This study proposes the new hydrological drought index, Korean Surface Water Supply Index (KSWSI), which overcomes some of the limitations in the calculation of previous SWSI applied in Korea and conducts the probabilistic drought forecasts using KSWSI. In this study, all hydrometeorological variables in the Geum River basin were investigated and appropriate variables were selected as KSWSI components for each sub-basin. And whereby only the normal distributions are applied to all drought components, probability distributions suitable for each KSWSI component were estimated.

Without exception, global warming affects the water resources in Korea. Several climate change projects have been initiated for future water resources assessment but have produced very different projections with a significant range of heterogeneities. Therefore, it is necessary to develop a standard procedure and scheme that can reduce this heterogeneity.