Water resources and their use comparison tables. Water consumption
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The total volume of the Earth's hydrosphere is enormous and amounts to almost 1.4 billion km. However, the resources of fresh water needed by mankind, animals and plants make up only 2-2.5% of this volume. World water consumption in 1985 was 4 thousand km3, according to experts' forecasts in 2000 it should increase to 6 thousand km3. In addition, about half of all fresh water used (63%) is irretrievably consumed, especially in agriculture. Industrial water consumption accounts for 27% of the total volume, household water consumption - 6%, and construction - only 4%. This situation creates a real threat of a shortage of fresh water globally.
Fresh water reserves are small, and even then most of it is in a solid state in the form of, and in the mountains. This part is still practically inaccessible for use. If this ice is evenly distributed over the Earth, it will cover it with a layer of 53 cm, and if melted, the level will rise by 64 meters.
Lakes are also a valuable source of fresh water, but they are unevenly distributed over the Earth's surface. In and in the northern part, fresh water is abundant, and per capita it accounts for 25 thousand cubic meters per year. In the belts of the planet, which cover 1/3 of the land, there is a very acute shortage of water. Here, per capita there is less than 5 thousand m per year, and agriculture is possible only under conditions. These contrasts are explained primarily by the climatic originality of the regions and the nature of their surface.
Fresh water has already become a commodity of world trade: it is in tankers, along distant water pipelines. For example, such water is imported from, - from, - from. There are projects for pumping water through water pipelines from and Antarctica to, from to. Installations are being developed where the heat of nuclear reactors will be used simultaneously for water desalination and electricity generation. The cost per liter will be low, since the productivity of the plants is very significant. This desalinated water will be used for irrigation.
SUSHI WATER RESOURCES
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 the water resources of the land has changed. This is due to the fact that fresh water resources account for 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 overwhelming part 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 World Ocean; 1% - salty groundwater; 2.5% - fresh water resources.
Fresh water: 68.7 - glaciers; 30.9% - groundwater.
Table 11. Distribution of world fresh water resources by large regions.
The data in this table lead to interesting conclusions. First of all, about how 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 Australia and Oceania have the smallest, while in terms of their specific supply, they change their places. Of course, the whole point is in the population, which in Asia has already reached 3.7 billion people, and in Australia barely exceeds 30 million. If you disregard Australia, then South America will be the richest region of the world 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 supplies and availability of fresh water. Based on the principle of "best-most", we will show which of them belong to the category of the richest and the poorest in fresh water.
Table 12. Top ten countries by freshwater resources.
In it, the rank of resources does not coincide with the rank of specific supply, and in each case such a difference can be explained. For example, in China and India there is a huge population, therefore, a low per capita income. But there are countries in the world that are even less supplied with fresh water, where less than 1,000 m 3 of water is per capita (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 sub-Saharan part of Africa (Algeria - 520 m 3, Tunisia - 440 m 3, Libya - 110 m 3) and in the Arabian Peninsula (Saudi Arabia - 250 m 3, Kuwait - 100 m 3).
These individual examples are interesting because they allow us to make an important generalization: at the end of the XX century. approximately 2/5 of the population of our planet suffer from 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. It should be borne in mind 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 household 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 unchanged river flow resources creates a real threat of a shortage of fresh water.
In this case, it is necessary to take into account not only the quantity, but also the quality of the water. In developing countries, one in three people suffer from a lack of drinking water. Consumption of contaminated water is the source of 3/4 of all diseases and 1/3 of all deaths. In Asia, more than 1 billion people lack access to clean water, 350 million in sub-Saharan Africa and 100 million in Latin America.
But, in addition, the reserves of fresh water on the Earth are extremely unevenly distributed. In the equatorial belt and in the northern part of the temperate belt, it is abundant and even abundant. The most abundant countries are located here, where more than 25 thousand m 3 per capita per year are located. In the arid belt of the Earth, which covers about 1/3 of the land area, the water shortage is felt especially acutely. The most dry countries are located here, where there is less than 5 thousand m 3 per capita 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 to reduce the water intensity of production processes and to reduce the irretrievable loss of water. 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 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, the Dnieper in Ukraine, Tennessee, Missouri, Columbia in the United States, and many others, have actually turned into cascades of reservoirs. Large and large reservoirs play an especially important role in the transformation of river flow. The problem is that the main source of satisfying mankind's needs for fresh water has been and remains river (channel) waters, which determine the "water ration" of the planet - 40 thousand km 3. It is not that significant, especially considering that you can actually use about 1/2 of this amount.
In terms of the number of large reservoirs, the United States, Canada, Russia, and some countries in Africa and Latin America stand out.
Table 13. The 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 of territorial redistribution of river runoff by means of its transfer have been implemented or are being designed. Recently, however, the largest inter-basin transfer projects have been canceled for economic and environmental reasons. In the countries of the Persian Gulf, the Mediterranean, Turkmenistan, the Caspian Sea, the southern United States, Japan, and the Caribbean islands, seawater 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 distant water pipelines. Projects are being developed for towing icebergs from Antarctica, which every polar summer sends 1200 million tons of fresh water conserved in them to the countries of the arid belt.
You know that river runoff is also widely used to obtain hydropower. World hydropower potential usable is estimated at nearly 10 trillion kWh. possible power generation. About 1/2 of this potential falls on only 6 countries: China, Russia, USA, Congo (formerly Zaire), Canada, Brazil.
