Hydrosphere is the watery shell of the Earth. Hydrosphere as the water shell of the earth What is the water shell of the earth in one word

Hydrosphere – the water shell of the Earth, including oceans, seas, rivers, lakes, groundwater and glaciers, snow cover, as well as water vapor in the atmosphere. The Earth's hydrosphere is 94% represented by salty waters of the oceans and seas, more than 75% of all fresh water is conserved in the polar caps of the Arctic and Antarctica (Table 1).

Table 1 – Distribution of water masses in the Earth’s hydrosphere

Water on Earth is present in all three states of aggregation, but the largest volume is in the liquid phase, which is very significant for the formation of other features of the planet. The entire natural water complex functions as
a single whole, being in a state of continuous movement, development and renewal. The surface of the World Ocean, which occupies about 71% of the earth's surface, is located between the atmosphere and the lithosphere. The diameter of the Earth, i.e. its equatorial diameter is 12,760 km, and the average depth of the ocean in its modern bed– 3.7 km. Consequently, the thickness of the layer of liquid water is on average only 0.03% of the Earth's diameter. In essence, it is the thinnest film of water on the surface of the Earth, but, like an ozone protective layer, it plays an extremely important role in the biosphere system.

Without water there could not be humans, animals and plants, since most plants and animals consist mainly of water. In addition, life requires temperatures in the range from 0 to 100 ° C, which corresponds to the temperature limits of the liquid phase of water. For many living creatures, water serves as a habitat. Thus, the main feature of the hydrosphere is the abundance of life in it.

The role of the hydrosphere in maintaining a relatively constant climate on the planet is great, since, on the one hand, it acts as a heat accumulator, ensuring the constancy of the average planetary temperature of the atmosphere, and on the other–Due to phytoplankton, it produces almost half of all oxygen in the atmosphere.

The aquatic environment is used for fishing and other seafood, collecting plants, mining underwater deposits of ore (manganese, nickel, cobalt) and oil, transporting goods and passengers. In production and economic activities, people use water for cleaning, washing, cooling equipment and materials, watering plants, hydrotransportation, and ensuring specific processes, such as generating electricity
and so on.

An important circumstance inherent in the aquatic environment is that infectious diseases are mainly transmitted through it (approximately 80% of all diseases). The simplicity of the flooding process compared to other types of burial, the inaccessibility of the depths for humans and the apparent isolation of water have led to the fact that humanity actively uses the aquatic environment to dump production and consumption waste. Intense anthropogenic pollution of the hydrosphere leads to serious changes in its geophysical parameters, destroys aquatic ecosystems and is potentially dangerous to humans.

The environmental threat to the hydrosphere has confronted the international community with the task of taking urgent measures to save the human habitat. Their peculiarity is that not a single state, even with the help of strict measures, is able to cope with the environmental threat. Therefore, international cooperation in this area is necessary, the adoption of an optimal environmental strategy that includes a concept and program of joint actions of all countries. These measures must comply with the principles of modern international law.

2. ECOLOGICAL – ECONOMIC ANALYSIS OF HYDROSPHERE

Analysis of the bioeconomy of seas and oceans includes several methodological aspects of determining the quantitative and qualitative characteristics of biological resources, the conditions for their use in the national economic complex. The results of this analysis are the basis for developing or improving the economic and organizational system for managing the rational use of biological resources. The controlled bioeconomic system of the oceans includes many determining and resulting ecological and economic indicators, parameters of their relationships and interdependencies. The level of controllability of a bioeconomic system is determined mainly by the knowledge of processes and phenomena at each hierarchical level (international, interstate and regional), the presence of interstate agreements on the rational use of sea and ocean resources and their protection.

The rational use of hydrosphere biological resources in general can be considered as a system of social measures of a legal, economic, economic and scientific-standardized nature, determined by the need for the systematic maintenance and reproduction of commercial biological resources, as well as the reliable protection of natural conditions and their aquatic habitat.

Over the past century-long history of economic management, humanity has developed an understanding of the need for careful use of natural resources. In recent decades, various assessment approaches have been intensively developed to create a system of program measures for the protection of land, water, forests and other resources.

Bioeconomic assessment of hydrosphere resources is sometimes carried out using an inventory. However, it should be noted that there is a fundamental difference between the use of the bioeconomic cadastre in the Russian Federation and its use in some other countries. In our country, the adopted land legislation contains a special section “State Land Cadastre”, which states that in order to ensure the rational use of land resources, the cadastre must contain a set of necessary information about the natural, economic and legal status of lands, soil classification and economic valuation of lands.

A distinctive feature of the bioeconomic cadastre from the land cadastre is that its compilation, processing of hydrological, physicochemical characteristics, as well as the species composition of living resources of the hydrosphere are more strictly centralized in official documents. The formation and use of the bioeconomic cadastre of the hydrosphere is at a high level, allowing the widespread use of information systems for data processing and the creation of data banks.

In a general sense, under bioeconomic cadastre implied a significant set of documents in which the necessary information about specific types of aquatic biological resources and their habitat, natural, legal and economic-organizational conditions for their economic use is systematized in an orderly form at a national or regional level.

The main objectives of the bioeconomic cadastre are to generalize and bring closer to objectivity the available information on the distribution, habitat conditions and reserves of specific species of the hydrosphere, on the conditions of economic activity and exploitation in the interests of maximizing the satisfaction of society's needs for food and non-food products. The bioeconomic cadastre acts as an advisory and sometimes as a directive document that provides the functions of national economic management related to the development, use, protection and reproduction of aquatic biological resources.

The bioeconomic cadastre of seas and oceans functionally provides the following main activities:

1) accounting and environmental - economic forecasting of reserves, distribution and condition of specific types of biological resources in national and international waters;

2) environmental - economic forecasting and planning of the activities of the domestic fishing and other industries in relation to the rationally permissible withdrawal of biological resources in terms of volume, species composition and other indicators, regions and seasons of formation of fishing aggregations, etc.;

3) comprehensive planning of the activities of other sectors of the national economy that have a certain impact on the state and dynamics of the number of biological resources of the hydrosphere;

5) development and implementation of long-term programs of environmental and reproductive measures at the regional, national and international levels;

6) implementation of measures for economic and mathematical modeling of bioeconomic processes of the hydrosphere;

7) determination of the amount of mutual settlements for the use of biological resources by national and foreign organizations;

8) determination of the amount of damage, as well as compensation by sectors of the national economy for biological resources of the hydrosphere;

9) development of integrated environmental - economic programs for the long-term use of resources by region and individual economic tasks related to the development of the World Ocean, etc.

The practical needs of the development and implementation of bioeconomic inventories require their implementation and classification according to certain criteria depending on the spatial and geographical distribution of the aquatic environment and biological resources and depending on their international legal status. Under these conditions, objective social needs arise for the development of environmental— economic assessment of natural resources in general and biological resources in particular.

In the studied object of hydrosphere biological resources there must certainly be an initial supply of them that is not equal to zero, while for artificially created resources (seaculture, etc.) this rule is not so necessary.

With regard to stocks of biological resources, two approaches to constructing a bioeconomic cadastre are possible. They are associated with the minimum or maximum state of stocks at the time of making a decision on the reproduction of resources of the seas and oceans and their protection.

