On a global scale, about two-thirds of all precipitation returns to the atmosphere. In terms of water resources, the most prosperous is the region of Latin America, which accounts for one third of the world gutter, followed by Asia and its fourth quarter of the world gutter. Then come the OECD countries (20%), sub-Saharan Africa and the countries of the former Soviet Union, each accounting for 10%. The most limited water resources of the countries of the Middle East and North America (1% each).The total volume of water on Earth is approximately 1,400 million km3, of which only 2.5%, that is, about 35 million km3, accounted for fresh water. Most of the fresh water reserves are concentrated in the perennial ice and snow of Antarctica and Greenland, as well as in deep aquifers. The main sources of water consumed by humans are lakes, rivers, soil moisture, and relatively shallow underlying groundwater reservoirs. The operational part of these resources is only about 200 thousand km3 - less than 1% of all fresh water reserves and only 0.01% of all water on Earth - and a significant proportion of them are located far from populated areas, which further aggravates the problems of water consumption.
The renewal of fresh water depends on evaporation from the surface of the oceans. Each year, the oceans evaporate about 505 thousand km3 of water, which corresponds to a layer with a thickness of 1.4 m. Another 72 thousand km3 of water evaporates from the land surface.
Of the total rainfall to the Earth, 79% of the water cycle falls to the ocean, 2% to lakes and only 19% to the land surface. Only 2,200 km3 of water per year penetrates into underground reservoirs.
On a global scale, about two-thirds of all precipitation returns to the atmosphere. In terms of water resources, the most prosperous is the region of Latin America, which accounts for one third of the world gutter, followed by Asia and its fourth quarter of the world gutter. Then come the OECD countries (20%), sub-Saharan Africa and the countries of the former Soviet Union, each accounting for 10%. The most limited water resources of the countries of the Middle East and North America (1% each).
About a third of the land area is occupied by arid belts. In the arid zone of the Earth, water scarcity is acute. Here are the most low-water countries, where per capita accounts for less than 5000 m3 of water.
The largest consumers of water (by volume) are India, China, USA, Pakistan, Japan, Thailand, Indonesia, Bangladesh, Mexico and the Russian Federation.
The figures of the total volume of water consumed range from 646 km3 / year (India) to less than 30 km3 / year in Cape Verde and the Central African Republic.
99% of 4000 km3 / year of water used for irrigation, domestic and industrial consumption, energy production, comes from underground and surface renewable sources. The rest are from non-renewable (fossil) aquifers, this applies mainly to Saudi Arabia, Libya and Algeria.
According to the United Nations (UN), rising freshwater consumption, caused in particular by demographic growth and population mobility, new needs and increased energy demands, coupled with the tangible effects of climate change, are leading to increasing water shortages.
Every three years, the UN World Water Assessment Program (WWAP) publishes the UN World Report, which provides the most comprehensive assessment of the state of freshwater in the world.
The last, third report, which was published at the Fifth World Water Forum, held in Istanbul (Turkey) in March 2009, is the result of the joint work of 26 different UN entities united under the UN Decade “Water for Life” (2005 - 2015).
The report emphasizes that many countries have already reached their limit on water use. The situation is deteriorating due to climate change. On the horizon, the contours of competition for water are already being outlined - between countries, between city and village, between different industries. All this will soon turn the problem of water scarcity into a political problem.
The authors of the report make an important conclusion that, in vast regions of the developing world, unequal access to basic water-related services remains, i.e. providing safe drinking water, treating water for food production, and wastewater treatment. If nothing would be done, without satisfactory water treatment by 2030 will remain almost 5 billion people, about 67% of the world's population.
In sub-Saharan Africa, nearly 340 million people are denied access to safe drinking water. Half a billion people in Africa do not have adequate treatment facilities, far behind in this from other regions of the world.
Nearly 80% of diseases in developing countries, of which nearly 3 million people die each year, are related to water quality. So, 5 thousand children die from diarrhea every day, i.e. every 17 seconds a child dies. In general, almost 10% of diseases in the world can be avoided by improving water supply, water treatment, hygiene and effective water management.
The consumption of fresh water has tripled over the past half century, and the irrigated area has doubled over this period, this is primarily due to demographic growth. According to estimates, the world's population today is 6.6 billion people, an annual increase of 80 million. This means an annual increase in the need for fresh water in the amount of 64 million cubic meters. At the same time, 90% of the three billion inhabitants of the planet who will be born by 2050 will increase the population of developing countries, where water is already scarce today.
In 2030, 47% of the world's population will live under the threat of water scarcity. Only in Africa by 2020 due to climate change in this situation will be from 75 to 250 million people. Lack of water in desert and semi-desert regions will cause intense population migration. It is expected that this will affect from 24 to 700 million people.
According to the UN, if in 2000 the world's water shortage, including agricultural and industrial needs, was estimated at 230 billion cubic meters / year, then by 2025 the deficit of fresh water on the planet will increase to 1.3-2.0 trillion cubic meters / year.
In terms of total freshwater resources, Russia occupies a leading position among European countries. According to the UN, by 2025, Russia, together with Scandinavia, South America and Canada, will remain the regions most provided with fresh water, more than 20 thousand cubic meters / year per capita.
According to the Institute of World Resources for the past year, the most unsecured countries in the world were 13 states, including 4 republics of the former USSR - Turkmenistan, Moldova, Uzbekistan and Azerbaijan.
Countries with up to 1 thousand cubic meters of fresh water on average per capita: Egypt - 30 cubic meters per person; Israel - 150; Turkmenistan - 206; Moldova - 236; Pakistan - 350; Algeria - 440; Hungary - 594; Uzbekistan - 625; Netherlands - 676; Bangladesh - 761; Morocco - 963; Azerbaijan - 972; South Africa - 982.
The material is based on open source information