ice drift (in case of a jam), terrain |
|
Wind speed, direction and duration, coincidence in time with high tide or low tide, slope of the water surface and river depth, distance from the sea coast, average depth and configuration of the reservoir, terrain |
|
|
Flooding due to dam failures |
The magnitude of the water level drop at the dam site: the volume filled with water in the reservoir at the time of the breakthrough; slope of the reservoir and river bottom; size of the hole and time of formation of the hole; distance from the dam, terrain |
Floods passing along rivers are divided by height:
to low or small ones (low floodplains are flooded);
medium (high floodplains, partially populated, are flooded);
strong or outstanding (cities and communications are partially flooded, evacuation of the population is required);
catastrophic (cities are significantly flooded, major rescue operations, mass evacuation are required).
Different types of floods occur in each region, with severe and catastrophic ones usually created by the coincidence of two or more factors (for example, snowmelt plus rainfall, rainfall plus dam failure, etc.), which made it possible to develop a classification of floods taking into account the scale of their distribution and frequency ( Table 2.15).
Table 2.15 - Classification of floods by scale
|
Flood class |
Extent of flood |
Repeatability (years) |
|
Low (small) |
Causes minor damage. Covers small coastal areas. Less than 10% of low-lying agricultural land is flooded. Almost no disruption to the rhythm of life of the population |
|
|
They cause significant material and moral damage, cover large areas of river valleys, and flood 10-15% of agricultural land. They significantly disrupt the economic and everyday life of the population. Lead to partial evacuation of people |
||
|
Outstanding (strong) |
They cause great material damage, covering river basins. 50-70% of agricultural land and some settlements are flooded. They paralyze economic activity and sharply disrupt the everyday life of the population. Lead to the need for mass evacuation of the population and material assets from the flood zone and protection of important economic facilities |
|
|
Catastrophic |
They cause enormous material damage and lead to loss of life, covering vast territories within one or more river systems. 70% of agricultural land, many settlements, industrial enterprises and utilities are flooded. Economic and production activities are completely paralyzed, the lifestyle of the population is temporarily changed |
Measures in case of threat of flooding of populated areas and territories
Flood protection measures are divided into operational (urgent) and technical (preventive).
Operational measures do not solve the problem of flood protection as a whole and must be carried out in conjunction with technical measures.
Technical measures include advance design and construction of special structures. These include: regulation of flow in the riverbed; drainage of flood waters; regulation of surface flow on spillways; embankment; river channel straightening and dredging; construction of bank protection structures; backfilling of the built-up area; restriction of construction in areas of possible flooding, etc.
The greatest economic effect and reliable protection of floodplain areas from floods can be achieved by using an extensive set of measures, combining active protection methods (drainage regulation) with passive methods (embankment, channel dredging, etc.). The choice of protection methods depends on a number of factors: the hydraulic regime of the watercourse, the terrain, engineering-geological and hydrogeological conditions, the presence of engineering structures in the riverbed and on the floodplain (dams, dikes, bridges, etc.), the location of economic facilities subject to flooding.
The main directions of action of executive authorities in the event of a threat of flooding are:
analysis of the situation, identification of sources and possible timing of flooding;
forecasting types (types), timing and scale of possible flooding;
planning and preparation of a set of standard measures to prevent flooding;
planning and preparation for emergency rescue operations in areas of possible flooding.