Of great importance for constructing a bioeconomic inventory of the hydrosphere is the study of the properties of these reserves, taking into account persistence, mobility, renewability, inclusion in consumption, reactivity and uniqueness.

Storability manifests itself in the fact that the reserves of biological resources of the hydrosphere in terms of volume or composition can only exist for a certain time, after which they either break up into smaller reserves, or are completely lost for use, or require some kind of cost to increase, etc.

Mobility manifests itself in the possibility of redistributing reserves or concentrating the production of biological resources hydrosphere.

Recoverability - This is a complete or limited bringing of the stock to the desired level. Under certain environmental conditions, the supply of biological resources may not be restored at all.

Inclusion in consumption as a property is manifested in the ability of biological resources to be used without certain conditions or in the presence of such conditions, for example, appropriate environmental conditions, the level of development of fishing technology, etc.

Reactivity involves studying the reaction of the influence of individual factors on the reserves of biological resources in quantitative and qualitative terms.

Uniqueness or ordinaryness is expressed in varying degrees of dispersion and availability of hydrosphere bioresources.

Modern data on the mineral, energy and chemical resources of the World Ocean are of significant practical interest for the national economy, especially the mineral wealth of the shelf subsoil - oil, natural gas, sodium, etc. Therefore, the marine environment can be considered as a “nature - production” object where processes take place creation of material resources for society and their reproduction.

Under shelf of seas and oceans should be understood underwater extensions of the continent towards the sea with a depth of 20 to 600 m. The width of the shelf can be on average about 40-1000 km, and the area - about 28 million km 2 (19% sushi).

For example, industrial oil production in the Caspian Sea began back in 1922, and now more than 18 million tons of oil are produced here annually. In 1949, offshore drilling began off the coast of Brazil in the Gulf of Makapkan, and now more than 60 countries are drilling the seabed and 25 of them are extracting oil and natural gas from the depths of the sea. World oil production in 1972 amounted to 2.6 billion tons, and according to forecasts in 2000 it will be 7.4 billion tons. About 40 billion tons of oil were extracted from the bowels of the earth throughout the history of mankind, and until 2000 150 billion tons will be produced.

In 1975, international oil concerns produced products worth approximately $40 billion, and the total value of marine mineral raw materials extracted in 1976 was estimated at $60–70 billion. For decades, coal has been extracted from land-based mines. subsoil of the seabed in England, Japan, Canada, Chile. Significant coal deposits are hidden in the depths of the shelf off the coast of Turkey, China, and. Taiwan, off the coast of Australia. The largest iron ore deposits on the seabed are concentrated off the eastern coast of the island. Newfoundland, where total ore reserves reach 2 billion tons. The marine placers of Australia, where gold, platinum, rutile, ilmenite, zircon, and mangancite were discovered, are world famous. In the USA, more than 900 kg of platinum are mined annually from sea placers, and in South-West Africa - about 200 thousand carats of diamonds. Currently, 1/3 of the world's salt production, 61% of magnesium metal, and 70% of bromine are obtained from sea water. Fresh drinking water is becoming increasingly important.

Nowadays, more than 500 million people get sick every year from the consumption of poor-quality water by the population of some areas of the globe. In the near future, freshwater resources on land will increasingly need to be replenished by desalinating seawater. However, water desalination is a very energy-intensive production, so it becomes necessary to find ways to use additional marine resources for this purpose. With the exception of oil and natural gas production, the energy resources of the seas are underutilized. Therefore, the relatively high cost of desalinated water is sometimes the main reason for the introduction of scientific and technological progress. According to preliminary estimates, the cost of desalinated water when using electrical energy from tidal and other conventional power plants is 6-20 thousand den. units/m3, and when using nuclear power plants - 1-4 thousand den. units/m3.

The total tidal energy capacity is just over 1 billion kW. Since 1968, the Kislogubskaya tidal power plant with a capacity of 1 thousand kW has been operating; in France, a similar station was built on the Cotentin Peninsula with a capacity of 33 million kW. The intensification of the development of the resources of the World Ocean and the development of energy do not occur without causing damage to it. Complex biological and other natural processes take place in the World Ocean, for example, more than half of all earth's oxygen is produced, and a violation of the ecological balance leads to a decrease in the productivity of phytoplankton, which, in turn, leads to a decrease in oxygen content and an increase in carbon dioxide in the atmosphere. Currently, the fauna and flora of the World Ocean are seriously threatened by pollution: municipal, industrial, agricultural and other wastewater is a source of bacterial and radioactive pollution; emergency discharges; oil leaks from tankers; pollutants coming from the air, etc. Every year, about 2 million tons of oil fall from tankers and offshore drilling rigs to the surface of the ocean. Not only offshore drilling is dangerous for the seas and oceans, but also seismic methods of oil exploration, since explosions kill eggs, larvae, juveniles and adult fish.

Thus, the problem of protecting the World Ocean is of national and international significance, and its successful solution will contribute to progress in the field of protecting the biosphere within an individual state and the entire planet. The country cooperates in protecting the marine environment from pollution with Germany, the USA, Canada, France, Japan, Sweden, Finland, and actively participates in the activities of the International Union for the Conservation of Nature and Natural Resources and other international organizations. To protect water resources, our country has adopted a number of resolutions “On measures to prevent pollution of the Caspian Sea”, “On measures to prevent pollution of the Volga and Ural river basins with untreated wastewater”, “On measures for the conservation and rational use of natural complexes of the lake. Baikal" and others.

The multifaceted use of the ocean creates problems and contradictions in the development of many industries. For example, oil production in coastal waters causes damage to fisheries and resorts. Hydrosphere pollution has a negative impact on biological resources and on humans, and causes enormous damage to the economy.

Available methods make it possible to determine the amount of economic and social damage caused to nature by sectors of the national economic complex of our country. The further task of increasing the environmental and economic efficiency of nature management is to improve the economic mechanism that allows the transfer of environmental measures from the state budget to economic accounting. Under these conditions, it will be possible to rationally use and protect resources and the hydrosphere, i.e. the World Ocean will be able to ensure the progress of mankind only by taking into account the reasonable interaction of society and nature.

3. ECOLOGICAL AND ECONOMIC ASSESSMENT OF THE CONSEQUENCES OF HYDROSPHERE POLLUTION

The growth in the possibilities of industrial, agricultural production and non-production spheres complicates the relationship between society and nature, resulting in the need to preserve and improve the life support system on a global and regional scale. External environment hydrosphere, atmosphere and metasphere becomes a direct participant in the production of a social product. Therefore, here, as in basic production, systematic accounting, control and planning for the rational use of natural resources and environmental protection are required. The effectiveness of these measures is closely related to determining the amount of economic and social damage caused to society and nature by negative anthropogenic impacts. Under economic and social damage should be understood losses in the national economy and society, directly or indirectly resulting from negative anthropogenic impacts leading to environmental pollution with aggressive substances, noise, electromagnetic or other wave effects.

In the general interpreted understanding, specific damage is the amount of reduction in national income per unit of emitted aggressive substances in hydrosphere, lithosphere, atmosphere. It can be calculated for 1 km 2 of sea, 1 hectare of agricultural land, 1 hectare of forests, per 1000 people, 1 million den. units fixed assets, etc.

