Current status of Earth’s water resources Read answers

Water resources on the earth, in a broad sense, refers to the overall amount of water in the hydrosphere. Since seawater is difficult to use directly, water resources we refer to mainly refer to freshwater resources on land. Through the water cycle, fresh water on land can be continuously renewed and replenished to meet human production and living needs.

In fact, the total freshwater resources on land only account for 2.53% of the total water on the earth, and most of them are solid glaciers mainly distributed in the North and South Poles. Although scientists are studying ways to utilize glaciers, large-scale utilization is not yet possible under current technical conditions. In addition, the freshwater reserves of groundwater are also large, but most of them are deep groundwater, which is rarely exploited and utilized. The freshwater resources that humans can easily utilize at present are mainly river water, freshwater lake water and shallow groundwater. These freshwater reserves only account for 0.3% of all freshwater, accounting for 7/100,000 of the world's total water. That is, the world's truly effectively utilized freshwater resources are about 9,000 cubic kilometers per year.

From the perspective of movement and renewal of terrestrial water bodies, river water is the most important and has the closest relationship with humans. River water has the characteristics of rapid renewal and short circulation cycle. Scientists divide water resources into static water resources and dynamic water resources accordingly. Static water resources include: glaciers, inland lakes, and deep groundwater. They have long cycle periods and slow renewal. Once contaminated, they are difficult to recover in the short term. Dynamic water resources include river water and shallow groundwater, which have fast circulation, rapid renewal, short alternation period, and can be restored in a short period of time after utilization.

Therefore, when humans develop water resources, they must make reasonable and full use of water resources according to the laws of the water cycle. Only by promoting the renewal of water resources and everyone cherishing them can we use water resources sustainably.

The uneven distribution of water resources is a big problem for mankind

97% of the water resources on the earth are salinized, and only 3% of the fresh water resources can be directly used. Among these Two-thirds of the fresh water is glaciers and snow, and one-third exists in aquifers, moist soil and air.

This is limited fresh water, and the distribution is extremely unbalanced. The world has about 65% of water resources are concentrated in less than 10 countries, while 80 countries accounting for 40% of the world's total population are seriously short of water. The places with the richest water resources are Latin America and North America, while in Africa, Asia, and Europe, the average per capita It has much less fresh water resources.

The Middle East is a region with severe water shortage. Its main water source is the Jordan River. Countries related to the river include Jordan, Syria, Lebanon, Israel and Palestine .There are almost no other alternative water sources in these countries. Therefore, the water shortage problem is extremely serious.

Since the founding of Israel in 1948, there have been extremely serious water disputes in this basin. The 1967 outbreak of A direct factor in the Middle East war was the attempt by members of the Arab League to change the course of the Jordan River away from Israel in the early 1960s. Israeli President Levy at the time declared that water was the life of Israel, and Israel would take action to To ensure the continued supply of river water, Israel occupied most of the Jordan River Basin by force, giving itself a relatively reliable water supply. In fact, disputes over water resources not only occur in the Middle East, but also in Europe, where disputes over the Danube River have occurred Political disputes. In South Asia, disagreements over the distribution of water from the Ganges River have not yet eased, while in Africa, the conflict over water in the Nile River basin has become more intense. This basin includes Egypt, Sudan, Ethiopia, Kenya and other nine of the world's most arid countries. The most serious country. If upstream countries use more water, Egypt will use less water and aggravate drought.

Economic development has made water pollution more and more serious. The famous Rhine River in Europe once caused pollution in the river due to industrial pollution. Fish have disappeared; 75% of industrial wastewater along the Volga River is discharged into the river without treatment; most rivers in Asia are polluted and have become the most degraded rivers in the world. An EU report pointed out that in Europe , the pollution of groundwater by pesticides is much more serious than expected. Within 50 years from now, 60,000 square kilometers of aquifers will be affected by this pollution.

According to World Bank statistics: In developing countries Half of the drinking water in big cities seeps into the soil through cracks. The amount of tap water leakage in our country reaches more than 1 billion tons every year.

Marin Formakenmark once proposed a per capita standard to measure water shortage, which is the so-called Water level. According to this standard, each person should have 1,000 cubic meters of available fresh water per year. If it is lower than this standard, modern society will be restricted. Measured by this standard, many countries are currently below this standard. For example, in Kenya, every person There are only 600 cubic meters per year, Jordan only has 300 cubic meters, and Egypt has only 20 cubic meters. The United Nations believes that by 2025, there will be a large number of countries with annual per capita water supplies as low as 1,000 cubic meters. Among them, Kuwait, Libya, Jordan, Saudi Arabia, Yemen, etc. are short of water. The per capita annual water use in countries with serious water shortages may be less than 100 cubic meters.

Some estimates say that by 2025, the world's population will reach 8.3 billion, and people may exhaust all water reserves...

Distribution of water resources on earth

Although there is a huge amount of water on the earth, very little can be directly utilized by people for production and daily life. First of all, seawater is salty and bitter, making it unfit for drinking, irrigation, and industrial use. Secondly, the earth’s freshwater resources only account for 2.5% of its total water volume, and of these very few freshwater resources, more than 70% are frozen in the ice caps of Antarctica and the Arctic. In addition, it is difficult to use mountain glaciers and permanent Due to frozen snow, 87% of fresh water resources are difficult to use. The freshwater resources that humans can really utilize are part of rivers, lakes and groundwater, accounting for about 0.26% of the earth's total water. Global freshwater resources are not only in short supply but also extremely unevenly distributed across regions. Distributed by region, the freshwater resources of nine countries, including Brazil, Russia, Canada, China, the United States, Indonesia, India, Colombia and Congo, account for 60% of the world's freshwater resources. 80 countries and regions, accounting for about 40% of the world's population, are severely short of water. At present, about 1.5 billion people in more than 80 countries around the world face lack of fresh water, of which 300 million people in 26 countries live in a state of complete water scarcity.