Table 14 . World economic hydro potential and its use
|
Regions |
Total |
Including used, % |
|
|
billion kWh |
v % |
||
|
CIS |
1100 |
11,2 |
|
|
Overseas Europe |
|||
|
Overseas asia |
2670 |
27,3 |
|
|
Africa |
1600 |
16,4 |
|
|
North America |
1600 |
16,4 |
|
|
Latin America |
1900 |
19,4 |
|
|
Australia and Oceania |
|||
|
The whole world |
Basic concepts: geographic (environment) environment, ore and non-metallic minerals, ore belts, basins of minerals; structure of the world land fund, southern and northern forest belts, forest cover; hydropower potential; shelf, alternative energy sources; resource availability, natural resource potential (NRP), territorial combination of natural resources (TPSR), areas of new development, secondary resources; environmental pollution, environmental policy. Skills: be able to characterize the natural resources of the country (region) according to the plan; use various methods of economic valuation of natural resources; to characterize the natural prerequisites for the development of industry, agriculture of the country (region) according to the plan; to give a brief description of the location of the main types of natural resources, to single out the countries "leaders" and "outsiders" in terms of the provision of this or that type of natural resources; give examples of countries that do not have rich natural resources, but have achieved a high level of economic development, and vice versa; give examples of rational and irrational use of resources. | ||
Water is the only substance that is naturally present in liquid, solid and gaseous states. The meaning 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. Another approx. 2% falls on the share of fresh waters trapped in the ice sheets and mountain glaciers, and only less than 1% - on the share of fresh waters of lakes and rivers, groundwater and groundwater.
Water, the most abundant 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 essential for the normal functioning of all living organisms. A water molecule is made up of two hydrogen atoms and one oxygen atom. Its molecular weight is only 18, and its boiling point reaches 100
° C at atmospheric pressure 760 mm Hg. Art. On bó At higher altitudes, where the pressure is lower than at sea level, water boils at lower temperatures. When water freezes, its volume increases by more than 11%, and the expanding ice can rupture water pipes and pavements and erode rocks, turning them into loose soil. The density of ice is inferior to liquid water, which explains its buoyancy.Water also has unique thermal properties. When her temperature drops to
0 ° C and it freezes, 79 calories are released from each gram of water. During night frosts, farmers sometimes spray their gardens with water to protect the buds from frost damage. When water vapor condenses, each gram of it releases 540 cal. This heat can be used in heating systems. Due to its high heat capacity, water absorbs a large amount of heat without changing the temperature.Water molecules are linked through "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 (called molecular attraction). The unique properties of water are determined by the strength of hydrogen bonds. The forces of adhesion and molecular attraction allow it to overcome the force of gravity and, due to capillarity, rise upward through small pores (for example, in dry soil).
DISTRIBUTION OF WATER IN NATUREWhen the temperature of water changes, the hydrogen bonds between its molecules also change, which in turn leads to a change in its state - from liquid to solid and gaseous. see also WATER, ICE AND STEAM
Because liquid water is an excellent solvent, it is rarely completely pure and contains dissolved or suspended minerals. Only 2.8% of 1.36 billion km
3 of all the water available on Earth is fresh, and bó Most of it (about 2.2%) is in a solid state in mountain and cover glaciers (mainly in Antarctica) and only 0.6% is in a liquid state. Approximately 98% of liquid fresh water is found underground. Salt waters of the oceans and inland seas, which occupy more than 70% of the earth's surface, make up 97.2% of all the waters of the Earth. see also OCEAN.The water cycle in nature. Although the world's total water supply is unchanged, it is constantly being redistributed and thus a renewable resource. The water cycle is influenced by solar radiation, which stimulates the evaporation of water. At the same time, the mineral substances dissolved in it are precipitated. Water vapor rises into the atmosphere, where it condenses, and due to the force of gravity, the water returns to the earth in the form of precipitation - rain or snow (see also RAIN)... Bó Most of the precipitation falls over the ocean and only less than 25% over land. As a result of evaporation and transpiration, about 2/3 of this precipitation enters the atmosphere, and only 1/3 flows into rivers and seeps into the ground. see also HYDROLOGY.The force of gravity promotes the redistribution of liquid moisture from higher areas to lower ones, 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 the clouds.
Geographic distribution of precipitation. The amount of natural renewal of water reserves due to precipitation differs depending on the geographic location and size of the parts of the world. For example, South America receives almost three times as much rainfall annually as Australia and almost twice as much as North America, Africa, Asia and Europe (listed in order of decreasing annual rainfall). Part 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 runs down the earth's surface and eventually reaches the ocean with river runoff.Within the continents, precipitation also varies greatly from place to place. For example, in Africa, Sierra Leone, Guinea and Cote d
" More than 2000 mm of precipitation falls annually in Ivoire, in most of central Africa - from 1000 to 2000 mm, but at the same time in some northern regions (Sahara and Sahel) the amount of precipitation is only 500-1000 mm, and in southern regions - Botswana (including the desert Kalahari) and Namibia - less than 500 mm.Eastern India, Burma and parts of Southeast Asia receive more than 2000 mm of precipitation per year, and b
ó most of the rest of India and China - from 1000 to 2000 mm, while northern China - only 500–1000 mm. In northwestern India (including the Thar Desert), Mongolia (including the Gobi Desert), Pakistan, Afghanistan and bó Most of the Middle East receives less than 500 mm of precipitation annually.In South America, the annual rainfall in Venezuela, Guyana and Brazil exceeds 2000 mm, b
ó Most of the eastern regions of this continent receive 1,000–2,000 mm, but Peru and parts of Bolivia and Argentina receive only 500–1,000 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 regions 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 precipitation is 1000-2000 mm, in some other northern regions it ranges from 500 to 1000 mm, but b
ó Most of the mainland and especially its central regions receive less than 500 mm.ó Most of the former USSR also receives less than 500 mm of precipitation per year.Time cycles of water availability. In any part of 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 specific sequence, i.e. are cyclical. For example, water discharge in rivers, the banks of which are covered with dense vegetation, are usually higher at night. This is due to the fact that from dawn to dusk, vegetation uses groundwater for transpiration, as a result of which there is a gradual decrease in river flow, but its volume increases again at night when transpiration stops.Seasonal cycles of water availability depend on the characteristics of the distribution of precipitation throughout the year. For example, in the West of the United States, snow melting occurs in spring. In India, there is little rainfall in winter, and heavy monsoon rains begin at the height of summer. Although the average annual river flow is almost constant over a number of years, it is extremely high or extremely low every 11–13 years. Perhaps this is due to the cyclical nature of solar activity. Information on the cyclicity of precipitation and river runoff is used in predicting water availability and frequency of droughts, as well as in planning water protection activities.
