Proportion of potable water in total water resources

Water is one of the most prevalent substances in the world, with a total volume of 100 million cubic kilometers, of which only fresh water is available.

Seventy-seven per cent of the fresh water is frozen in ice and glaciers at the poles and in the mountains, making it difficult to use. There are only about 21,000 cubic kilometers of freshwater resources that can be used by humans.

Water is an important part of natural resources. Seawater accounts for the total reserves of water on the planet, and only freshwater. Icebergs and glaciers account for the proportion of freshwater resources.

Water in groundwater and soil, water in lakes and swamps, water in rivers, and water in the atmosphere. Water is cyclical in nature.

The amount of water circulating on the earth is roughly 420,000 km per year, of which about 100,000 km falls on land. After that, about 40,000 km of water flows into the ocean through rivers.

The amount of water on Earth is distributed in such a way that oceans account for icebergs and glaciers, groundwater for lakes. The atmosphere (water vapour) is accounted for, while rivers and streams are only accounted for.

Of these, only fresh water from groundwater, lakes, rivers and streams can be used by people, animals and plants, which means that the Earth can supply less than 1% of its total water to life on land

Now the environment is polluted. As a result, the quality of some drinking water is seriously exceeded. It's not a few percent anymore.

Freshwater accounts for only 3% of all water resources. Freshwater resources on Earth.

Nearly 3% of the total water volume. The oceans account for about the total amount of water on Earth. Terrestrial freshwater accounts for only the total amount of water, with glaciers accounting for terrestrial freshwater. Lakes with brackish water and underground brackish water occupy. Only one of the world's freshwater resources can be directly used by humans.

The current situation of freshwater resources in China.

Worldwide, the top 10 countries in terms of water reserves are: Brazil, Russia, the United States, Indonesia, Canada, China, and Bangladesh.

India, Venezuela.

Colombia. Although China's total freshwater resources rank sixth in the world, accounting for about 6% of the world's total, its per capita freshwater resources are only 2,400 cubic meters, making it one of the poorest countries in the world.

Although the Earth's surface area is covered by oceans, the deepest trenches reach 10 km. However, compared to the Earth, which has a radius of 6,378 kilometers, this deep ocean of filial piety is as thin as the skin of an apple.

The earth's water reserves have reached 100 million cubic kilometers, however, most of them are resources that cannot be used by human beings, and seawater occupies them, which is a resource that human beings cannot hope for.

And the rest of them are not completely exploitable by humans. Some of them are glaciers and polar ice sheets, and groundwater is only on the surface. Counting the small amount of groundwater that can be used, the water resources that can be used by humans account for only the total water reserves of the world.

Today (22 March) is World Water Day

The United Nations sets 2021.

The theme of World Water Day is:

Cherish water, love water".

The theme of our commemoration is:

thoroughly implement the new development concept and promote the intensive and safe use of water resources".

What is the situation of water resources in our country?

How to improve water efficiency?

Let's find out.

The source of life, the key to production, the foundation of ecology".

Water. When it comes to "water", everyone must be familiar with it, but this may not be the case. For as long as we can remember, there have been thousands of caring instructions from parents and friends, among which "drink more hot water" is definitely at the top.

From the perspective of human survival and development, water is regarded as an extremely important natural resource, and is known as "the source of life, the key to production, and the foundation of ecology". However, there is a conceptual difference between water and water resources, and water is not the same as water resources.

A spoonful of "that "drop" in fresh water

Water, air and food are the three basic substances on which human beings depend, and clean drinking water and vaccines are known as the two guardians of modern health. The content of water in living organisms is 60% to 95%, and it can be said that any living thing cannot do without the nourishment of water.

Water and water resources are conceptually distinct, and water is not the same as water resources. It is estimated that the total amount of water on Earth is about 100 million cubic kilometers, covering 71% of the Earth's surface area. Based on the world's current population of 7.6 billion, it is equivalent to 100 million tons of water that can be allocated to each person.

Unfortunately, not all of this huge amount of water is a "water resource" that can be exploited and utilized by humans.

According to the definition of water resources in the third edition of the Encyclopedia of China, water resources refer to the natural fresh water on the earth that is renewed through the natural water cycle, meets certain quality standards, and can be used by human society. This water source is mainly rivers, freshwater lakes and shallow groundwater.

How much of the planet's water is this water? About 7 100,000!

It has been likened that "if the earth's water could fill a large tank of water, only one spoonful of fresh water would be used, and only one drop of water would be available for human exploitation."

It is not easy to renew resources, and drinking water should think about the source.

With the development of social economy, the development and utilization of water resources by human beings is becoming more and more diverse, and the intensity is also increasing. First of all, human life, agricultural irrigation, industrial production, etc. are inseparable from water resources. Secondly, the waste from human life and production will be discharged into rivers and other water bodies to purify and absorb the water.

In addition, in order to obtain water energy resources, human beings will build dams and power stations on rivers; will build ships and develop water transportation; It will take advantage of the characteristics of large specific heat capacity of water for cooling or heating, and so on.

Rivers have to purify and absorb sewage for humans.

Although water resources can be regenerated by atmospheric precipitation through the water cycle, the cycle of renewal of different freshwater resources varies greatly: it only takes 8 days for atmospheric water to renew, rivers need 16 days, and groundwater takes 1,400 years.

According to the United Nations' World Water Development Report, global water consumption increased in the 20th century6

Water resources refer to the total water resources of a region or country as a whole, including rivers, lakes, groundwater and glacial meltwater. The amount of water resources available refers to the amount of water resources that can be rationally used and used to maintain the balance of the natural hydrological cycle. The relationship between the two is:

The amount of water resources can provide the basic support for the availability of water resources, and the amount of water resources available represents the actual amount of water resources that can be used. Generally speaking, the amount of water resources is related to geographical environment and climatic conditions, while the availability of water resources is affected by more factors, including population, industry, agriculture, ecological environment and other needs, as well as the level of water resources management and protection. If the gap between the amount of water resources and the amount of water available is too large, it may lead to problems such as water shortage, water quality deterioration, water environment deterioration and ecological environment degradation.

Therefore, it is of great significance to reasonably assess the relationship between water resources and water availability, and implement effective water resources management and protection to promote sustainable development.