Using the calculated characteristics of changes in the magnitude of damage from the concentration of an aggressive substance in the environment and the duration of its impact on a subject or object, it is possible to develop a pollution assessment monogram hydrosphere, lithosphere or atmosphere, in which zones are distinguished according to the degree of danger. When determining the danger zone of water pollution, the directions of use of water resources should be taken into account. For example, the requirements for water quality are different when people use it for cooking or for cultural and domestic needs. The absolute and comparative effectiveness of environmental protection measures is closely related to the requirements for maintaining the quality of water and other natural resources. The criteria for the comparative effectiveness of environmental protection measures can be the achievement of growth in national income by preventing economic damage with minimal costs for environmental protection measures. It follows from this that the amount of economic damage can act as a general measure when optimizing the relationship between society and nature. The need to optimize resource-saving and environmental measures is of particular importance, since their implementation requires expenditures of more than 20% of all capital investments in the national economic complex. At the same time, comparative indicators ecological—

Water shell of the Earth.

• they all communicate with each other;
• the water surface level in them is almost the same;
• the average salinity is 35%; they have a bitter-salty taste due to the large amount of mineral salts dissolved in them.

Rice. 3. Comparative volumes of the atmosphere and ocean per 1 m3 of land.

• juvenile, formed during magmagenic processes;
• infiltration, formed due to the seepage of atmospheric precipitation through the thickness of permeable soils and soils on waterproof layers;
• condensation, accumulated in rocks during the transition of water vapor in the ground atmosphere into a liquid state;
• waters buried by sediments in surface bodies of water.

Reservoirs located in natural depressions of the relief.

• riding (watershed) – mossy, convex;
• lowland (mainly valley and floodplain) - grass and woody, flat, even;
• transitional.

Fig.4 Scheme of lake overgrowth according to A.D. Potapov.

1. moss cover (ryam);
2. bottom sediments of organic remains;
3. "window" or space of clear water.

Lecture 3.

Hydrosphere is the watery shell of the earth.

Hydrosphere pollution.

Sources of hydrosphere pollution.

Methods for monitoring water quality.

Water protection measures.

Wastewater treatment methods.

Hydrosphere is the watery shell of the Earth.

Hydrosphere- the water shell of the Earth, including all waters in liquid, solid and gaseous states.

The hydrosphere includes the waters of the oceans, seas, groundwater and surface waters of the land. Some water is found in the atmosphere and in living organisms.

Water occupies the predominant part of the Earth's biosphere (71% of the total area of ​​the earth's surface).

The hydrosphere already 4 billion years ago was represented by the following three components: terrestrial (the World Ocean, river, soil, lake waters, glaciers), underground (water of the lithosphere), air (vapor water of the atmosphere). The hydrosphere includes the following types of water (in parentheses the share of the total volume of water in the hydrosphere, %, according to M.I. Lvovich, 1974):

World Ocean (94.0);

groundwater (4.3);

glaciers (1.7);

land waters (lakes, river waters, soil moisture) (0.03);

atmospheric vapor (0.001).

Water is an essential component of living matter (70–99%). In essence, living matter is an aqueous solution of “living” molecules. It is water that ensures their life. Terrestrial life originated in an aquatic environment, and therefore can be considered a derivative of water.

Fundamental properties of water:

1. First property hydrosphere – unity and ubiquity"(according to V.I. Vernadsky) natural waters. All waters are interconnected and represent a single whole. This unity of natural waters is determined by:

a) easy transition of water from one phase state to another. Within the limits of earthly temperatures, three states are known: liquid, solid, vapor. The plasma state of water exists at high temperatures and pressures in the deep parts of the subsurface;

b) the constant presence of gas components in water. Natural water is an aqueous solution (gas, suspended solids, minerals).

2. Second property hydrosphere is determined special structure of the water molecule. The structure and properties of water provide the most favorable conditions for the development of life on Earth. From physics we know that all bodies expand when heated and contract when cooled. Water behaves differently. If it were to compress when turning into ice (cooling), the ice would be heavier than water and would sink to the bottom of rivers and lakes. The rivers would be frozen to the bottom, and life in these reservoirs would be impossible. Ice is an insulator that keeps the water beneath the ice from freezing, which protects all underwater life. If it were not for this property, the Earth would turn into an ice-bound planet.

The special structure of the water molecule provides variety of structure it when external factors change (temperature, pressure, chemical composition). In winter we had to observe the variety and beauty of ice patterns on the windows, snowflakes, frost on the trees. Just as no two drops of water are exactly alike, no two types of water are identical in structure.

3. Third property hydrosphere is expressed in geologically its eternal mobility. The movement of water is very diverse and manifests itself in numerous cycles. The main movement of water is the geological cycle of matter. Every second, under the influence of the sun's heat, millions of cubic meters of water rise up and form clouds. The wind sets the clouds in motion. When conditions are right, moisture falls in the form of rain or snow. Raindrops have a favorable size for everything on earth and fall quietly and softly. Are all favorable coincidences in life random? Thus, water participates in peculiar cycles of matter and energy. This system was established on Earth with the advent of free water and continues to this day.

Why is there movement? Movement can occur under the influence of: a) gravity; b) solar (thermal) energy; c) molecular movement when changing phase state.

4. Fourth property hydrosphere is determined by high chemical activity of water. Under the conditions of the earth's crust, there are no natural bodies that, to one degree or another, would not dissolve in natural waters. Water in the biosphere acts as a universal solvent, because, interacting with all substances, as a rule, it does not enter into chemical reactions with them. This ensures the exchange of substances between land and ocean, organisms and the environment.

The most important abiotic factors of the aquatic environment are the following:

1. Density and viscosity.

The density of water is 800 times, and the viscosity is approximately 55 times greater than air.

2. Heat capacity.

Water has a high heat capacity, so the ocean is the main receiver and accumulator of solar energy.

3. Mobility.

The constant movement of water masses helps maintain the relative homogeneity of physical and chemical properties.

4. Temperature stratification.

A change in water temperature is observed along the depth of the water body.

5. Periodic (annual, daily, seasonal) temperature changes

The lowest water temperature is considered to be - 2 ° C, the highest + 35-37 ° C. The dynamics of fluctuations in water temperature are less than those of air.

6. Transparency and turbidity of water.

Determines the light regime below the surface of the water. The photosynthesis of green bacteria, phytoplankton, higher plants, and, consequently, the accumulation of organic matter depends on transparency (and its inverse characteristic - turbidity).

Turbidity and transparency depend on the content of suspended substances in water, including those entering water bodies along with industrial discharges. In this regard, transparency and suspended solids content are the most important characteristics of natural and waste waters that are subject to control at an industrial enterprise.

7. Salinity of water.

According to the degree of salinity, all reservoirs are conventionally divided into

fresh with salinity less than 0.5 0 / 00,

brackish water - salinity ranges from 0.5 - 16 0 / 00,

salty - more than 16 0 / 00.

The salinity of oceanic water bodies is 32 - 38 0/00,

The highest salt content is in salt lakes, where the concentration of electrolytes reaches 370 0/00.

Main difference sea ​​water from river salt is that the overwhelming majority of sea salt is chlorides, and in river water prevail carbonic salts. A person uses only fresh water to ensure life. Of the total water resources on earth, share of fresh water have to no more than 3%.

