Surface runoff (rivers, lakes and other bodies of water), underground runoff (underground and groundwater), glacial waters, precipitation, which are sources of water to meet economic and domestic needs. Water is a unique type of resource. It combines the nature of both exhaustible (groundwater) and inexhaustible (surface runoff) reserves. Water in nature is in continuous movement, so its distribution over the territory, seasons and years is subject to significant fluctuations.

Russia has significant reserves of fresh water. River waters are most widely used in the national economy. The rivers of Russia belong to the basins of three oceans, as well as to the internal Caspian basin, which occupies most of the European part of Russia. Most of the rivers in Russia belong to the Arctic Ocean basin. The rivers flowing into the northern seas are the longest and deepest. The longest river is the Lena (4400 km), the deepest river is the Yenisei. In the southern parts of Siberia the rivers are swift and rapid. The largest hydroelectric power stations in the country were built on these sections - Krasnoyarsk and Sayano-Shushenskaya on the Yenisei, Novosibirsk on the Ob, Irkutsk, Bratsk, Ust-Ilimsk on the Angara, etc. The rivers of the European part of the Arctic Ocean basin - Pechora, Mezen, Northern Dvina, Onega - are much shorter than Siberian rivers. To the pool Pacific Ocean include many rivers. The main rivers of this basin are the Amur and its tributaries the Zeya, Bureya, and Ussuri.

Pool Atlantic Ocean occupies the smallest area of ​​the entire country. Rivers flow west to the Baltic Sea (Neva) and south to the Azov and Black Sea (Don, Kuban, etc.). The Neva occupies a special place. This short river (74 km) carries a huge amount of water - four times more than the Dnieper, which is over 2000 km long.

Most of European Russia is occupied by the internal basin of the Caspian Sea. The rivers Volga, Ural, Terek and others flow into the Caspian Sea. In European Russia, the longest river is the Volga (3530 km). There are many hydroelectric power stations on the Volga: Volzhskaya named after. Lenin, Saratov, Volzhskaya named after. XXI Congress of the CPSU, etc.

The main consumers of water resources in our country are water supply, hydropower, and artificial irrigation.

Water supply - totality different ways use of water resources by industry, public utilities and population with a large share irretrievable losses and varying degrees of pollution. It is this aspect of water use that creates the problem of qualitative deterioration and reduction of water reserves, which becomes increasingly aggravated as production grows. Solving it requires the redistribution of water resources between regions, careful use of reserves, construction of treatment facilities, wide application closed loops water use, etc.

Hydropower uses the energy of flowing water, the reserves of which are then completely returned to the watercourse. Russia has the world's largest hydropower reserves, which account for about 1/10 of the world's reserves. Russia's hydropower resources are distributed unevenly. Most of them are in Siberia and Far East, with the main hydropower reserves concentrated in the basins of the Yenisei, Lena, Ob, Angara, Irtysh and Amur rivers. The Lena ranks first among Russian rivers in terms of hydropower reserves. The rivers of the North Caucasus are rich in hydropower resources. A significant part of the country's technically possible hydropower resources is located in the Volga and Central regions of Russia, where the hydropower reserves of the Volga basin are especially large.

River flow and glacier resources are used for artificial irrigation. The main irrigation areas are dry areas: North Caucasus, Trans-Volga region.

USE AND PROTECTION OF WATER BODIES.

Water resources represent a very important part of the natural resources used by humans, which also include land resources, mineral resources (including fuel and energy and other minerals), plant resources (for example, forest resources), animal resources, solar energy, wind energy, intra-terrestrial warmth, etc.

Water resources in a broad sense are all the natural waters of the Earth, represented by the waters of rivers, lakes, reservoirs, swamps, glaciers, aquifers, oceans and seas. Water resources in a narrower sense are natural waters that are currently used by humans and can be used in the foreseeable future (definition by S. L. Vendrov). A similar formulation is given in the Water Code of the Russian Federation: “water resources are the reserves of surface and groundwater located in water bodies that are used or can be used.” In this interpretation, water resources are not only a natural category, but also a socio-historical one.

