Marginal Utility-based Determination of Water Supply Quantity Considering Climate Change Scenarios

This study proposed a new robust decision framework to determine the water supply quantity for instreamflow requirement considering multiple climate change scenarios. The concept of marginal utility was used to quantify the effectiveness of additional unit capacity for water supply and minimax regret approach was introduced to determine the final quantity for robust utility to various periods of multiple climate change scenarios. This framework was applied to the Korean watershed which has suffered drought frequently. The Soil and Water Assessment Tool (SWAT) was used to simulate the daily runoff after its calibration and validation and representative concentration pathways (RCP) 4.5 and 8.5 were included in this study. The marginal numbers of satisfied days with instreamflow requirement were analyzed for the historical and RCP 4.5 and 8.5 scenarios, respectively. The results from the marginal utilities were concluded to be all different according to the selected data periods and scenarios. Therefore, the minimax regret approach was used to determine the final robust water supply quantity considering all uncertainties inherent in various climate change scenarios