Water resources of the earth. Water resources and their importance

WATER RESOURCES LAND

Until relatively recently, water, like air, was considered one of the free gifts of nature, only in areas of artificial irrigation it always had a high price. Recently, the attitude towards land water resources has changed. This is explained by the fact that fresh water resources make up only 2.5% of the total volume of the hydrosphere. In absolute terms, this is a huge value (30-35 million m 3), which exceeds the current needs of mankind by more than 10 thousand times! However, the vast majority of fresh water is, as it were, conserved in the glaciers of Antarctica, Greenland, in the ice of the Arctic, in mountain glaciers and forms a kind of "emergency reserve" that is not yet available for use.

Indicators:
96.5% - salty waters of the oceans; 1% - saline groundwater; 2.5% - fresh water resources.

Fresh water: 68.7 - glaciers; 30.9% - groundwater.

Table 11. Distribution of world fresh water resources by major regions.

The data in this table allow us to draw interesting conclusions. First of all, about the extent to which the ranking of countries according to the first indicator does not coincide with their ranking according to the second. It can be seen that Asia has the largest fresh water resources, and the smallest - Australia and Oceania, while in terms of their specific provision they change their places. Of course, it's all about the population, which in Asia has already reached 3.7 billion people, and in Australia it barely exceeds 30 million. If we discount Australia, then South America will be the region of the world most provided with fresh water. And it is no coincidence, because it is here that the Amazon is located - the most full-flowing river in the world.

Individual countries differ even more in terms of reserves and availability of fresh water. Based on the principle of "most-most", we will show which of them belong to the category of the richest and poorest in fresh water.

Table 12. Top ten countries by freshwater resources.

In it, too, the ranking of resources does not coincide with the ranking of the specific endowment, and in each individual case, such a difference can be explained. For example, in China and India - a huge population, therefore - low security per capita. But there are also countries in the world that are even less provided with fresh water, where per capita there is less than 1 thousand m 3 of water (that is, the amount that a resident of a large European or American city consumes in about two days). The most striking examples of this kind can be found in the Saharan part of Africa (Algeria - 520 m 3, Tunisia - 440 m 3, Libya - 110 m 3) and in the region of the Arabian Peninsula (Saudi Arabia - 250 m 3, Kuwait - 100 m 3).

These individual examples are interesting in that they allow us to make an important generalization: at the end of the 20th century. Approximately 2/5 of the population of our planet experience a chronic lack of fresh water. In this case, we are talking mainly about those developing countries that are located in the arid belt of the Earth. One cannot ignore the fact that even the available fresh water in these countries is so polluted that it is the main cause of most diseases.

The main consumer of fresh water is agriculture, where irretrievable water consumption is very high, especially for irrigation. Industrial-energy and municipal water consumption is also growing all the time. In economically developed countries, a city dweller uses 300-400 liters of water per day. Such an increase in consumption with constant river runoff resources creates a real threat of fresh water shortages.

In this case, it is necessary to take into account not only the quantity, but also the quality of water. In developing countries, every third inhabitant suffers from a lack of drinking water. The consumption of polluted water is the source of 3/4 of all diseases and 1/3 of all deaths. More than 1 billion people in Asia lack access to clean water, 350 million in sub-Saharan Africa and 100 million in Latin America.

But, in addition, fresh water reserves on Earth are distributed extremely unevenly. In the equatorial zone and in the northern part of the temperate zone, it is available in abundance and even in excess. The most water-abundant countries are located here, where more than 25 thousand m 3 per capita per year. In the arid belt of the Earth, which covers about 1/3 of the land area, water shortage is felt especially acutely. The countries with the least water per capita are located here, where per capita is less than 5 thousand m 3 per year, and agriculture is possible only with artificial irrigation.

