Developing Sustainability Index for Water Use with a Regret-based Decision Making Approach for Hydrologic Units in South Korea

This study aimed to develop sustainability index for water use over hydrologic units in South Korea. We identified major indicators for sustainable water use with considering multiple aspects of water use: not only physical, biological and chemical aspects but also social and environmental aspects. Furthermore, stressors for sustainable water use were of major interests because they were straightforward and easy to measure in comparison to indicators representing the state- and impact-related indictors. As a result, sustainability index was constructed with a theme-based hierarchical approach. It is comprised of two components of stress and response to sustainable water use and each component includes five sub-components of 1) human water requirements, 2) renewability of water resources, 3) water quality requirements, 4) health of aquatic ecosystems and 5) equitable water use. Then for each sub-component, multiple indicators, i.e., proxy variables were identified. For drainage basins in South Korea, standard hydrologic units with their total number of about 100 across the country, 19 stress indicators and 11 response indicators were identified in this study. Indicator data were collected for concurrent time, 2010 per se, with number of datasets from earlier or later times and integrated to estimate the sustainability index with a regret-based multi-criteria decision making (MCDM) approach. At last, we evaluated sustainability index with focusing on the spatial variability of indices and indicators and the sensitivity of indices to individual indicators. Also the sensitivity of indices to different MCDM approaches were examined.