Search

ABSTRACT Kim, M.; Lim, H.S.; Do, J.-D.; Kim, S.-S.; Lee, H.J., and Shim, J.-S., 2018. Variations of nearshore currents induced by seasonal waves in Haeundae. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1551–1555. Coconut Creek (Florida), ISSN 0749-0208. Haeundae, located on the southeastern coast of the Korean Peninsula, is a famous sand beach with a 1.6 km long, 70 m wide coastline. It suffers from wave-induced beach erosion in both summer and winter. For beach restoration, the Korean government has conducted beach nourishment (620,000 m3), and installed submerged breakwaters at both ends of the beach. Despite these efforts, the beach is still vulnerable to erosion caused by high waves. To understand beach erosion processes and sediment transport mechanisms, the government initiated an R&D project for the development of coastal erosion control technology since 2013. As part of the project, we have measured over three years of AWAC measurements at a water depth of 22 m and 1.8 km from the beach. Intensive measurements of wave, current, sediment transport near the surf-zone in summer and winter have been made using AWAC, VECTOR, and ADV with OBS. Analyses of nearshore currents induced by seasonal waves in the surf-zone have shown that cross-shore currents in summer are mainly induced by strong waves from the SSW or S that propagate to the beach due to wave breaking and shoaling effects on the reef near the beach. However, longshore currents in winter are induced by high waves from the E or ESE that propagate to the shoreline by diffraction at the east coastline. Eroded sand in summer returns along the beach by cross-shore and weak longshore currents induced by waves from the SSW or S. However, suspended sand in winter is moved to the west by strong longshore currents induced by waves from the E or ESE. Due to its pocket beach shape, beach erosion and sediment transport are caused by variations of nearshore currents induced by seasonal waves. [ABSTRACT FROM AUTHOR]

Lim, H.S.; Kim, M.; Do, J.-D.; Kim, S.-S.; Lee, H.J., and Kim, D.H., 2018. Variation of nearshore currents induced by seasonal waves in Haeundae. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 686–690. Coconut Creek (Florida), ISSN 0749-0208. Wave-induced currents at Anmok, located on the eastern coast of the Korean Peninsula, are one of the main causes of beach erosion related to high waves. Coastline changes induced by beach erosion and deposition are predominantly caused by sediment transport in the surf zone. This sediment transport is generated by wave-induced currents and depends on the wave height and direction. To understand beach erosion processes and the sediment transport mechanisms, field measurements of beach elevation and water depth were conducted for one month in winter 2015–2016. Using AWAC, ADP, VECTOR, and Aquadopp Profiler with OBS, intensive observations were made of waves, currents, and sediment transport in the surf zone. Wave and current variations were simultaneously analyzed at a water depth of approximately 18 m (W1) using long-term deployed AWAC data. Wave statistical analysis at station W1 shows that high waves from the NNE and NE are dominant in winter due to strong northeasterly winds from the NE. However, in summer, high waves coming from the NE and ENE are prevalent due to seasonal winds from the E and SE. By analyzing currents observed in the surf zone with waves, we found that a cross-shore current is generated by high waves, predominantly in winter, with incoming waves normal to the shoreline. Following the direction of incoming waves, longshore currents are separated into SE or NW directions depending on high waves come from the NNE or ENE, respectively. The variations of wave-induced currents caused by incoming wave height and direction accounts for the observed beach erosion and sediment transport, which in turn leads to beach cusp formation and crescentic sand bar migration during high wave periods. [ABSTRACT FROM AUTHOR]

Lee, Y.-K.; Choi, J.-K., and Lee, H.-J., 2020. A study on seasonal dynamics of suspended particulate matter in Korea coastal waters using GOCI. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 232-245. Coconut Creek (Florida), ISSN 0749-0208. Analysis of suspended particulate matter (SPM) is a key to understanding the turbulent sediment flow in the Heuksan mud belt (HMB), located along the southwestern coast of the Korean Peninsula. The purpose of this study was to investigate intra-annual variability in remotely sensed SPM data derived from the Geostationary Ocean Color Imager (GOCI) around the HMB over a period of 1 year (2013). Monthly averaged SPM images obtained by the GOCI showed pronounced seasonal changes in turbid water. Dominant environmental factors for intra-annual and diurnal variability of SPM, including river discharge, winds, and tides, were assessed. Monsoon wind dominated seasonal variation in SPM dispersion; the extent of turbid water increased during the winter and decreased during the summer months. Diurnal variation observed from 1-day composite images showed clearly that tidal current was the dominant factor affecting the short-term dispersal pattern of SPM. The gate-controlled river discharge showed the reverse seasonal pattern compared with SPM concentration. However, a turbid plume from the Geum River observed in GOCI data could support the identification of this river as the major source of the HMB. In conclusion, this study demonstrated that the spatial and temporal dynamics of the HMB, including intra-annual and diurnal variability, can be successfully detected using the GOCI. [ABSTRACT FROM AUTHOR]