Textural fades and distribution of surface sediments and morphology on Korean tidal flats

Abstract

The aim of this study is to understand the regional distribution patterns of surface sediment together with morphology and to infer regional transport and sedimentation along the western and southwestern coast of Korea. Based on the analysis of 1027 surface sediment samples at 74 tidal flats and the morphologic profiles at 29 tidal flats obtained from estuarine, open coast, embayment, and islands along the western and southwestern coasts of Korea, tidal flats were divided spatially into four sectors; 1) Gyeonggi (GG), 2) Chungcheong (CH), and 3) Western Jeonnam (WJ) and 4) Southern Jeonnam (SJ). The tidal flats in the CH sector exhibit coarser (or more sandy) sediment facies and steeper slope gradient, probably resulting from more influence of waves on tidal-flat sedimentation caused by the geomorphic conditions of relatively straight coastline and non-barrier systems. The common occurrence of tidal channels on tidal flats in the WJ and SJ sectors could be ascribed to the fine-grained (or muddy) faceis and the gentle slope gradient. From GG (north) to SJ (south) sector along the coastline, the content (%) of fine-grained sediments increases. Fine-grained sediments supplied from the Han and Keum rivers in the western coast of Korea appear to have been transported to the south along the western and southwestern coast of Korea by Korea Coastal Currents (KCC). The fine-grained sediments settled on the tidal flats by the tidal currents and a residual coastal current.