Multiobjective Analysis of the Sedimentation behind Sangju Weir, South Korea

This paper presents a new multiobjective approach to solve sedimentation problems behind weirs and low-head dams. The multicriteria decision analysis (MCDA) framework is used to improve reservoir operation rules for Sangju Weir in South Korea. A series of stage and discharge constraints can be developed to include consideration for reservoir sedimentation, hydropower generation, flood control, water supply, irrigation and drainage, and environment. Seasonally changing operation rules can help mitigate reservoir sedimentation while improving hydropower production, water supply, water quality, and environmental issues. Based on a 22-year daily reservoir operation simulation, improved operation rules to mitigate reservoir sedimentation include: (1) a nonflood season stage kept high (EL 47.0 m); (2) a flood season stage between EL 47.0 m and EL 44.5 m depending on the magnitude of the upstream flow discharge; and (3) gates should be opened during floods (Q>600 m3/s).