At the federal level, the Russian Ministry of Emergency Situations carries out planning and preparation of events on a national scale. At the regional level, regional centers of the Russian Ministry of Emergency Situations plan and prepare activities within their competence. At the level of the region, territory, republic, events are planned and prepared in their territories. During the period of threat of flooding, the management bodies of the Civil Defense and Emergency Situations of the constituent entities of the Russian Federation operate on high alert. When there is a threat of flooding, flood control commissions operate on standby:
organize round-the-clock monitoring of flood conditions in their area of responsibility, using Roshydromet posts and their observers;
maintain constant contact and exchange information with emergency commissions and operational duty officers of civil and emergency situations management bodies;
conduct exercises (trainings) on flood control topics and organize training for the population on rules of conduct and actions during floods;
send reports to higher authorities;
clarify and adjust flood control plans taking into account the current situation;
by decision of the heads of territorial administrations, round-the-clock duty of rescue forces and equipment is organized;
specify (provide) places (areas) for the temporary resettlement of affected residents from flooded (destroyed) houses, organize the preparation of public buildings or tent camps to accommodate evacuees;
provide for the provision of the evacuated population with everything necessary for life;
coordinate with local authorities of the Ministry of Internal Affairs of the Russian Federation and local self-government the procedure for protecting property located in the flood zone;
organize round-the-clock duty to monitor changes in water levels at flood sources;
participate in the organization and equipment of bypass transport routes to replace flooded sections of roads;
organize (control) the strengthening of existing and construction of new dams and embankments;
organize and maintain interaction with the governing bodies of the Ministry of Defense of the Russian Federation, the Ministry of Internal Affairs of the Russian Federation, territorial departments (departments) of Roshydromet, territorial divisions of the All-Russian Service for Disaster Medicine.
During the period of threat of spring floods and floods on rivers, flood control commissions must provide for:
boundaries and sizes (areas) of flood zones, the number of administrative districts, settlements, economic facilities, roads, bridges, communication and power lines falling into flood and inundation zones;
the number of victims, as well as those temporarily resettled from the flood zone, destroyed (emergency) houses, buildings, etc.;
volumes of pumping water from flooded structures;
number of heads of dead farm animals;
location and dimensions of constructed dams, dams, embankments, fastenings of bank slopes, drainage channels, pits (siphons);
preliminary amount of material damage;
the number of forces and assets involved;
measures to protect the population.
During the preparatory period, an important role is played by analyzing the situation and forecasting possible flooding of populated areas. Analysis of the situation involves identifying possible causes of the threat of flooding of populated areas, which may include high water and high water, as well as factors contributing to the occurrence of flooding and flooding. At the same time, possible emergency scenarios are identified in which:
the living conditions of people on the territory of administrative districts of a constituent entity of the Russian Federation are significantly violated;
human casualties or damage to the health of a large number of people are possible;
there may be significant material losses;
significant damage to the environment is possible.
Identification of the listed emergency situations associated with flooding of territories is carried out on the basis of: statistical data on floods and long-term observation data for a given territory; studying action plans for industrial facilities in the event of an emergency; own assessments of the territorial management bodies of the RSChS.
Based on the identified factors contributing to the occurrence of emergencies, as well as secondary factors that pose a threat to the population and economic facilities, the following is carried out: an assessment of the likelihood of an emergency occurrence; assessment of the scale of a possible emergency.
The scale should be understood as: the number of deaths; number of victims; the amount of material damage; the volume of evacuation measures and protection associated with the evacuation of the population; costs of emergency response and restoration work; indirect losses (short production, costs of benefits, compensation payments, pensions, etc.), etc.
An assessment of the probability of occurrence and scale of emergencies caused by accidents at industrial facilities and life support systems due to the influence of secondary factors is carried out by the administration of the relevant facilities. Forecasting and assessing the scale of emergencies should be carried out taking into account the requirements of laws, other regulations and methods recommended by the Russian Ministry of Emergency Situations. In the absence of such documents for individual specific cases, the executive authorities of the constituent entities of the Russian Federation will organize research to assess the likelihood of an emergency occurrence and to assess the scale of the emergency by the forces of the constituent entity of the Russian Federation.
The results of identifying factors contributing to the occurrence of emergencies associated with flooding of territories and populated areas serve as the basis for making decisions on the implementation of preventive measures. Based on an analysis of the situation, flood prevention measures are planned. Planning is regulated by the Federal Law “On the Protection of the Population and Territories from Natural and Technogenic Emergencies”, regulatory legal acts of state authorities of the constituent entities of the Russian Federation and local governments. In this case, it is advisable to distinguish between subject (target) and operational planning.