8. Dissolved oxygen and carbon dioxide.

Excessive consumption of oxygen for the respiration of living organisms and for the oxidation of organic and mineral substances entering the water with industrial discharges leads to the impoverishment of the living population to the point where aerobic organisms cannot live in such water.

9. Hydrogen ion concentration (pH).

All aquatic organisms have adapted to a certain pH level: some prefer an acidic environment, others prefer an alkaline environment, and others prefer a neutral one. A change in these characteristics can lead to the death of aquatic organisms.

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Introduction “What is water?” Water is one of the principles of everything that exists on Earth - they said in ancient times. For thousands of years people have been admiring and enjoying water. And all this time, People did not stop thinking about its origin, composition, and properties. All practical human activities since ancient times have been associated with the use of water and aqueous solutions. A variety of solutions for the production of building materials, paints, glass, ceramics. Much attention is still paid to water; this amazing liquid is revealed from different sides.

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Water on Earth Water on Earth is the most common substance. The globe clearly shows that only 1/4 of our planet is land, and the remaining 3/4 is water. The astronauts who first saw the Earth from space said that it did not look like a globe at all, but rather like a water balloon. However, water must be conserved.

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Distribution of water on Earth Distribution of water on Earth. Water forms the water shell of our planet - the hydrosphere (from the Greek words “hydro” - water, “sphere” - ball). It includes water in all three states - liquid, solid (ice, snow) and gaseous (steam). Currently, water occupies 3/4 of the Earth's surface.

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Composition of the hydrosphere The hydrosphere includes three main components: the World Ocean, land waters, water in the atmosphere Groundwater about 2% Glaciers about 2% rivers, lakes, swamps 0.02% Water in the atmosphere is water vapor, water droplets, ice crystals. Together they make up a fraction of a percent of the total amount of water on Earth. But without them the water cycle on our planet would be impossible. Water vapor in the atmosphere serves as a powerful filter of solar radiation, and on Earth - a neutralizer of extreme temperatures and a climate regulator.

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World Ocean The Earth is a water planet, because... The World Ocean occupies 70.8% of its territory. In the Northern Hemisphere, the water surface accounts for 60.6%, and in the Southern Hemisphere - 81% OCEAN (Greek Okeanos) (World Ocean), a continuous water shell of the Earth surrounding continents and islands and characterized by a common salt composition.

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Oceans OCEAN RESOURCES Man used the ocean as a route for trade and communication. Swimming along them, he made discoveries. He turned to the sea in search of food, energy, material resources and inspiration. RELIEF OF THE OCEAN BOTTOM At the bottom of the oceans there are huge mountain ranges, deep chasms with steep walls, long ridges and deep reef valleys. In fact, the seabed is no less rugged than the land surface. The world's oceans are divided into four oceans

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Division of the World Ocean: Pacific Its area is 178.62 million km2, average depth (3980 m) B). Within its borders is the deepest Mariana Trench (11,022 m). More than half the volume of water in the World Ocean is concentrated in the Pacific Ocean (710.4 out of 1341 million km3). Indian Atlantic Ocean Its area is 76.2 million km2, the average depth is 3710 m, the greatest is 7729 m (near the Sunda Islands), the volume of water is 282.6 million km3. Atlantic Its area is 91.6 million km2, average depth 3600 m, greatest 8742 m (near Puerto Rico), volume 329.7 million km3 Arctic Its area is only 14.8 million km2 (4% of the World Ocean), average depth 1220 m (maximum 5527 m), water volume 18.1 million km3.

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Land waters Land waters are rivers, lakes, swamps, glaciers and groundwater. Most of the land's waters are fresh, but among lakes and groundwater there are also salty ones. You know what a huge role rivers, lakes, and swamps play in nature and people’s lives. But here’s what’s surprising: in the total amount of water on Earth, their share is very small - only 0.02%.

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Groundwater Groundwater is the water found in the earth's crust. For its formation, two conditions are necessary: ​​precipitation (rain, snow) falling in sufficient quantities on the land surface, and the ability of the rocks composing this surface to pass water. In some areas, groundwater has a high temperature and contains various salts in dissolved form , gases i.e. are mineral. These waters flow to the surface, forming springs, streams, and rivers. Sometimes they burst out like a hot fountain, rising to a height of several tens of meters.

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Rivers Natural water streams flowing in a depression they have created, called a channel, and are fed by surface and underground runoff from their basins. The place where the river originates is called the source. The source can be a lake, glacier, or spring. The place where a river flows into another river, lake or sea is called its mouth. The direction and speed of the river flow depend on the topography of the surface along which the river flows. There are lowland and mountain rivers. , .

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Mountain and lowland rivers Even on calm lowland rivers there can be sections where the flow of the river changes sharply. Outcrops of hard rock crossing the riverbed and piles of stones form rapids. Overcoming them, the river foams, splashes fly high up, and whirlpools arise. In areas with rapids, lowland rivers are similar to mountain rivers. The rapids greatly hinder navigation. The tallest waterfall on Earth is Angel Falls in South America. A stream of water falls from a height of 1054 m to the bottom of a deep gorge. Niagara Falls is not one of the highest. Its greatest height is only 51 m. The left part, 800 m wide, belongs to Canada, and the right part, 300 m wide, belongs to the USA.

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Lakes LAKES, natural bodies of water in depressions of land (basins), filled within the lake bowl (lake bed) with heterogeneous water masses and not having a one-way slope. The largest lake on Earth is the Caspian. In the past it was connected to the Ocean. Due to its enormous size and water, similar in composition of salts to ocean water, it is called the sea. The deepest lake on Earth is Baikal. Its greatest depth is 1620 m. Recesses. in which lakes are located are called lacustrine basins. Types of lake basins

Abstract on the topic:

"WATER COVER OF THE EARTH"

1. General information about water

2. The world's oceans

3. Groundwater

4. Rivers

5. Lakes and swamps

List of used literature

1. General information about water

Hydrosphere. The hydrosphere is the watery shell of the Earth. It consists of land waters - rivers, swamps, glaciers, groundwater and waters of the World Ocean.

The bulk of water on Earth is in the seas and oceans - almost 94% of it there; 4.12% of water is contained in the earth's crust and 1.69% in glaciers in Antarctica, the Arctic and mountainous countries. Fresh water accounts for only 2% of its total reserves.

Properties of water. Water is the most abundant mineral in nature. Pure water is transparent, colorless and odorless. It has amazing properties that distinguish it from other natural bodies. It is the only mineral that exists naturally in three states - liquid, solid and gaseous. Its transition from one state to another occurs constantly. The intensity of this process is determined primarily by air temperature.

When water changes from a gaseous state to a liquid, heat is released, and when liquid water evaporates, heat is absorbed. On sunny days and in summer, the water column warms up to a considerable depth and, as it were, condenses heat, and in the absence of sunlight or its decrease, heat is gradually released. For this reason, at night the water is warmer than the surrounding air.

When water freezes, it increases in volume, so an ice cube is lighter than a water cube of the same volume and does not sink, but floats.

Water becomes the densest and, accordingly, the heaviest at a temperature of +4 °C. Water at this temperature sinks to the bottom of reservoirs, where this temperature remains stable, which makes it possible for living organisms to exist in frozen reservoirs in winter.

