Seasonal variations of sedimentary processes in the Nakdong River Estuary, Busan, South Korea

Seasonal variations of sedimentary processes in the Nakdong River Estuary, Busan, South Korea
우한준; 이준호; 강정원; 최재웅; 정은지
KIOST Author(s)
Woo, Han Jun(우한준)Jeong, Ji Hye(정지혜)Kang, Jeong Won(강정원)
Publication Year
The Nakdong river estuary is located on the southern coast of South Korea in the city of Busan. Two large estuarine dams were constructed, one in 1934 and one between 1983 and 1987. The construction of these dams has led to the geomorphological evolution of barrier islands within the Nakdong river estuary. The estuary has been characterized as a barrier-lagoon system with various subenvironments and micro-tidal ecosystem and a mean tidal range of 1.07 m. The monitoring short-term sedimentation rates and suspended sediment characteristics were investigated to understand sedimentary processes in the barrier-lagoon system of the Nakdong river estuary. The surface sediments generally showed sand sediment was dominated along the seaward side of the barrier islands and muddy sand sediment was dominated within the lagoon. The short-term sedimentation rates for a year showed that deposition dominated the tidal flats between the mainland and Jinudo (JW-line) and the mainland and Sinjado (SJ-line), with net deposition rates of 10.09 and 12.38 mm/year, respectively. Erosion dominated the tidal flat for two years at the southern end of Eulsukdo (ES-line), which is located on the eastern side of the system, at an annual rate of -12.76 mm/year. The surface sediments along three lines were generally deposited in spring and summer and eroded during autumn and winter. Four 12.5-hour anchoring surveys conducted at the inlets and channel revealed that net suspended sediments were transported to the open sea during a tidal cycle in summer. Seasonal variations in sedimentation and characteristics of suspended sediments revealed that the barrier-lagoon system in the estuary was dominated by redistribution of sediments based on relative input energy from waves, tidal currents, and dam discharges. Sediments in the estuary system were transported into the lagoon through inlets during flood-tide conditions without dam discharge. Sediments in the lagoon moved westward and/or northwestward and mostly deposited sediments on the tidal flats and in the channels near the dams under low energy conditions. During ebb tides, fine-sediments flowed out to the sea with discharges from the Nakdong Dam. Along the eastern side of the system, changes in the geomorphologies of subenvironments such as sand shoals, spits, tidal flats, and marshes were more influenced by waves than by tidal currents. The results of the study will provide an important baseline for future assessments of the environmental impacts of open dams.
Bibliographic Citation
9th International Conference Asian Marine Geology, 2018
Related Researcher
Research Interests

Coastal Sedimentary Processes,Micropaleontology(Foraminifera and Pollen),Paleoenvironmental Reconstruction,연안퇴적작용,미고생물(유공충 및 화분),고환경 복원

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