What are water resources examples. Water resources

Water is the only substance that exists in nature in liquid, solid and gaseous states. The value of liquid water varies significantly depending on location and application. Fresh water is more widely used than salt water. Over 97% of all water is concentrated in the oceans and inland seas. Still ok. 2% is accounted for by fresh waters contained in ice sheet and mountain glaciers, and only less than 1% is accounted for by fresh waters of lakes and rivers, underground and groundwater.

Water, the most common compound on Earth, has unique chemical and physical properties. Since it easily dissolves mineral salts, living organisms absorb nutrients with it without any significant changes in their own chemical composition. Thus, water is necessary for the normal functioning of all living organisms. The water molecule consists of two hydrogen atoms and one oxygen atom. Its molecular weight is only 18, and the boiling point reaches 100

Water also has unique thermal properties. When its temperature drops to

Water molecules are linked by "hydrogen (or intermolecular) bonds" when the oxygen of one water molecule combines with the hydrogen of another molecule. Water is also attracted to other hydrogen- and oxygen-containing compounds (the so-called molecular attraction). The unique properties of water are determined by the strength of hydrogen bonds. Cohesive and molecular attraction forces allow it to overcome gravity and, due to capillarity, rise up through small pores (for example, in dry soil).

The main source of fresh water is atmospheric precipitation, but two other sources can also be used for consumer needs: groundwater and surface water.Underground sources. Approximately 37.5 million km 3 , or 98% of all fresh water in the liquid state falls on groundwater, with approx. 50% of them lie at depths of no more than 800 m. However, the volume of available groundwater is determined by the properties of aquifers and the capacity of pumps pumping water. Groundwater reserves in the Sahara are estimated at about 625 thousand km 3 . Under modern conditions, they are not replenished at the expense of surface fresh waters, but are depleted during pumping. Some of the deepest underground waters are never included in the general water cycle at all, and only in areas of active volcanism do such waters erupt in the form of steam. However, a significant amount of groundwater still penetrates the earth's surface: under the influence of gravity, these waters, moving along impermeable sloping rock layers, emerge at the foot of the slopes in the form of springs and streams. In addition, they are pumped out by pumps, and are also extracted by plant roots and then enter the atmosphere through the process of transpiration.

The groundwater table represents the upper limit of available groundwater. In the presence of slopes, the groundwater table intersects with the earth's surface, and a source is formed. If groundwater is under high hydrostatic pressure, then artesian springs are formed in the places where they come to the surface. With the advent of powerful pumps and the development of modern drilling technology, the extraction of groundwater has become easier. Pumps are used to supply water to shallow wells installed in aquifers. However, in wells drilled on b

In some parts of the world, the growing demand for groundwater is having serious consequences. The pumping out of a large volume of groundwater, incomparably exceeding their natural replenishment, leads to a lack of moisture, and a decrease in the level of these waters requires

In coastal areas, excessive abstraction of groundwater leads to the replacement of fresh water in the aquifer with salt water, and thus the degradation of local fresh water sources occurs.

Gradual deterioration of groundwater quality as a result of salt accumulation can have even more dangerous consequences. Salt sources can be both natural (for example, the dissolution and removal of minerals from soils) and anthropogenic (fertilization or excessive watering with water with a high salt content). Rivers fed by mountain glaciers usually contain less than 1 g/l of dissolved salts, but the salinity of water in other rivers reaches 9 g/l due to the fact that they drain areas composed of salt-bearing rocks for a long distance.

The indiscriminate release or disposal of toxic chemicals causes them to seep into aquifers that provide drinking or irrigation water. In some cases, just a few years or decades are enough for harmful chemicals to get into groundwater and accumulate there in tangible quantities. However, if an aquifer was once polluted, it would take 200 to 10,000 years for it to naturally clean itself.

When water demand exceeds water supply, the difference is usually offset by storage in reservoirs, as both demand and supply usually vary seasonally. A negative water balance is formed when evaporation exceeds precipitation, so a moderate decrease in water reserves is a common occurrence. Acute scarcity occurs when water supply is insufficient due to a prolonged drought or when, due to poor planning, water consumption is constantly growing at a faster rate than expected. Throughout history, humanity has suffered from time to time due to lack of water. In order not to experience a shortage of water even during droughts, many cities and regions try to store it in reservoirs and underground collectors, but sometimes additional water-saving measures are needed, as well as its normalized consumption. OVERCOMING WATER SHORTAGE

The redistribution of runoff is aimed at providing water to those areas where it is not enough, and the protection of water resources is aimed at reducing irreplaceable water losses and reducing the need for it on the ground.Redistribution of runoff. Although traditionally many large settlements have been established near permanent water sources, some settlements are now also being established in areas that receive water from afar. Even where the source of the supplemental water supply is within the same state or country as the destination, there are technical, environmental, or economic problems, but if the imported water crosses national boundaries, the potential complications increase. For example, spraying silver iodide on clouds results in increased rainfall in one area, but this can result in reduced precipitation in other areas.

One of the major water transfer projects proposed in North America is to divert 20% of excess water from the northwest to arid regions. At the same time, up to 310 million m3 would be redistributed annually

Much attention is drawn to the project of towing icebergs from Antarctica to arid regions, such as the Arabian Peninsula, which will annually provide fresh water from 4 to 6 billion people or irrigate approx. 80 million hectares of land.

One of the alternative methods of water supply is the desalination of salt water, mainly ocean water, and its transportation to the places of consumption, which is technically feasible due to the use of electrodialysis, freezing and various distillation systems. The larger the desalination plant, the cheaper it is to obtain fresh water. But with the increase in the cost of electricity, desalination becomes economically unprofitable. It is used only in cases where energy is readily available and other methods of obtaining fresh water are impractical. Commercial desalination plants operate on the islands of Curacao and Aruba (in the Caribbean Sea), Kuwait, Bahrain, Israel, Gibraltar, Guernsey and the USA. Numerous smaller demonstration plants have been built in other countries.

However, each of these methods of conserving water resources has some impact on the environment. For example, dams spoil the natural beauty of unregulated rivers and prevent the accumulation of fertile silt on floodplains. Prevention of water loss as a result of filtration in canals can disrupt the water supply of swamps and thus adversely affect the state of their ecosystems. It may also prevent groundwater recharge, thus affecting the water supply of other users. And to reduce the volume of evaporation and transpiration by agricultural crops, it is necessary to reduce the area under crops. The latter measure is justified in areas suffering from water shortages, where it is carried out a savings regime by reducing irrigation costs due to the high cost of energy needed to supply water.

For irrigation by sprinkling or drip irrigation, practiced recently, pumps of small power are used. In addition, there are giant central-pivot irrigation systems that pump water from wells right in the middle of the field directly into a pipe equipped with sprinklers and rotating in a circle. From the air, fields irrigated in this way appear to be giant green circles, some of which reach a diameter of 1.5 km. Such installations are common in the US Midwest. They are also used in the Libyan part of the Sahara, where more than 3,785 liters of water per minute are pumped out of the deep Nubian aquifer.