Water is called the universal solvent. It dissolves almost all substances with which it comes into contact, except fats and some minerals. As a result, there is no pure water in nature. It is always found in the form of solutions of greater or lesser concentration.

Being a mobile (flowing) body, water penetrates into different environments, moves in all directions and acts as a transporter of solutions. In this way, it ensures the exchange of substances in the geographic envelope, including between organisms and the environment.

Water has the ability to “stick” to the surface of other bodies and rise up through thin capillary vessels. This property is associated with the circulation of water in soils and rocks, the blood circulation of animals, and the movement of plant juices up the stem.

Water is omnipresent. It fills large and small reservoirs, is found in the bowels of the Earth, is present in the atmosphere in the form of water vapor, and serves as an indispensable component of all living organisms. Thus, the human body is 65%, and the bodies of the inhabitants of the seas and oceans are 80–90% water.

The importance of water is not limited to its impact on life and economic activity. It has a huge impact on our entire planet. Academician V.I. Vernadsky wrote that “there is no natural body that could compare with it (water) in its influence on the course of the main, most vital geological processes.”

Origin of water. It would seem that humanity knows everything about water. Nevertheless, the question of the origin of water on Earth still remains open. Some scientists believe that water was formed as a result of the synthesis of hydrogen and oxygen released from the bowels of the Earth, others, for example academician O. Yu. Schmidt, believe that water was brought to Earth from space during the formation of the planet.

Along with cosmic dust and mineral particles, pieces and blocks of space ice fell onto the nascent Earth. As the planet warmed up, the ice turned into water vapor and water.

2. Oceans

Division of the World Ocean. The world's oceans are divided into four main parts - oceans– Pacific, Atlantic, Indian and Arctic.

The waters of the World Ocean have a number of common characteristics:

– all the waters of the World Ocean are interconnected;

– the water surface level in them is almost the same;

– the water of the World Ocean contains a significant amount of dissolved mineral salts and has a bitter-salty taste, which does not allow this water to be used for food purposes under natural conditions. Salinity of water is measured in ppm(%O). The ppm number shows how many grams of salt are contained in 1 liter of water. The average salinity of the World Ocean is 35%.

The waters of the World Ocean are distributed unevenly. In the Southern Hemisphere, between 30–70° latitude, the ocean occupies more than 95%, and in the Northern Hemisphere - just over 44%, which made it possible to call the Southern Hemisphere oceanic, and the Northern Hemisphere continental.

The waters of the World Ocean, flowing into the land, form seas and bays. The sea is a relatively isolated part of the ocean, differing from it in salinity and water temperature, and sometimes in the presence of currents. Thus, the salinity of the Baltic Sea ranges from 3 to 20%o, and the Red Sea – more than 40%o.

The bays are less isolated from the ocean; their waters differ little in properties from the waters of the oceans or seas to which they belong.

Historically, some typical seas have been called bays. These are, for example, the Bay of Bengal, the Hudson, and the Gulf of Mexico. Some parts of the ocean are called seas conventionally due to the peculiarities of their nature. This is, for example, the Sargasso Sea.

Depending on the geographical location, the seas are divided into mainland(Mediterranean, etc.) and inland(Baltic, etc.). According to the degree of isolation and features they distinguish internal(Black, White, etc.), outlying(Barents, Okhotsk, etc.) and interisland(Javanskoe, Banda, etc.).

Seas and oceans are connected by straits - more or less narrow stretches of water located between parts of the land. There is usually a current in straits. Some straits are very vast and carry huge masses of water (Drake Passage), others are narrow, winding and shallow (Bosporus, Strait of Magellan).

In addition to salts, many gases are dissolved in ocean water, including oxygen, which is necessary for the respiration of living organisms. The cold waters of the polar seas contain more oxygen.

Marine animals use carbon dioxide contained in ocean waters to build skeletons and shells.

The water temperature in the oceans varies and ranges from 27–28 °C at the equator to -20 °C in the polar latitudes.

In temperate latitudes there are seasonal temperature fluctuations from 0 to +20 °C.

The waters of the polar seas and oceans freeze. Ice boundary runs from the shores of Newfoundland to the western coast of Greenland, then to the shores of Spitsbergen and the Kola Peninsula. In the Pacific Ocean, this border drops further south and runs from the northern part of the Korean Peninsula to the island of Hokkaido and further through the Kuril Islands to the shores of America.

In the Southern Hemisphere, the ice cover rises to 40–45° S. w.

Movement. The water in the World Ocean is in constant motion. There are three types of movements: wave, translational and mixed.

Wave movements They arise under the influence of wind and cover only the surface of the ocean. Under the pressure of the wind, in the upper part of the wave, water particles move in the direction of the wave, and in the lower part - in the opposite direction, traveling in circular orbits. For this reason, objects that are on the water and do not have windage do not move horizontally in the direction of the wind, but oscillate in place. It is no coincidence that these waves are called oscillatory.

Each wave has ridge, slope And sole(Fig. 30). The vertical distance between the crest and the sole is called the height, and between the two crests is called the wavelength. The stronger the wind, the larger the waves. In some cases, they reach a height of up to 20 m and even up to 1 km. The waves fade with depth.

Rice. thirty. Wave structure

Under the pressure of the wind, waves move towards the shore faster than from the shore, as a result of which their foamy crests move forward, tilt and collapse onto the shore. On rocky shores, the force with which the wave hits the coastal rocks reaches several tons per 1 m2.

Underwater earthquakes produce waves tsunami, which cover the entire water column. The length of these waves is very long and amounts to several tens of kilometers. These waves are very gentle, and encountering them in the open ocean is not dangerous. The speed of the tsunami wave reaches 900 km/h. When approaching the shore, as a result of the friction of the wave on the ocean bottom, its speed drops, the wave rapidly shortens, but at the same time grows in height, sometimes reaching 30 m. These waves cause devastating destruction in the coastal zone.

The forward movements of huge masses of ocean water lead to the appearance marine or ocean currents. Such currents occur at different depths, causing the water to mix.

The main cause of currents is constant winds blowing in one direction. Such currents are called drift (surface). They involve in movement a mass of water up to 300 m deep and several hundred kilometers wide. This gigantic water stream - a river in the ocean - moves at a speed of 3 to 9-10 km/h. The length of such “rivers” can reach several thousand kilometers. For example, the Gulf Stream, starting in the Gulf of Mexico, has a length of more than 10 thousand km and reaches the island of Novaya Zemlya. This current carries 20 times more water than all the rivers of the globe taken together.

Among the drift currents of the World Ocean, the first to be mentioned are the northern and southern trade wind currents, which have a general direction from east to west, caused by trade winds - constant winds blowing towards the equator at a speed of 30–40 km/h. Encountering an obstacle in the form of continents on their way, the currents change the direction of movement and move along the coasts of the continents to the south and north.

Depending on the water temperature, currents can be warm, cold or neutral.

The waters of warm currents have a higher temperature compared to the adjacent ocean water, cold waters have a lower temperature, and neutral waters have the same temperature. This is due to where the current brought water from - from low, high or the same latitudes.