Subject planning should include organizational, financial, economic, engineering and technical measures to prevent or reduce the risk of flooding. Operational planning provides for a set of organizational and technical measures to prepare the population, economic facilities and territories for an emergency situation. These measures should be reflected in plans for the socio-economic development of territories, plans for the development of economic sectors, and economic facilities.
A typical procedure for planning measures to prevent emergencies caused by flooding includes:
identification of organizations and institutions that may be involved in organizing and implementing emergency prevention measures;
development and feasibility study of organizational and engineering measures to prevent or reduce the risk of emergency situations;
development and feasibility study of measures to reduce the severity of the consequences of emergency situations on the population, economic facilities and the environment.
The developed plans are coordinated with interested bodies and organizations, approved by the relevant heads of executive authorities and sent to the implementers. Control over the implementation of plans is carried out by the executive power of the territory through the territorial management bodies of the RSChS.
Let's consider the main measures to reduce the consequences of congestion and gluttons. Congestion cannot be eliminated; it can only be loosened somewhat or moved to another location. When combating ice jam floods, it is necessary to regulate the flow of ice material. Effective measures to combat congestion are:
destruction by blowing up ice fields with explosive charges, bombing, and artillery shelling;
chemical destruction of ice by sprinkling with various salts;
ice breaking by icebreakers or hovercraft;
maneuvering water flow through a dam.
It is advisable to use an explosive method of control during the period of congestion. On wide rivers, the detonation of ice fields begins below the jam and along the banks. On narrow and medium-sized rivers, ice should be undermined from top to bottom downstream or simultaneously along the entire length of the jam.
With the chemical method of breaking ice, its melting point is lowered by distributing salt over its surface. Sometimes, to destroy the ice cover, it is sprinkled with ground slag with the addition of salt, that is, the ice is blackened at a consumption rate of 1-3 t/ha, scattered in strips 5-10 m wide in places of future cracks and near the coast.
When destroying ice fields and the body of the jam by icebreakers, the latter must move from bottom to top along the river bed and create a zigzag channel in the body of the jam with a width of at least the length of the vessel. Hovercraft are used to destroy ice cover up to 1 m thick.
The most radical means of combating congestion is to maneuver the flow of water through the dam. The effectiveness of this method depends on the power of the mash, the volume and duration of water flow, ice conditions and weather conditions.
1. Residents of any settlement should know whether the settlement in which they live is located in a possible flood zone. If it is, then you need to know: where, to which areas evacuation should be carried out in the event of a flood threat, and along what routes. Evacuation should be carried out upon receipt of information about the threat of flooding. If possible, pets are also evacuated.
2. Before leaving the house, you must turn off the electricity and gas. When evacuating, you must take with you documents, valuables, the most necessary things and a supply of food. It is advisable to protect part of the property that cannot be taken with you from flooding and move it to the upper floors, to high places.
3. During a flood, you must:
try to collect everything that may be useful: flotation devices, lifebuoys, ropes, ladders, signaling devices;
save people cut off from others by the elements, provide first aid to the victims;
if there is a danger of ending up in the water, then before help arrives, take off your shoes and get rid of heavy and tight clothing;
fill your shirt and trousers with light floating objects (balls, empty closed plastic bottles, etc.);
use tables, car tires, spare tires, life belts to stay on the surface;
before slipping into the water, you need to inhale the air, grab the first object you come across and float with the flow, trying to remain calm;
jump into the water only at the last moment, when there is no hope of salvation.
4. The crossing (exit) of people during a flood is permitted only along a ford with a depth of no more than 1 m designated for this purpose. If necessary, evacuation is carried out on rafts, boats, cutters, all-terrain vehicles and other means.