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) can be in liquid, solid or gaseous state. 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.

The content of the article

WATER RESOURCES, water in liquid, solid and gaseous state and their distribution on Earth. They are found in natural water bodies on the surface (oceans, rivers, lakes and swamps); in the bowels (groundwater); in all plants and animals; as well as in artificial reservoirs (reservoirs, canals, etc.).

The water cycle in nature.

Although the total supply of water in the world is constant, it is constantly redistributed, and thus it is a renewable resource. The water cycle occurs under the influence of solar radiation, which stimulates the evaporation of water. At the same time, mineral substances dissolved in it are deposited. Water vapor rises into the atmosphere, where it condenses, and due to gravity, the water returns to earth in the form of precipitation - rain or snow. Most of the precipitation falls over the ocean and less than 25% over land. About 2/3 of this precipitation enters the atmosphere as a result of evaporation and transpiration, and only 1/3 flows into rivers and seeps into the ground.

Gravity contributes to the redistribution of liquid moisture from higher to lower areas both on the earth's surface and below it. Water, originally set in motion by solar energy, moves in the seas and oceans in the form of ocean currents, and in the air - in clouds.

Geographical distribution of precipitation.

The volume of natural renewal of water reserves due to precipitation varies depending on the geographical location and size of parts of the world. For example, South America receives nearly three times as much annual rainfall as Australia and almost twice as much as North America, Africa, Asia and Europe (listed in descending order of annual rainfall). Some of this moisture is returned to the atmosphere as a result of evaporation and transpiration by plants: in Australia this value reaches 87%, and in Europe and North America - only 60%. The rest of the precipitation flows down the earth's surface and eventually reaches the ocean with river runoff.

Within the continents, rainfall also varies greatly from place to place. For example, in Africa, on the territory of Sierra Leone, Guinea and Côte d "Ivoire, more than 2000 mm of precipitation falls annually, in most of central Africa - from 1000 to 2000 mm, but at the same time in some northern regions (Sahara and Sahel desert) the amount rainfall is only 500-1000 mm, and in the south - Botswana (including the Kalahari Desert) and Namibia - less than 500 mm.

Eastern India, Burma and part of Southeast Asia receive more than 2000 mm of precipitation per year, while most of the rest of India and China receive between 1000 and 2000 mm, while northern China receives only 500–1000 mm. Northwestern India (including the Thar Desert), Mongolia (including the Gobi Desert), Pakistan, Afghanistan and most of the Middle East receive less than 500 mm of precipitation annually.

In South America, the annual rainfall in Venezuela, Guyana and Brazil exceeds 2000 mm, most of the eastern regions of this continent receive 1000–2000 mm, but Peru and parts of Bolivia and Argentina receive only 500–1000 mm, and Chile less than 500 mm. In some areas of Central America located to the north, more than 2000 mm of precipitation falls annually, in the southeastern regions of the United States - from 1000 to 2000 mm, and in some areas of Mexico, in the northeast and Midwest of the United States, in eastern Canada - 500–1000 mm, while in central Canada and the western United States it is less than 500 mm.

In the far north of Australia, the annual rainfall is 1000-2000 mm, in some other northern regions it varies from 500 to 1000 mm, but most of the mainland and especially its central regions receive less than 500 mm.

Most of the former USSR also receives less than 500 mm of precipitation per year.

Time cycles of water availability.

At any point in the world, river runoff experiences daily and seasonal fluctuations, and also changes with a frequency of several years. These variations are often repeated in a certain sequence, i.e. are cyclic. For example, discharges in rivers with heavily vegetated banks tend to be higher at night. This is because, from dawn to dusk, vegetation uses groundwater for transpiration, resulting in a gradual decrease in river flow, but its volume increases again at night when transpiration stops.

Seasonal cycles of water supply depend on the distribution of precipitation throughout the year. For example, in the Western United States, snowmelt occurs in the spring. In India, there is little rainfall in winter, and heavy monsoon rains begin in mid-summer. Although the average annual river flow is almost constant over a number of years, it is extremely high or extremely low once every 11–13 years. Perhaps this is due to the cyclical nature of solar activity. Information about the cyclicity of precipitation and river runoff is used in forecasting water availability and the frequency of droughts, as well as in planning water protection activities.

WATER SOURCES

The main source of fresh water is atmospheric precipitation, but two other sources can also be used for consumer needs: groundwater and surface water.

Underground sources.

Approximately 37.5 million km 3 or 98% of all fresh water in the liquid state falls on groundwater, and approx. 50% of them lie at depths of no more than 800 m. However, the volume of available groundwater is determined by the properties of aquifers and the capacity of pumps pumping water. Groundwater reserves in the Sahara are estimated at about 625 thousand km3. Under modern conditions, they are not replenished at the expense of surface fresh waters, but are depleted during pumping. Some of the deepest underground waters are never included in the general water cycle at all, and only in areas of active volcanism do such waters erupt in the form of steam. However, a significant amount of groundwater still penetrates the earth's surface: under the influence of gravity, these waters, moving along impermeable sloping rock layers, emerge at the foot of the slopes in the form of springs and streams. In addition, they are pumped out by pumps, and are also extracted by plant roots and then enter the atmosphere through the process of transpiration.

The groundwater table represents the upper limit of available groundwater. In the presence of slopes, the groundwater table intersects with the earth's surface, and a source is formed. If groundwater is under high hydrostatic pressure, then artesian springs are formed in the places where they come to the surface. With the advent of powerful pumps and the development of modern drilling technology, the extraction of groundwater has become easier. Pumps are used to supply water to shallow wells installed in aquifers. However, in wells drilled to a greater depth, to the level of pressure artesian waters, the latter rise and saturate the overlying groundwater, and sometimes come to the surface. Groundwater moves slowly, at a speed of several meters per day or even per year. They are usually found in porous pebbly or sandy horizons or relatively impermeable shale layers, and only rarely are they concentrated in underground cavities or in underground streams. For the correct choice of a well drilling site, information about the geological structure of the territory is usually required.

In some parts of the world, the growing demand for groundwater is having serious consequences. Pumping out a large volume of groundwater, incomparably greater than its natural recharge, leads to a lack of moisture, and lowering the level of these waters requires more expensive electricity used to extract them. In places where the aquifer is depleted, the earth's surface begins to subside, and the restoration of water resources in a natural way is complicated there.

In coastal areas, excessive abstraction of groundwater leads to the replacement of fresh water in the aquifer with salt water, and thus the degradation of local fresh water sources occurs.

Gradual deterioration of groundwater quality as a result of salt accumulation can have even more dangerous consequences. Salt sources can be both natural (for example, the dissolution and removal of minerals from soils) and anthropogenic (fertilization or excessive watering with water with a high salt content). Rivers fed by mountain glaciers usually contain less than 1 g/l of dissolved salts, but the salinity of water in other rivers reaches 9 g/l due to the fact that they drain areas composed of salt-bearing rocks for a long distance.