The importance of currents on Earth is enormous. They serve either as “heating batteries” or as “cold chambers” for the adjacent parts of the ocean and continent. The Gulf Stream, for example, has a temperature of 20–26 °C, which is quite enough to “heat” Western Europe and warm the Barents Sea. At the same time, the cold Labrador Current determines the harsh, cold climate of the Labrador Peninsula, located at the latitude of France.

In addition, sea currents provide water exchange and mixing of equatorial, tropical, temperate and polar water masses, and contribute to the redistribution of marine animals and plants. Where warm and cold currents meet, the organic world of the ocean is much richer and more productive.

In addition to drift currents, compensation, drainage and density currents are known.

Compensating flows are caused by drift and are formed in cases where winds from the continent drive away surface waters. In place of these waters, compensating for their deficiency, water rises from the depths. She's always cold. For this reason, the cold Canary, California and Peruvian currents pass off the hot coasts of Western Sahara, California, and Chile.

Katabatic currents are formed due to the surge of water by drift currents, the removal of river waters, or strong evaporation of water, as a result of which equalization begins due to the flow of adjacent waters. For example, thanks to the flow from the Gulf of Mexico, the Gulf Stream appeared.

Density currents are formed when two sea basins, the water of which has different densities, are connected by a strait. For example, the saltier and denser water of the Mediterranean Sea flows into the Atlantic Ocean along the bottom of the Strait of Gibraltar, and counter to this flow along the surface of the strait there is a runoff current from the ocean to the sea.

Mixed movements of ocean waters include tides And low tides, arising as a result of the attraction of the Moon on the water surface of the ocean and the rotation of the Earth around its axis.

During the day, the tides occur twice, every 6 hours. In the open ocean, tidal waves are invisible, since their height does not exceed 1.5 m and their length is very long. Near the coast, especially rocky ones, the wave length is shortened, and since the mass of water remains the same, the wave height rapidly increases. For example, in the Bay of Fundy (North America) the height of the tidal wave reaches 20 m, in the Sea of ​​Okhotsk (off the coast of Russia) it exceeds 13 m.

During high tide, large ocean-going ships can enter seaports that are inaccessible to them at other times.

Tidal waves carry enormous energy, which is used to build tidal power plants (TPPs). In Russia, such a station has been created and operates in Kislaya Bay on the Barents Sea. The importance of PES is extremely high, primarily because they are environmentally friendly and do not require the creation of giant reservoirs that occupy valuable land.

3. Groundwater

Groundwater is water that is found below the surface of the Earth in liquid, solid and gaseous states. They accumulate in pores, cracks, and voids in rocks.

Groundwater was formed as a result of the seepage of water that fell on the surface of the Earth, the condensation of water vapor that entered through pores from the atmosphere, as well as the formation of water vapor during the cooling of magma at depth and its condensation in the upper layers of the earth's crust. The processes of water seepage from the Earth's surface are of decisive importance in the formation of groundwater. In certain regions, for example in sandy deserts, the main role is played by water coming from the atmosphere in the form of water vapor.

Water that is influenced by gravity is called gravitational. It moves along the inclined surface of the waterproof layers.

Water held by molecular forces is called film. Water molecules that come into direct contact with rock grains form hygroscopic water. Film and hygroscopic water can be removed from the rock only by calcination. Therefore, plants do not use this water.

Plant root systems absorb capillary water(located in the capillaries of the soil) and gravitational.

The speed of groundwater movement is insignificant and depends on the structure of rocks. There are fine-grained rocks (clays, loams), granular (sands), fractured (limestones). Through sands and along cracks, gravitational water flows freely at a speed of 0.5–2 m per day, in loams and loess – 0.1–0.3 mm per day.

Rocks, depending on their ability to pass water, are divided into permeable and water-resistant. TO permeable rocks sands include waterproof– clays and crystalline rocks. Water that has passed through permeable rocks accumulates at depth above the impermeable layer, forming aquifers. The upper level of the aquifer, called mirror of underground waters, follows the curves of the relief: it rises above the hills, and decreases below the basins. In the spring, when the snow melts, the soil becomes very waterlogged, the groundwater level rises, and in winter it decreases. The groundwater level also rises during heavy rains.

The release of an aquifer to the surface is called spring (source, key). They are usually found in ravines, ravines, and river valleys. Sometimes springs can be found on the plains - in small depressions or on the slopes of hills and hills (Fig. 31).

Rice. 31. Descending (1) and ascending (2) sources

Groundwater, enclosed between two impervious layers, is usually under pressure, so it is called pressure or artesian. They are usually found at great depths - in depressions in the bends of waterproof layers (Fig. 32).

Rice. 32. Simple (1) , artesian (2) wells and spring (3)

Deep groundwater located near magma chambers gives rise to hot springs. In Russia they are found in Kamchatka, the North Caucasus and other places. The water temperature in them reaches 70–95 °C. Fountaining hot springs are called geysers. More than 20 large geysers have been discovered in the Valley of Geysers in Kamchatka, including the Giant, which throws water to a height of 30 m, as well as many small ones. Outside our country, geysers are common in Iceland, New Zealand, and the USA (Yellowstone National Park).

Passing through various rocks, groundwater partially dissolves them - this is how mineral springs are formed. Depending on the chemical composition, sulfur (Pyatigorsk), carbon dioxide (Kislovodsk), alkali-salt (Essentuki), ferrous-alkaline (Zheleznovodsk) and other sources are distinguished. They are used for medicinal purposes. Resorts are built where they emerge.

4. Rivers

Flowing waters – temporary watercourses, streams and rivers that level the surface of the Earth; they destroy hills, mountains, and carry the products of destruction to lower places.

The importance of flowing waters in human economic activity is also great. Springs, rivers and streams are the main sources of water supply. Settlements are located along streams and rivers; rivers are used as communication routes, for the construction of hydroelectric power stations and for fishing. In arid areas, river water is used for irrigation.

Rivers - These are natural permanent watercourses flowing along a slope and enclosed in banks.

Rivers often originate from springs that emerge onto the earth's surface. Many rivers originate in lakes, swamps, and mountain glaciers.

Each river has a source, an upper, middle and lower course, tributaries, and an mouth. Source- This is the place where the river originates. Estuary– the place where it flows into another river, lake or sea. In deserts, rivers are sometimes lost in the sand, their water spent on evaporation and filtration.

Rivers flowing through any territory form river network, which consists of separate systems including the main river and its tributaries. Usually the main river is longer, deeper and occupies an axial position in the river system. As a rule, it is older than its tributaries. Sometimes it happens the other way around. For example, the Volga carries less water than the Kama, but is considered the main river because its basin was historically inhabited earlier. Some tributaries are longer than the main river (the Missouri is longer than the Mississippi, the Irtysh is longer than the Ob).

The tributaries of the main river are divided into tributaries of the first, second and subsequent orders.

River basin name the territory from which it receives food. The area of ​​the basin can be determined from large-scale maps using a palette. The basins of different rivers are separated watersheds. They often pass through higher elevations, and in some cases through flat wetlands.

Density of the river network is the ratio of the total length of all rivers to the area of ​​the basin (km/km 2). It depends on the terrain, climate, and local rocks. In places where there is more precipitation and evaporation is low, the river network is more dense. In the mountains the density of the river network is greater than on the plain. Thus, on the northern slopes of the Caucasus Mountains it is 0.49 km/km 2 , and in the Ciscaucasia – 0.05 km/km 2 .