The most valuable water resources are freshwater reserves (this is the narrowest concept of water resources). Freshwater resources consist of so-called static (or secular) water reserves and continuously renewable water resources, i.e. river flow.

Static (secular) freshwater reserves are represented by a part not subject to noticeable annual changes water volumes lakes, glaciers, groundwater. These reserves are measured in volumetric units (m 3 or km 3).

Renewable water resources are those waters that are restored annually through the water cycle on the globe. This type of water resource is measured in runoff units (m 3 /s, m ​​3 /year, km 3 /year)

Renewable water resources are often assessed using a water balance equation. Thus, in general, for land, precipitation, continental runoff and evaporation amount to 119, 47 and 72 thousand km 3 of water per year, respectively. Thus, on average for the entire landmass, of the total volume of atmospheric precipitation, 61% is spent on evaporation, and 39% enters the World Ocean. Continental runoff constitutes the globe's renewable water resources. More often, however, only the part of continental runoff represented by river flow (41.7 km 3 of water per year, or 35% of atmospheric precipitation on the planet) is considered renewable water resources. River water flow is truly an annually renewable natural resource that can (up to some limits, of course) be withdrawn for economic use. In contrast, static (secular) water reserves in lakes, glaciers, aquifers cannot be withdrawn for economic needs without causing damage to either the water body in question or the rivers associated with it. What are the main features of water resources that distinguish them from other natural resources?

First. Water as a substance has unique properties and, as a rule, cannot be replaced by anything. Many other natural resources can be substituted, and as civilization and the technological capabilities of human society developed, such substitution began to be used more and more widely.

In ancient times, only wood was most often used as a building material. In Rus', for example, not only huts were built from wood, but also temples, bridges and dams. Later, wood as a building material was replaced first by brick, and then by concrete, steel, glass, and plastic. Wood was also used as fuel. Then they began to replace it with coal, then with oil and gas. There is no doubt that in the future, as the reserves of these minerals are depleted, the main sources of energy resources will be nuclear, thermonuclear and solar energy, energy of tides and sea waves. Currently, attempts are being made to create artificial soil for growing plants, and to replace some food products with synthetic analogues.

With water the situation is much worse. Practically nothing can replace drinking water - both for humans and animals. Nothing can replace water when irrigating land, for feeding plants (after all, the capillaries of plants by nature are “designed” only for water), as a mass coolant, in many industries, etc.

Second. Water is an inexhaustible resource. Unlike the previous feature, this one turns out to be very favorable. In the process of using minerals, for example, when burning wood, coal, oil, gas, these substances, turning into heat and producing ash or gaseous waste, disappear. Water, when used, does not disappear, but only passes from one state to another (liquid water turns into water vapor) or moves in space - from one place to another. When heated and even when boiling, water does not decompose into hydrogen and oxygen. The only case of actual disappearance of water as a substance is the binding of water with carbon dioxide (carbon dioxide) in the process of photosynthesis and formation organic matter. However, the volumes of water used for the synthesis of organic matter are very small, as well as small losses of water leaving the Earth into outer space. It is also believed that these losses are fully compensated by the formation of water during degassing of the Earth's mantle (about 1 km 3 of water per year) and when water enters from space along with icy meteorites.

The term “irrecoverable water consumption” used in the water industry must be understood as follows: for a specific section of a river (maybe even for the entire river basin), lake or reservoir, water withdrawal for economic needs (irrigation, water supply, etc.) can indeed become irrevocable. The collected water is partially later evaporated from the surface of irrigated lands or during industrial production. However, according to the law of conservation of matter, the same volume of water should fall in the form of precipitation in other regions of the planet. For example, significant water intake in the basins of the Amudarya and Syrdarya rivers, which led to the depletion of the flow of these rivers and the shallowing of the Aral Sea, is inevitably accompanied by an increase in precipitation in the vast mountainous areas of Central Asia. Only the consequences of the first process - a decrease in the flow of the mentioned rivers - are clearly visible to everyone, but an increase in river flow over a vast territory is almost impossible to notice. Thus, “irretrievable” water losses apply only to a limited space; in general, for the continent, and especially the entire planet, there cannot be an irreversible waste of water. If water disappeared without a trace during use (like coal or oil when burned), then there could be no talk of any development of humanity on the globe.