The indiscriminate release or disposal of toxic chemicals causes them to seep into aquifers that provide drinking or irrigation water. In some cases, just a few years or decades are enough for harmful chemicals to get into groundwater and accumulate there in tangible quantities. However, if an aquifer was once polluted, it would take 200 to 10,000 years for it to naturally clean itself.

surface sources.

Only 0.01% of the total volume of fresh water in the liquid state is concentrated in rivers and streams and 1.47% in lakes. Dams have been built on many rivers to store water and provide it continuously to consumers, as well as to prevent unwanted floods and generate electricity. The Amazon in South America, the Congo (Zaire) in Africa, the Ganges with the Brahmaputra in South Asia, the Yangtze in China, the Yenisei in Russia, and the Mississippi with the Missouri in the USA have the highest average water consumption and, consequently, the highest energy potential.

Natural freshwater lakes containing approx. 125 thousand km 3 of water, along with rivers and artificial reservoirs, are an important source of drinking water for people and animals. They are also used for irrigation of agricultural land, navigation, recreation, fishing and, unfortunately, for the discharge of domestic and industrial wastewater. Sometimes, due to the gradual filling with sediments or salinization, the lakes dry up, but in the process of evolution of the hydrosphere, new lakes are formed in some places.

The water level even in “healthy” lakes can decrease during the year as a result of water flow through the rivers and streams flowing from them, due to water infiltration into the ground and its evaporation. The restoration of their level usually occurs due to precipitation and the inflow of fresh water from rivers and streams flowing into them, as well as from springs. However, as a result of evaporation, salts that come with river runoff accumulate. Therefore, after millennia, some lakes can become very salty and unsuitable for many living organisms.

USE OF WATER

Water consumption.

Water consumption is growing rapidly everywhere, but not only because of the increase in population, but also due to urbanization, industrialization and especially the development of agricultural production, in particular irrigated agriculture. By 2000, the world's daily water consumption had reached 26,540 billion liters, or 4,280 liters per person. 72% of this volume is spent on irrigation, and 17.5% on industrial needs. About 69% of irrigation water is lost irretrievably.

water quality,

used for different purposes, is determined depending on the quantitative and qualitative content of dissolved salts (i.e. its mineralization), as well as organic substances; solid suspensions (silt, sand); toxic chemicals and pathogens (bacteria and viruses); odor and temperature. Typically, fresh water contains less than 1 g/l of dissolved salts, brackish water 1–10 g/l, and saline water 10–100 g/l. Water with a high salt content is called brine, or brine.

Obviously, for navigational purposes, water quality (seawater salinity reaches 35 g/l, or 35‰) is not essential. Many species of fish have adapted to life in salt water, but others live only in fresh water. Some migratory fish (such as salmon) start and end their life cycle in inland fresh waters but spend most of their lives in the ocean. Some fish (like trout) need cold water, while others (like perch) prefer warm water.

Most industries use fresh water. But if such water is in short supply, then some technological processes, such as cooling, can proceed based on the use of low-quality water. Water for domestic purposes should be of high quality, but not absolutely pure, since such water is too expensive to produce, and the absence of dissolved salts makes it tasteless. In some parts of the world, people are still forced to use low-quality muddy water from open reservoirs and springs for everyday needs. However, in industrialized countries, all cities are now supplied with piped, filtered and specially treated water that meets at least minimum consumer standards, especially in terms of potability.

An important characteristic of water quality is its hardness or softness. Water is considered hard if the content of calcium and magnesium carbonates exceeds 12 mg/l. These salts are bound by some components of detergents, and thus foaming worsens, an insoluble residue remains on the washed items, giving them a dull gray tint. Hard water calcium carbonate forms scale (limescale) in kettles and boilers, which reduces their service life and the thermal conductivity of the walls. Water is softened by adding sodium salts to replace calcium and magnesium. In soft water (containing less than 6 mg/l of calcium and magnesium carbonates), the soap lathers well and is more suitable for washing and washing. Such water should not be used for irrigation, as excess sodium is harmful to many plants and can disturb the loose, cloddy soil structure.

Although elevated concentrations of trace elements are harmful and even poisonous, their small content can have a beneficial effect on human health. An example is water fluoridation to prevent caries.

Reuse of water.

Used water is not always completely lost, part of it or even all of it can be returned to the circulation and reused. For example, water from a bath or shower through sewer pipes enters the city's wastewater treatment plant, where it is treated and then reused. Typically, more than 70% of urban runoff returns to rivers or aquifers. Unfortunately, in many large coastal cities, municipal and industrial wastewater is simply dumped into the ocean and not disposed of. Although this method eliminates the cost of cleaning and returning them to circulation, there is a loss of potentially usable water and pollution of marine areas.

In irrigated agriculture, crops consume a huge amount of water, sucking it out by the roots and irretrievably losing up to 99% in the process of transpiration. However, when irrigating, farmers usually use more water than is needed for crops. Part of it flows to the periphery of the field and returns to the irrigation network, while the rest seeps into the soil, replenishing groundwater reserves that can be pumped out.

Use of water in agriculture.

Agriculture is the largest consumer of water. In Egypt, where there is almost no rain, all agriculture is based on irrigation, while in the UK, almost all crops are provided with moisture from precipitation. In the US, 10% of agricultural land is irrigated, mostly in the west of the country. A significant part of agricultural land is artificially irrigated in the following Asian countries: China (68%), Japan (57%), Iraq (53%), Iran (45%), Saudi Arabia (43%), Pakistan (42%), Israel ( 38%), India and Indonesia (27% each), Thailand (25%), Syria (16%), Philippines (12%) and Vietnam (10%). In Africa, apart from Egypt, a significant proportion of irrigated land is in Sudan (22%), Swaziland (20%) and Somalia (17%), and in America - in Guyana (62%), Chile (46%), Mexico (22%). ) and Cuba (18%). In Europe, irrigated agriculture is developed in Greece (15%), France (12%), Spain and Italy (11% each). Australia irrigates approx. 9% agricultural land and approx. 5% - in the former USSR.

Water consumption by different cultures.

To obtain high yields, a lot of water is required: for example, 3,000 liters of water are spent on growing 1 kg of cherries, 2,400 liters of rice, 1,000 liters of corn on the cob and wheat, 800 liters of green beans, 590 liters of grapes, and 510 liters of spinach. l, potatoes - 200 l and onions - 130 l. Approximate amount of water used only for growing (and not for processing or cooking) food crops consumed daily by one person in Western countries is for breakfast approx. 760 liters, for lunch (lunch) 5300 liters and for dinner - 10,600 liters, which is 16,600 liters per day.

In agriculture, water is used not only to irrigate crops, but also to recharge groundwater (to prevent the groundwater level from dropping too quickly); for leaching (or leaching) of salts accumulated in the soil to a depth below the root zone of cultivated crops; for spraying against pests and diseases; frost protection; fertilizer application; decrease in air and soil temperature in summer; for the care of livestock; evacuation of treated wastewater used for irrigation (mainly cereals); and processing of harvested crops.

