Science and Management of Altered Yeongsan Estuary of Korea

초록

Estuaries provide habitats for living organisms and support high productivity. However, many estuaries over the world have been degraded due to alteration caused by various human activities. Efforts have been made in recent decades to understand the nature of altered estuaries and the natural response to these modifications with the intension of restoration and/or improved management practices of estuaries. Yeongsan estuary of Korea has been altered due mainly to the construction of an estuarine dam in 1981 as well as the reclamation of extensive tidal flats along the Yeongsan estuary. The alteration blocked estuarine circulation. Moreover, the dam operation became the main controlling factor for the discharge and transport of freshwater, nutrients and sediment. Consequently, the Yeongsan estuary underwent high rates of sediment accumulation (up to 10 cm per year) downstream of the estuarine dam, and severe water quality degradation upstream. A four-year research program, ‘Development of Integrated Estuarine Management System of Korea’, was initiated in 2010 to understand physical and biogeochemical processes of the altered Yeongsan estuary in order to recommend restoration measures to policy makers. Potential scenarios for restoration include reduction of nutrient input from watershed, dredging of contaminated bed sediment, pumping of degraded bottom water, and restoration of estuarine circulation. Based on two-years of observational study and model simulation of above-described various scenarios, removal or permanent opening of the dam to restore estuarine circulation appears to be the best solution in Yeongsan estuary. However, the suggested method is highly controversial in Korea and it remains to be seen whether policy makers in fact implement the suggested measure.