Third. Fresh water is a renewable natural resource. This restoration of water resources is carried out in the process of a continuous water cycle on the globe.

The renewal of water resources in the process of the water cycle, both in time and space, occurs unevenly. This is determined both by changes in meteorological conditions (precipitation, evaporation) over time, for example, by seasons, and by spatial heterogeneity climatic conditions, in particular, latitudinal and altitudinal zoning, so water resources on the planet are subject to great spatiotemporal variability. This feature often creates a shortage of water resources in some areas of the globe (for example, in arid areas, in places with high economic water consumption), especially during low-water periods of the year. All this forces people to artificially redistribute water resources in time, regulating river flow, and in space, transferring water from one area to another.

Fourth. Water is a multi-purpose resource. Water resources are used to satisfy a wide variety of human economic needs. Often water from the same water body is used by different sectors of the economy.

Fifth. Water is mobile. This difference between water resources and other natural resources has a number of significant consequences.

Firstly, water can naturally move in space - along the earth's surface and in the soil, as well as in the atmosphere. In this case, water can change its state of aggregation, passing, for example, from liquid to gaseous (water vapor), and vice versa. The movement of water on Earth creates the water cycle in nature.

Secondly, water can be transported (via canals, pipelines) from one area to another.

Thirdly, water resources “do not recognize” administrative ones, including state borders. It could even create complex interstate problems. They can arise when using water resources of border rivers and rivers flowing through several states (with the so-called transboundary water transfer).

Fourthly, being mobile and participating in the global cycle, water transports sediment, dissolved substances, including pollutants, and heat. And although a complete cycle of sediment, salts and heat does not occur (unilateral transfer from land to the ocean predominates), the role of rivers in the transfer of matter and energy is very large.

A natural question arises: is the movement of pollutants along with water good or bad for nature? On the one hand, pollutants that enter the water, for example oil as a result of imperfect production technology, a rupture of an oil pipeline or a tanker accident, can be transported over long distances along with water (river, sea currents). This undoubtedly contributes to the spread of pollutants in space and pollution of adjacent waters and shores. But, on the other hand, flowing water removes harmful substances from the area of ​​pollution, purifying it, and contributes to the dispersion and decomposition of harmful impurities. In addition, flowing waters have the ability to “self-purify”.

Water resources of parts of the world.

Fresh water reserves of all continents, with the exception of Antarctica, are about 15 million. km 2. They are concentrated primarily in the upper layer earth's crust, in large lakes and glaciers. Water resources are distributed unevenly between continents. The largest static (secular) freshwater resources are found in North America and Asia, and to a lesser extent - South America and Africa. Europe and Australia and Oceania are the least rich in this type of resource.

Renewable water resources - river flow - are also unevenly distributed around the globe. The largest flow is in Asia (32% of the flow of all rivers on the planet) and South America (26%), the smallest is in Europe (7%) and Australia and Oceania (5%). The water availability of the territory per 1 km 2 is greatest in South America and lowest in Africa. The population is most provided with river water (per capita) in South America and on the islands of Oceania, in the least - the population of Europe and Asia (77% of the planet's population and only 37% of the world's reserves of annually renewable fresh water are concentrated here) (Table 12 )

Table 12. Water resources of parts of the world"

Part of the world	Centuries-old fresh water reserves, thousand km 2	Renewable water resources (river flow)	Water availability of the territory, thousand m 3 /year per 1 km 2
km 3 /year	%
Europe			7,2
Asia			32,3
Africa			10,3
North America			18,4
South America			26,4
Australia and Oceania			5,4

Water availability for both territory and population varies significantly within individual continents depending on climatic conditions and population distribution. For example, in Asia there are areas both well supplied with water (Eastern Siberia, the Far East, Southeast Asia) and those experiencing its shortage (Central Asia, Kazakhstan, the Gobi Desert, etc.).