There are several ways to solve the water problem of mankind. The main one is the reduction of the water intensity of production processes and the reduction of irretrievable water losses. First of all, this applies to such technological processes as the production of steel, synthetic fiber, cellulose and paper, to the cooling of power units, to the irrigation of rice and cotton fields. Of great importance for solving the water problem is the construction of reservoirs that regulate river flow. Over the past fifty years, the number of reservoirs on the globe has increased by about 5 times. In total, more than 60 thousand reservoirs have been created in the world, the total volume of which (6.5 thousand km 3) is 3.5 times greater than the one-time volume of water in all the rivers of the globe. Taken together, they occupy an area of ​​400 thousand km 2, which is 10 times the area of ​​the Sea of ​​Azov. Such large rivers as the Volga, Angara in Russia, Dnieper in Ukraine, Tennessee, Missouri, Columbia in the USA, and many others, have actually turned into cascades of reservoirs. A particularly important role in the transformation of river runoff is played by large and largest reservoirs. The problem is that the main source of meeting the needs of mankind in fresh water has been and remains river (channel) water, which determines the "water ration" of the planet - 40 thousand km3. It is not so significant, especially considering that about 1/2 of this amount can actually be used.

According to the number of large reservoirs, the United States, Canada, Russia, some countries of Africa and Latin America stand out.

Table 13. Largest reservoirs in the world by volume of water (countries)

In the USA, Canada, Australia, India, Mexico, China, Egypt, and a number of CIS countries, numerous projects have been implemented or are being planned for the territorial redistribution of river flow with the help of its transfer. However, most major inter-basin transfer projects have recently been canceled for economic and environmental reasons. In the countries of the Persian Gulf, the Mediterranean, in Turkmenistan, on the Caspian Sea, in the south of the USA, in Japan, on the Caribbean islands, sea water desalination is used; the world's largest producer of such water is Kuwait. Fresh water has already become a commodity of world trade: it is transported in sea tankers, along long-distance water pipelines. Projects are being developed to tow icebergs from Antarctica, which each polar summer sends 1200 million tons of fresh water preserved in them to the countries of the arid zone.

You know that river runoff is also widely used to generate hydropower. World hydropower potential, suitable for use, is estimated at almost 10 trillion kWh. possible power generation. About 1/2 of this potential falls on only 6 countries: China, Russia, USA, Congo (former Zaire), Canada, Brazil.

Table 14 . World economic hydro potential and its use

The most important component of Russia's water resources is rivers. The center of the state territory of Russia was determined by the upper reaches of the rivers, the area of ​​\u200b\u200bthe territory. - their mouths, resettlement - the direction of river basins. Rivers have influenced our history in many ways. On the river, the Russian man came to life. During the resettlement, the river showed him the way. During a significant part of the year she fed. For a merchant, it is a summer and winter road.

The Dnieper and Volkhov, Klyazma, Oka, Volga, Neva, and many other rivers entered the history of Russia as places of the most important events in the life of the country. It is no coincidence that rivers occupy a prominent place in the Russian epic.

On the geographical map of Russia, an extensive river network attracts attention.
There are 120,000 rivers in Russia over 10 km long, including more than 3,000 medium (200-500 km) and large (more than 500 km) rivers. The annual river runoff is 4270 km3 (including 630 km3 in the Yenisei basin, 532 in the Lena, 404 in the Ob, 344 in the Amur, and 254 in the Volga River). Generic river runoff is taken as the initial value when assessing the country's water supply.

Reservoirs have been created on many rivers, some of which are larger than large lakes.

Russia's huge hydropower resources (320 million kW) are also unevenly distributed. More than 80% of the hydropower potential is located in the Asian part of the country.

In addition to the function of water storage for the operation of hydroelectric power stations, reservoirs are used for watering land, water supply for the population and industrial enterprises, shipping, timber rafting, flood control, and recreation. Large reservoirs change natural conditions: they regulate the flow of rivers, affect the climate, conditions for fish spawning, etc.

