Characteristics of sedimentation based on data from the Nakdong estuary information service system (NEISS), South Korea

Abstract

The sedimentary environment of the Nakdong River Estuary (NRE) in Busan, South Korea, is governed by natural erosion, sedimentation, and various anthropogenic factors (e.g., the NRE Dam, completed in November 1987). In the present study, we assessed sedimentation processes during 2015–2021 using data from the Nakdong Estuary Information Service System (NEISS) to clarify land–sea interactions and characterize the brackish water zone around the NRE barrier island system. The data included periodic observations of sediment distributions (n = 90). Sand dominated the seaward side of the barrier islands, whereas muddy sand dominated the lagoon side. The depth-integrated net suspended sediment load over one tidal cycle showed seaward movement of 1698 kg m−1 of sediment; the net suspended sediment fluxes at the surface, middle, and bottom layers of the water column were −2.1 × 10−3, −2.0 × 10−3, and 3.3 × 10−3 kg m−2 s−1, respectively. Stratification index analysis revealed a distinctive saltwater wedge with strong stratification in both ebb and flood currents in the mainstream of the NRE. Overall, the NEISS enabled effective analysis of the changes in the sedimentary environment of the NRE over the study period. And the NEISS data collected after May 2015 were used to support Marine Spatial Planning (MSP) in the brackish water zone. This system will be useful for monitoring future changes in the NRE following partial opening of the dam after February 18, 2022.