Year of Publication



Martin School of Public Policy and Administration

Date Available


Degree Name

Master of Public Administration

Committee Chair

JS Butler

Executive Summary

On the four major rivers in South Korea (Han River, Nakdong River, Geum River, and Yeongsan River), 16 weirs were installed in 2011 to secure water resources. However, there is controversy that the weirs allow the summer Green Tide (hereafter referred to as GT) to thrive, so the South Korean government has been opening them since 2017 to evaluate their effectiveness. The opening of the weirs was mainly done at three weirs on the Geum River, where there are few constraints, and some on the Yeongsan and Nakdong rivers, depending on the degree of constraints, while the Han River was rarely opened. This study analyzes the correlation between the opening policy and the increase and decrease of GT by dividing the period before the opening (2012-2016) and after the opening (2019-2023) based on 2017-2018, when the weirs were opened, using the difference in difference method. The analysis was divided into two main categories. The first is to compare weirs with high (Gongju weir) and low (Chilgok weir) opening rates in the Geum River and Nakdong River, two rivers with serious GT problems. The second is a comparison between rivers with high and low weir opening rates. I compared a river with a high opening rate (Geum River) with a low opening rate (Nakdong River, Han River). The analysis showed that the weir opening of the Geum River was statistically significant in reducing GT compared to the Han River. The rest of the analysis was not statistically significant. Considering that the effects on GT are water temperature and nutrients in addition to changes in retention time due to weir opening, there are limitations of this study, so comparative studies between weirs in the same water system are needed if weir opening is expanded in the future. In addition, since there is a statistical significance between weir opening and GT reduction in the Geum River, and since the summer season in South Korea is characterized by flood risk and low water demand, it would be desirable to improve related facilities so that weir opening can be done flexibly in the future.

Available for download on Wednesday, May 01, 2024