Abstract
Coastal development is supporting improvement of economic activity and convenience for city residents. On the other hand, the development has brought loss of 90% or more of natural beach line and disappearance of the tideland,which has purification function in Tokyo-bay. In the recent years, sustainability is one of the important keywords for the development. In general, the development such as constructing an offshore airport carries both economical advantage and environmental disadvantage. It is generally very difficult to consider their balances and to judge which is important. Inclusive Impact Index (Triple I) is proposed by Marine Environmental Committee in JASNAOE. The index includes environment factor, which is obtained by the method of Ecological Footprint, and economical factor,which is converted to global hectare. We can objectively discuss the social importance of the development by using this index. In this research, we obtained the Triple I (III) of construction of an offshore airport and discussed its social importance from both environment viewpoint and economical viewpoint.