5. After the end of the flood, before entering the building, make sure that it does not threaten to collapse and inspect the existing damage. In this case, you must not use open fire. You should check whether the power supply is turned off, whether there are exposed electrical wiring or possible short circuits, or whether there is a gas leak.
6. You should not eat food that has been in contact with flood waters. Drinking water should also be tested before use.
7. Floods may be accompanied by natural phenomena such as landslides, mudflows, and the fact that hazards caused by floods include outbreaks of epidemics, loss of livestock, destruction of agricultural crops, destruction of sewer lines, water pollution, destruction of gas and electricity supply lines .
earthquake fire tsunami
The globe is covered by a geographical envelope, which includes the lithosphere, biosphere, atmosphere and hydrosphere. Without the complex of geospheres and their close interaction there would be no life on the planet. Let's take a closer look at what the Earth's hydrosphere is and what the importance of the water shell is in all vital processes.
Structure of the hydrosphere
The hydrosphere is the continuous water shell of the planet, which is located between the solid shell of the earth and the atmosphere. It includes absolutely all water, which, depending on environmental conditions, can be in three states: solid, gaseous and liquid.
The hydrosphere is one of the oldest shells of the planet, which existed in almost all geological eras. Its emergence became possible thanks to the most complex geophysical processes, which resulted in the formation of the atmosphere and hydrosphere, between which there has always been the closest connection.
The hydrosphere, one way or another, permeates all geospheres of the globe. Groundwater seeps down to the lowest boundary of the earth's crust. The bulk of water vapor is distributed in the lower part of the atmosphere - the troposphere.
The hydrosphere accounts for about 1390 million square meters. km. It is usually divided into three main parts:
- World Ocean - the main part of the hydrosphere, which includes all the oceans: Pacific, Indian, Atlantic, Arctic. The totality of the oceans is not a single shell of water: it is divided and limited by continents and islands. Salty ocean waters make up 96% of the total volume of the hydrosphere.
The main characteristic of the World Ocean is its general and unchanged salt composition. Fresh water also enters ocean waters along with river runoff and precipitation, but its amount is so insignificant that it does not affect the concentration of salts.
Rice. 1. Waters of the World Ocean
- Continental surface waters - these are all water basins located on the surface of the globe: swamps, reservoirs, seas, lakes, rivers. Surface waters can be either salty or fresh, artificial or natural.
The seas of the hydrosphere are marginal and internal, which, in turn, are divided into inland, intercontinental and interisland.
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- The groundwater - these are all the waters located underground. Sometimes the concentration of salts in them can reach a very high level; gases and various elements may be present in them.
The classification of groundwater is based on its depth. They are mineral, artesian, soil, interlayer and soil.
Fresh water is of great importance in metabolic processes, which in total makes up only 4% of the total water reserves on the planet. The bulk of fresh water is contained in snow covers and glaciers.
Rice. 2. Glaciers are the main sources of fresh water
General properties of all parts of the hydrosphere
Despite the differences in composition, states and locations, all parts of the hydrosphere are interconnected and represent a single whole. All its parts take an active part in the global water cycle.
The water cycle - a continuous process of movement of water bodies under the influence of solar energy. This is the connecting link of the entire earth's shell, a necessary condition for the existence of life on the planet.
In addition, water performs a number of important functions:
- The accumulation of a large amount of heat, due to which the planet maintains a stable average temperature.
- Oxygen production. The water shell contains a large number of microorganisms that produce valuable gas necessary for the existence of all life on Earth.
- Resource base. The waters of the World Ocean and surface waters are of great value as resources for human life. Catching commercial fish, mining, using water for industrial purposes - and this is only an incomplete list of human uses of water.
The influence of the hydrosphere on human activity can also be negative. Natural phenomena in the form of high waters and floods pose a great threat and can occur in almost any region of the planet.
