To assess distribution of metal contamination and grain size in the sediments of Nakdong River (South Korea), surface sediments were collected from 21 sites and analyzed. Within the study area, sand was typically the dominant grain size. However, because of the reduced flow rate and flow velocity, sites adjacent to weirs were composed of relatively fine sediments. A comparison of sediment metal concentrations with sediment quality guidelines proposed by the USA, Canada, and South Korea revealed that sites adjacent to weirs had concentrations that exceeded the standard values. The enrichment factor, index of geo-accumulation, and pollution load index calculation results that the sites adjacent to weirs showed high contamination, with Cd accounting for the highest contamination levels. The metals in the study area varies due to the effect of fine sediments; therefore, high concentrations of metals accumulated adjacent to weirs where fine sediments were distributed in greater proportions. Furthermore, Cd exhibited the greatest contribution to metal contamination in the study area and the highest contamination levels were found at NS19 (adjacent to the Haman weir). Thus, the accumulation of fine sediment increased due to the influence of the weirs, thereby increasing the overall amount of metal contamination.

In this study, an integrated system for the comprehensive analysis of climate change, runoff, reservoir operation, and power generation was developed. In order to apply reliable climate change scenarios to the Geum River Basin, we applied representative concentration pathway (RCP) scenarios adopted by the Intergovernmental Panel on Climate Change for its fifth assessment report in 2014 to the streamflow synthesis and reservoir regulation model at a regional scale with 1-km spatial resolution to analyze future runoff. This analyzed future runoff was applied to the Hydrologic Engineering Center—Reservoir System Simulation to analyze the hydrological behavior caused by reservoir operation through flow duration analysis at each of several important points. The objective was to provide initial data suitable for future basin management through an examination of power generation. Applying the RCP 4.5 and 8.5 scenarios showed that runoff would increase continuously compared with the past. However, in the RCP 8.5 scenario (where carbon reductions have not been achieved), runoff from flooding would be reduced considerably. It was found that power generation would be reduced compared with the past under the climate change scenarios, but additional power generation could be realized with the coordinated operation of reservoirs and weirs. These results suggest that, despite climate change, the risk to power generation could be reduced with the coordinated operation of reservoirs and weirs.