SOURCES OF WATERThe main source of fresh water is 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 a liquid state falls on groundwater, with approx. 50% of them occur 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 that pump out water. Groundwater reserves in the Sahara are estimated at about 625 thousand km 3 ... In modern conditions, they are not replenished by surface fresh water, but are depleted when pumped out. Some of the deepest underground waters are never included in the general water cycle, and only in areas of active volcanism such waters are erupted in the form of steam. However, a significant mass of groundwater nevertheless penetrates the earth's surface: under the influence of gravity, these waters, moving along waterproof inclined layers of rocks, come out at the foot of the slopes in the form of springs and streams. In addition, they are pumped out by pumps, and also extracted by plant roots and then, in the process of transpiration, enter the atmosphere.The groundwater table is the upper limit of the available groundwater. In the presence of slopes, the water 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 exit 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 ensure the supply of water to shallow wells installed on aquifers. However, in the wells drilled at b
ó At 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 a year. They are usually saturated with porous pebble or sandy horizons or relatively impermeable strata of shale, and only rarely are they concentrated in underground cavities or underground streams. To choose the right location for drilling a well, information about the geological structure of the territory is usually required.In some parts of the world, the growing consumption of groundwater is having serious consequences. Pumping out 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 b
ó higher costs for expensive electricity used to extract them. In places of depletion of the aquifer, the earth's surface begins to sink, and there it is difficult to restore water resources in a natural way.In coastal areas, excessive abstraction of groundwater leads to replacement of fresh water in the aquifer with sea, saline, and thus degradation of local fresh water sources.
The gradual deterioration of groundwater quality as a result of salt accumulation can have even more dangerous consequences. Sources of salts are both natural (for example, dissolution and removal of minerals from soils) and anthropogenic (application of fertilizers 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 saline-bearing areas over a long distance.
As a result of the indiscriminate discharge or disposal of toxic chemicals, they seep into aquifers that are sources of drinking or irrigation water. In some cases, just a few years or decades is enough for harmful chemicals to get into groundwater and accumulate there in tangible quantities. However, if the aquifer was once contaminated, it would take 200 to 10,000 years for it to naturally cleanse itself.
Surface sources. Only 0.01% of the total volume of fresh water in a liquid state is concentrated in rivers and streams and 1.47% in lakes. For the accumulation of water and the constant supply of it to consumers, as well as to prevent unwanted floods and generate electricity, dams have been built on many rivers. The Amazon in South America, the Congo (Zaire) in Africa, the Ganges with Brahmaputra in southern Asia, the Yangtze in China, the Yenisei in Russia and the Mississippi with Missouri in the USA have the highest average water discharge, and therefore the greatest energy potential. see also RIVER.Water consumption by different crops. To obtain high yields, a lot of water is required: for example, growing 1 kg of cherries requires 3000 liters of water, rice - 2400 liters, corn on the cob and wheat - 1000 liters, green beans - 800 liters, grapes - 590 liters, spinach - 510 l, potatoes - 200 l and onions - 130 l. The approximate amount of water used only for cultivation (and not for processing or preparation) of 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 in total per day is 16 600 liters.In agriculture, water is used not only for irrigation of crops, but also for replenishment of groundwater reserves (to prevent too rapid lowering of the groundwater level); for washing out (or leaching) salts accumulated in the soil to a depth below the root zone of cultivated crops; for spraying against pests and diseases; frost protection; fertilization; lower air and soil temperatures in summer; for the care of livestock; evacuation of treated wastewater used for irrigation (mainly grain crops); and processing of the harvested crop.
