Changes in Stream–Aquifer Interactions Due to Gate Opening of the Juksan Weir in Korea

Abstract

The Juksan weir, installed in the Yeongsan river in South Korea from 2010 to 2012, has secured sustainable water resources and helped control flooding. However, low river flow velocities due to the weir have deteriorated the quality of the river water. For natural river restoration, the water gate was opened in 2017. In this study, the three-dimensional finite difference model Visual MODFLOW was used to analyze the effects of gate opening on stream–aquifer interactions. A conceptual model was developed to simulate the stream–aquifer dynamics caused by the operation of the water gate at the Juksan weir. Groundwater data were also analyzed to determine the impacts of weir operations on groundwater quality. Our results indicate that a lower river level due to the weir opening changed the groundwater flow, which then affected the water balance. The change in groundwater flow increased the variability of the groundwater quality which had homogenized because of induced recharge after the construction of the weir. This could affect groundwater use in agricultural areas near the weir. Therefore, further groundwater monitoring and hydrodynamic analyses are required to anticipate and address any potential issues.