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− Contents − 1.Basic of Water §1.Water and the Earth
2.Water Crisis
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§2.Water and JapanAnnual rainfall in Japan is approximately 1,700 mm. Average annual rainfall in the world is approximately 970 mm, so it seems that Japan is high rainfall area where is rich for water. However, Japan has small national land and high population density. Thus, to estimate the water amount for one person, it can't be conclude that Japan is rich for water.
Moreover, 2/3 of Japan national land is mountain so that rivers are steep. Also, the amount of rainfall depends on season. Even though we have large rainfall amount, there is not so much water that we can use. We have floods by temporal storm rainfall at typhoon season, while we must regulate water supply due to lack of water when little rainfall season. To calculate dam usable storage amount per one person, it is 1/17 of America and 1/16 of Korea.
Vapored water from the surface of the earth stays in the atmosphere, and then it falls down on the ground as rain or snow. On lands, the water flows and it washes the surface of grand. By dissolving substances, water amount gradually increases and small brooks will be mighty rivers which will be then connected to the ocean. Moreover, water which penetrates under the ground becomes subsoil water or underground water.
Water penetrates in rocks as rain or snow, and then water gradually dissolves minerals contained in rock. Water stays for a while and then becomes spring water which contains minerals (Calcium or Magnesium). Depending on mineral amount, the water is regarded as soft water or hard water.
The water difference affects on food. Since hard water contains lots of minerals, it is not suitable for food. Thus, in western-style food, people steam or fly up by oil rather than boiling by water. Moreover, they use milk or wine for boiling. In Japan, people has used water for stew, soup, and boiled food for long time.
Environment agency in Japan has researched about water environment and water resource in the nation, and it selected "best water" in 1985 to conserve water environment. For the background, Japanese water environment has had serious issue due to agricultural contamination, industrial wastewater, and chemical pollution in underground water by rapid economical development. Thus, in such situation, Japan decided to conserve water environment by selecting best water. Ministry of the Environment HP |
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