Food industry. Different food crops require different amounts of water to process, depending on the product, the manufacturing technology and the availability of water of adequate quality in sufficient volume. In the United States, the production of 1 ton of bread requires 2,000 to 4,000 liters of water, while in Europe - only 1,000 liters and only 600 liters in some other countries. Canning fruits and vegetables requires 10,000 to 50,000 liters of water per ton in Canada, while in Israel, where water is in short supply, only 4,000 to 1,500. The "champion" in terms of water consumption is lima beans, for canning 1 ton of which 70,000 liters of water are consumed in the United States. To process 1 ton of sugar beet, 1800 liters of water are used in Israel, 11,000 liters in France and 15,000 liters in Great Britain. The processing of 1 ton of milk requires 2,000 to 5,000 liters of water, and for the production of 1,000 liters of beer in the UK - 6,000 liters, and in Canada - 20,000 liters.Industrial water consumption. The pulp and paper industry is one of the most water-intensive due to the huge volume of processed raw materials. The production of each ton of pulp and paper requires an average of 150,000 liters of water in France and 236,000 liters in the United States. The production of newsprint in Taiwan and Canada requires approx. 190,000 liters of water per 1 ton of product, while the production of a ton of high-quality paper in Sweden requires 1 million liters of water.Fuel industry. The production of 1,000 liters of high quality aviation gasoline requires 25,000 liters of water, while motor gasoline requires two-thirds less.Textile industry requires a lot of water for soaking raw materials, cleaning and rinsing them, 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 is required, 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, when extracting 1 ton of gold ore, 1000 liters of water are consumed, in the United States, when extracting 1 ton of iron ore, 4000 liters and 1 ton of bauxite, 12,000 liters. Iron and steel production in the United States requires approximately 86,000 liters of water per ton of production, but up to 4,000 liters of this is deadweight (mainly evaporation), and therefore approximately 82,000 liters of water can be reused. Water consumption in the iron and steel industry varies considerably across countries. For the production of 1 ton of pig iron in Canada, 130,000 liters of water are spent, for the smelting of 1 ton of pig iron in a blast furnace in the USA - 103,000 liters, steel in electric furnaces in France - 40,000 liters, and in Germany - 8,000-12,000 liters.Electric power industry. Hydroelectric power plants use the power of falling water to drive hydraulic turbines. In the United States, 10 600 billion liters of water are consumed daily at hydroelectric power plants. (see also HYDROPOWER ENGINEERING). Wastewater.Water is necessary for the evacuation of household, industrial and agricultural wastewater. Although about half of the population in the United States, for example, is served by sewerage systems, wastewater from many homes is still simply discharged into septic tanks. But all bó Increased awareness of the consequences of water pollution through such outdated sewerage systems has stimulated the installation of new systems and the construction of wastewater treatment plants to prevent the infiltration of pollutants into groundwater and the flow of untreated wastewater into rivers, lakes and seas (see also WATER POLLUTION). WATER DEFICIENCYWhen water demand exceeds water input, the difference is usually compensated for by storage in reservoirs, since both demand and water supply usually vary from season to season. Negative water balances form when evaporation exceeds precipitation, so a moderate decrease in water reserves is common. Severe shortages occur when water supply is insufficient due to prolonged drought or when, due to inadequate planning, water consumption continues to grow at a faster rate than expected. Throughout its history, mankind 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 DEFICIENCYThe redistribution of runoff is aimed at providing water to those regions where it is scarce, and the protection of water resources is aimed at reducing irreplaceable water losses and reducing the need for it on the ground.Flow redistribution.
Although traditionally many large settlements arose near permanent water sources, at present, some settlements are also created in areas that receive water from afar. Even when the source of additional water supply is located within the same state or country as the destination, technical, environmental or economic problems arise, but if the imported water crosses state borders, the number of potential complications increases. For example, spraying silver iodide in clouds increases precipitation in one area, but it can affect precipitation in other areas. One of the large-scale diversion projects proposed in North America involves the diversion of 20% of excess water from the northwest regions 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, for example, to the Arabian Peninsula, which will make it possible to provide fresh water from 4 to 6 billion people annually or irrigate approx. 80 million hectares of land. One of the alternative methods of water supply is the desalination of salt water, mainly oceanic, and its transportation to places of consumption, which is technically feasible thanks to the use of electrodialysis, freezing and various distillation systems. The larger the desalination plant, the cheaper it is to obtain fresh water. But as the cost of electricity increases, desalination becomes economically disadvantageous. 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), Kuwait, Bahrain, Israel, Gibraltar, Guernsey and the United States. In other countries, numerous smaller demonstration units have been built. However, each of these ways 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 deposits on floodplains. Prevention of water loss as a result of filtration in canals can disrupt water supply to swamps and thus adversely affect the state of their ecosystems. It can also hinder groundwater recharge, thus affecting water supplies to other consumers. And in order to reduce the volume of evaporation and transpiration by agricultural crops, it is necessary to reduce the sown area. The latter measure is justified in areas suffering from water scarcity, where this is a regime of savings by reducing the cost of irrigation due to the high cost of energy required to supply water.
The sources of water supply and reservoirs themselves are important only when water is supplied in sufficient volume to consumers - to residential buildings and institutions, to fire hydrants (devices for taking water for fire needs) and other utilities, to 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 taking water from a river, passing it through a coarse filter to eliminate the bulk of the pollutants, and then through a metering post where its volume and flow rate are recorded. After that, the water enters the water tower, from where it is passed through an aeration unit (where impurities are oxidized), a microfilter to remove silt and clay, and a sand filter to remove 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 to consumers, the treated water is pumped into a storage tank.
The pipes at the central waterworks are usually cast iron, of large diameter, which gradually decreases as the distribution network branches. From street water mains with pipes 10–25 cm in diameter, water is supplied to individual houses through galvanized copper or plastic pipes.
Irrigation in agriculture. Because irrigation is a huge waste of water, agricultural water supply systems must have a high carrying capacity, especially in arid conditions. Water from the reservoir is directed into a lined, and more often not lined, main canal and then along branches to distribution irrigation canals of various orders to farms. Water is discharged into the fields by spill or along irrigation furrows. Since many reservoirs are located above irrigated land, water flows mainly by gravity. Farmers, who store water themselves, pump it out of wells directly into irrigation ditches or storage reservoirs.For sprinkler irrigation or drip irrigation, which has been practiced recently, low-power pumps are used. In addition, there are giant central-rod irrigation units that pump water from wells right in the middle of the field directly into a pipe equipped with sprinklers and rotating in a circle. The fields irrigated in this way appear from the air as giant green circles, some of them reaching 1.5 km in diameter. Such attitudes are common in the US Midwest. They are also used in the Libyan Sahara, where more than 3,785 liters of water per minute are pumped out of the deep Nubian aquifer.