Russian lakes, which are more than 2 million, contain more than half of the country's fresh water. At the same time, about 95% of lake water in Russia is in Baikal. There are relatively few large lakes in the country, only 9 of them (excluding the Caspian) have an area of ​​\u200b\u200bmore than 1 thousand km2 - Baikal, Ladoga, Onega, Taimyr, Khanka, Chudsko-Pskovskoye, Chany, Ilmen, Beloe. Navigation is established on large lakes, their water is used for water supply and irrigation. Some of the lakes are rich in fish, have reserves of salts, healing mud, and are used for recreation.

Bogs are common on plains in zones of excessive moisture and permafrost. In the tundra zone, for example, the swampiness of the territory reaches 50%. Severe waterlogging is characteristic of the taiga. The swamps of the forest zone are rich in peat. The best quality peat - low-ash and high-calorie - is given by raised bogs located on watersheds. Wetlands are the source of food for many rivers and lakes. The most swampy region of the world is Western Siberia. Here, swamps occupy almost 3 million km2, they contain more than 1/4 of the world's peat reserves.

Groundwater is of great economic importance. It is an important source of food for rivers, lakes and swamps. Groundwater of the first aquifer from the surface is called groundwater. The processes of soil formation and the associated development of vegetation cover depend on the depth of occurrence, abundance and quality of groundwater. When moving from north to south, the depth of groundwater increases, their temperature rises, and mineralization increases.

The groundwater- a source of pure water. They are much better protected from pollution than surface waters. An increase in the content of a number of chemical elements and compounds in groundwater leads to the formation of mineral waters. About 300 springs are known in Russia, 3/4 of which are located in the European part of the country (Mineralnye Vody, Sochi, North Ossetia, Pskov region, Udmurtia, etc.).

Nearly 1/4 of Russia's fresh water reserves is located in glaciers occupying about 60 thousand km2. These are mainly cover glaciers of the Arctic islands (55.5 thousand km2, water reserves 16.3 thousand km3).

Large areas in our country are occupied by permafrost - rock strata containing ice that does not thaw for a long time - about 11 million km2. These are the territories east of the Yenisei, the north of the East European Plain and the West Siberian Lowland. The maximum thickness of permafrost in the north of Central Siberia and in the lowlands of the basins of the Yana, Indigirka and Kolyma rivers. Permafrost has a significant impact on economic life. The shallow occurrence of the frozen layer impairs the formation of the root system of plants, reduces the productivity of meadows and forests. The laying of roads, the construction of buildings change the thermal regime of the permafrost and can lead to subsidence, sinking, swelling of soils, distortions of buildings, etc.

The territory of Russia is washed by the waters of 12 seas: 3 seas of the Atlantic Ocean basin, 6 seas of the Arctic Ocean, 3 seas of the Pacific Ocean.

The Atlantic Ocean approaches the territory of Russia with its inland seas - the Baltic, Black and Azov. They are very desalinated and quite warm. These are important transport routes from Russia to Western Europe and other parts of the world. A significant part of the coast of these seas is a recreational zone. Fishery value is small.

The seas of the Arctic Ocean, as it were, "lean" on the Arctic coast of Russia over a vast area - 10 thousand km. They are shallow and covered with ice for most of the year (except for the southwestern part of the Barents Sea). The main transport routes pass through the White and Barents Seas. The Northern Sea Route is of great importance.

Offshore oil and gas fields are promising. The Barents Sea is of the greatest commercial importance.

Seas of the Pacific Ocean- the largest and deepest of those washing Russia. The southernmost of them - Japan - is the richest in biological resources and is widely used for international shipping.

Water is the most abundant substance on our planet: although in varying amounts, it is available everywhere and plays a vital role for the environment and living organisms. Fresh water is of the greatest importance, without which human existence is impossible, and it cannot be replaced by anything. People have always consumed fresh water and used it for a variety of purposes, including domestic, agricultural, industrial and recreational uses.

Water reserves on Earth

Water exists in three aggregate states: liquid, solid and gaseous. It forms the oceans, seas, lakes, rivers and groundwater located in the upper layer of the crust, and the soil cover of the Earth. In the solid state, it exists in the form of snow and ice in polar and mountainous regions. A certain amount of water is contained in the air in the form of water vapor. Huge volumes of water are found in various minerals in the earth's crust.

