Author(s): Kyonghwan Kwon; Kwangsik Yoon
Linked Author(s): Kwangsik Yoon
Keywords: Estuary sluice gate; Hydraulic modeling; Salinity; Brackish; Irrigation
Abstract: The Yeongsan River estuary barrage was constructed to protect the lower and middle course of the Yeongsan River from seawater intrusion. The protected freshwater resources have been used to support agricultural activities occurring in the river basin and thus improve income of farmers in the area and over 40 years of national food security. The central government of South Korea recently passed an act recommending the development of an integrated water management system that can satisfy the multiple needs of stakeholders. Introduction of new policies brought to the surface issues such as agricultural water supply' that had been a challenge, after local governments and environmental groups requested the reopening of the barrage gates based on the belief that the interaction between freshwater and seawater can improve the water quality and restore the ecosystem. However, such expected benefits may come at the cost of loss of freshwater availability. Thus, it is necessary to understand the tradeoff between the ecosystem services provided by the Yeongsan River estuary, which will help the decision-making process for improved sustainability of the river basin. We investigated how the gate opening and resulting seawater intrusion into the river may affect the quantity and quality of freshwater confined in the river and estuary. We conducted a modeling experiment with multiple gateopening scenarios including the current opening rule. A three-dimensional hydraulic model was used to calculate the hydraulics of river flow and seawater intrusion through the gates, and the model parameters were calibrated to water level and salinity concentrations observed in the estuary. The modeling experiment results showed that the gate opening can control seawater to intrude within 15 km upstream from the estuary barrage, even in drought conditions. As a consequence of the anticipated changes in seawater and freshwater, it is estimated that there could be a shortage of irrigation water due to a reduction in freshwater resources.
DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0608-cd
Year: 2023