Water resources are the reserves of surface and groundwater located in water bodies that are used or can be used.
Water occupies 71% of the Earth's surface. 97% of water resources are salt water and only 3% are fresh water. Water is also found in soil and rocks, in plants and animals. A large amount of water is constantly present in the atmosphere.
Water is one of the most valuable natural resources. One of the main properties of water is its irreplaceability. By itself, it has no nutritional value, but it has an exceptional role in metabolic processes that form the basis of the life of all life on Earth, which determine its productivity.
The daily human need for water under normal conditions is about 2.5 liters.
Water has a high heat capacity. Absorbing a huge amount of thermal space and intraterrestrial energy and slowly releasing it, water serves as a regulator and stabilizer of climatic processes, softening strong temperature fluctuations. Evaporating from water surfaces, it turns into a gaseous state and is carried by air currents to various regions of the planet, where it falls in the form of precipitation. A special place in the water cycle belongs to glaciers, since they retain moisture in a solid state for a very long time (millennia). Scientists have come to the conclusion that the water balance on Earth is practically constant.
For many millions of years, water has been activating the processes of soil formation. It purifies the environment to a great extent by dissolving and removing impurities.
Lack of water can slow down economic activities and reduce production efficiency. In the modern world, water has acquired an independent importance as an industrial raw material, often in short supply and very expensive. Water is an essential component of almost all technological processes. High purity water is required in medicine, food production, nuclear technology, semiconductor production, etc. Huge amounts of water are consumed for the domestic needs of people, especially in big cities.
The predominant part of the earth's waters is concentrated in the oceans. This is the richest storehouse of mineral raw materials. For every 1 kg of ocean water there are 35 g of salts. Sea water contains more than 80 elements of D.I. Mendeleev, the most important of which for economic purposes are tungsten, bismuth, gold, cobalt, lithium, magnesium, copper, molybdenum, nickel, tin, lead, silver, uranium.
The oceans are the main link in the water cycle in nature. It releases most of the evaporated moisture into the atmosphere. By absorbing a huge amount of thermal energy and slowly releasing it, the ocean waters serve as a regulator of climate processes on a global scale. The warmth of the oceans and seas is spent on maintaining the vital activity of marine organisms, which provide food, oxygen, medicines, fertilizers, luxury goods to a significant part of the world's population.
Aquatic organisms inhabiting the surface layer of the World Ocean provide the return of a significant part of the planet's free oxygen to the atmosphere. This is extremely important, since vehicles and oxygen-intensive metallurgical and chemical industries often consume more oxygen than the nature of individual regions can compensate for.
The fresh waters of the land include glacial, underground, river, lake, and bog waters. In recent years, drinking water of good quality has become a renewable resource of strategic importance. Its deficit is explained by a significant deterioration in the general environmental situation around the sources of this resource, as well as by the tightening of requirements for the quality of consumed water both for drinking and for high-tech industries worldwide.
The bulk of fresh water resources on land are concentrated in the ice sheets of Antarctica and the Arctic. They represent a huge reservoir of the planet's fresh water (68% of all fresh water). These reserves have been preserved for many millennia.
In terms of chemical composition, underground waters are very different: from fresh to waters with a high concentration of minerals.
Fresh surface waters have a significant ability to self-purify, which is provided by the Sun, air, mic-
Roorganisms and oxygen dissolved in water. However, fresh water is becoming a major scarcity on the planet.
The swamps contain 4 times more water than the rivers of the world; 95% of bog water is located in peat layers.
The atmosphere contains water mainly in the form of water vapor. Its main mass (90%) is concentrated in the lower layers of the atmosphere, up to an altitude of 10 km.
Fresh water is unevenly distributed over the Earth. The problem of supplying the population with drinking water is very acute and in recent years has become more and more aggravated. About 60% of the Earth's surface is made up of zones where fresh water is either absent, or is acutely deficient, or of poor quality. About half of humanity suffers from a shortage of drinking water.
Fresh surface waters (rivers, lakes, marshes, soil and ground waters) are subject to the most severe pollution. Most often, sources of pollution are insufficiently treated or not at all treated discharges from industrial facilities (including hazardous ones), discharges from large cities, and wastewater from landfills.
Environmental pollution in the Volga basin is 3-5 times higher than the national average. Not a single city on the Volga is secured
quality drinking water. There are many environmentally hazardous industries and enterprises in the basin without treatment facilities.
The exploitable reserves of the explored underground water deposits in Russia are estimated at about 30 km / year. The development rate of these reserves is currently a little over 30% on average.
Post on the topic
Earth's water resources
female 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. Water sushi
6. Water resources 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 envelope 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 million km3, which is 1/800 of the total volume of the planet; 96.5% of the hydrosphere is concentrated in the oceans and seas, 1.74% in polar and mountain glaciers, and only 0.45% in fresh waters. rivers, swamps and lakes.
The aquatic environment includes surface and groundwater. Surface waters are mainly concentrated in the ocean, containing 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 about 2.4 times the land area of the territory occupying 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 about 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.