Of the countries in the world, Brazil is the most endowed with river water resources - 9230, Russia -4348, USA -2850, China -2600 km 3 of water per year.

According to estimates of the Intergovernmental Panel on Climate Change, in the 21st century. changes are expected in the distribution of water resources on the globe. Water resources will increase in the high latitudes of the Northern Hemisphere, in Southeast Asia, and decrease in Central Asia, southern Africa, and Australia. The main conclusion of the IPCC report (2001) is as follows: climate change will lead to the 21st century. to a significant reduction in available water resources in those areas of the planet where they are already lacking. The problem of fresh water shortage will worsen in many areas with scarce water resources. The demand for water will increase as the population grows and economic development countries

Water resources of Russia.

Russian Federation In terms of total fresh water reserves, it ranks first among the countries of the world and is second only to Brazil in terms of renewable water resources - river flow.

Renewable water resources. The average long-term value of Russia's renewable water resources (i.e. river flow) is 4348 km 3 /year. From this value, a runoff with a volume of 4113 km 3 is formed annually on the territory of Russia; an additional 235 km 3 /year comes from outside the country (this is, for example, for the Irtysh, some tributaries of the Amur, Selenga and other rivers flowing from neighboring countries) (Table 13).

A number of scientists explain the increase in river flow and renewable water resources in Russia over the past 20 years by the intensification of atmospheric circulation, the mixing of the cyclone trajectory to the south and the increase in the frequency of cyclones of Atlantic origin with increased content moisture, an increase in the amount of precipitation (mainly winter), which is ultimately a consequence of general climate warming.

The specific water supply in Russia currently averages 255 thousand m 3 /year on 1 km 2 of territory. There are about 30 thousand m 3 /year per resident of Russia (approximately the same as in 1980).

Despite the generally favorable state of Russia's renewable water resources, in a number of areas there are serious problems with water supply to the population and economy. These problems are related to the extremely uneven and inappropriate distribution of water resources.

Table 13.Water resources of Russian regions

Economic region	Territory area, thousand km 2	Average annual volume, km 3 /year
Local runoff	Influx from outside	Shared Resources
total	From abroad
Northern			18,3	8,24
Northwestern			64,5	38,2
Central			24,9	0,52
Central Black Earth			5,05	0,27
Volgo-Vyatsky
Povolzhsky
North Caucasian			25,1	6,27
Ural			7,03	0,55
West Siberian			78,7	28,84
East Siberian				32,2
Far Eastern
Russian Federation

The Siberian and Far Eastern federal districts are well supplied with water, the Ural and Northwestern federal districts are to a lesser extent, and the Volga, Central and Southern federal districts are the worst.

Static (secular) water resources of Russia. According to RosNIIVKh estimates (2000), they are represented by water reserves in fresh lakes (26.5 thousand km 3, of which Baikal accounts for 23 thousand km 3, or 87%); in glaciers (15.1 thousand km 3); swamps (3 thousand km 3); fresh groundwater (28 thousand km 3); underground ice(15.8 thousand km 3). The full and useful volume of large reservoirs in Russia, according to the State Hydrological Institute, in the 80s of the 20th century. was 810 and 364 km 3, respectively.

Thus, the total static (secular) fresh water reserves of Russia are about 90 thousand km 3.

Potential hydropower resources rivers are defined by their individual sections e i = a Q i, Where Qi– average water flow in the area, – river fall in the area, a– dimension factor. Potential energy resources for the entire river uh = ∑e i.

In the use of water, a distinction is made between water consumption and water use. Water consumption- withdrawal of water from natural water bodies with its further partial return after use. Unreturned part - consumptive water consumption.