Food industry.

The processing of different food crops requires different amounts of water depending on the product, the manufacturing technology and the availability of water of the appropriate quality in sufficient volume. In the United States, 2,000 to 4,000 liters of water are used to produce 1 ton of bread, while in Europe it is only 1,000 liters and only 600 liters in some other countries. Preserving fruits and vegetables requires between 10,000 and 50,000 liters of water per ton in Canada, while in Israel, where water is a severe shortage, only 4,000–1,500. The “champion” in terms of water consumption is lima beans, for the conservation of 1 ton of which in the USA 70,000 liters of water are consumed. Processing 1 tonne of sugar beet consumes 1,800 liters of water in Israel, 11,000 liters in France and 15,000 liters in the UK. The processing of 1 ton of milk requires from 2000 to 5000 liters of water, and the production of 1000 liters of beer in the UK - 6000 liters, and in Canada - 20,000 liters.

Industrial water consumption.

The pulp and paper industry is one of the most water-intensive industries due to the sheer volume of raw materials processed. The production of each ton of pulp and paper uses an average of 150,000 liters of water in France and 236,000 liters in the United States. The process of producing newsprint in Taiwan and Canada consumes approx. 190,000 liters of water per 1 ton of production, while the production of a ton of high-quality paper in Sweden requires 1 million liters of water.

Fuel industry.

To produce 1,000 liters of high-quality aviation gasoline, 25,000 liters of water are needed, and motor gasoline requires two-thirds less.

Textile industry

requires a lot of water for soaking raw materials, cleaning and washing, bleaching, dyeing and finishing fabrics and for other technological processes. For the production of each ton of cotton fabric, from 10,000 to 250,000 liters of water are needed, for woolen - up to 400,000 liters. The production of synthetic fabrics requires much more water - up to 2 million liters per 1 ton of products.

Metallurgical industry.

In South Africa, the extraction of 1 ton of gold ore consumes 1,000 liters of water; in the USA, the extraction of 1 ton of iron ore is 4,000 liters and 1 ton of bauxite is 12,000 liters. The production of iron and steel in the United States requires approximately 86,000 liters of water per ton of product, but up to 4,000 liters of this is a deadweight loss (mainly to evaporation), and therefore approximately 82,000 liters of water can be reused. Water consumption in the iron and steel industry varies considerably by country. 130,000 liters of water are spent on the production of 1 ton of pig iron in Canada, 103,000 liters of water are spent on smelting 1 ton of pig iron in a blast furnace in the USA, 40,000 liters of steel in electric furnaces in France, and 8,000–12,000 liters in Germany.

Power industry.

Hydroelectric power plants use the energy of falling water to generate electricity, driving hydraulic turbines. In the US, hydroelectric power plants use 10,600 billion liters of water daily.

Wastewater.

Water is necessary for the evacuation of domestic, industrial and agricultural wastewater. While about half of the population in the United States, for example, is served by sewer systems, effluent from many homes is still simply dumped into septic tanks. But increasing awareness of the consequences of water pollution through such outdated sewer systems has spurred the construction of new systems and the construction of wastewater treatment plants to prevent pollutants from infiltrating into groundwater and untreated runoff into rivers, lakes and seas.

WATER DEFICIENCY

When water demand exceeds water supply, the difference is usually offset by storage in reservoirs, as both demand and supply usually vary seasonally. A negative water balance is formed when evaporation exceeds precipitation, so a moderate decrease in water reserves is a common occurrence. Acute scarcity occurs when water supply is insufficient due to a prolonged drought or when, due to poor planning, water consumption is constantly growing at a faster rate than expected. Throughout history, humanity has suffered from time to time due to lack of water. In order not to experience a shortage of water even during droughts, many cities and regions try to store it in reservoirs and underground collectors, but sometimes additional water-saving measures are needed, as well as its normalized consumption.

OVERCOMING WATER SHORTAGE

The redistribution of runoff is aimed at providing water to those areas where it is not enough, and the protection of water resources is aimed at reducing irreplaceable water losses and reducing the need for it on the ground.

Redistribution of runoff.

Although traditionally many large settlements have been established near permanent water sources, some settlements are now also being established in areas that receive water from afar. Even where the source of the supplemental water supply is within the same state or country as the destination, there are technical, environmental, or economic problems, but if the imported water crosses national boundaries, the potential complications increase. For example, spraying silver iodide on clouds results in increased rainfall in one area, but this can result in reduced precipitation in other areas.

One of the major water transfer projects proposed in North America is to divert 20% of excess water from the northwest to arid regions. At the same time, up to 310 million m 3 of water would be redistributed annually, a through system of reservoirs, canals and rivers would contribute to the development of navigation in the interior, the Great Lakes would receive an additional 50 million m 3 of water annually (which would compensate for the decrease in their level), and up to 150 million kW of electricity would be generated. Another grandiose plan for the transfer of runoff is associated with the construction of the Great Canadian Canal, through which water would be directed from the northeastern regions of Canada to the western regions, and from there to the USA and Mexico.

Much attention is drawn to the project of towing icebergs from Antarctica to arid regions, such as the Arabian Peninsula, which will annually provide fresh water from 4 to 6 billion people or irrigate approx. 80 million hectares of land.

One of the alternative methods of water supply is the desalination of salt water, mainly ocean water, and its transportation to the places of consumption, which is technically feasible due to the use of electrodialysis, freezing and various distillation systems. The larger the desalination plant, the cheaper it is to obtain fresh water. But with the increase in the cost of electricity, desalination becomes economically unprofitable. It is used only in cases where energy is readily available and other methods of obtaining fresh water are impractical. Commercial desalination plants operate on the islands of Curacao and Aruba (in the Caribbean Sea), Kuwait, Bahrain, Israel, Gibraltar, Guernsey and the USA. Numerous smaller demonstration plants have been built in other countries.

Protection of water resources.

There are two widely used ways to conserve water resources: maintaining existing supplies of usable water and increasing its supply by building better collectors. The accumulation of water in reservoirs prevents it from flowing into the ocean, from where it can only be extracted again through the water cycle or through desalination. Reservoirs also make it easier to use water at the right time. Water can be stored in underground cavities. At the same time, there is no loss of moisture for evaporation, and valuable land is saved. The preservation of existing water reserves is facilitated by channels that prevent water from seeping into the ground and ensure its efficient transportation; applying more efficient irrigation methods using wastewater; reducing the volume of water flowing from fields or filtering below the root zone of crops; careful use of water for domestic needs.

However, each of these methods of conserving water resources has some impact on the environment. For example, dams spoil the natural beauty of unregulated rivers and prevent the accumulation of fertile silt on floodplains. Prevention of water loss as a result of filtration in canals can disrupt the water supply of swamps and thus adversely affect the state of their ecosystems. It may also prevent groundwater recharge, thus affecting the water supply of other users. And to reduce the volume of evaporation and transpiration by agricultural crops, it is necessary to reduce the area under crops. The latter measure is justified in areas suffering from water shortages, where it is carried out a savings regime by reducing irrigation costs due to the high cost of energy needed to supply water.