Groundwaters are salty, brackish (less salinity) and fresh; existing geothermal waters have an elevated temperature (more than 30 ° WITH.). 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 fraction of it (only 0.36%) is available in places easily accessible for extraction. Most of the fresh water is found in snow and freshwater icebergs, found in areas mostly in the Antarctic Circle. The annual world river flow of fresh water 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, salt surface or underground water is used, making it 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, it is of interest to propose that freshwater icebergs (or parts of them) be used as a source of fresh water, which for this purpose are towed along the water to the shores that do not have fresh water, where they will melt. According to the preliminary calculations of the developers of this proposal, the production of fresh water will be approximately half the energy consumption in comparison with 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, for example, 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 to be the decade of drinking water.
2. 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 World Ocean. The other part (4%) is groundwater. It should be borne in mind that most of them belong to deep brines, and fresh waters make up 1/15 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 is about 1/4180 of the mass of our planet. However, fresh water, excluding water trapped 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 the discontinuous water envelope of the Earth, a collection of seas, oceans, continental waters (including groundwater) and ice sheets. Seas and oceans occupy about 71% of the earth's surface, about 96.5% of the total volume of the hydrosphere are concentrated in them. The total area of all inland water bodies of land is less than 3% of its area. Glaciers account for 1.6% of the water reserves in the hydrosphere, and their area is about 10% of the continental area.
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 and the force of gravity coming to the surface of the Earth, which ensure 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 into the upper atmosphere, condenses into tiny droplets, forming clouds from which water returns to the earth's surface in the form of precipitation, rain, snow. The water falling on the surface of the globe is partially supplied
directly into natural water bodies, partially collected in the upper layer
soil, 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, providing not only the renewal of its most valuable component - fresh land water, but also their high quality. An indicator of the activity of water exchange in natural waters is the high rate of their renewal, although different 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 hydrospheric waters is concentrated in the World Ocean. The oceans are the main closing link in the water cycle in nature. It releases most of the evaporated moisture into the atmosphere. Aquatic organisms inhabiting the surface layer of the World Ocean provide the return of a significant part of the planet's free oxygen to the atmosphere.
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 onshore river waters, annually receiving about 39 thousand m3 of water. The outlined pollution of the World Ocean threatens to disrupt the natural process of moisture circulation in its most important link - evaporation from the ocean surface.
4. World Ocean.
The average depth of the World Ocean is 3700 m, the greatest is 11022 m (Mariana Trench). The volume of the waters of the World Ocean, as mentioned above, cubic meters. km.
Almost all substances known on Earth are dissolved in seawater, but in different quantities. Most of them are difficult to detect due to their small content. Most of the salts dissolved in seawater are chlorides (89%) and sulfates (almost 11%), much less carbonates (0.5%). Salt ( NaCl) gives the 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. River waters and waters of melting ice reduce salinity. 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 low, in tropical latitudes, it is high.
Inland seas differ noticeably in salinity. The salinity of water in the Baltic Sea is up to 11% o, in the Black Sea - up to 19% o, and in the Red Sea - up to 42% o. This is explained by the different ratio of the inflow (precipitation, river runoff) and consumption (evaporation) of fresh water, i.e., climatic conditions. Ocean - heat regulator
The highest temperature near the surface of the water in the Pacific Ocean is 19.4 ° С; The Indian Ocean is 17.3 ° C; Atlantic - 16.5 ° C. At these average temperatures, the water in the Persian Gulf regularly heats up to 35 ° C. As a rule, water temperature drops 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 was no ocean, the average temperature of the Earth's surface would be - 21 ° C, that is, it would be 36 ° lower than what is in reality.
World ocean currents
Ocean waters are in constant motion under the influence of various forces: cosmic, atmospheric, tectonic, etc. The most pronounced surface sea currents, mainly of wind origin. But 3 flows are very common, arising due to different mass densities. The currents in the World Ocean are subdivided according to the direction prevailing in them into zonal (going to the west and east) and meridional (carrying waters 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 the coastal monsoons, are called monsoons.
The most powerful in the entire World Ocean is the Circumpolar, or Antarctic, circular current, caused by strong and stable westerly winds. It covers an area of 2500 km in width and kilometer strata in depth, carrying about 200 million tons of water every second. For comparison, the largest river in the world, the Amazon, carries only about 220 thousand tons of water per second.
In the Pacific Ocean, the strongest 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 is the North trade wind current from east to west. Knowing the direction of the currents, local residents have long used them for their movements. Following them, T. Heyerdahl also used this knowledge for his famous trip to the Kon-Tiki. Analogs of the trade winds (literally "favorable for moving") currents and countercurrents are found in the Indian and Atlantic oceans.
The most famous of the meridional currents are the Gulf Stream and the Kuroshio, which transport 75 and 65 million tons of water per second, respectively.
For many areas of the oceans (western coasts of North and South America, Asia, Africa, Australia), upwelling is characteristic, which can be caused by the wind drive of surface waters from the coast. Rising deep waters often contain large amounts of 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, water cycle on Earth. The ocean contains vital waterways connecting 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 annually reproduced number of commercial fish is estimated at 200 million tons, of which about 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 Ocean - about 35%.
The shelf of the World Ocean has huge reserves of oil and gas, large reserves of iron-manganese ores and other minerals. Humanity is just beginning to use the energy resources of the World Ocean, including the energy of tides. The oceans account 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 wisely use the natural resources of the World Ocean. Its biological resources are depleted in many areas. A significant part of the water area is polluted with wastes of anthropogenic activities, primarily oil products.
Sushi waters.Land waters include waters, 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 found in the rock mass in the upper part of the earth's crust in a liquid, solid and vapor state. Most of them are formed as a result of 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 waterproof layer from the surface;
3) interstratal, located between two water-resistant layers;
The latter are often pressure-bearing and then are called artesian.