Water use– use of water without withdrawal from water bodies.

Water balance- the relationship between various sources of water resources and types of water consumption for a particular territory, as well as for individual enterprises or economic complexes.

Water balance deficit– lack of water resources to ensure the development of the economy and household needs of the population, taking into account the provision of environmental well-being in general for the year or in certain periods of the year. Ways to overcome it are regulating flow, transferring water from other areas, saving water resources by changing economic technology (rational irrigation methods, introducing closed industrial water supply systems, etc.).

The most important factor ecological state water bodies - water quality in them. To evaluate it, hydrobiological, hydrochemical, sanitary and hygienic, and medical indicators are used.

The most common hydrobiological indicators include estimates of the proportion in the biological community of organisms that are resistant to water pollution (“indicator organisms,” for example, oligochaetes), as well as species diversity biological community.

Assessment of water quality based on hydrochemical indicators is carried out by comparing the concentration of pollutants in a water body with their maximum permissible concentrations (MPC). Pollutants include substances that have a harmful effect on humans and aquatic organisms, or limit the ability to use water for household needs. Often small amounts of the same substances are necessary for normal development aquatic organisms. For different types use, their own maximum permissible concentrations are established.

The main sanitary indicator is the coli index, i.e. the number of E. coli in 1 cm 3 of water.

Medical indicators are based on statistical data on the health problems of the population using the water of a particular water body.

Sources of pollution natural waters:

– wastewater from housing and communal services and industrial enterprises, livestock farms;

– washing away of contaminants from the territory of industrial zones with melt and rainwater and residential developments, from agricultural fields, from the territory of livestock farms;

– shipping and timber rafting;

– recreational use of rivers and reservoirs;

– fish farming;

– emergency pollution caused by the breakdown of pipelines, dams of wastewater settling tanks, destruction of treatment facilities, etc.;

–household pollution– dumping garbage into the river, washing cars, etc.

Measures to improve water quality:

• creation of new and improvement of existing water treatment facilities;
• transition to industrial recycling water supply;
• introduction of new less water-intensive technologies in industrial production;
• introduction of the most rational methods of irrigation;
• improvement of techniques for applying fertilizers, pesticides, herbicides; replacement existing drugs less harmful to humans.

If you look at our planet from space, the Earth appears as a blue ball completely covered with water. And the continents are like small islands in this endless ocean. This is understandable. Water occupies 70.8% of the planet's surface, leaving only 29.2% of land. The watery shell of our planet is called the hydrosphere. Its volume is 1.4 billion cubic meters.

Water appeared on our planet about 3.5 billion years ago in the form of vapor that was formed as a result of degassing of the mantle. Currently, water is the most important element in the Earth's biosphere, since it cannot be replaced by anything. Fortunately, water resources are considered inexhaustible because scientists have come up with a way to desalinate salt water.

The main purpose of water as a natural resource is to support the life of all living things - plants, animals and humans. It is the basis of all life on our planet, the main supplier of oxygen in important process on Earth - photosynthesis.

Water - most important factor climate formation. By absorbing heat from the atmosphere and releasing it back, water regulates climate processes.

It is impossible not to note the role water sources in the modification of our planet. From time immemorial, people have settled near reservoirs and water sources. Water serves as one of the main means of communication. There is an opinion among scientists that if our planet were entirely dry land, then, for example, the discovery of America would be delayed for several centuries. And we would hardly have learned about Australia for another 300 years.

Types of Earth's water resources

The water resources of our planet are the reserves of all water. But water is one of the most common and most unique compounds on Earth, since it is present in three states at once: liquid, solid and gaseous. Therefore, the Earth's water resources are:

. Surface waters (oceans, lakes, rivers, seas, swamps)

. Groundwater.

. Artificial reservoirs.

. Glaciers and snowfields (frozen water from glaciers in Antarctica, the Arctic and highlands).

. Water contained in plants and animals.

. Atmospheric vapors.

