[Based on information provided by the National Institute for Land and Infrastructure Management - Ministry of Land, Infrastructure and Transport of Japan (NILIM-MLIT)]

Background

The Japanese archipelago (consisting of four major islands, Honshu, Hokkaido, Kyushu, Shikoku, and about 3,900 smaller islands) lies on the eastern coast of the Asian continent. It stretches in a narrow arc that is 3,800 kilometers long, ranging from 20.25' to 45.33' north latitude between the North Pacific Ocean and the Sea of Japan, east of the Korean Peninsula. Japan's total area of 377,815 square kilometers, represents less than 0.3% of the world's land area with a total population of about 125 million. Japan's complex topography presents a contrast to its relatively mild climate, providing the landscape with beautiful and at times dramatic scenery including snow-fed mountain lakes, rocky gorges and turbulent rivers, rugged peaks, graceful waterfalls, and a long irregular coastline with many small but excellent harbors. Mountains account for about 71% of Japan's total land area. More than 532 of these mountains reach over 2,000 meters high; Mount Fuji is the tallest and rises 3,776 meters.

Click on the Greater Tokyo Region to access a detailed view. Map prepared for the World Water Assessment Programme by AFDEC.

The islands of Japan lie in the temperate zone and at the northeastern end of the monsoon area that reaches from Japan through the Korean Peninsula, China, and Southeast Asia to as far as India. The climate is generally mild, though it varies considerably from place to place, largely due to the continental air currents from the northwest that dominate the winter weather and the oceanic air currents from the southeast that prevail in the summer season. Spring and autumn are the best seasons of the year, with balmy days and sunshine across the country, although September brings typhoons, which may strike inland with their torrential rains and violent winds. The annual average rainfall across the country ranges from 1,000 to 2,500 millimeters a year.

Tokyo, the capital city, located at almost the same latitude as Athens, Los Angeles, and Tehran, enjoys a relatively mild winter with low humidity and occasional snow, in contrast to the high temperatures and humidity of the summer season with an annual average rainfall of about 1500 mm.

Greater Tokyo Region

The Tokyo Region of WWAP includes 5 river basins, namely Tone river, Ara river, Tama river, Sagami river, Tsurumi river. The total area covered by the 5 river basins is about 22 600 km2 with a total population of 27 million inhabitants and assets worth about 3,3 trillion US dollars.

Despite worldwide acknowledgement of its "best practices" in water resources management and environmental protection, the Tokyo Region is well known for its water stress and vulnerability to water related disasters including flood (e.g., sub-basins of the Tone rivers), drought (e.g., Ara river) and water quality deterioration (e.g., sub-basin of the Tone river).

The region has been selected as a Pilot Case Study for WWAP. The contribution provides an interesting example because it combines small river basins and a Mega City scale. The Tokyo Region Pilot Case Study of WWAP is led by the Japanese Government represented actively by the Ministry of Land, Infrastructure, and Transport, and co-ordinated by the Secretariat of the Third Word Water Forum in Tokyo.

Useful links

Read the complete case study, published in the first World Water Development Report (WWDR).
[PDF format - 1 MB]

To know more about the Greater Tokyo Region, here is a list of interesting projects and organizations:

- Ministry of the Environment of Japan- [in english and japanese]
- River Administration in Japan (part of the MLIT site)