Groundwater feeds rivers and lakes.
Rivers are constant streams of water flowing in depressions they have developed - channels.
The most important characteristic of rivers is their feeding. Four power sources are distinguished: snow, rain, glacial and underground.
The regime of the rivers largely depends on the feeding of the rivers, i.e. the change in the amount of water discharge by the seasons of the year, the fluctuation of the level, the change in the temperature of the water. The water regime of the river is characterized by water discharge and runoff. The flow rate is the amount of water passing through the cross-section of the flow in one second. Water consumption for a long time - a month, a season, a year - is called a runoff. The volume of water carried by rivers on average per year is called their water flow. The most abundant river in the world is the Amazon, at its mouth the average annual water consumption is 220,000 cubic meters. m / s. In second place is the Congo (46,000 cubic meters per second), followed by the Yangtze. In our country, the most abundant river is the Yenisei (19800 cubic meters per second). Rivers are characterized by a very uneven distribution of runoff over time. Most rivers in Russia carry 60-70% of their water volume in a relatively short period of spring floods. At this time, melt water flows down the frozen and well-moistened surface of catchments with the least losses for filtration and evaporation.
It is during the flood period that rivers most often overflow their banks and flood the adjacent territories. In summer and winter, there is usually low water - 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 groundwater level and even more so to the rivers. In winter, precipitation accumulates in the form of snow. Small floods occur on Russian rivers only in autumn.
The rivers of the Far East and the Caucasus differ from the lowland rivers of Russia in terms of their hydrological regime. The first ones flood in the fall - during the monsoon rains; on the Caucasian rivers, the maximum water discharge is observed in summer, when high-mountain glaciers and snowfields melt.
River flow changes from year to year. Often there are low and high water periods, when the river is characterized by low or, on the contrary, increased water content. For example, in the 1970s, low water levels were observed on the Volga, as a result of which the level of the endless Caspian Sea was rapidly falling, for which the Volga is the main supplier of water. Since 1978, a phase of increased moisture began in the Volga basin, its annual runoff 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 covered with ice every year. The duration of freeze-up in the north of Russia is 7-8 months (from October to May). The breaking up of rivers from the ice - ice drift - is one of the most impressive spectacles, 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, irrigation of fields 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 part of the environment. The widespread involvement of rivers in economic circulation has led to the complete transformation of many of them. The runoff of such rivers as the Volga, Dnieper, Angara is largely regulated by reservoirs. Many of them, especially those flowing in the southern regions, where the need for irrigation is great, are dismantled for the needs of irrigation. For this reason, the Amu Darya and Syr Darya practically do not 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 a qualitative depletion of river water resources can be avoided if a complex of water management measures is carried out, including not only traditional wastewater treatment, but also such drastic measures as changing production technology in order to significantly reduce water consumption and waste generation.
Lakes are natural reservoirs in the depressions of the land (hollows), filled within the lake basin (lake bed) with heterogeneous water masses and do not have a one-sided slope. Lakes are characterized by the absence of a direct connection with the World Ocean. 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 land area with excessive stagnant soil moisture, overgrown with moisture-loving vegetation. Bogs are characterized by the process of accumulation of undecomposed plant residues and the formation of peat. Swamps are widespread mainly in the Northern Hemisphere, especially in lowland areas where permafrost soils are developed, and occupy an area of about 350 million hectares.
Glaciers are natural moving accumulations of ice of atmospheric origin on the earth's surface; are formed in areas where more solid precipitation is deposited than it melts and evaporates. Within the glaciers, areas of nutrition and ablation are distinguished. Glaciers are divided into land ice sheets, shelf and mountain ones. 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 for the purpose of water supply the currently underutilized water resources of the desalinated waters of the World Ocean, groundwater and glacier waters. At present, the share of desalinated water in the total volume of water supply in the world is small - 0.05%, which is explained by the high cost and significant energy intensity of desalination technological processes. Even in the USA, where the number of desalination plants has increased 30 times since 1955, desalinated water accounts for only 7% of water consumption.
In Kazakhstan, in 1963, the first pilot industrial desalination plant was commissioned in Aktau (Shevchenko). Due to the high cost, desalination is used only where there are absolutely no or extremely inaccessible resources of surface or ground fresh water, and their transportation is more expensive compared to desalination
increased mineralization directly on site. 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 represented by fresh groundwater, which makes up 24% of the volume of the fresh part of the hydrosphere. Brackish and salty groundwater can also serve as a reserve for water supply when used in a mixture with fresh water or after artificial desalination. The factors limiting groundwater withdrawal include:
1) the unevenness of their distribution over the territory of the earth;
2) difficulties in processing saline underground waters;
3) rapidly decreasing rates of natural renewal with
an increase in the depth of occurrence of aquifers.
Utilization of water in the solid phase (ice, ice sheets) is supposed, firstly, by increasing the fluid loss of mountain glaciers, and secondly, by transporting ice from the polar regions. However, both of these methods are practically difficult to implement and the ecological 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. It is necessary to point out the uneven distribution of water resources over the territory of the globe. The highest provision of resources for river and groundwater flows 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 (3780 km3 annual flow), Congo (1200 km3), Mississippi (600 km3), Zamberi (599 km3), Yangtze (639 km3), Ayeyarwady (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, 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 thousand km3 of water, the same as in Lake Baikal. To characterize the location of water resources, the volume of the total river runoff is calculated per unit of territory (1 km3) and population. 1 million inhabitants of the USSR accounts for 5.2 km3 of the total sustainable runoff (including regulated by reservoirs) versus 4 km3 for the whole
the globe; 19 km3 of total river runoff versus 13 km3; 4.1 stable underground runoff 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 territorial flow diversion.