The last 3 points relate to potential resources, because humanity has not yet learned to use them.

Fresh water is the most valuable; it is used much more widely than sea, salt water. Of the total water reserves in the world, 97% of water comes from seas and oceans. 2% of fresh water is contained in glaciers, and only 1% is fresh water reserves in lakes and rivers.

Use of water resources

Water resources - essential component and human life. People use water in industry and at home.

According to statistics, most water resources are used in agriculture (about 66% of all fresh water reserves). About 25% is used by industry and only 9% goes to meet the needs of utilities and households.

For example, to grow 1 ton of cotton, about 10 thousand tons of water are needed, for 1 ton of wheat - 1,500 tons of water. To produce 1 ton of steel requires 250 tons of water, and to produce 1 ton of paper you need at least 236 thousand tons of water.

A person needs to drink at least 2.5 liters of water per day. However, on average, 1 person in large cities spends at least 360 liters per day. This includes the use of water in sewers, water supply, for watering streets and extinguishing fires, for washing vehicles, etc., etc.

Another option for using water resources is water transport. Every year, over 50 million tons of cargo are transported across Russian waters alone.

Don't forget about fisheries. Marine and freshwater fish plays an important role in the economies of countries. Moreover, fish farming requires clean water saturated with oxygen and free of harmful impurities.

An example of the use of water resources is also recreation. Who among us doesn’t like to relax by the sea, barbecue on the river bank or swim in the lake? In the world, 90% of recreational facilities are located near water bodies.

Water conservation

Today there are only two ways to conserve water resources:

1. Preservation of existing fresh water reserves.

2. Creation of more advanced collectors.

The accumulation of water in reservoirs prevents its flow into the world's oceans. And storing water, for example, in underground cavities, allows you to protect water from evaporation. The construction of canals allows us to solve the issue of delivering water without it seeping into the ground. New methods of irrigating agricultural land are also being developed that make it possible to use wastewater.

But each of these methods has an impact on the biosphere. Thus, the reservoir system prevents the formation of fertile silt deposits. The canals impede the replenishment of groundwater. And water filtration in canals and dams is the main risk factor for swamps, which leads to disturbances in the planet’s ecosystem.

Today is the most effective measure Water conservation is considered a wastewater treatment method. Various ways allow you to remove up to 96% of harmful substances from water. But this is often not enough, and the construction of more advanced treatment facilities often turns out to be economically unprofitable.

Water pollution problems

Population growth, development of production and agriculture - these factors have led to a shortage of fresh water for humanity. The share of polluted water resources is growing every year.

Main sources of pollution:

. Industrial wastewater;

. Wastewater utility routes;

. Drains from fields (when the water is oversaturated with chemicals and fertilizers);

. Burial in reservoirs radioactive substances;

. Drains from livestock complexes (such water contains a lot of biogenic organic matter);

. Shipping.

Nature provides for the self-purification of reservoirs, which occurs due to the water cycle in nature, due to the life activity of plankton, irradiation ultraviolet rays, sedimentation of insoluble particles. But all these processes can no longer cope with the mass of pollution that human activity brings to the planet’s water resources.

...glaciers, groundwater...

Most of the world's reserves water make up salty water world ocean, the reserves of fresh water technically accessible to humans account for only 0.3% of all water resources on Earth.

World water resources - the big picture

With the Earth's water resources, the overall picture is:

• total volume water resources is 1,390,000,000 cubic meters. km;
• less than 3% of the earth's water resources are fresh water;
• 0.3% of available fresh water is the water of rivers, lakes...ground and underground.