River feeding It is carried out by groundwater, as well as precipitation falling in the form of rain and snow. Rainwater that falls on the surface partially evaporates, and some of it seeps deep into the earth or flows into rivers. The fallen snow melts in the spring. Meltwater flows down slopes and eventually ends up in rivers. Thus, the constant sources of river nutrition are groundwater, rain in summer and snow melt water in spring. In mountainous regions, rivers are fed by water from melting glaciers and snow.

The water level in rivers depends on the nature of nutrition. The greatest rise in water in our country is observed in the spring, during the melting of snow. Rivers overflow their banks, flooding vast areas. During spring floods, more than half of the annual volume of water flows off. In places where more precipitation falls in the summer, rivers have a summer flood. For example, the Amur has two floods: a less powerful one in the spring and a stronger one at the end of summer, during the monsoon rains.

Observations of river levels make it possible to distinguish periods of highest and lowest water levels. They received the names “flood”, “flood” and “low water”.

High water– an annual repeating rise of water in the same season. In the spring, when the snow melts, the rivers maintain high water levels for 2–3 months. At this time, river floods occur.

Flood– short-term non-periodic rise of water in rivers. For example, during heavy, prolonged rains, some rivers of the East European Plain overflow their banks, flooding vast areas. On mountain rivers, floods occur in hot weather, when snow and glaciers melt rapidly.

The height of water rise during floods varies (in mountainous countries - higher, in plains - lower) and depends on the intensity of snow melting, rainfall, forest cover of the area, the width of the floodplain and the nature of the ice drift. Thus, on large Siberian rivers, during the formation of ice jams, the water rise reaches 20 m.

Low water– the lowest water level in the river. At this time, the river is fed mainly by groundwater. In the middle zone of our country, low water occurs at the end of summer, when water evaporates heavily and seeps into the ground, as well as at the end of winter, when there is no surface recharge.

According to the method of feeding, all rivers can be divided into the following groups:

– rain fed rivers(in the equatorial, tropical and subtropical zones - Amazon, Congo, Nile, Yangtze, etc.);

- rivers receiving powered by melting snow and glaciers(rivers of mountainous regions and the Far North - Amu Darya, Syr Darya, Kuban, Yukon);

– rivers of underground feeding(rivers of mountain slopes in an arid zone, for example small rivers of the northern slope of the Tien Shan);

– rivers of mixed feeding(temperate rivers with pronounced stable snow cover - Volga, Dnieper, Ob, Yenisei, etc.).

River work. Rivers constantly produce work, which manifests itself in erosion, transport and accumulation of material.

Under erosion understand the destruction of rocks. A distinction is made between deep erosion, aimed at deepening the channel, and lateral, aimed at destroying the banks. In rivers you can see bends called meanders. One bank of the river is usually washed away, the other is washed away. The river can transport and deposit washed-up material. Deposition begins when the current slows down. First, larger material settles (stones, pebbles, coarse sand), then fine sand, etc.

The accumulation of brought material occurs especially actively at river mouths. Islands and shoals with channels between them are formed there. Such formations are called deltas.

On the map you can see a large number of rivers forming deltas. But there are rivers, for example the Pechora, whose mouths resemble an expanding wedge. Such mouths are called estuaries. The shape of the mouth usually depends on the stability of the seabed in the area where the river enters. Where it constantly decreases as a result of secular movements of the earth's crust, estuaries. Deltas form in places where the seabed rises. Rivers may not have deltas if there is a strong current in the sea in the area where the river flows, carrying river sediments far into the sea.

The structure of the river valley. River valleys have the following elements: bed, floodplain, terraces, slopes, bedrock banks. Along the riverbed called the lower part of the valley through which the river flows. The riverbed has two banks: right and left. Usually one bank is flat, the other is steep. The bed of a flat river often has a tortuous shape, since in addition to gravity and friction, the nature of the flow is also influenced by the centrifugal force that arises at the turns of the river, as well as the deflecting force of the Earth's rotation. Under the influence of this force at the turn, the flow is pressed against the concave bank, and jets of water destroy it. The direction of the current changes, the flow is directed to the opposite, flat bank. The deflecting force of the Earth's rotation forces the flow to the right bank (in the Northern Hemisphere). It is being destroyed, the river bed is moving.

The process of formation of bends (meanders) is continuous. Sometimes meander loops approach each other to such a distance that they join, and water begins to flow along a new channel, and part of the former channel becomes old lady, a crescent-shaped lake.

In the beds of lowland rivers, stretches and riffles usually alternate. Plyosy– the deepest sections of the river with a slow flow. They are formed on its bends. Rifles– small parts of a river with a fast current. They form on straightened areas. Reaches and riffles are gradually moving along the river.

The river constantly deepens its channel, but deep erosion stops when the water level in the river drops to the same level as where the river flows into another river, lake, or sea. This level is called basis of erosion. The final basis for erosion for all rivers is the level of the World Ocean. As the erosion base decreases, the river erodes more strongly and the channel deepens; When the temperature rises, this process slows down and sedimentation occurs.

Floodplain called the part of the valley that is flooded with spring waters. Its surface is uneven: extensive elongated depressions alternate with small elevations. The highest areas are coastal ramparts are located along the coast. They are usually covered with vegetation. Terraces They are leveled areas stretching along the slopes in the form of steps. On large rivers, several terraces are observed, they are counted from the floodplain upward (first, second, etc.). Near the Volga there are from four to seven terraces, and on the rivers of Eastern Siberia - up to 20.

Slopes border the valley from the sides. More often than not, one slope is steep and the other is gentle. For example, the Volga has a steep right slope and a gentle slope on the left. The slopes end with indigenous banks, usually not affected by erosion.

Young rivers often have sections in their longitudinal profile with rapids(places with fast currents and rocky soil reaching the surface of the water) and waterfalls(areas where water falls from steep ledges). Waterfalls are found on many mountain rivers, as well as on lowland ones, in the valleys of which hard rocks come to the surface.

One of the largest waterfalls in the world - Victoria on the Zambezi River - falls from a height of 120 m with a width of 1800 m. The sound of falling water can be heard tens of kilometers away, and the waterfall is always shrouded in a cloud of spray - water dust.

The waters of Niagara Falls (North America) fall from a height of 51 m, the width of the stream is 1237 m.

Many mountain waterfalls are even higher. The highest of them is Angel on the Orinoco River. Its water falls from a height of 1054 m.

When building settlements, it is very important to know whether there is enough water in the river, whether it can provide water to the population and enterprises. For this purpose, determine consumption, i.e., the amount of water (in m3) passing through the living section of the river in 1 s.

For example, the river flow speed is 1 m/s, the living cross-sectional area is 10 m 2. This means that the water flow in the river is 10 m 3 /s.

The flow of water in a river over a long period is called river flow. It is usually determined from long-term data and is expressed in km 3 /year.

The amount of runoff depends on the area of ​​the river basin and climatic conditions. Large amounts of precipitation with low evaporation contribute to increased runoff. In addition, the flow depends on the rocks that make up the given territory and the terrain.

