Evaluation of lake modification alternatives for Lake Sihwa, Korea

After the construction of an embankment at the Bay of Sihwa in Korea, a lake of 56.5 km2 surface area and 330 million m3 volume was created. Because of rapid socioenvironmental changes and the lowering of water quality in Lake Sihwa, various external measures have been proposed and some of them are being implemented. In this paper, we examine two alternatives for in-lake modification: one alternative is zoning of the lake by constructing two submerged dams and the other is channeling of the lake through reclamation. Water quality modeling was conducted for both alternatives to assess their effects. Results of the modeling revealed that the reduction of the lake size through two different approaches, when accompanied with other external measures, would improve the water quality, but to different degrees. The zonation is expected to improve the freshwater quality up to the level supplying 45 million m3 of water per year for agricultural use. The quality of channeled water would be inappropriate for agricultural use, but suitable for outdoor activities such as recreation or fishing regardless of reclamation plans considered.