Determining the exact amount of water in the world is quite difficult, since water is dynamic and is in constant motion, changing its state from liquid to solid to gaseous, and vice versa. As a rule, the total amount of water resources of the world is estimated as the totality of all waters of the hydrosphere. This is all free water that exists in all three states of aggregation in the atmosphere, on the surface of the Earth and in the earth's crust to a depth of 2000 meters.

Current estimates have shown that our planet contains a huge amount of water - about 1386,000,000 cubic kilometers (1.386 billion km³). However, 97.5% of this volume is salt water and only 2.5% is fresh water. Most of the fresh water (68.7%) is in the form of ice and permanent snow cover in the Antarctic, Arctic, and mountain regions. Further, 29.9% exists as groundwater, and only 0.26% of the total fresh water on Earth is concentrated in lakes, reservoirs and river systems, where it is most readily available for our economic needs.

These indicators were calculated over a long period of time, however, if shorter periods (one year, several seasons or months) are taken into account, the amount of water in the hydrosphere may change. It has to do with the exchange of water between the oceans, land and atmosphere. This exchange is generally referred to as the , or global hydrological cycle.

Fresh water resources

Fresh water contains a minimum amount of salts (no more than 0.1%) and is suitable for human needs. However, not all resources are available to people, and even those that are available are not always usable. Consider fresh water sources:

• Glaciers and snow covers occupy about 1/10 of the world's land and contain about 70% of fresh water. Unfortunately, most of these resources are located far from settlements, and therefore are difficult to access.
• Groundwater is by far the most common and accessible source of fresh water.
• Freshwater lakes are mainly located at high altitudes. Canada contains about 50% of the world's freshwater lakes. Many lakes, especially those located in arid regions, become salty due to evaporation. The Caspian Sea, the Dead Sea, and the Great Salt Lake are among the world's largest salt lakes.
• The rivers form a hydrological mosaic. There are 263 international river basins on Earth, which cover more than 45% of the land of our planet (the exception is Antarctica).

Water resources objects

The main objects of water resources are:

• oceans and seas;
• lakes, ponds and reservoirs;
• swamps;
• rivers, canals and streams;
• soil moisture;
• underground waters (soil, ground, interstratal, artesian, mineral);
• ice caps and glaciers;
• atmospheric precipitation (rain, snow, dew, hail, etc.).

Problems in the use of water resources

For many hundreds of years, human impact on water resources was insignificant and was of an exclusively local nature. The excellent properties of water - its renewal due to the circulation and the ability to purify - make fresh water relatively purified and with quantitative and qualitative characteristics that will remain unchanged for a long time.

However, these features of water gave rise to the illusion of the immutability and inexhaustibility of these resources. Out of these prejudices, a tradition has arisen of the careless use of vital water resources.

The situation has changed a lot in recent decades. In many parts of the world, the results of long-term and wrong actions towards such a valuable resource have been discovered. This applies to both direct and indirect use of water.

Throughout the world, for 25-30 years, there has been a massive anthropogenic change in the hydrological cycle of rivers and lakes, affecting the quality of water and their potential as a natural resource.

The volume of water resources, their spatial and temporal distribution, are determined not only by natural climate fluctuations, as before, but now also by the types of economic activities of people. Many parts of the world's water resources are becoming so depleted and heavily polluted that they can no longer meet ever-increasing demands. It may
become the main factor hindering economic development and population growth.

Water pollution

The main causes of water pollution are:

• Wastewater;

Domestic, industrial and agricultural wastewater pollutes many rivers and lakes.

• Waste disposal in the seas and oceans;

The dumping of garbage in the seas and oceans can cause huge problems, because it negatively affects the living organisms that live in the waters.

• Industry;

Industry is a huge source of water pollution, which produces substances that are harmful to people and the environment.

• radioactive substances;

Radioactive pollution, in which there is a high concentration of radiation in the water, is the most dangerous pollution and can spread into ocean waters.

