Until relatively recently, water, like air, was considered one of the free gifts of nature, only in areas of artificial irrigation it always had high price. AT recent times the attitude towards land water resources has changed.
Per last century consumption fresh water in the world has doubled, and the planet's water resources do not meet such a rapid increase in human needs. According to the World Commission on Water, today every person needs 40 (20 to 50) liters of water daily for drinking, cooking and personal hygiene.
However, about a billion people in 28 countries do not have access to that many vital important resources. More than 40% of the world's population (about 2.5 billion people) live in areas experiencing moderate or acute shortage water.
It is assumed that by 2025 this number will increase to 5.5 billion and will amount to two-thirds of the world's population.
The vast majority of fresh water is, as it were, conserved in the glaciers of Antarctica, Greenland, in the ice of the Arctic, in mountain glaciers and forms a kind of "emergency reserve" that is not yet available for use.
Different countries differ greatly in fresh water reserves. Below is a ranking of the countries with the most great resources fresh water in the world. However, this ranking is based on absolute figures and does not match per capita figures.
10. Myanmar
Per capita- 23.3 thousand cubic meters m
The rivers of Myanmar - Burma are subject to the monsoon climate of the country. They originate in the mountains, but do not feed on glaciers, but on precipitation.
Over 80% annual nutrition rivers - rain. In winter, the rivers become shallow, some of them, especially in central Burma, dry up.
There are few lakes in Myanmar; the largest of them is the tectonic lake Indoji in the north of the country with an area of 210 sq. km.
Despite the rather high absolute indicators, residents of some areas of Myanmar suffer from a lack of fresh water.
9. Venezuela
Per capita- 60.3 thousand cubic meters. m
Nearly half of Venezuela's more than 1,000 rivers run off the Andes and the Guiana Plateau into the Orinoco, Latin America's third largest river. Its basin covers an area of about 1 million square meters. km. The Orinoco drainage basin occupies approximately four-fifths of the territory of Venezuela.
8. India
Per capita- 2.2 thousand cubic meters m
India has a large number of water resources: rivers, glaciers, seas and oceans. The most significant rivers are: Ganges, Indus, Brahmaputra, Godavari, Krishna, Narbada, Mahanadi, Kaveri. Many of them have importance as sources of irrigation.
Eternal snows and glaciers in India occupy about 40 thousand square meters. km of territory.
However, given the huge population in India, the security fresh water per capita is quite low.
7. Bangladesh
Per capita- 19.6 thousand cubic meters. m
Bangladesh is one of the countries in the world with highest density population. This is largely due to the extraordinary fertility of the Ganges Delta and regular floods caused by monsoon rains. However, overcrowding and poverty have become a real disaster for Bangladesh.
There are many rivers flowing through Bangladesh, and the floods of large rivers can last for weeks. Bangladesh has 58 transboundary rivers, and issues arising from the use of water resources are very sensitive in discussions with India.
However, despite the relatively high level of water resources, the country is facing a problem: Bangladesh's water resources are often poisoned by arsenic due to its high content in the soil. Up to 77 million people are exposed to arsenic poisoning through drinking contaminated water.
6. USA
Per capita- 2.4 thousand cubic meters. m
The United States occupies a vast territory, on which there are many rivers and lakes.
However, despite the fact that the United States has such fresh water resources, this does not save California from the worst drought in history.
In addition, given the high population of the country, the supply of fresh water per capita is not so high.
5. Indonesia
Per capita- 12.2 thousand cubic meters. m
The special relief of the territories of Indonesia, combined with favorable climate at one time contributed to the formation of a dense river network in these lands.
In Indonesian territories all year round a sufficiently large amount of precipitation falls, because of this, the rivers are always full-flowing and play essential role in the irrigation system.
Almost all of them flow from the Maoke Mountains north into the Pacific Ocean.
4. China
Per capita- 2.3 thousand cubic meters. m
China has 5-6% of the world's water reserves. But China is the most populous country in the world, and water on its territory is distributed extremely unevenly.
The south of the country has been fighting for thousands of years and today is fighting floods, building and building dams to save crops and people's lives.
north of the country and central regions languish from lack of water.
