The development of natural environmental indices to set targets for a local environmental plan: A case study in Miyagi Prefecture

Japanese local governments have developed environmental indicators/indices since the late 1970s to evaluate the effect of the total environment on local environmental plans. In 1997, the national government published a draft of indicators for the National Basic Environment Plan, since new functions of indicators/indices were required. Environmental indicators/indices must be selected from wildlife and global issues, be linked to policies, and be easily updated. This study attempts to develop environmental indices for Basic Environment Plan of Miyagi Prefecture. Four natural environmental indices were needed for the plan: life support index on land; air purification index; soil erosion prevention index; and flood prevention index. These indices were measured from 1972 to 1994 and estimated from 1995 to 2005, on the basis of the future land use scenario in Miyagi's Comprehensive Plan. They were also measured by height zone in 1990 and 1994, and by 1-km grid in 1990. The life support index on land has decreased and will continue to decrease in the future. The air purification index increased until the 1980s but recently has decreased and will decrease more in the future. The soil erosion prevention index has not changed and will continue at the present level. The flood prevention index has decreased and will continue to decrease. As a result of calculations using the 1-km grid, most grids which have high scores are located in the 300-600 height zone. Some policy problems have been identified using these indices: conservation of neighboring natural resources; planting in city areas; management of woodland or farmland; conservation of rain permeability in woodland or city areas.