Hydrosphere and man
With the development of scientific and technological progress, the anthropogenic impact on the hydrosphere began to gain momentum. Human activity has caused the emergence of geo-ecological problems, as a result of which the water shell of the Earth began to experience the following negative effects:
- water pollution with chemical and physical pollutants that significantly worsen the quality of water and the living conditions of inhabiting animals and plants;
- a sharp decrease or depletion of a water resource, during which its further restoration is impossible;
- loss of a water body’s natural qualities.
Rice. 3. The main problem of the hydrosphere is pollution
To solve this problem, it is necessary to use the latest protection technologies in production, thanks to which water basins will not suffer from all kinds of pollution.
What have we learned?
While studying the most important topic in 5th grade geography, we learned what the hydrosphere is and what the water shell consists of. We also found out what is the classification of hydrosphere objects, what are their differences and similarities, how does the hydrosphere influence the life of our planet.
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The most dangerous phenomena in the hydrosphere include giant seismic waves - tsunami. They occur in the event of an underwater or coastal earthquake, or a major landslide. A sudden rise or collapse of significant sections of the bottom leads to the rise or collapse of a many-kilometer column of water over a large area. As a result, the energy of an earthquake or underwater eruption is transferred to water and surface waves arise, which spread across the World Ocean at enormous speeds (up to 1000 km/h). Colossal energy drives them 10-15 thousand km at intervals of about 10 minutes. In the deep part of the water area they are practically invisible, since due to their large length (up to 150 km) they have a height of up to 1.5 m. When approaching the shore and entering shallow water, the wave slows down, its base begins to slow down against the bottom and the wave energy goes to increase the height to 10-30 m. Long narrow bays (fjords) with steep banks are especially dangerous. Entering the narrowing bay, the wave gradually increases its height, rising to 40-50 m or more.
The tsunami in the Indian Ocean on December 26, 2004 is known to have the most widespread catastrophic consequences. Shifts of the ocean floor in the subduction zone of the Java Trench off the coast of Indonesia led to the formation of a powerful earthquake with a magnitude of 8.8 and a strength of 9.3. This one of the most powerful earthquakes recorded triggered a tsunami that killed more than 230 thousand people. Its victims were residents of Indonesia (about 130 thousand dead), Sri Lanka (more than 35 thousand dead), India (about 17 thousand dead), Thailand (more than 8 thousand) and other countries. In different areas, the tsunami consisted of 3-7 waves, 7-27 meters high, moving at speeds from 320 to 800 km/h. In some areas, waves moved inland by 4 km. Giant waves were formed after the Burma Plate, which the Australian plate had been pulling down into the upper mantle for centuries, unexpectedly rose, throwing up a multi-meter layer of water.
To prevent the catastrophic consequences of a tsunami, an international tsunami warning service has been created. It works more efficiently in the Pacific Ocean. The danger of a tsunami leads to the need to change approaches to the choice of location and design of buildings. In particular, the layout, purpose and construction materials of the first floors, which allow the passage or redirection of the shock force of waves without causing significant damage to the entire building, infrastructure and people. To do this, garages and utility rooms are placed on the ground floor, and the filling between the main supporting structures (columns) is made of less durable materials.
Powerful tsunamis are also formed when large masses of rocks, glaciers or underwater landslides collapse into the water. The reason for this may be earthquakes, volcanic eruptions, weathering processes, excess moisture, climate change, etc. Particularly high waves are formed when rocks or glaciers collapse into a deep bay. In these cases, waves are formed hundreds of meters high (the maximum recorded height is 600 m), which rush in a relatively confined space for several hours from coast to coast, gradually calming down. Such events have occurred repeatedly in Alaska, Scandinavia, the Mediterranean and other areas.
There is an assumption about a powerful catastrophe that occurred about 120 thousand years in the Pacific Ocean. Due to the activity of the Mauna Loa volcano in the Hawaiian Islands, a rock with a volume of 120 cubic miles fell into the ocean, and a wave of more than 200 m high rose from the site of the fall. Currently, a similar threat is posed by the dormant volcano Cumbre Vieja in the Canary Islands. If it awakens, a colossal rock may fall into the Atlantic Ocean, causing a wave up to 300 m high. In this case, according to the calculations of American experts, in 9 hours Florida will be covered by a wave 25 meters high.