• Oil spill;

An oil spill poses a threat not only to water resources, but also to human settlements located near a contaminated source, as well as to all biological resources for which water is a habitat or a vital necessity.

• Leaks of oil and oil products from underground storage facilities;

A large amount of oil and oil products are stored in tanks made of steel, which corrodes over time, which in consequence creates leakage of harmful substances into the surrounding soil and groundwater.

• Precipitation;

Precipitation, such as acid precipitation, is formed when air is polluted and changes the acidity of water.

• Global warming;

An increase in water temperature causes the death of many living organisms and destroys a large number of habitats.

• Eutrophication.

Eutrophication is the process of reducing the quality characteristics of water associated with excessive enrichment with nutrients.

Rational use and protection of water resources

Water resources provide for rational use and protection, from individuals to enterprises and states. There are many ways we can reduce our impact on the aquatic environment. Here is some of them:

Water saving

Factors such as climate change, population growth and increasing aridity are increasing pressure on our water resources. The best way to conserve water is to reduce consumption and avoid rising wastewater.

At the household level, there are many ways to save water, such as: shorter showers, installing water-saving appliances, and low-flow washing machines. Another approach is to plant gardens that do not require much water.

The water resources of the Earth consist of groundwater and surface water of the planet. They are used not only by humans and animals, but are also needed for various natural processes. Water (H2O) is available in liquid, solid or gaseous form. The totality of all water sources makes up the hydrosphere, that is, the water shell, which makes up 79.8% of the Earth's surface. It consists of:

• oceans;
• seas;
• lakes;
• swamps;
• artificial reservoirs;
• groundwater;
• atmospheric vapors;
• soil moisture;
• snow covers;
• glaciers.

In order to sustain life, people must drink water every day. Only fresh water is suitable for this, but on our planet it is less than 3%, but only 0.3% is available now. Russia, Brazil and Canada have the largest reserves of drinking water.

Use of water resources

Water appeared on Earth approximately 3.5 billion years ago and cannot be seen by any other resource. The hydrosphere is considered one of the inexhaustible riches of the world, in addition, scientists have invented a way to make salty water fresh so that they can be used for drinking.

Water resources are necessary not only to support the life of people, flora and fauna, but also supply oxygen in the process of photosynthesis. Water also plays a key role in climate formation. People use this most valuable resource in everyday life, in agriculture and industry. Experts estimate that in big cities a person consumes about 360 liters of water per day, and this includes the use of plumbing, sewerage, cooking and drinking, cleaning the house, washing, watering plants, washing vehicles, extinguishing fires, etc.

The problem of hydrosphere pollution

One of the global problems is water pollution. Sources of water pollution:

• domestic and industrial waste water;
• oil products;
• burial of chemical and radioactive substances in water bodies;
• shipping;
• municipal solid waste.

In nature, there is such a phenomenon as self-purification of water bodies, but the anthropogenic factor affects the biosphere so much that over time, rivers, lakes, and seas are more and more difficult to recover. Water becomes polluted, becomes unsuitable not only for drinking and domestic use, but also for the life of marine, river, oceanic species of flora and fauna. In order to improve the state of the environment, and in particular the hydrosphere, it is necessary to rationally use water resources, save them and carry out protection measures for water bodies.

USE AND PROTECTION OF WATER BODIES.

Water resources are a very important part of the natural resources used by man, which also include land resources, mineral resources (including fuel and energy and other minerals), plant (for example, forest), animal world resources, solar energy, wind energy, domestic - earth heat, 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 man and can be used in the foreseeable future (definition by S. L. Vendrov). A similar wording is given in the Water Code of the Russian Federation: "water resources - reserves of surface and ground waters 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 fresh water reserves (this is the narrowest concept of water resources). Fresh water resources are made up of the so-called static (or secular) water reserves and continuously renewable water resources, i.e. river flow.

Static (secular) fresh water reserves are represented by a part of the water volumes of lakes, glaciers, and groundwater that is not subject to noticeable annual changes. These reserves are measured in volume units (m 3 or km 3).