WATER SUPPLY

The sources of water supply and reservoirs themselves matter only when water is delivered in sufficient volume to consumers - to residential buildings and institutions, to fire hydrants (devices for taking water for fire needs) and other public utilities, industrial and agricultural facilities.

Modern systems for filtering, purifying and distributing water are not only convenient, but also help prevent the spread of water-borne diseases such as typhoid and dysentery. A typical urban water supply system involves drawing water from a river, passing it through a coarse filter to remove most of the pollutants, and then through a measuring post, where its volume and flow rate are recorded. After that, the water enters the water tower, from where it passes through the aeration unit (where impurities are oxidized), a microfilter to remove silt and clay, and a sand filter to remove the remaining impurities. Chlorine, which kills microorganisms, is added to the water in the main pipe before entering the mixer. Ultimately, before being sent to the distribution network for consumers, the treated water is pumped into a storage tank.

Pipes at the central waterworks are usually cast iron, of large diameter, which gradually decreases as the distribution network expands. From street water mains with pipes with a diameter of 10–25 cm, water is supplied to individual houses through galvanized copper or plastic pipes.

Irrigation in agriculture.

Since irrigation requires huge amounts of water, the water supply systems of agricultural areas must have a large capacity, especially in arid conditions. Water from the reservoir is directed to a lined, and more often unlined main canal and then through branches to distribution irrigation canals of various types to farms. Water is released to the fields by flooding or by irrigation furrows. Because many reservoirs are located above irrigated land, water mostly flows by gravity. Farmers who store water themselves pump it from wells directly into canals or storage reservoirs.

For irrigation by sprinkling or drip irrigation, practiced recently, pumps of small power are used. In addition, there are giant central-pivot irrigation systems that pump water from wells right in the middle of the field directly into a pipe equipped with sprinklers and rotating in a circle. From the air, fields irrigated in this way appear to be giant green circles, some of which reach a diameter of 1.5 km. Such installations are common in the US Midwest. They are also used in the Libyan part of the Sahara, where more than 3,785 liters of water per minute are pumped out of the deep Nubian aquifer.

Message on the topic

Earth's water resources

students

Ι course group 251(b)

Sazonova Daria

Kazan 2006.

1. General characteristics of water resources

2. Water balance of the Earth

3. Hydrosphere as a natural system

4. World Ocean

5. Land waters

6. Water management

7. Sources of water pollution

8. Measures for the protection and economical use of water resources

9. International Decade: "Water for Life".

1. General characteristics of water resources.

The water shell of the globe - oceans, seas, rivers, lakes - is called the hydrosphere. It covers 70.8% of the earth's surface. The volume of the hydrosphere reaches 1370.3 mln. rivers, swamps and lakes.

The aquatic environment includes surface and ground waters. Surface waters are mainly concentrated in the ocean, with a content of 1 billion 338 million km3 - about 98% of all water on Earth. The surface of the ocean (water area) is 361 million km2. It is approximately 2.4 times larger than the land area of ​​the territory, which occupies 149 million km2. The water in the ocean is salty, and most of it (more than 1 billion km3) maintains a constant salinity of about 3.5% and a temperature of approximately 3.7° C. Noticeable differences in salinity and temperature are observed almost exclusively in the surface water layer, as well as in the marginal and especially in the Mediterranean seas. The content of dissolved oxygen in water decreases significantly at a depth of 50-60 meters.

Groundwater can be saline, brackish (lower salinity) and fresh; existing geothermal waters have an elevated temperature (more than 30 ° FROM.). For the production activities of mankind and its household needs, fresh water is required, the amount of which is only 2.7% of the total volume of water on Earth, and a very small share of it (only 0.36%) is available in places that are easily accessible for extraction. Most of the fresh water is found in snows and freshwater icebergs found in areas mostly in the Antarctic Circle. The annual global freshwater river runoff is 37.3 thousand km3. In addition, a part of groundwater equal to 13 thousand km3 can be used. Unfortunately, most of the river flow in Russia, amounting to about 5000 km3, falls on the marginal and sparsely populated northern territories. In the absence of fresh water, salty surface or underground water is used, producing its desalination or hyperfiltration: it is passed under a large pressure drop through polymer membranes with microscopic holes that trap salt molecules. Both of these processes are very energy intensive, therefore, the proposal is of interest, which consists in using freshwater icebergs (or parts of them) as a source of fresh water, which for this purpose are towed along the water to shores that do not have fresh water, where they organize their melting. According to the preliminary calculations of the developers of this proposal, the production of fresh water will be about half as energy-intensive as compared to desalination and hyperfiltration. An important circumstance inherent in the aquatic environment is that infectious diseases are mainly transmitted through it (approximately 80% of all diseases). However, some of them, such as whooping cough, chickenpox, tuberculosis, are transmitted through the air. To combat the spread of disease through the aquatic environment, the World Health Organization (WHO) has declared the current decade the decade of drinking water.

2. The water balance of the earth.

To imagine how much water is involved in the cycle, we characterize the various parts of the hydrosphere. More than 94% of it is the oceans. The other part (4%) is groundwater. At the same time, it should be taken into account that most of them belong to deep brines, and fresh waters make up 1/15 of the share. The volume of ice of polar glaciers is also significant: in terms of water, it reaches 24 million km, or 1.6% of the volume of the hydrosphere. Lake water is 100 times less - 230 thousand km., And the riverbeds contain only 1200 m. of Water, or 0.0001% of the entire hydrosphere. However, despite the small volume of water, rivers play a very important role: they, like groundwater, satisfy a significant part of the needs of the population, industry and irrigated agriculture. There is quite a lot of water on Earth. The hydrosphere makes up about 1/4180 of the mass of our planet. However, the share of fresh water, excluding water bound in polar glaciers, accounts for a little more than 2 million km, or only 0.15% of the total volume of the hydrosphere.

3. Hydrosphere as a natural system

The hydrosphere is a discontinuous water shell of the Earth, a combination of seas, oceans, continental waters (including groundwater) and ice sheets. Seas and oceans occupy about 71% of the earth's surface, they contain about 96.5% of the total volume of the hydrosphere. The total area of ​​all inland water bodies of land is less than 3% of its area. Glaciers account for 1.6% of water reserves in the hydrosphere, and their area is about 10% of the area of ​​the continents.

The most important property of the hydrosphere is the unity of all types of natural waters (the World Ocean, land waters, water vapor in the atmosphere, groundwater), which is carried out in the process of the water cycle in nature. The driving forces of this global process are the thermal energy of the Sun coming to the Earth's surface and the force of gravity, which ensures the movement and renewal of natural waters of all kinds.

Under the influence of solar heat, water in nature makes a continuous cycle. Water vapor, which is lighter than air, rises to the upper layer of the atmosphere, condenses into tiny droplets, forming clouds of which water returns to the earth's surface in the form of precipitation, rain, snow. The water that falls on the surface of the globe is partly

directly into natural water bodies, partially collected in the upper layer

soils, forming surface and groundwater.