Not less catastrophic consequences can have not seismic or landslide, but tidal and surge waves in the World Ocean. Typhoons and heavy rainfall contribute to their intensification. The interaction of these two factors can lead to a reversal of river flows, the formation of huge waves and a sharp increase in water levels. The most severe consequences develop in regions with a slight elevation of land above sea level, which include the coastal zones of the Mesopotamian Lowland and the Bay of Bengal (Bangladesh, Burma). Under the influence of heavy rainfall and wind in 1737 and 1876, these territories were flooded with water tens of kilometers from the coast within 2-3 weeks. The water level rose by 10-15 m. In each case, the death toll was hundreds of thousands of people. Events similar in nature, but less catastrophic, occur here every 10-15 years.
Similar, but smaller-scale phenomena also occur in relatively isolated reservoirs. For example, in the Sea of Azov. Here, especially intense floods are formed in the event of a change in the strong southern wind, driving water from the Kerch Strait to the western one. In this case, a large mass of water under wind pressure moves along the shallow bed of the sea, retreating from the western shore (Ukraine) by hundreds of meters and even kilometers and flooding the eastern one (the Azov flood plains of the Krasnodar Territory). In this case, sea level may rise by 2-3 m. Due to the absence of land areas with an elevation above sea level of more than 1.5 m, the abundance of swamps and estuaries, the coastal area is completely covered with water at a distance of up to 20-25 km from the sea. In the fifties, thus, all fishing brigades and canneries on the Azov coast of the Krasnodar Territory were destroyed and hundreds of people died. When the wind weakens, this entire mass of water, due to a level imbalance, begins to move in the opposite direction, forming surge waves (seiches) several meters high and flooding the western coast of the Sea of Azov.
If a similar situation develops in winter, active ice hummocking develops and squeezes it tens of meters onto the shore, which leads to the destruction of engineering structures and ships (the latter in the winter of 2006 in the Taganrog Bay).
Hazardous phenomena associated with terrestrial water bodies are of a much smaller scale and have catastrophic consequences. However, in total they cause no less damage than tsunamis or earthquakes. An example is the events near Novorossiysk in August 2002. Their root cause, of course, was extremely intense precipitation - on August 8, in sixteen hours, 362 mm of precipitation fell on Novorossiysk and the surrounding area, which is the six-month norm. But, the tragic results were amplified by human actions.
The scale of the disaster in the Shirokaya Balka tract is largely related to the spontaneous development of the floodplain, banks and mouth of the stream, the amateur construction of a large number of bridges and dams across it to recreation centers and garden plots. It was this, and not the “mythical” tornado, that intensified the consequences of the disaster. Each of these structures, not designed for high water throughput and clogged with debris, stones, and fallen trees, became an obstacle to the raging flow and raised the level in the resulting dam by 3-5, and in some areas up to 6-8 meters. Noted by many witnesses, at some point a sharp increase in the water level in the stream (up to 1 meter per minute) is the result of the successive breakthrough of some of these spontaneous dams.
The second group of disasters in the Novorossiysk area on these same days was also caused by precipitation and intensified by human actions, or rather inaction. They are associated with the destruction of dams of overflowing reservoirs on the Durso (Fig. 2.3.) and Tsemess rivers.
The latter was especially catastrophic, because... The burst water flooded a significant part of the industrial and residential zone of Novorossiysk, which led to the destruction of hundreds of houses and the death of dozens of people. And in this case, a decisive contribution to the scale of the incident was made by the lack of attention to the condition of hydraulic structures, the long-uncleaned river bed draining the entire valley, and the development of the floodplain. Roads raised 1-2 meters above its surface are a kind of dams and dams that direct water flows, prevent the spread of water, the rapid decrease in its level and enhance the effect of flooding.