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

Renewable water resources are often estimated using the water balance equation. So, 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 land, out of the total volume of precipitation, 61% is spent on evaporation, and 39% enters the World Ocean. Continental runoff is the world's renewable water resources. More often, however, only a part of the continental runoff, represented by river runoff, is considered renewable water resources (41.7 km 3 of water per year, or 35% of atmospheric precipitation on the planet). River runoff is indeed an annually renewable natural resource that can (up to certain limits, of course) be withdrawn for economic use. In contrast, static (secular) water reserves in lakes, glaciers, and aquifers cannot be withdrawn for economic needs without damaging 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, it cannot be replaced by anything. Many other natural resources are substitutable, and with the development of civilization and the technical capabilities of human society, such substitution has been used more and more widely.

In ancient times, only wood was most often used as a building material. In Russia, for example, not only huts were built of 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, the energy of tides and sea waves. At present, attempts are being made to create artificial soil for growing plants, and some foodstuffs - to replace them with synthetic counterparts.

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

Second. Water is an indestructible resource. Unlike the previous feature, this one turns out to be quite favorable. In the process of using minerals, for example, when burning wood, coal, oil, gas, these substances, turning into heat and giving ash or gaseous waste, disappear. Water, however, does not disappear during its use, 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 the actual disappearance of water as a substance is the binding of water with carbon dioxide (carbon dioxide) in the process of photosynthesis and the formation of organic matter. However, the volumes of water used for the synthesis of organic matter are very small, as well as the 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 the degassing of the Earth's mantle (about 1 km 3 of water per year) and when water enters from space along with ice meteorites.

The term “irreversible water consumption” used in the water sector should be understood as follows: for a specific section of a river (perhaps even for the entire river basin), lake or reservoir, water intake for household needs (irrigation, water supply, etc.) can indeed become irretrievable. The withdrawn water partially evaporates later from the surface of irrigated lands or during industrial production. However, according to the law of conservation of matter, the same volume of water must fall in the form of precipitation in other regions of the planet. For example, a 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 expanses of Central Asia. Only the consequences of the first process - a decrease in the flow of the mentioned rivers - are well seen by everyone, and an increase in the flow of rivers over a vast territory is almost impossible to notice. Thus, "irrecoverable" water losses refer only to a limited area, but in general, for the continent, and even more so for the entire planet, there can be no irretrievable waste of water. If water in the process of use would disappear without a trace (like coal or oil when burned), then there could be no question of any development of mankind on the globe.

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

The renewal of water resources in the process of the water cycle, both in time and in space, is uneven. This is determined both by the change in meteorological conditions (precipitation, evaporation) over time, for example, by the seasons of the year, and by the spatial heterogeneity of climatic conditions, in particular by latitudinal and altitudinal zonality, therefore, water resources are subject to great spatial and temporal variability on the planet. This feature often creates a shortage of water resources in some areas of the globe (for example, in arid regions, in places with high economic water consumption), especially during a dry period 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 multipurpose resource. Water resources are used to meet a variety of human economic needs. Often, water from the same water body is used by different sectors of the economy.

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

Firstly, water can naturally move in space - along the earth's surface and in the thickness of 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 (through canals, pipelines) from one region to another.

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

Fourth, being mobile and participating in the global cycle, water carries sediment, dissolved substances, including pollutants, and heat. And although there is no complete circulation of sediments, salts and heat (unilateral transfer from land to the ocean prevails), the role of rivers in the transfer of matter and energy is very large.

A natural question arises: Is the movement of pollutants together with water good or bad for nature? On the one hand, pollutants that have entered the water, such as oil as a result of imperfect production technology, a breakthrough in 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, pollution of adjacent waters and coasts. But, on the other hand, flowing water removes harmful substances from the area of ​​pollution, cleansing it, and contributes to the dispersion and decomposition of harmful impurities. In addition, flowing waters are characterized by 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 cubic meters. km 2. They are concentrated primarily in the upper layer of the earth's crust, in large lakes and glaciers. Distributed water resources between the continents unevenly. North America and Asia have the largest static (secular) freshwater resources, and to a lesser extent - South America and Africa. Europe and Australia with Oceania are the least rich in this kind of resources.