3. Canada
Per capita- 98.5 thousand cubic meters. m
Canada has 7% of the world's renewable freshwater resources and less than 1% of total strength the population of the earth. Accordingly, per capita income in Canada is one of the highest in the world.
Most of Canada's rivers belong to the Atlantic and North Atlantic basins. arctic oceans, significantly fewer rivers flow into the Pacific Ocean.
Canada is one of the richest countries in the world with lakes. On the border with the United States are the Great Lakes (Upper, Huron, Erie, Ontario), connected by small rivers into a huge basin of more than 240 thousand square meters. km.
Less significant lakes lie on the territory Canadian shield(Great Bear, Great Slave, Athabasca, Winnipeg, Winnipegosis), etc.
2. Russia
Per capita- 30.5 thousand cubic meters. m
In terms of reserves, Russia accounts for more than 20% of the world's fresh water resources (excluding glaciers and groundwater). In calculating the volume of fresh water per inhabitant of Russia, there are about 30 thousand cubic meters. m of river flow per year.
Russia is washed by the waters of 12 seas belonging to three oceans, as well as the inland Caspian Sea. On the territory of Russia there are over 2.5 million large and small rivers, more than 2 million lakes, hundreds of thousands of swamps and other objects of the water fund.
1. Brazil
Per capita- 43.0 thousand cubic meters m
Brazil's water resources are presented huge amount rivers, the main of which is the Amazon ( greatest river worldwide).
Almost a third of this big country occupies the Amazon River basin, which includes the Amazon itself and more than two hundred of its tributaries.
This gigantic system contains a fifth of all the river waters of the world.
The rivers and their tributaries flow slowly, during the rainy seasons they often overflow their banks and flood vast areas. rainforest.
The rivers of the Brazilian Plateau have significant hydropower potential. Most large lakes countries - Mirim and Patos. Main rivers: Amazon, Madeira, Rio Negro, Parana, Sao Francisco.
At present, water, especially fresh water, is an extremely important strategic resource. Per last years The world's water consumption has increased, and there are fears that there simply won't be enough for everyone. According to the World Commission on Water, each person today requires 20 to 50 liters of water daily for drinking, cooking and personal hygiene.
However, about a billion people in 28 countries around the world do not have access to so many vital resources. About 2.5 billion people live in areas experiencing moderate or severe water scarcity. It is assumed that by 2025 this number will increase to 5.5 billion and will amount to two-thirds of the world's population.
, in connection with the negotiations between the Republic of Kazakhstan and the Kyrgyz Republic on the use of transboundary waters, ranked 10 countries with the largest reserves of water resources in the world:
10th place
Myanmar
Resources - 1080 cubic meters. km
Per capita - 23.3 thousand cubic meters. m
The rivers of Myanmar - Burma are subject to the monsoon climate of the country. They originate in the mountains, but do not feed on glaciers, but on precipitation.
More than 80% of the annual river nutrition is rain. In winter, the rivers become shallow, some of them, especially in central Burma, dry up.
There are few lakes in Myanmar; the largest of them is the tectonic lake Indoji in the north of the country with an area of 210 sq. km.
9th place
Venezuela
Resources - 1,320 cubic meters. km
Per capita - 60.3 thousand cubic meters. m
Almost half of the thousand rivers in Venezuela run off the Andes and the Guiana Plateau into the Orinoco, the third largest river in Latin America. Its basin covers an area of about 1 million square meters. km. The Orinoco drainage basin occupies approximately four-fifths of the territory of Venezuela.
8th place
India
Resources - 2085 cubic meters. km
Per capita - 2.2 thousand cubic meters. m
India has a large amount of water resources: rivers, glaciers, seas and oceans. The most significant rivers are: Ganges, Indus, Brahmaputra, Godavari, Krishna, Narbada, Mahanadi, Kaveri. Many of them are important as sources of irrigation.
Eternal snows and glaciers in India occupy about 40 thousand square meters. km of territory.