It is obvious that similar disasters on large rivers and reservoirs have even more tragic consequences. Life safety problems associated with increased technogenic transformation of our environment and climate change are becoming increasingly acute. The floods that have become more frequent in Europe and North America in recent decades, the events that took place in the North Caucasus in 2002 (the Krasnodar Territory alone suffered at least four impacts in a year) due to their extraordinary nature and severe consequences, should become the subject of serious engineering-geological analysis, and their conclusions were taken into account when designing new structures and determining technospheric safety criteria.
Rice. 2.3. A dam on the Durso River destroyed by a flood (photo by A.E. Kambarova)
Test questions for lecture 5
1. What is the difference between floods and floods?
2. What is a hydrograph?
3. List the main types of river nutrition.
4. What is M.I. Lvovich’s classification based on?
5. List the phases of the water regime.
6. The role of water in the biosphere.
7. What is a hydrograph?
8. How is the drain modulus measured?
10. In what units is physiological evaporation measured?
11. River flow and urbanization.
12. The influence of reservoirs on river flow.
13. What do the concepts of deduction and transpiration characterize?
14. Explain the reasons for fluctuations in the salinity of the World Ocean.
15. What is the difference between the concepts of salinity and mineralization?
16. What is a tsunami?
17. What parameters are the waves characterized by?
18. What is the cause of surface currents in the World Ocean?
Often natural processes and phenomena turn into spontaneous natural phenomena. In cases where they cause damage to the economy and pose a danger to human life, they are called natural disasters . Natural disasters usually include earthquakes, floods, mudflows, landslides, snow drifts, volcanic eruptions, landslides, droughts, hurricanes, storms, etc.
Natural disasters can occur either independently of each other or in conjunction: one of them can lead to another. Some of them often arise as a result of human activity (for example, forest and peat fires, industrial explosions in mountainous areas, during the construction of dams, foundation (development) of quarries, which often leads to landslides, snow avalanches, glacier collapses, etc.) .
Regardless of the source of occurrence, natural disasters are characterized by significant scales and varying durations - from several seconds and minutes (earthquakes, avalanches, limnological disasters) to several hours (mudflows), days (landslides) and months (floods).
Examples of natural disasters
| № | Name | Shell | Features of occurrence and causes | Areas of most frequent distribution in Russia | Consequences |
| 1. | Earthquake | Lithosphere | Shocks and vibrations of the earth's surface caused by ruptures and displacements in the earth's crust | Kamchatka, Kuril Islands, Transbaikalia, Stanovoy Range, Caucasus | Destruction, loss of life, cracks, landslides |
| 2. | Mudflow (mud-stone flow) | Lithosphere | Rain, rapid snowmelt | Caucasus, Ural, Altai, Sayan Mountains, Verkhoyansk Range, Chersky Range | Destruction, destruction of crops, dams |
| 3. | Landslide, collapse | Lithosphere | The influence of gravity; most often appear on slopes composed of alternating water-resistant and aquiferous rocks | On the slopes of river banks, in the mountains, on the shores of the seas, for example, in the Ulyanovsk region on the banks of the Volga, on the banks of the Moscow River, on the Black Sea coast in the Novorossiysk region, etc. | Damage to agricultural land, enterprises, populated areas |
| 4. | Volcanic eruption | Lithosphere | Under the strong pressure of the released gases, magma, melting the surrounding rocks, breaks out to the surface of the earth | Kamchatka, Kuril Islands | Destruction, loss of life |
| 5. | Drought | Atmosphere | Lack of rain, strong winds, drying soils | South of the East European Plain, the Urals, Siberia, Ciscaucasia | Death of plants, occurrence of fires |
| 6. | Tornado | Atmosphere | Local heterogeneity of the atmosphere, alternation of warm and cold layers of air. Earth's magnetic field. | European part of Russia – center and south, less often north | Destroys buildings, lifts objects into the air, uproots trees |
| 7. | Hurricane, typhoon (atmospheric vortex with low atmospheric pressure in the center) | Atmosphere | Occurs primarily in the intertropical convergence zone over superheated oceanic areas | Far East | Catastrophic devastation on land and rough seas |
| 8. | Flood | Hydrosphere | Precipitation during rains, melting snow and ice, typhoons, emptying of reservoirs | St. Petersburg, basin of the Amur, Yenisei, Lena rivers | Material damage, personal injury and loss of life |
| 9. | Tsunami | Hydrosphere | Shocks and vibrations of the oceanic crust, underwater landslides | Far Eastern coast, Kamchatka, Kuril Islands, Sakhalin | Property damage and loss of life |
During 2009, more than 900 hazardous natural phenomena were observed on the territory of the Russian Federation, of which 385 caused significant damage to sectors of the economy and the life of the population (in 2008 there were 348). In the cold period there were 85 of them, in the warm period – 300.