Evaporation from the surface of the World Ocean and from the land surface is the initial link in the water cycle in nature, ensuring not only the renewal of its most valuable component - fresh water on land, but also their high quality. An indicator of the activity of the water exchange of natural waters is the high rate of their renewal, although various natural waters are renewed (replaced) at different rates. The most mobile agent of the hydrosphere is river waters, the renewal period of which is 10-14 days.

The predominant part of the hydrospheric waters is concentrated in the World Ocean. The world ocean is the main closing link of the water cycle in nature. It releases most of the evaporating moisture into the atmosphere. Aquatic organisms inhabiting the surface layer of the World Ocean provide the return to the atmosphere of a significant part of the free oxygen of the planet.

The huge volume of the World Ocean testifies to the inexhaustibility of the planet's natural resources. In addition, the World Ocean is a collector of land river waters, annually receiving about 39 thousand m3 of water. The pollution of the World Ocean, which has been outlined in some areas, threatens to disrupt the natural process of moisture circulation in its most critical link - evaporation from the ocean surface.

4. World Ocean.

The average depth of the World Ocean is 3700 m, the greatest is 11022 m (Marian Trench). The volume of waters of the World Ocean, as mentioned above, cubic meters. km.

Almost all substances known on Earth are dissolved in sea water, but in different quantities. Most of them are difficult to detect due to their low content. The main part of salts dissolved in sea water is chlorides (89%) and sulfates (almost 11%), much less carbonates (0.5%). Salt ( NaCl) gives water a salty taste, magnesium salts (MqCl) - bitter. The total amount of all salts dissolved in water is called salinity. It is measured in thousandths - ppm (% o).

The average salinity of the World Ocean is about 35% o.

The salinity of water in the ocean depends primarily on the ratio of precipitation and evaporation. Reduce the salinity of river waters and waters of melting ice. In the open ocean, the distribution of salinity in the surface layers of water (up to 1500 m) has a zonal character. In the equatorial zone, where there is a lot of precipitation, it is lower, in tropical latitudes it is higher.

Inland seas differ markedly in salinity. The salinity of the water in the Baltic Sea is up to 11%o, in the Black Sea - up to 19%o, and in the Red - up to 42%o. This is explained by the different ratio of the inflow (atmospheric precipitation, river runoff) and consumption (evaporation) of fresh water, i.e., climatic conditions. Ocean - heat regulator

The highest temperature at the surface of the water in the Pacific Ocean is 19.4 ° C; The Indian Ocean has 17.3 °C; Atlantic - 16.5 ° С. With such average temperatures, the water in the Persian Gulf regularly heats up to 35 °C. The water temperature tends to decrease with depth. Although there are exceptions due to the rise of deep warm waters. An example is the western part of the Arctic Ocean, where the Gulf Stream invades. At a depth of 2 km throughout the entire water area of ​​the World Ocean, the temperature usually does not exceed 2-3 °C; in the Arctic Ocean it is even lower.

The World Ocean is a powerful heat accumulator and a regulator of the Earth's thermal regime. If there were no ocean, the average surface temperature of the Earth would be - 21 ° C, that is, it would be 36 ° lower than that which is in reality.

Currents of the oceans

The waters of the ocean are in constant motion under the influence of various forces: cosmic, atmospheric, tectonic, etc. The most pronounced are surface sea currents, mainly of wind origin. But 3 currents that arise due to different mass densities are very common. The currents in the World Ocean are divided according to the direction prevailing in them into zonal (going to the west and east) and meridional (carrying water to the north and south). Currents going towards neighboring, more powerful currents are called countercurrents. Equatorial currents (along the equator) are specially distinguished. Currents that change their strength from season to season, depending on the direction of coastal monsoons, are called monsoons.

The most powerful in the entire World Ocean is the Circumpolar, or Antarctic, circular current, due to strong and stable westerly winds. It covers a zone of 2500 km in width and kilometer depths, carrying about 200 million tons of water every second. For comparison, the largest river in the world, the Amazon, carries only about 220,000 tons of water per second.

In the Pacific Ocean, the strongest is the South Trade Wind Current, heading from east to west, at a speed of 80-100 miles per day. To the north of it there is a countercurrent, and even to the north - the Northern trade wind current from east to west. Knowing the direction of the currents, the locals have long used them for their movements. Following them, T. Heyerdahl used this knowledge for his famous trip to the Kon-Tiki. Analogues of the trade winds (literally "favorable to moving") currents and countercurrents are found in the Indian and Atlantic oceans.

Of the meridional currents, the most famous are the Gulf Stream and Kuroshio, which carry 75 and 65 million tons of water per second, respectively.

For many areas of the World Ocean (the western coasts of North and South America, Asia, Africa, Australia), upwelling is typical, which can be caused by wind-driven surface water from the coast. Rising deep waters are often rich in nutrients, and upwelling sites are associated with a zone of high biological productivity.

The role of the ocean in people's lives

It is difficult to overestimate the role of the World Ocean in the life of mankind. It largely determines the face of the planet as a whole, including its climate, the water cycle on Earth. In the ocean, there were vital waterways connecting the continents and islands. Its biological resources are colossal. More than 160 thousand species of animals and about 10 thousand species of algae live in the World Ocean. The annual reproducible number of commercial fish is estimated at 200 million tons, of which approximately 1/3 is caught. More than 90% of the world's catch comes from the coastal shelf, especially in the temperate and high latitudes of the Northern Hemisphere. The share of the Pacific Ocean in the world catch is about 60%, the Atlantic - about 35%.

The shelf of the World Ocean has huge reserves of oil and gas, large reserves of iron-manganese ores and other minerals. Mankind is just beginning to use the energy resources of the World Ocean, including the energy of the tides. The World Ocean accounts for 94% of the volume of the hydrosphere. Desalination of sea waters is associated with the solution of many water problems of the future.

Unfortunately, humanity does not always use the natural resources of the oceans wisely. In many areas, its biological resources are depleted. A significant part of the water area is polluted with anthropogenic waste, primarily oil products.

Land waters are water, rivers, lakes, swamps, glaciers. They contain 3.5% of the total amount of water in the hydrosphere. Of these, only 2.5% is fresh water.

Groundwater is located in the rock masses of the upper part of the earth's crust in a liquid, solid and vapor state. Their main mass is formed due to seepage from the surface of rain, melt and river waters.

According to the conditions of occurrence, groundwater is divided into:

1) soil, located in the uppermost, soil layer;

2) ground, lying on the first permanent water-resistant layer from the surface;

3) interstratal, located between two water-resistant layers;

The latter are often pressure and then are called artesian.

Groundwater feeds rivers and lakes.

Rivers are constant water streams flowing in depressions developed by them - channels.

The most important characteristic of rivers is their feeding. There are four power sources: snow, rain, glacial and underground.