7th place
Bangladesh
Resources - 2,360 cubic meters. km
Per capita - 19.6 thousand cubic meters. m
There are many rivers flowing through Bangladesh, and the floods of large rivers can last for weeks. Bangladesh has 58 transboundary rivers, and issues arising from the use of water resources are very sensitive in discussions with India.
6th place
Resources - 2,480 cubic meters. km
Per capita - 2.4 thousand cubic meters. m
The United States occupies a vast territory, on which there are many rivers and lakes.
5th place
Indonesia
Resources - 2,530 cubic meters. km
Per capita - 12.2 thousand cubic meters. m
In the territories of Indonesia, a fairly large amount of precipitation falls all year round, because of this, the rivers are always full-flowing and play a significant role in the irrigation system.
4th place
China
Resources - 2,800 cubic meters. km
Per capita - 2.3 thousand cubic meters. m
China has 5-6% of the world's water reserves. But China is the most populous country in the world, and its water distribution is highly uneven.
3rd place
Canada
Resources - 2,900 cubic meters. km
Per capita - 98.5 thousand cubic meters. m
Canada is one of the richest countries in the world with lakes. On the border with the United States are the Great Lakes (Upper, Huron, Erie, Ontario), connected by small rivers into a huge basin of more than 240 thousand square meters. km.
Less significant lakes lie on the territory of the Canadian Shield (Great Bear, Great Slave, Athabasca, Winnipeg, Winnipegosis), etc.
2nd place
Russia
Resources - 4500 cubic meters. km
Per capita - 30.5 thousand cubic meters. m
Russia is washed by the waters of 12 seas belonging to three oceans, as well as the inland Caspian Sea. On the territory of Russia there are over 2.5 million large and small rivers, more than 2 million lakes, hundreds of thousands of swamps and other objects of the water fund.
1 place
Brazil
Resources - 6,950 cubic meters. km
Per capita - 43.0 thousand cubic meters. m
The rivers of the Brazilian Plateau have significant hydropower potential. The largest lakes in the country are Mirim and Patos. Main rivers: Amazon, Madeira, Rio Negro, Parana, Sao Francisco.
Also list of countries by total renewable water resources(based on the CIA Country Directory).
WATER RESOURCES, 2014, Volume 41, No. 3, p. 235-246
WATER RESOURCES AND REGIME OF WATER BODIES
UDC 556.18:338.439:628.1
WATER RESOURCES AND THE FOOD PROBLEM
A. P. Demin © 2014
Institute of Water Problems of the Russian Academy of Sciences 119333 Moscow, st. Gubkina, 3 [email protected] Received 13.06. 2012
The data on the volume of renewable water resources and the specific water supply of the countries with the most and least water resources are presented. Modern data on the volume of withdrawal of water resources, the area of irrigated land, and the population are given. largest countries peace. Measures taken are shown foreign countries to improve the availability of water resources Agriculture. It was revealed that a further increase in the area of arable and irrigated land while maintaining existing technologies in agriculture is unacceptable. The role of land reclamation in ensuring the food security of Russia is shown.
Keywords: renewable water resources, water supply, food security, water pollution, irrigated land, wastewater, salt waters, melioration.
DOI: 10.7868/S0321059614030055
According to various estimates, global renewable water resources range from 42,000 to 43,800 km3/year and are extremely unevenly distributed over the land area, depending on the climatic and physiographic conditions of their formation. Most of the water resources (47%) are concentrated in the Americas, followed by Asia (32), Africa (10), Europe (6) and Australia with Oceania (5%). The countries most and least provided with renewable water resources are listed in Table. one.
To assess the state of water resources in countries and regions of the world, in addition to volume, two criteria are usually used: the specific water supply of the region, calculated as the provision of water resources per capita, and the degree of use of water resources, characterized by the ratio of total water consumption to renewable water resources. Provision of water resources per capita - from 90-100 thousand m3 / (person per year) and more in countries such as Canada, Iceland, Gabon, Suriname, to less than 10 m3 / (person year) in Kuwait . Of the large countries of the world, Russia is one of the few where the indicator of specific water supply is at a fairly high level.
