Current State of Water Problem
The earth is called “the planet only liquid water exists”, but how much water is there?
There are about 1.4 billion㎦ of water on the earth, 97.5% of it is seawater, and other 2.5% is freshwater. However, a large part of freshwater is existing as ice in Antarctic or Arctic, so water existing as groundwater or river for people to use is only 0.01%.
We tend to think that there are a large amount of water, but actually, it is limited.
Then let us look at how this limited water circulates.
The original graph made on the basis of the data of World Water Resources at the Beginning of the 21st Century: UNESCO, 2003
Mainly, water evaporate from the surface of the sea and become clouds. Then clouds dump rain and snow, and it goes down to a river and flows into the sea again.
It is called “circulation of water”.
However, there are various climates in the world, for example the area where there is no rain at all and the area where the humidity is high.
Water resources changes by the climate around the world.
So how water is used across the world?
According to ministry of land “the circumstance of world and Japan related to water resources”, water consumption of the entire world is comprised by 70% of agricultural water, 20% of industrial water and 10% of domestic water. Usage of water and its proportion is different by country to country like “a country where agriculture is thriving”, but everything relates to our lives.
According to the United Nations “population estimates of world (2017 revised version)”, world population will reach about 9.8 billions in 2050. Accordingly, the consumption of water will increase significantly as well. How should we use water from now on?