The high water content of the world's deepest river, the Amazon (3160 km 3 per year), is explained by the huge area of ​​its basin (about 7 million km 2) and the abundance of precipitation (more than 2000 mm per year). The Amazon has 17 first-order tributaries, each of which brings almost as much water as the Volga.

5. Lakes and swamps

Lakes. About 2% of all land is occupied by lakes, depressions in the land filled with water. On the territory of our country (partially) is located the largest lake in the world - the Caspian and the deepest - Baikal.

Man has long used lakes for water supply; they serve as routes of communication, many of them rich in fish. Valuable raw materials were found in some lakes: salts, iron ores, sapropel. People relax on the shores of lakes; rest houses and sanatoriums have been built there.

Types of lakes. Based on the nature of their flow, lakes are divided into flow-through, drainage and drainage-free. IN flowing lake many rivers flow in and several rivers flow out of it. This type includes Ladoga and Onega.

Sewage lakes receive a large number of rivers, but only one river flows out of them. This type includes lakes Baikal and Teletskoye.

In dry areas there are endorheic lakes, from which not a single river flows - the Caspian, Aral, Balkhash. Many tundra lakes also belong to this type.

The origin of lake basins is extremely diverse. There are basins that arose as a result of the manifestation of the internal forces of the Earth (endogenous). This is the case with most of the world's large lakes. Small lakes are generated by the activity of external forces (exogenous).

TO endogenous basins include tectonic and volcanic. Tectonic basins They are sunken areas of the earth's crust. Subsidence may occur as a result of subsidence of layers or faults along fractures. This is how the largest lakes were formed - Aral (trough of the earth's layers), Baikal, Tanganyika, Verkhnee, Huron, Michigan (fault).

Volcanic basins They are volcanic craters or valleys covered by lava flows. There are similar basins in Kamchatka, for example Kronotskoye Lake.

Variety of lakes basins of exogenous origin. In river valleys there are often oxbow lakes that have an oblong shape. They arose on the site of former river beds.

Many lakes were formed during the Ice Age. As the glaciers moved, they plowed out huge basins. They filled with water. Such glacial lakes are found in Finland, Canada, and the north-west of our country. Many lakes are elongated in the direction of movement of glaciers.

In areas composed of water-soluble rocks - limestone, dolomite and gypsum - basins of karst origin are not uncommon. Many of them are very deep.

Lake basins are often found in the tundra and taiga thermokarst, resulting from uneven thawing of permafrost.

In the mountains, strong earthquakes can cause dammed lakes. Thus, in 1911, in the Pamirs, Lake Sarez appeared literally before people’s eyes: as a result of an earthquake, part of the mountain range was thrown into the river valley, and a dam more than 500 m high was formed.

Many basins were created by man - this artificial reservoirs.

In our country, the flow of most large rivers is regulated (Volga, Angara, Yenisei). Dams have been built on them and large reservoirs have been created.

Many lake basins have mixed origin. For example, Lakes Ladoga and Onega are tectonic, but their basins changed their appearance under the influence of glaciers and rivers. The Caspian Lake is the remnant of a large sea basin, which was once connected through the Kuma-Manych depression with the Azov and Black Seas.

The lakes are fed by groundwater, precipitation and rivers flowing into them. Part of the water from the lake is carried into rivers, evaporates from the surface, and goes to underground drainage. Depending on the ratio of incoming and outgoing parts, the water level fluctuates, which leads to changes in the areas of lakes. For example, Lake Chad has an area of ​​12 thousand km 2 in the dry season, and increases to 26 thousand km 2 in the rainy season.

Changes in water levels in lakes are associated with climatic conditions: a decrease in the amount of precipitation in the lake basin, as well as evaporation from its surface. The water level in the lake can also change as a result of tectonic movements.

Based on the amount of substances dissolved in water, lakes are divided into fresh, brackish and saline. Fresh lakes have dissolved salts less than 1%o. Brackish lakes those where the salinity is more than 1%o are considered, and salty– over 24.7%o.

Flowing and drainage lakes are usually fresh, since the inflow of fresh water is greater than the outflow. Endorheic lakes are predominantly brackish or saline. In these lakes, the inflow of water is less than the outflow, so the salinity increases. Salt lakes are located in the steppe and desert zones (Elton, Baskunchak, Mertvoe, Bolshoye Solenoye and many others). Some lakes have a high soda content, for example the soda lakes in the south of Western Siberia.

Life of lakes. Lakes develop depending on environmental conditions. Rivers, as well as temporary water flows, bring huge amounts of inorganic and organic substances into the lakes, which are deposited at the bottom. Vegetation appears, the remains of which also accumulate, filling the lake basins. As a result, the lakes become shallow, and swamps can form in their place (Fig. 33).

Rice. 33. Scheme of lake overgrowth: 1 – moss cover (ryam); 2 – bottom sediments of organic residues; 3 – “window”, or space of clean water

The distribution of lakes is zonal. In Russia, the densest lake network is observed in areas of ancient glaciation: on the Kola Peninsula, in Karelia. Here the lakes are fresh, mostly flowing and quickly overgrown. In the south, in the forest-steppe and steppe zones, the number of lakes decreases sharply. The desert zone is dominated by drainless salt lakes. They often dry out, turning into salt marshes. Tectonic lakes are found in all zones. They have great depths, so the change occurs slowly and is hardly noticeable to humans.

Swamps. Swamps are excessively moist areas of land covered with moisture-loving vegetation.

Waterlogging in forest belts often occurs during deforestation. Conditions for the formation of swamps are also favorable in the tundra zone, where permafrost does not allow groundwater to penetrate deep into the soil, and it remains on the surface.

Based on nutritional conditions and location, swamps are divided into lowland and highland. Lowland swamps are fed by precipitation, surface and groundwater. Groundwater is rich in minerals. This causes rich vegetation in lowland swamps (alder, willow, birch, sedge, horsetail, reed, and among the shrubs - wild rosemary). Lowland swamps are widespread in forest belts on the floodplains of large rivers.

Under certain conditions, lowland swamps can turn into riding. As peat grows, the amount of mineral substances decreases, and plants that are demanding of mineral food give way to less demanding plants. Typically these plants appear in the center of the bog (sphagnum mosses). They secrete organic acids that slow down the breakdown of plant matter. Elevations arise from peat. Water flowing into the swamp can no longer reach the center, where sphagnum mosses grow, feeding on atmospheric moisture. Raised bogs occur on poorly dissected watersheds.

Swamps occupy vast spaces. Approximately 1/10 of the territory of our country is covered with swamps. There are vast areas of swamps in the Pskov, Novgorod regions, Meshchera and Western Siberia, and there are many swamps in the tundra.

Peat is extracted from the swamps, which is used as fuel and fertilizer.

List of used literature

1. Arutsev A.A., Ermolaev B.V., Kutateladze I.O., Slutsky M. Concepts of modern natural science. With study guide. M. 1999

2. Petrosova R.A., Golov V.P., Sivoglazov V.I., Strout E.K. Natural science and basic ecology. Textbook for secondary pedagogical educational institutions. M.: Bustard, 2007, 303 pp.

3. Savchenko V.N., Smagin V.P.. The beginnings of modern natural science. Concepts and principles. Tutorial. Rostov-on-Don. 2006.