According to the UN, the minimum required water consumption for the needs of agriculture, industry, energy and so-
keeping balance environment is assumed to be 1700 m3/(person per year). With a specific water supply of 1000-1700 m3, it is customary to speak of a state of water stress, with 500-1000 m3 - a shortage of water resources, and less than 500 m3 - an absolute water shortage. Today, ~700 million people in 43 countries live under water stress. With an annual water supply averaging 1200 m3/person, the Middle East is the region experiencing the most water stress in the world. African region Sub-Saharan Africa is generally well endowed with water, but it has a higher number of water stressed countries than any other region in the world, nearly a quarter of its population now lives under water stress, and a portion of this population is steadily growing.
The temporal variability of water availability is also extremely high. Combined with underdeveloped water storage infrastructure and poor protection river basins this variability puts millions of people at risk from droughts and floods. In countries where water availability is dependent on monsoons or short periods of rainfall, national averages give a distorted picture of real water availability. Huge territories in Asia receive a significant part
Table 1. Data on the most and least provided countries with renewable water resources
Country Volume of renewable water resources, km3/year Specific water supply, m3/person
Countries most endowed with water resources
Brazil 8233 31 795
Russia 4507 29642
Canada 2902 92662
Indonesia 2838 13381
China 2830 2245
Columbia 2132 50160
USA 2071 7153
Peru 1913 62973
India 1897 1249
Countries least endowed with water resources
Israel 1.67 245
Jordan 0.88 154
Libya 0.60 99
Mauritania 0.40 131
Cape Verde 0.30 578
Djibouti 0.30 366
Qatar 0.05 61
Malta 0.05 123
Gaza Strip 0.06 320
Bahrain 0.12 163
Kuwait 0.02 7
annual precipitation over a period of several weeks. This gives rise to the danger of short-term but intense flooding during these periods and prolonged drought during the rest of the year. The actual availability of water during the year depends not only on the amount of precipitation, but also on the water reserves in reservoirs, the volume of river runoff and replenishment of groundwater reserves.
In the middle of the twentieth century. the ratio of water consumption to renewable water resources was low (<10%) или умеренным (10-20%) в подавляющем большинстве регионов, где проживает более 75% населения Земли. Лишь в одном регионе - Северной Африке степень использования водных ресурсов превышала 40%. К концу ХХ в. ситуация кардинальным образом изменилась: в 1995 г. более 40% населения проживало в регионах с очень высокой (40-60%) и критически высокой (>60%) pressure on water resources.
The amount of water necessary for man for drinking and household purposes, insignificant in relation to the volumes required for food production. For drinking purposes, a person needs 2-4 liters of water per day, for domestic needs - 30-300 liters. A person needs 3,000 liters of water per day to grow the daily necessary food. In 2000, 65% of the world's fresh water consumption was accounted for by agriculture, 20% by industry, 10% by domestic utilities, and 5% by additional water losses due to evaporation from the surface of reservoirs. In the structure of non-returnable water consumption, the share of agriculture exceeded 84%.
IMPACT OF WATER SCARCITY ON AGRICULTURE
Over 50 years (1950-2000), water consumption by agriculture in the world increased by 1525 (64% of the total increase in water consumption), by industry - by 572, and by households - by 297 km3. Biggest Influence irrigated agriculture contributes to the depletion of the planet's water resources in agriculture. The question arises: how big is the trend of a further increase in the withdrawal of water resources due to the growing population of the planet and the need to provide it with food?
Currently most of population lives in developing countries. Demographers predict that by 2030 world population will approach 8 billion, and by 2050 will exceed 9 billion people. In the coming decades, the population of the least developed and developing countries will grow. The depletion of water resources, the deterioration of water quality and the growth of its scarcity have little effect on population growth, but have an extremely negative impact on economic growth and welfare of countries. As a result, the possibilities of solving the problem of water scarcity are decreasing, while population growth continues.
