|Water for Urban Areas (UNU, 2000, 243 p.)|
|2. Water management in Metropolitan Tokyo|
|Water circulation and urban civilization|
Urban developments that contribute to the convenience of urban life and economic efficiency have altered the nature of water circulation in Tokyo. As a result, the populace has been troubled by new types of flood hazard since 1985, a decrease in water bodies, a decrease in the ability to control the temperature in the city, and the heat island phenomenon, which has become acute in recent years. Tokyo waterworks have eagerly sought to meet the increased demand for water and have developed water resources by means of dam construction. New technologies, based on visions worthy of the twenty-first century and not limited to conventional planning ideas, have been sought for the water management of the future.
This could be called the materialization of the philosophy of recycling. The characteristics of water as a natural resource are intrinsic in the meaning of the recycling of resources. The utilization of treated sewage in buildings and to recharge rivers since the latter half of the 1980s in Tokyo, no matter how limited, should be recognized as the forerunner of water recycling measures from the point of view of the history of technologies.
New technologies must be developed to cope with the utilization of treated sewage, which is expected to grow in volume in Tokyo in the future. In order to achieve this goal, it is important to offer water of acceptable quality at low cost. The administration that produces treated sewage and the administrative bodies for waterworks, rivers, and streams, and the environments expected to use the treated sew- age are related to each other. In order to realize the philosophy of water recycling, an all-around administration is a must. In order to achieve this academically, the development of interdisciplinary fields of studies and cooperation is required. At the moment, treated sewage is sent underground from treatment plants to buildings, rivers, and water channels. For the future, however, studies are already under way on numerous technologies for sending it back to the upper basins of rivers and streams supplying purification plants.
In this context, the utilization of treated sewage must be recognized as one part of water resource development. Water resource development for big cities in the future should be a combination of dams, the utilization of treated sewage, the use of rainwater, as is being done in Sumida District, Tokyo, the conversion of existing water rights, etc. The designers and the executors of development plans must recognize that projects that do not take recycling into account affect the natural circulation of water in that area. If this concept is not accepted, the philosophy of recycling will not be able to be applied to Tokyo as a basic element in city planning.
The concept of recycling should not be limited to the waterworks of Tokyo; it should be applied to the water management of any future megalopolis and especially to the future planning of water-related infrastructure. As water-related projects become bigger and more complicated, the concept will expand its influence beyond borders. Hence, the concept is undoubtedly the key to the global problems of water and the environment.