Renewable water resources - river runoff - are also unevenly distributed around the globe. Asia (32% of the runoff of all the planet's rivers) and South America (26%) have the largest runoff, Europe (7%) and Australia with Oceania (5%) have the smallest. The water supply of the territory per 1 km 2 is the highest in South America and the lowest in Africa. To the greatest extent, the population is provided with river water (per inhabitant) in South America and on the islands of Oceania, in the least - the population of Europe and Asia (77% of the world'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"

The water supply of both the territory and the population varies significantly within individual continents, depending on climatic conditions and population distribution. For example, in Asia there are regions both well supplied with water (Eastern Siberia, the Far East, Southeast Asia) and those that feel its lack (Central Asia, Kazakhstan, the Gobi Desert, etc.).

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

According to the estimates of the Intergovernmental Panel on Climate Change, in the XXI 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 the following: climate change will bring into the XXI century. to a significant reduction in available water resources in those areas of the planet where there is already a lack of them. 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 countries develop economically.

Water resources of Russia.

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

Renewable water resources. The average long-term value of renewable water resources in Russia (ie river runoff) is 4348 km 3 /year. Of 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 the flow of rivers and renewable water resources in Russia over the past 20 years by the intensification of atmospheric circulation, the mixing of the trajectory of cyclones to the south and the increase in the frequency of cyclones of Atlantic origin with a high moisture content, an increase in the amount of precipitation (mainly winter), which, ultimately , is a consequence of global warming.

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

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

Table 13. Water resources of Russian regions

The Siberian and Far Eastern federal districts are well supplied with water, to a lesser extent - the Urals and North-West, the worst - the Volga, Central and Southern.

Static (secular) water resources of Russia. According to RosNIIVKh (2000), they are represented by water reserves in fresh lakes (26.5 thousand km 3 , of which 23 thousand km 3 or 87% fall on Baikal); 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 total and useful volume of large reservoirs in Russia, according to the SGI, in the 80s of the XX century. was 810 and 364 km3, respectively.

Thus, the total static (secular) reserves of fresh water in Russia are about 90 thousand km3.

Potential hydropower resources rivers are determined by its individual sections e i = aQ i, where Qi is the average water flow in the area, is the fall of the river in the area, a– dimension factor. For the entire river, potential energy resources uh = ∑e i.

In the use of water, water consumption and water use are distinguished. Water consumption- withdrawal of water from natural water bodies with its further partial return after use. Unreturned part - irretrievable water consumption.

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

Water management balance- the ratio between different 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 the 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 flow regulation, water transfer from other areas, saving water resources by changing economic technology (rational irrigation methods, the introduction of closed industrial water supply systems, etc.).

The most important factor ecological state water bodies - water quality in them. For its assessment, hydrobiological, hydrochemical, sanitary and hygienic, 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 the species diversity of the biological community.

The assessment of water quality by hydrochemical indicators is carried out by comparing the concentration of pollutants in a water body with their maximum allowable concentrations (MPC). Pollutants include substances that have a harmful effect on humans and aquatic organisms, or limit the possibility of using water for household needs. Often a small amount of the same substances is necessary for the normal development of aquatic organisms. For different types of use, their own MPCs are set.

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

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

Sources of pollution of natural waters:

- wastewater from housing and communal and industrial enterprises, livestock farms;

– flushing with melt and rain waters of pollution from the territory of industrial zones and residential buildings, from agricultural fields, from the territory of livestock farms;

– shipping and timber rafting;

– recreational use of rivers and reservoirs;

– fish farming;

– accidental pollution caused by bursting of pipelines, dams of wastewater sedimentation tanks, destruction of treatment facilities, etc.;

–domestic pollution – garbage dumping into the river, car washing, etc.

Measures to improve water quality:

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