Currently, the main users of water on the planet are developing countries, especially Asian countries (~ 70% of the annual volume of water withdrawn from water bodies) (Table 2). Current indicators for water consumption, irrigated land, population are given according to FAO, Eurostat, OECD, CIS Statistical Committee (for 80 largest countries in the world in terms of water withdrawal by agriculture) . In some cases, materials from national publications were used
Table 2. Fresh water withdrawal for agriculture and area of irrigated land in the countries of the world in 2003-2007
No. Withdrawn Including agriculture, km3 Share of water intake by rural areas Population, mln. Volume of water withdrawn Area of irrigated land, mln ha Area of irrigated land per person, ha
Freshwater farming in the ob- rural
water, km3
brine water, % per 1 person, m3
1 India 761.0 688.0 90.4 1134.0 607 55.8 0.049
2 China 581.9 360.0 61.9 1329.1 271 54.5 0.041
3 USA 482.2 186.8 38.7 301.3 620 24.7 0.082
4 Pakistan 183.5 172.4 94.0 159.6 1080 18.2 0.114
5 Iran 95.0 86.0 90.5 71.5 1203 7.65 0.107
6 Indonesia 86.0 78.5 91.3 225.6 348 4.50 0.020
7 Philippines 79.0 65.6 83.0 88.7 740 1.88 0.021
8 Mexico 78.9 60.6 76.8 105.8 573 6.32 0.060
9 Egypt 69.3 59.3 85.6 74.0 806 3.42 0.046
10 Japan 83.4 56.2 67.4 127.8 440 2.59 0.020
11 Uzbekistan 60.0 54.0 90.0 27.1 1993 4.28 0.158
12 Iraq 66.0 52.0 78.8 28.5 1825 3.52 0.124
13 Thailand 57.3 51.8 90.4 66.0 785 5.00 0.076
14 Vietnam 75.0 51.1 68.1 85.2 599 3.00 0.035
15 Sudan 37.3 36.1 96.8 37.2 970 1.86 0.050
16 Turkey 45.0 34.0 75.6 70.6 482 4.85 0.069
17 Brazil 58.5 31.9 54.5 19.0 166 2.92 0.015
18 Bangladesh 35.9 31.5 87.7 142.6 221 4.73 0.033
19 Mnyama 33.2 32.6 98.2 49.6 659 1.84 0.037
20 Italy 58.0 28.8 49.7 59.6 483 2.75 0.046
21 Spain 33.8 24.5 72.5 45.3 540 3.78 0.083
22 Turkmenistan 25.0 24.0 96.0 6.7 3582 1.74 0.260
23 Afghanistan 23.2 22.8 98.3 28.4 804 3.20 0.113
24 Argentina 29.2 21.5 73.6 39.5 544 1.55 0.039
25 Russia 74.6 21.5 28.8 142.2 151 4.60 0.032
26 Saudi Arabia 23.7 20.8 87.8 25.2 827 1.62 0.064
statistical, water management and environmental organizations some countries and cross-checked with various sources.
The main consumers of water among developing countries are India, China, Pakistan. In most countries of Asia, Africa, Latin America, 75-90 (in some - up to 98)% of the volume of annually used water falls on the agricultural sector and only 10-25% - on industry and utilities. However, in many of these countries, agriculture takes up the vast majority of the water resources used. So, In India, Pakistan, Iran, Indonesia, Uzbekistan, Thailand, Sudan, Myanmar and other countries
NOVITSKAYA NATALIA NIKOLAEVNA - 2007
Water resources include all types of water, excluding water that is physically and chemically associated with rocks and the biosphere. They are divided into two various groups, consisting of stationary water reserves and renewable reserves involved in the water cycle and estimated balance method. For practical needs, mainly fresh water is needed.
As already mentioned, water resources are all the water reserves on the planet. But on the other hand, water is the most common and most specific compound on Earth, because only it can exist in three states (liquid, gaseous and solid).
The water resources of the Earth consist of:
Surface waters (oceans, seas, lakes, rivers, swamps) are the most valuable source of fresh water, but the thing is that these objects are distributed quite unevenly over the Earth's surface. Yes, in equatorial belt, as well as in the northern part temperate zone water is in excess (25 thousand m3 per year per person). And the tropical continents, which consist of 1/3 of the land, are very acutely aware of the shortage water reserves. Based on this situation, their agriculture develops only under the condition of artificial irrigation;
groundwater;
reservoirs created artificially by man;
Glaciers and snowfields (frozen water of the glaciers of Antarctica, the Arctic and snowy mountain peaks). It contains the largest part of fresh water. However, these reserves are practically inaccessible for use. If all the glaciers are distributed over the Earth, then this ice will cover the earth with a ball 53 cm high, and having melted it, we thereby raise the level of the World Ocean by 64 meters;
moisture contained in plants and animals;
the vapor state of the atmosphere.