The regime of rivers largely depends on the feeding of rivers, i.e., the change in the amount of water discharge by the seasons of the year, level fluctuations, and changes in water temperature. The water regime of the river is characterized by water flow and runoff. The flow rate is the amount of water passing through the cross section of the flow in one second. The flow of water over a long time - a month, a season, a year - is called a runoff. The volume of water that rivers carry on average per year is called their water content. The most abundant river in the world is the Amazon, at its mouth the average annual water flow is 220,000 cubic meters. m/s. In second place is the Congo (46,000 cubic meters per second), then the Yangtze. In our country, the most abundant river is the Yenisei (19,800 cubic meters per second). Rivers are characterized by a very uneven distribution of runoff over time. Most rivers in Russia carry 60-70% of the volume of water in a relatively short period of spring floods. At this time, melt water flows down the frozen and well-moistened surface of the watersheds with the least loss of filtration and evaporation.

It is during the flood period that rivers most often overflow their banks and flood the surrounding areas. In summer and winter, low water is usually observed - low water, when the rivers are fed by groundwater, the resources of which are also largely replenished in the spring. In summer, most of the precipitation is spent on evaporation; only a small part of atmospheric precipitation reaches the level of groundwater, and even more so, rivers. In winter, precipitation accumulates in the form of snow. Only in autumn there are small floods on Russian rivers.

The rivers of the Far East and the Caucasus differ from the plain rivers of Russia in terms of hydrological regime. The first spill in the fall - during the monsoon rains; on the Caucasian rivers, the maximum water discharges are observed in summer, when high-mountain glaciers and snowfields melt.

The flow of rivers varies from year to year. Often there are low-water and high-water periods when the river is characterized by low or, on the contrary, high water content. For example, in the 1970s, low water was observed on the Volga, in connection with which the level of the inland Caspian Sea, for which the Volga is the main supplier of water, was rapidly falling. Since 1978, a phase of increased humidity began in the Volga basin, its runoff annually began to exceed the long-term average, and the level of the Caspian Sea began to rise, as a result of which coastal areas were flooded. Most of the rivers in Russia are annually covered with ice. The duration of freeze-up in the north of Russia is 7-8 months (from October to May). The opening of rivers from ice - ice drift - is one of the most impressive sights, often accompanied by flooding.

Rivers have played an outstanding role in the history of mankind, the formation and development of human society is associated with them. Since historical times, rivers have been used as communication routes, for fishing and fish farming, timber rafting, field irrigation and water supply. People have long settled along the banks of rivers - this is also confirmed by folklore, in which the Volga is called "mother", and Amur - "father". The river is the main source of hydropower and the most important transport route. Rivers are of great aesthetic and recreational importance as an integral element of the environment. The wide involvement of rivers in economic circulation has led to a complete transformation of many of them. The flow of such rivers as the Volga, Dnieper, Angara is largely regulated by reservoirs. Many of them, especially those flowing in the southern regions, where there is a great need for irrigation, are dismantled for the needs of irrigation. For this reason, the Amu Darya and Syr Darya no longer flow into the Aral Sea, and it is rapidly drying up.

One of the most negative results of anthropogenic impact on rivers is their massive pollution with sewage and other waste from economic activities. The threat of qualitative depletion of river water resources can be avoided if a complex of water management measures is implemented, including not only traditional wastewater treatment, but also such cardinal measures as changing production technology in order to reduce water consumption and waste generation many times over.

Lakes are natural reservoirs in land depressions (hollows), filled within the lake bowl (lake bed) with heterogeneous water masses and not having a one-sided slope. Lakes are characterized by the absence of a direct connection with the oceans. Lakes occupy about 2.1 million km2, or almost 1.4% of the land area. This is about 7 times the surface of the Caspian Sea - the largest lake in the world.

A swamp is a piece of land with excessive stagnant soil moisture, overgrown with moisture-loving vegetation. Swamps are characterized by the accumulation of undecomposed plant residues and the formation of peat. Bogs are distributed mainly in the Northern Hemisphere, especially in flat areas where permafrost soils are developed, and occupy an area of ​​about 350 million hectares.

Glaciers are moving natural accumulations of ice of atmospheric origin on the earth's surface; are formed in those areas where solid atmospheric precipitation is deposited more than it melts and evaporates. Within the glaciers, areas of nutrition and ablation are distinguished. Glaciers are divided into terrestrial ice sheets, shelf and mountain. The total area of ​​modern glaciers is approx. 16.3 million km2 (10.9% land area), total ice volume approx. 30 million km3.

6. Water resources management.

One of the directions for solving water problems is to attract the currently underused water resources of desalinated waters of the World Ocean, groundwater and glacier waters for the purposes of water supply. At present, the share of desalinated water in the total volume of world water supply is small - 0.05%, which is explained by the high cost and significant energy intensity of desalination processes. Even in the United States, where the number of desalination plants has increased 30-fold since 1955, desalinated water accounts for only 7% of water consumption.

In Kazakhstan, in 1963, the first pilot-industrial distiller was put into operation in the city of Aktau (Shevchenko). Due to the high cost, desalination is used only where surface or underground fresh water resources are completely absent or extremely difficult to access, and their transportation is more expensive compared to water desalination.

increased mineralization directly on the spot. In the future, water desalination will be carried out in a single technical complex with the extraction of useful components from it: sodium chloride, magnesium, potassium, sulfur, boron, bromine, iodine, strontium, non-ferrous and rare metals, which will increase the economic efficiency of desalination plants.

An important reserve of water supply is groundwater. The greatest value for society is fresh groundwater, which makes up 24% of the volume of the fresh part of the hydrosphere. Brackish and saline underground waters can also serve as a reserve in water supply when they are used in a mixture with fresh water or after their artificial desalination. Factors limiting underground water intake include:

1) the uneven distribution of their distribution over the territory of the earth;

2) difficulties in processing saline groundwater;

3) rapidly declining rates of natural renewal since

increase in the depth of aquifers.

Utilization of water in the solid phase (ice, ice sheets) is expected, firstly, by increasing the water yield of mountain glaciers, and secondly, by transporting ice from the polar regions. However, both of these methods are practically difficult to implement and the environmental consequences of their implementation have not yet been studied.

Thus, at the present stage of development, the possibilities of attracting additional volumes of water resources are limited. The uneven distribution of water resources across the globe should also be pointed out. The highest availability of river and underground runoff resources falls on the equatorial belt of South America and Africa. In Europe and Asia,

where 70% of the world's population lives, only 39% of river waters are concentrated. The largest rivers in the world are the Amazon (annual flow 3780 km3), Congo (1200 km3), Mississippi (600 km3), Zamberi (599 km3), Yangtze (639 km3), Irrawaddy (410 km3), Mekong (379 km3), Brahmaputra ( 252 km3) . In Western Europe, the average annual surface runoff is 400 km3, including about 200 km3 in the Danube, 79 km3 on the Rhine, and 57 km3 on the Rhone. The largest lakes in the world are the Great American Lakes (total area - 245 thousand km3), Victoria (68 thousand km3), Tanganyika (34 thousand km3), Nyasa (30.8 thousand km3).

