Long-term morphologic change at Nakdong altered estuary of Korea: Pathways for conservation and restoration

초록

Morphologic equilibrium following dam construction and subsequent restoration at Nakdong Estuary of Korea was investigated using a realistic long-term morphodynamic modeling, COAWST. The model results revealed that the estuary achieved equilibrium approximately 15 years after restoration. In contrast, human-altered estuaries stabilized more quickly?within about 9 years?due to hydrodynamic adjustments and sediment redistribution that reduced energy dissipation. Model simulations effectively reproduced key morphological changes, including the transition from barrier island formation under wave-dominated conditions after dam construction to sand shoal development under tide-dominated conditions following restoration. Additionally, the model captured shifts in sediment texture: from sand-dominated under pristine conditions, to mud-dominated during the construction phase, and ultimately returning to sand-dominated post-restoration. This study highlights the value of realistic, long-term numerical simulations in understanding estuarine responses to human interventions and restoration efforts. The findings offer valuable insights for developing sustainable management strategies - conservation in low- and mid-income countries and restoration in high-income countries.