Availability of water resources:
The world's water reserves on Earth are huge. However, this is predominantly salty water World Ocean. Fresh water reserves, the need of people for which is especially large, are insignificant (35029.21 thousand km3) and exhaustive. In many places on the planet, there is a shortage of it for irrigation, industrial needs, drinking and other domestic needs.
Main source fresh water - rivers. Of all the river waters of the planet (47 thousand km3, only half can actually be used.
Fresh water consumption is constantly growing, while river flow resources remain unchanged. This poses a threat of fresh water scarcity.
The main consumer of fresh water is agriculture, in which its irretrievable consumption is high (especially for irrigation).
To solve the problem of water supply, projects of economical water consumption, construction of reservoirs, desalination are used. sea water, redistribution of river flow; iceberg transportation projects are being developed.
Countries are differently provided with water resources. About 1/3 of the land area is occupied by the arid belt, in which 850 million people live.
· Countries with insufficient provision of water resources include Egypt, Saudi Arabia, Germany;
· with medium security - Mexico, USA;
· with sufficient and excess security - Canada, Russia, Congo.
One of the ways to provide the population with fresh water is the desalination of salt water. Two millennia ago, people learned how to get fresh water from salt water by distillation. The first seawater desalination plants appeared at the beginning of the 20th century, for which solar desalination plants were used, for example, in the Atacama Desert (Chile). In the second half of the 20th century, nuclear desalination plants began to be used. Most of all they are used by tropical climate countries: Tunisia, Libya, Egypt, Saudi Arabia, Kuwait, UAE, etc. Most of the desalinated water per inhabitant is obtained in the Persian Gulf countries. In Kuwait, 100% of the water used is desalinated sea water.
WATER RESOURCES LAND
Until relatively recently, water, like air, was considered one of the free gifts of nature, only in areas of artificial irrigation it always had a high price. Recently, the attitude towards land water resources has changed. This is explained by the fact that fresh water resources make up only 2.5% of the total volume of the hydrosphere. In absolute terms, this is a huge value (30-35 million m 3), which exceeds the current needs of mankind by more than 10 thousand times! However, the vast majority of fresh water is, as it were, conserved in the glaciers of Antarctica, Greenland, in the ice of the Arctic, in mountain glaciers and forms a kind of "emergency reserve" that is not yet available for use.
Indicators:
96.5% - salty waters of the oceans; 1% - salty The groundwater; 2.5% - fresh water resources.
Fresh water: 68.7 - glaciers; 30.9% - groundwater.
Table 11. Distribution of world fresh water resources by major regions.
The data in this table allow us to draw interesting conclusions. First of all, about the extent to which the ranking of countries according to the first indicator does not coincide with their ranking according to the second. It can be seen that Asia has the largest fresh water resources, and the smallest - Australia and Oceania, while in terms of their specific provision, they change their places. Of course, it's all about the population, which in Asia has already reached 3.7 billion people, and in Australia it barely exceeds 30 million. South America. And it is no coincidence, because it is here that the Amazon is located - the most deep river peace.
They differ even more in terms of reserves and availability of fresh water. individual countries. Based on the principle of "most-most", we will show which of them belong to the category of the richest and poorest in fresh water.
Table 12. Top ten countries by freshwater resources.
In it, too, the ranking of resources does not coincide with the ranking of the specific endowment, and in each individual case, such a difference can be explained. For example, in China and India - a huge population, therefore - low security per capita. But there are also countries in the world that are even less provided with fresh water, where less than 1 thousand m 3 of water falls per capita (i.e., such an amount that a resident of a large European or American city consumed in about two days). Most bright examples 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 region Arabian Peninsula(Saudi Arabia - 250 m3, Kuwait - 100 m3).
