Possible origin of coastal sands and their long-term distribution along the high slope-gradient, wave-dominated eastern coast, Korea

Abstract

This study aims to investigate possible source and long-term distributional patterns of coastal sands in the high slope-gradient, wave-dominated coast with no large rivers, eastern Korea. Chirp (2-7 kHz) seismic profiles show that the coastal sand deposits, the uppermost transparent layer, are up to 7.1 m thick off small, mountainous stream mouths, and thins laterally, showing a radial distribution from the stream mouths with a slightly SE-skewed elongated (i.e., alongshore) geometry. These features suggest that the terrigenous coarse sediments emptied by the streams during the summer flash flooding season have been a major source to the adjacent coastal sands. Hydrodynamic measurements with benthic tripod systems indicate that alongshore currents occurring during episodic storms play a significant role in the displacement of the coastal sands toward the southeast, resulting in the slightly SE-skewed elongated (i.e., alongshore) distributional geometry of the sands.