The Great American Lakes contain 23,000 km3 of water, the same amount as Baikal. To characterize the distribution of hydro resources, the volume of total river flow per unit of territory (1 km3) and population is calculated. 5.2 km3 of total sustainable runoff (including regulated by reservoirs) falls on 1 million inhabitants of the USSR against 4 km3 for the total

the globe; 19 km3 of total river flow versus 13 km3; 4.1 sustainable groundwater flow versus 3.3 km3. The average water supply per 1 km2 is 212 thousand m3 in the CIS, and 278 thousand m3 in the world. The main ways to manage water resources are the creation of reservoirs and the territorial transfer of runoff.

7. Sources of pollution of water resources.

The Earth's hydrosphere is of great importance in the exchange of oxygen and carbon dioxide with the atmosphere. Oceans and seas have a softening, regulating effect on air temperature, accumulating heat in summer and giving it back to the atmosphere in winter. Warm and cold waters circulate and mix in the ocean. The biomass of the vegetation of the oceans and seas is many times

smaller than land, but animal biomass is at least an order of magnitude greater. Oceans and seas absorb carbon dioxide. The hydrosphere is an important food source for humans and other land dwellers. The catch of fish, which at the beginning of this century was 3 million tons per year, now reaches 80 million tons. This growth is associated with the progress of technology, the widespread use of special trawlers, seiners with hydroacoustic devices for detecting accumulations of fish, equipment for impact on her

light, electricity.

There were fish pumps, nylon nets, trawl fishing, freezing and canning of fish on board. As a result of the increased catch, its composition deteriorated, the share of herring decreased,

Sardine, salmon, cod, flounder, halibut and increased proportions of tuna, mackerel, sea bass and bream. With significant investments, it is really possible to increase the catch of seafood to 100-130 million tons. These figures include, for example, krill-small crustaceans, whose reserves are huge in the southern seas. Krill contains protein, these crustaceans can be used for food and other purposes. A large number of fish are caught. Not for food, but for food

livestock or processed into fertilizer. For a number of years, especially after the war, a significant part of the whales has been exterminated, and some of their species are on the verge of complete destruction. By international agreement, further whale fishing is limited. The destruction of the inhabitants of the oceans and seas as a result of their unreasonable catch raises the question of the expediency of the transition from extensive fishing to artificial breeding of fish. In this regard, we may recall the transition from hunting and gathering fruits and roots in the earlier stages of the development of society to the breeding of animals and plants.

8. Measures for the protection and economical use of water resources.

Serious measures are being taken to prevent the growing pollution of water bodies with sewage. Waste water is water discharged after use in domestic and industrial human activities. By their nature, pollution is divided into mineral, organic, bacteriological and biological. The criterion for the harmfulness of wastewater is the nature and degree of restriction of water use. The quality of natural waters in Kazakhstan is standardized in places of water use. The developed normative indicators - the maximum permissible concentrations of harmful substances in the water of water bodies for various purposes - refer to the composition of water in reservoirs, and not to the composition of wastewater.

In accordance with the Regulations on the state accounting of waters and their

use (1975), primary accounting of wastewater discharged into water bodies is carried out by water users themselves. This control is exercised by the majority of water users unsatisfactorily. This is evidenced by the fact that only 20% of the discharged wastewater is controlled by hydraulic

equipment, and the rest - by indirect methods. Currently, the transition to the system of standards for maximum allowable emissions (MAE) is being carried out. The MPE values ​​are determined for each specific emission source so that the total emissions from all sources in the region do not exceed the MPC standard. The use of MPE standards will facilitate the planning and control of environmental activities, increase

responsibility of the enterprise for compliance with environmental requirements, eliminate conflict situations. Of the total amount of wastewater, 69% is conditionally clean, 18% is polluted and 13% is normatively purified. There are no strict criteria for dividing industrial wastewater into normatively treated, polluted and conditionally clean. Raw wastewater needs to be repeatedly diluted with clean water.

water. Particularly polluting are the production of the oil refining, pulp and paper and chemical industries. Regulatory purified water

The main market method of regulation of environmental activities is pollution charges. There are two types of payment per unit of emissions and payment for the use of public wastewater treatment plants. The fee level in the first case is determined by the desired quality of the environment. The mechanism of such a board automatically ensures the optimal allocation of resources. The fee for the use of treatment facilities includes

the basic fee for the discharge of standard wastewater, the additional fee for excess discharge, the fee for transporting water and the service fee for the water inspection. To assess the pollution of river waters, the indicator of conditional pollution is used. The amount of the fee depends on the age of the treatment plant, the ability of water bodies to self-purify, as well as the composition of the effluent. The fee mechanism is most efficient under pure competition, where each firm seeks to minimize unit costs.

release. In the conditions of monopolies, firms may not set themselves such a goal, therefore, in monopolized industries, methods of direct administrative regulation gain advantages.

10. International Decade Water for Life

4,000 children die every day due to diseases caused by undrinkable water; 400 million children do not have even the bare minimum of safe water necessary for life; as many as 2.6 billion people live without sanitation - all of which defy the UN's fight for clean water.

The United Nations Children's Fund (UNICEF) highlighted the fact that lack of clean water is responsible for at least 1.6 million of the 11 million preventable child deaths each year. Nearly three children die every minute due to diseases caused by unfit water, such as diarrhea and typhoid fever. In sub-Saharan Africa, where one in five children die before age five, 43% of children drink unsafe water, risking illness and death with every sip.

The Office of the United Nations High Commissioner for Refugees (UNHCR) spoke about the situation in Zhegriyad - the "Valley of Death" in Somalia. It got its name from the fact that every year people die of thirst here, especially drivers whose trucks or cars break down on the way to Djibouti.

This is just a small part of the challenge facing UNHCR, an organization that is trying to help 17 million people in more than 116 countries. In Tindouf, Algeria, a project is currently under way to improve the water supply of the Smara camp in the heart of the Sahara Desert, where tens of thousands of Western Saharan refugees live.

In another camp in eastern Chad, where more than 200,000 refugees are fleeing the conflict in Sudan's Darfur, UNHCR continues to provide water to refugees by delivering water, drilling wells, digging wells and using high technology to find additional sources of water.

On March 22, 2005, the UN celebrated World Water Day by proclaiming International Decade "Water for Life". The data on the scale of the problem and the stories of specific people, apart from the speeches of the leaders of the organizations of the UN system, make you realize how difficult it will be for the world to achieve one of the Millennium Development Goals: by 2015, to halve the number of people who are deprived clean drinking water and minimum sanitary conditions.

List of used literature:

1. Geography. Complete exam preparation course. Moscow. AST-press; 2004

2., "Environmental Protection"

3. B. Nebel "Environmental Science" Moscow. "Science" 2002

4. Great Soviet Encyclopedia. Moscow. "Soviet Encyclopedia", 1972