These selected examples interesting in that they allow us to make an important generalization: at the end of the 20th century. Approximately 2/5 of the population of our planet experience a chronic lack of fresh water. AT this case we are talking mainly about those developing countries that are located in the arid belt of the Earth. One cannot ignore the fact that even the available fresh water in these countries is so polluted that it is the main cause of most diseases.
The main consumer of fresh water is agriculture, where irretrievable water consumption is very high, especially for irrigation. Industrial-energy and municipal water consumption is also growing all the time. In economically developed countries a city dweller uses 300-400 liters of water per day. Such an increase in consumption with constant river runoff resources creates real threat occurrence of fresh water scarcity.
In this case, it is necessary to take into account not only the quantity, but also the quality of water. In developing countries, from a lack drinking water every third person suffers. The consumption of polluted water is the source of 3/4 of all diseases and 1/3 of all deaths. In Asia access to clean water do not have more than 1 billion, in sub-Saharan Africa - 350 million and in Latin America - 100 million people.
But, in addition, fresh water reserves on Earth are distributed extremely unevenly. In the equatorial zone and in the northern part of the temperate zone, it is available in abundance and even in excess. The most water-abundant countries are located here, where more than 25 thousand m 3 per capita per year. In the arid belt of the Earth, which covers about 1/3 of the land area, water shortage is felt especially acutely. The countries with the least water per capita are located here, where per capita is less than 5 thousand m 3 per year, and agriculture is possible only with artificial irrigation.
There are several ways to solve the water problem of mankind. The main one is the reduction of water capacity. production processes and reduction irretrievable losses water. First of all, this applies to 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. Great importance to solve the water problem, it has 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 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 major rivers, like the Volga, the Angara in Russia, the Dnieper in Ukraine, Tennessee, Missouri, Columbia in the USA, and many others, have actually turned into cascades of reservoirs. Especially important role large and largest reservoirs play a role in the transformation of river runoff. The problem is that the main source of meeting the needs of mankind in fresh water has been and remains river (channel) water, which determines the "water ration" of the planet - 40 thousand km3. It is not so significant, especially considering that about 1/2 of this amount can actually be used.
According to the number of large reservoirs, the United States, Canada, Russia, some countries of Africa and Latin America stand out.
Table 13 The largest reservoirs world by volume of water (countries)
In the USA, Canada, Australia, India, Mexico, China, Egypt, and a number of CIS countries, numerous projects have been implemented or are being planned for the territorial redistribution of river flow with the help of its transfer. However, in recent times the most major projects inter-basin transfers were canceled for economic and environmental reasons. In the countries of the Persian Gulf, the Mediterranean, in Turkmenistan, on the Caspian Sea, in the south of the USA, in Japan, on the islands caribbean desalination of sea water is used; the world's largest producer of such water is Kuwait. Fresh water has already become a commodity of world trade: it is transported in sea tankers, along long-distance water pipelines. Projects are being developed to tow icebergs from Antarctica, which every polar summer sends 1200 million tons of fresh water preserved in them to the countries of the arid zone.
You know that river runoff is also widely used to generate hydropower. World hydropower potential, suitable for use, is estimated at almost 10 trillion kWh. possible power generation. About 1/2 of this potential falls on only 6 countries: China, Russia, USA, Congo (former Zaire), Canada, Brazil.
Table 14 . World economic hydro potential and its use
|
Regions |
Total |
Including used, % |
|
|
billion kWh |
in % |
||
|
CIS |
1100 |
11,2 |
|
|
Foreign 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, pools of minerals; structure of the world land fund, southern and northern forest belts, forest cover; hydropower potential; shelf, alternative sources energy; resource availability, natural resource potential(PRP), 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 economic evaluation natural resources; characterize the natural prerequisites for the development of industry and agriculture of the country (region) according to the plan; give brief description location of the main types of natural resources, single out the countries "leaders" and "outsiders" in terms of availability of one or another type of natural resources; give examples of countries that do not have rich natural resources, but reached high level economic development and vice versa; give examples of rational and irrational use of resources. | ||
