Water quality projection in the Geum River basin in Korea to support integrated basin-wide water resources management

Abstract

When establishing long- and short-term reservoir operation to support integrated water resources management, reservoir operation emphasizes not only water quantity but also water quality downstream of the reservoir. This study proposes a water quality projection scheme in the Geum River basin based on the pollutant loadings of biochemical oxygen demand, total nitrogen (TN), and total phosphorus (TP) combining with a long-term hydrologic simulation model. In the Geum River basin in Korea, two multipurpose dams, Daechung and Yongdam reservoirs, exist. Downstream of the Daechung reservoir is especially subject to the pollutant loadings released from the metropolitan cities which contribute to water quality degradation in the main stream of the Geum River. To identify the hydrologic cycle in the Geum River basin, long-term hydrologic simulation models have been employed and calibrated with two control points from 1983 to 2008. Water quality simulation based on the flow rates and pollutant loadings estimated in the Geum River basin shows a good agreement with observed ones along the main stream of the Geum River. As a result, the combination of water quality and the hydrologic simulation model provides systematic approach to project water quality downstream of the reservoir and to support reservoir operation in determination of discharge release considering downstream water quality.