7. Sources of water pollution.
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. Biomass of vegetation of oceans and seas many times over
less than land, but the biomass of animals is at least an order of magnitude higher. Oceans and seas absorb carbon dioxide. The hydrosphere is an important source of food for humans and other land-dwellers. The fish catch, which at the beginning of this century amounted to 3 million tons per year, currently reaches 80 million tons.This growth is associated with the progress of technology, the widespread use of special trawler vessels, seiners with hydroacoustic devices for detecting fish accumulations, equipment for impact on her
light, electric shock.
There were fish pumps, nylon nets, trawling, freezing and canning of fish on board. As a result of the increased catch, its composition worsened, the share of herring decreased,
Sardines, salmonids, cod, flounder, halibut and an increased share of tuna, mackerel, sea bass and bream. With significant investments, it is really possible to bring seafood catches up to 100-130 million tons. These figures include, for example, krill-small crustaceans, the reserves of which are enormous in the southern seas. Krill contains protein and can be used for food and other purposes. A large number of fish are being caught. Not for food, but for feed
livestock or processed into fertilizers. For a number of years, especially after the war, a significant part of whales have been exterminated, and some of their species are on the verge of complete destruction. Further catching of whales is limited by international agreement. The destruction of the inhabitants of the oceans and seas due to their unreasonable catch raises the question of the advisability of switching from extensive fishing to artificial fish farming. In this respect, the transition from hunting and collecting fruits and roots at earlier stages of the development of society to the breeding of animals and plants can be recalled.
8. Measures for the protection and economical use of water resources.
Serious measures are being taken to prevent the growing pollution of water bodies by wastewater. Wastewater is water discharged after being used in domestic and industrial human activities. By their nature, pollution is divided into mineral, organic, bacteriological and biological. The criterion for the hazardousness of wastewater is the nature and degree of restrictions on water use. The quality of natural waters in Kazakhstan is standardized in places of water use. The developed normative indicators - the maximum permissible concentration 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 Regulation on 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 carried out by the majority of water users unsatisfactorily. This is evidenced by the fact that only 20% of discharged wastewater is controlled by hydraulic engineering
equipment, and the rest - by indirect methods. At present, the transition to the system of maximum permissible emissions (MPE) standards is under way. The ELVs are determined for each specific emission source in such a way 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 protection activities, increase
the responsibility of the enterprise for compliance with environmental requirements, will eliminate conflict situations. Of the total amount of wastewater, 69% is conditionally clean, 18% is contaminated and 13% is normatively treated. There are no strict criteria for dividing industrial wastewater into normatively treated, polluted and relatively clean. Untreated wastewater needs to be diluted multiple times with clean
water. The most polluting industries are the oil refining, pulp and paper and chemical industries. Normally treated water
The main market method for regulating environmental protection is pollution charges. There are two types of payments per unit of emissions and payments for the use of public sewage treatment plants. The level of payment 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 payment for the use of treatment facilities includes
basic charge for discharge of standard wastewater, additional charge for excess discharge, charge for water transportation and service charge for water inspection. To assess the pollution of river waters, an indicator of conditional pollution is used. The amount of the fee depends on the age of treatment facilities, the ability of reservoirs to self-purify, as well as the composition of the effluent. The payment mechanism is most effective in a purely competitive environment, when each firm seeks to minimize unit costs
release. Under monopoly conditions, firms may not set themselves such a goal, therefore, methods of direct administrative regulation gain advantages in monopolized industries.
10. International Decade "Water for Life"
4,000 children die every day from illnesses caused by unfit for drinking water; 400 million children lack even the very minimum of safe water needed to live; a whopping 2.6 billion people live without sanitation - all of which challenge the UN's fight for clean water.
The United Nations Children's Fund (UNICEF) highlighted the fact that a lack of clean water is responsible for at least 1.6 million of the 11 million avoidable child deaths each year. Nearly three children die every minute from illnesses caused by unfit for drinking water, such as diarrhea and typhoid fever. In sub-Saharan Africa, where one in five children die before the age of five, 43% of children drink unsafe water, risking sickness and death with every gulp.
The Office of the United Nations High Commissioner for Refugees (UNHCR) spoke about the situation in Jegriyad, the "Valley of Death" in Somalia. It got its name from the fact that every year people here die of thirst, 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 seeks to help 17 million people in more than 116 countries. In Tindouf, Algeria, a project is currently underway to improve the water supply to the Smara camp in the center of the Sahara Desert, where tens of thousands of refugees from Western Sahara live.
In another camp in eastern Chad, where more than 200,000 refugees are fleeing conflict in Sudan's Darfur, UNHCR continues to provide water for refugees by delivering water, drilling wells, digging wells and using high technology to find additional water sources.
On March 22, 2005, the UN celebrated World Water Day by proclaiming years. International Decade "Water for Life". Data on the magnitude of the problem and the histories of specific individuals are what, in addition to the speeches of the heads of the UN organizations, makes one realize how difficult it will be for the world to achieve one of the Millennium Development Goals: by 2015, halve the number of people living in poverty. clean drinking water and minimum sanitary conditions.
List of used literature:
1. Geography. Complete exam preparation course. Moscow. AST-press; 2004 r.
2., "Environmental protection"
3. B. Nebel "Environmental Science" Moscow. "Science" 2002
4. Great Soviet Encyclopedia. Moscow. "Soviet Encyclopedia", 1972