international cooperation activities and information on human resources and technologies in Japan and build the network of sewage-related organizations in Japan and abroad (Figure 4-2-11).

It is also necessary for the Japanese government, businesses and citizens alike to take on the role of sending messages on leading-edge initiatives to the world on efforts to tackle global warming as well as activities to conserve the aquatic environment and diffusion and educational efforts related to such activities.

# Restoration of the Cheong Gye Chon River in Seoul

## Column

The Cheong Gye Chon River, which runs from east to west through the central part of South Korea's capital city, had been gradually slipping away from the memory of Seoul citizens. Because of the progressive contamination, the river had become a hotbed of contagious diseases. Construction work to cover the river continued over some 20 years between 1958 and 1978, and the 16-meter-wide Cheong Gye elevated highway was then built over the river cover for a total length of 5.8 kilometers. Together with the Cheong Gye road that runs under it, the highway served as the artery of Seoul, carrying some 170,000 automobiles a day.

About 20 years since then, calls grew among citizens for the restoration of the Cheong Gye Chon River. In 2003, the Seoul mayor, Mr. Lee Myung-bak, who is now president of the country, decided to bring down the degraded highway and developed the hydrophilic space by planting trees along the river.

Currently, the riverside provides a comfortable recreation area for Seoul citizens, and the restored Cheong Gye Chon River has become one of the best-known tourist spots in the sightseeing city of Seoul.

## 3 Efforts and Measures in Japan

Photo4-1-4 Restoration of the Cheong Gye Chon River

Photo: Seoul City

## a) Measures to cope with decrepit facilities

## (1) Aquatic infrastructure

Waterworks and sewage systems in Japan had been constructed rapidly during the high growth period. Many of them are now becoming decrepit. In order to forestall accidents or failures due to aging facilities and use water resources effectively and appropriately, it is necessary to carry out well-planned replacement or reconstruction of water-related infrastructure, including measures to prolong the life of existing facilities from the early years of the 21 $ ^{st} $ century, also giving heed to the perspective of minimizing life cycle costs (Figure 4-2-12). Water supply systems across Japan have the combined water-purifying capacity of some 88 million cubic meters per day, with the water-purifying capacity of facilities past the statutory useful life standing at some 2.4 million cubic meters per day, or about 2.7% of the total (Figure 4-2-13). The total extension of water conduits, water pipes and distributing pipes runs about 610,000 kilometers, with the extension of these pipes past the statutory useful life standing at some 2.4 million cubic meters per day, or about 2.7% of the total.

Figure4-2-13 Water Purification Capacity Past Statutory Useful Life in FY 2007

Note: The total water-purifying capacity stands at some 88 million cubic meters per day, with the water-purifying capacity of facilities past the statutory useful life standing at some 2.4 million cubic meters per day, or about 2.7% of the total Source: Health, Labour and Welfare Ministry, "Water Works Statistics"