The most frequently reported hazardous events were: very heavy rain (heavy downpour) – about 16% and very strong wind (including squalls) – more than 14% of the total. A significant part was also accounted for by hydrological phenomena (mudflows, exceeding dangerous levels of water levels in rivers during periods of spring floods and rain floods, etc.) - more than 14% of the total number of dangerous phenomena.
In a number of cases, individual hazardous events caused significant damage to the economy and livelihoods of the country's population.
Heavy accumulation of wet snow was observed in the Volgograd region on January 23-24, 2009 and in the Tver region on January 28-29, 2009. In five districts of the Volgograd region, 105 power line supports were damaged and toppled; power lines are damaged; in the Tver region, due to an emergency shutdown of 475 transformer substations, there was a disruption in the power supply in 8 districts of the region (322 settlements were left without electricity).
As a result of snow avalanches in January-March 2009 in the regions of the North Caucasus, the Trans-Caucasus Highway, local and federal roads were repeatedly blocked, and several people died.
Very strong winds (gusts up to 25 m/s) in the Lipetsk and Tambov regions on April 18, 2009 led to numerous damage to power lines, and power was cut off in a number of settlements. In the Lipetsk region, due to the loss of power to the water intake, 120 thousand people were left without water for 7 hours, the work of vehicles was hampered, and the roofs of houses were damaged; In the Tambov region, 1,845 houses remained without power supply.
Frosts were observed (temperature -10...-3 o C, in some places down to -12 o C) in the Southern Federal District during the periods from April 10 to 15 and from April 20 to 27. In the Kabardino-Balkarian Republic, the Republic of North Ossetia-Alania, the Krasnodar and Stavropol Territories, the Astrakhan and Rostov Regions, damage and death of winter, spring, vegetable and seed crops, as well as fruit and berry plantings were noted.
Severe and prolonged (from late May to August) drought (atmospheric and soil) in the republics of Bashkortostan, Kalmykia, Tatarstan, the Kabardino-Balkarian Republic, the Udmurt Republic, the Astrakhan, Volgograd, Rostov, Samara, and Ulyanovsk regions caused significant damage to grain crops . Crops were written off on the following areas: in the Republic of Tatarstan - 313 thousand hectares, Samara and Orenburg regions - over 1 million 120 thousand hectares, Saratov region - over 555 thousand hectares, Ulyanovsk region - over 116 thousand hectares.
In the Moscow region on June 3, in the Krasnodar and Stavropol territories on July 4, 5, 12 and 13, large hail damaged the roofs of houses, power lines, and agricultural crops.
As a result of very heavy rain in the Republic of Dagestan on September 20-21 and 26-28, 2009, residential buildings were flooded and in some places partially destroyed, household plots were flooded, roads were washed out, and in the Kizilyurt district - 150 m of the railway track, which caused the accident freight train.