Parts of the hydrosphere

Stationary water resources of the world according to M. I. Lvovich:

• World Ocean:
  • Volume of water, thousand km 3 - 1,370,000;
  • Water exchange activity, number of years - 3,000.
• Groundwater:
  • Volume of water, thousand km 3 - ~ 60,000;
• Groundwater... including zones of active exchange:
  • Volume of water, thousand km 3 - ~ 4,000;
  • Water exchange activity, number of years - ~ 330.
• Glaciers:
  • Volume of water, thousand km 3 - 24,000;
  • Water exchange activity, number of years - 8,600.
• Lakes:
  • Volume of water, thousand km 3 - 230;
  • Water exchange activity, number of years - 10.
• Soil moisture:
  • Volume of water, thousand km 3 - 82;
  • Water exchange activity, number of years - 1.
• River (channel) waters:
  • Volume of water, thousand km 3 - 1.2;
  • Water exchange activity, number of years - 0.032.
• Atmospheric vapors:
  • Volume of water, thousand km 3 - 14;
  • Water exchange activity, number of years - 0.027.

Water exists in natural natural conditions in three basic states - ice, liquid and steam, due to which there is a constant circulation and redistribution of water resources - the water cycle in nature (the continuous movement of water in the hydrosphere, atmosphere, lithosphere). Under the influence of heat, liquid water evaporates, the steam, in turn, rises into the atmosphere, where it condenses and returns to the earth in the form of precipitation - rain, snow, dew... part of the water accumulates in glaciers, which in turn return part of the water again to a liquid state.

It should be noted that 98% of all fresh water liquid water accounts for groundwater.

Water resources and ecology

Note important fact — total quantity water in nature remains unchanged. However, it is necessary to understand that the active activities of mankind lead to environmental deterioration and upset the balance of the planet’s ecosystems, and this in turn significantly reduces the quantity and availability of clean drinking water, necessary for a person for a healthy and quality life.

In some regions of the planet, intensive human economic activity is already leading to a noticeable shortage of fresh water. This is especially noticeable in those regions that previously experienced a lack of fresh water due to natural reasons.

Maintaining a system that guarantees the sustainable replenishment of clean drinking water on our planet is an important condition development of modern civilization.

And finally, some more background information.

River flow by parts of the world

• Europe:
  • Volume of annual runoff, km 3 - 2,950;
  • Drain layer, mm - 300.
• Asia:
  • Volume of annual runoff, km 3 - 12,860;
  • Drain layer, mm - 286.
• Africa:
  • Volume of annual runoff, km 3 - 4,220;
  • Drain layer, mm - 139.
• North and Central America:
  • Volume of annual runoff, km 3 - 5,400;
  • Drain layer, mm - 265.
• South America:
  • Volume of annual runoff, km 3 - 8,000;
  • Drain layer, mm - 445.
• Australia, including Tasmania, New Guinea and New Zealand:
  • Volume of annual runoff, km 3 - 1,920;
  • Drain layer, mm - 218.
• Antarctica and Greenland:
  • Volume of annual runoff, km 3 - 2,800;
  • Drain layer, mm - 2,800.
• All land:
  • Volume of annual runoff, km 3 - 38,150;
  • Drain layer, mm - 252.

Balance assessment of water resources. Sources of Water Resources

• Total river flow:
  • All land, km 3 - 38,150;
  • All land, mm - 260.
• Underground drain:
  • All land, km 3 - 12,000*;
  • All land, mm - 81.
• Evaporation:
  • All land, km 3 - 72,400;
  • All land, mm - 470.
• Atmospheric precipitation:
  • All land, km 3 - 109,400;
  • All land, mm - 730.
• • All land, km 3 - 26,150;
  • All land, mm - 179.
• Surface (flood) runoff:
  • All land, km 3 - 82,250;
  • All land, mm - 551.