It is estimated that by 2025, 3 billion people around the world will be short of water, involving more than 40 countries and regions. In the 21st century, water resources are becoming a precious and scarce resource. Water resources issues are no longer just a resource issue, but also a major strategic issue related to the sustainable development of the country's economy, society and long-term peace and stability.

China’s total water resources are 2.8 trillion m3. Among them, surface water is 2.7 trillion m3 and groundwater is 0.83 trillion m3. Since surface water and groundwater are mutually converted and recharge each other, deducting the double calculation amount of 0.73 trillion m3, the amount of groundwater resources that do not overlap with river runoff is about 1,000 100 million m3. According to internationally recognized standards, water resources per capita below 3000 m3 are considered mild water shortages; water resources per capita below 2000 m3 are moderate water shortages; water resources per capita below 1000 m3 are severe water shortages; water resources per capita below 500 m3 are severe water shortages. m3 indicates extreme water shortage. Currently, 16 provinces (autonomous regions and municipalities) in China have per capita water resources (excluding transit water) below the severe water shortage level, and 6 provinces and regions (Ningxia, Hebei, Shandong, Henan, Shanxi and Jiangsu) have per capita water resources. The volume is less than 500m3.

The main characteristics are: the total amount is not abundant, and the per capita possession is even lower. China's total water resources rank sixth in the world, with a per capita share of 2,240 m3, about 1/4 of the world's per capita, and China ranks 88th among 153 countries continuously counted by the World Bank.

Regional distribution is uneven and water and land resources do not match. The Yangtze River Basin and the areas south of it account for only 36.5% of the country's land area, and its water resources account for 81% of the country's water resources; the Huaihe River Basin and the areas north of it account for 63.5% of the country's land area, and its water resources only account for 81% of the country's water resources. 19% of total resources.

The distribution within and between years is uneven, and droughts and floods are frequent. In most areas, the precipitation for four consecutive months accounts for more than 70% of the whole year, and consecutive wet years or consecutive dry years are more common.

Water is the source of life. In extraterrestrial exploration, an important basis for scientists to determine whether a planet has life is the presence of water. Water is the most abundant resource on earth, covering 71% of the earth's surface. However, about 98% of the earth's water is seawater that can neither be consumed by humans nor irrigated farmland, and less than 3% is fresh water. Of this pitifully small amount of fresh water, about 87% exists in glaciers, ice caps, atmosphere and deep soil layers. The fresh water resources that humans can utilize under current conditions only account for 0.003% of the total global water resources.

Since the beginning of this century, with the expansion of population and the rapid expansion of the scale of industrial and agricultural production, global freshwater consumption has grown rapidly. From 1900 to 1975, the world's agricultural volume increased seven times, and industrial water consumption increased 20 times. In recent decades, water consumption has continued to increase at an annual rate of 4% to 8%, and the contradiction between freshwater supply and demand has become increasingly prominent." "Water shortage" is no longer a myth.

Terrestrial freshwater resources mainly come from rainfall. Due to the uneven distribution of water resources on the earth in time and space, some countries suffer from constant floods, while others experience drought and no rain. At least 80 countries in the world are arid and semi-arid, and about 40% of the world's population is affected by synchronic droughts. Atmospheric warming has intensified the process of drought, and drought is causing more and more people to leave the places where their ancestors thrived and become "environmental refugees."

While water shortages are becoming more and more prominent, people are polluting water sources on a large scale, causing water quality to deteriorate. Water pollution mainly comes from wastewater, waste gas and waste residues discharged by all human manufacturing.

For a long time, people have not paid much attention to sewage treatment, but have allowed sewage to flow across the country. They even regard large rivers and small rivers as urban "cleaners", only hoping that the spring water of the river will flow eastward, taking away garbage and waste. The world currently discharges about 426 billion tons of sewage every year, causing 5.5 trillion cubic meters of water to be polluted, accounting for more than 14% of global runoff. Another United Nations survey shows that about 40% of the stable flow of global rivers has been polluted.

Water pollution is alarming not only for fresh water but also for ocean pollution. The vastness and automatic purification capabilities of the ocean have led humans to regard the ocean as the best and largest natural garbage pit. Dumping is the main way humans use the ocean. Countries, especially industrial countries, dump large amounts of waste into the ocean every year, such as sewage sludge, industrial waste, dredging sludge, radioactive waste, etc.

Among all kinds of dumping, the dumping of radioactive waste is of particular concern, because it is equivalent to placing one runaway nuclear bomb after another around people. Once the waste leaks, the ecological disaster it will cause is far greater than the nuclear explosion of Hiroshima, Japan in World War II. degree. Despite this, sea dumping is still a hobby of some countries.

In addition, offshore oil pollution is also the murderer of ocean pollution. Oil pollution forms an oil film on the sea surface, which affects the reoxygenation of seawater and the survival of marine life. The toxic components contained in oil are passed to humans through the food chain, and the harm is difficult to ignore.

Looking back at history, it is water that has nourished mankind and created civilization. The ancient Babylonian civilization arose in the two river basins, the Nile River created the ancient Egyptian civilization, the Yellow River was the birthplace of the Chinese civilization, and the ocean made the ancient Greek civilization once glorious. But today, water has become an obstacle to human survival. In 1977, the United Nations warned the world: "Water will soon become a serious social crisis. The next crisis after the oil crisis is water."