February 28, 2003



Keywords: Newsletter 

JFS Newsletter No.6 (February 2003)

Japan, positioned in Monsoon Asia, has rainfall close to twice the world average (although per capita rainfall is one-fifth of the world average due to the country's large population). The average annual rainfall in Japan is 1,718 mm, but in recent decades, precipitation has been on the decreasing trend.

According to "Water Resources in Japan 1998" (Ministry of Land, Infrastructure and Transport, Water Resource Division), the average annual total precipitation in Japan is 650 billion cubic meters. Evapotranspiration per annum is 230 billion cubic meters, leaving potential water resources of 420 billion cubic meters. From this potential, 54.9 billion cubic meters are used in agriculture, 14.8 billion cubic meters in industry and 13.2 billion cubic meters for residential purposes.

From groundwater, 3.9 billion cubic meters is used in agriculture, 4.9 billion cubic meters by industry and 4.0 billion cubic meters for household uses. Wastewater from various uses and stages returns to the ocean via rivers and other flows. This is the overall hydrological picture in Japan.

On the front of water use, according to "Water Resources in Japan 2002" (Ministry of Land, Infrastructure and Transport, Water Resource Division), Japan used approximately 87.7 billion cubic meters of water (amount withdrawn) in 1999, consisting of about 57.9 billion cubic meters for agriculture, about 13.5 billion cubic meters for industry and about 16.4 billion cubic meters for residential uses. Statistics show that total water use has increased by 2.7 billion cubic meters since 1975, a 3.1 billion cubic meter decrease in water for industry, and a 5.0 billion cubic meter increase in water for household uses.

The water used by industry has been decreasing because the recovery (recycling) rate of water has been improving. At present, the water recovery rate is 78.1 percent, a 0.1 percent point increase from the previous year.

The effective water use amount for residential purposes is approximately 14.3 billion cubic meters. Per capita water use per day is 322 litters. Compared with 1974 level, water used for household uses has increased by 63 percent and water use per capita per day by 30 percent.

In households, 20 percent of water is used for washing clothes, 22 percent for cooking, 24 percent for flushing toilets and 26 percent for bathing.

Japan experienced an abnormal drought in 1994 and people living in the western part of Japan, in particular, suffered considerably. In addition, the destruction of the environment by dam construction has been attracting attention.

Approximately 40 percent of Japanese people have experienced cuts in water supply or water rationing and people in general have been increasingly concerned about their water supplies during droughts or disasters. Awareness for water conservation can be seen in a 30 percent increase over 15 years of people who make water conservation efforts in their daily life. About 75 percent of people are for utilization of rainwater or recycled water. About 36 percent say they would be willing to install such equipment in their homes even if they have to pay for it. These results indicate a high level of awareness about effective water use.

People are increasingly aware of water conservation at home. Many attach a small device to restrict the flow to water taps and re-use bathwater for washing clothes and watering gardens.

Japan experienced serious problem with ground subsidence in many areas during the 1960s and 1970s due to excessive pumping of underground water for industrial development. Since then, ordinances and regulations to restrict groundwater pumping have been put in place, mitigating the problem of ground subsidence. Reports of major ground subsidence are no longer common. In fiscal 2000, 7 locations, with a total area of 6 square kilometers, were reported to have suffered from ground subsidence of over 2 centimeters per year.

Japan needs to continue promoting efficient water use in agriculture and water conservation at home and office. At the same time, Japan needs to join efforts to tackle problems affecting water worldwide.

The problem is Japan's huge imports of agricultural crops, industrial products, timbers and other commodities from various countries in the world. For example, Japan's self-sufficiency ratio is only 9 percent for wheat and 5 percent for beans. In order to produce the amount of wheat Japan imports, 1.1 billion cubic meters of water are needed. Over 2 billion cubic meters of water are used to produce the beans imported by Japan. A total of about 5 billion cubic meters of water in the rest of the world is used for Japan's imports of agricultural products. This amount is equivalent to the amount of water used by one third of entire Japanese population of about 126 million.

Japan also imports more than 60 percent of its demand for textile products, which consume a huge amount of water in production. Japan has been one of the major timber importing countries, importing 25 percent of all exports in the world. A calculation indicates that approximately 40 billion cubic meters of water are needed to produce food, industrial products and other items Japan now imports.

How effectively and efficiently we use rainfall in Japan is an important challenge for Japan. But, at the same time, the fact that Japan, blessed with rain compared with many other areas in the world, relies on imports for 60 percent of its food (caloric basis) and over 80 percent of its timber is a major problem for the world. How we can reduce these "water imports" in the form of agricultural products or timber? This is also an important challenge among water issues for Japan.