Water resources are the reserves of surface and groundwater located in water bodies that are used or can be used.
Water occupies 71% of the Earth's surface. 97% of water resources are salt water and only 3% are fresh water. Water is also found in soil and rocks, in plants and animals. Large quantity water is constantly in the atmosphere.
Water is one of the most valuable natural resources. One of the main properties of water is its irreplaceability. On my own nutritional value it does not have, but it has an exceptional role in the metabolic processes that form the basis of the life activity of all life on Earth, determining its productivity.
Daily requirement man in the water normal conditions is about 2.5 liters.
Water has a high heat capacity. Absorbing a huge amount of thermal cosmic and intraterrestrial energy and slowly releasing it, water serves as a regulator and stabilizer of climate processes, softening strong temperature fluctuations. Evaporating from water surfaces, it turns into a gaseous state and is transported by air currents to various regions of the planet, where it falls in the form of precipitation. Glaciers have a special place in the water cycle, since they retain moisture in a solid state very long time(for thousands of years). Scientists have concluded that the water balance on Earth is almost constant.
For many millions of years, water activates soil formation processes. It greatly cleanses the environment by dissolving and removing contaminants.
Lack of water can slow down economic activity, reduce production efficiency. IN modern world water acquired independent importance as an industrial raw material, often scarce and very expensive. Water is mandatory component almost everyone technological processes. Water of special purity is needed in medicine, food production, nuclear technology, semiconductor production, etc. Huge amounts of water are spent on people’s domestic needs, especially in big cities.
The predominant part of the earth's waters is concentrated in the World Ocean. This is a rich storehouse of mineral raw materials. For every 1 kg of ocean water there are 35 g of salts. IN sea ​​water contains more than 80 elements Periodic table DI. Mendeleev, the most important of which for economic purposes are tungsten, bismuth, gold, cobalt, lithium, magnesium, copper, molybdenum, nickel, tin, lead, silver, uranium.
The world ocean is the main link in the water cycle in nature. It releases most of the evaporated moisture into the atmosphere. Absorbing a huge amount of thermal energy and slowly releasing it, ocean waters serve as a regulator of climate processes on a global scale. The heat of the oceans and seas is spent on maintaining the vital activity of marine organisms, which provide food, oxygen, medicines, fertilizers, and luxury goods to a significant part of the planet's population.
Aquatic organisms inhabiting surface layer The oceans provide the return of a significant part of the planet's free oxygen to the atmosphere. This is extremely important, since vehicles and oxygen-intensive metallurgical and chemical production often consume more oxygen than the nature of individual regions can compensate.
Fresh waters on land include glacial, underground, river, lake, and swamp waters. A renewable resource of strategic importance in recent years becomes drinking water good quality. Its shortage is explained by a significant deterioration in the general environmental situation around the sources of this resource, as well as tightening worldwide requirements for the quality of consumed water, both for drinking and for high-tech industries.
The bulk of fresh water reserves on land are concentrated in the ice sheets of Antarctica and the Arctic. They represent a huge reservoir of fresh water on the planet (68% of all fresh water). These reserves are preserved for many millennia.
The chemical composition of groundwater is very different: from fresh to water with high concentrations minerals.
Fresh surface water have a significant ability for self-cleaning, which is provided by the Sun, air, micro-

roorganisms and oxygen dissolved in water. Nevertheless, fresh water is becoming the major shortage on the planet.
Swamps contain 4 times more water than the world's rivers; 95% of swamp water is located in peat layers.
The atmosphere contains water mainly in the form of water vapor. Its bulk (90%) is concentrated in the lower layers of the atmosphere, up to a height of 10 km.
Fresh water is distributed unevenly across the Earth. The problem of supplying the population drinking water It is very acute and has become increasingly worse in recent years. About 60% of the Earth's surface is made up of zones where fresh water is either absent, severely deficient, or of poor quality. Approximately half of humanity experiences a shortage of drinking water.
Fresh surface waters (rivers, lakes, swamps, soil and groundwater) are subject to the most severe pollution. Most often, sources of pollution are insufficiently treated or not treated at all discharges from production facilities (including hazardous ones), discharges big cities, wastewater from landfills.
Pollution environment in the Volga basin is 3-5 times higher than the national average. Not a single city on the Volga is provided with
quality drinking water. There are many environmentally hazardous industries and enterprises in the basin without treatment facilities.
The exploitable reserves of explored groundwater deposits in Russia are estimated at approximately 30 km/year. The degree of development of these reserves currently averages just over 30%.