Ⅰ. Background
oIn order to evaluate the sustainability of environmental development, complex environmental information such as information on the impacts of development projects and the status of environmental quality is needed. This study proposes methods to quantitatively produce the following environmental indicators (indices) that can support policy decision-making for consultation and review of environmental impact assessment (EIA).

oEnvironmental Impact Index (EII): A quantified value of the accumulated environmental impact of major development projects on a regional (national) scale based on information from the environmental impact assessment reports

oEnvironmental Quality Index: A value of the state of environmental quality quantified with multiple parameters in different domains (e.g., air, water, and soil), taking into consideration the characteristics of each environmental medium based on national monitoring networks

oSpecifically, this study introduces the statistical methods for the two indices and demonstrated them through case studies: the environmental impact index of a solar power generation project and the environmental quality index of the air quality domain are presented.
Ⅱ. Environmental Impact Index (EII)
oEIA reports provide the cumulative environmental impacts of several development projects by integrating their information. Here, the EII can be suggested by a linear combination of the degree of impacts of a development project (the pollution load or environmental footprints, etc.) and the environmental status (weight of receptor characteristics)