이작도 주변해역 Side Scan Sonar 해저면 음향영상

Abstract

Ijakdo is located 44km west of Incheon and divided into Daeijakdo and Soijakdo. The coastal area of Ijakdo has natural conditions with clean sea water and sandy beaches. Tide is typically semidiurnal with mean range of 491.1cm. Tidal currents are relatively high in velocity in Seosudo between Daeijakdo and Soado. Surface sediments for sedimentary analyses were sampled at 72 stations. Surface sediments consisted of six sedimentary facies and dominated well-sorted sand except near the islands. According to the acoustic pressure of side scan sonar calculated from the back-scattering intensity, seafloor image in Ijakdo coast is mainly divided into two characteristics, the rocky bottom with gravels (high intensity) and the well-sorted sand area (low intensity). Specially the large scaled rocky bottom structures are found out at the northern part of the Ijakdo coast. The distribution boundary of rock (gravel) and sand is shown as a clean linear type. The seafloor image in the eastern part of the Ijakdo coast, where the semidiurnal tidal current is passing through, is interpreted to the scarped out-crop rocky bottom with gravels.