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In this study, a swash-zone model, using Larson and Wamsley formula (LW07), was combined into the Telemac-2D model system to examine the performance of modeling swash-zone processes through comparisons with field observation data. The experimental site was the Haeundae Beach in South Korea where Typhoon Phanfone occurred in October 2014, and bathymetric surveys were performed before and after the typhoon. Hydrodynamic data were also measured to validate the modeled data. The performance of LW07 was tested by running the model in two modes, with and without LW07. First, the model was run to simulate the shoreline response to an imaginary coastal breakwater. The result showed a clear discrepancy between the two modes as the sediments were considerably cumulated behind the breakwater in the case with the swash-zone formula (LW07) in the wide range along the shoreline behind the breakwater, indicating that the sediments more actively and rapidly responded to the shadowing by the breakwater with LW07. The model was also run for a realistic case from August to October 2014, which included the typhoon's period during 2–6 October. The results showed that the morphological changes at both ends of the beach in the swash zone were simulated with higher accuracy with LW07, supporting the effectiveness of LW07 in simulating the short-term morphological changes induced by the typhoon attack. In particular, the successful simulation of the sand accumulation at the end sides of the beach's swash zone indicates that LW07 was effective in estimating not only the cross-shore transport but also longshore transport, which was likely due to the characteristics of LW07 that calculated sand transport in both directions. The enhanced modeling performance with LW07 was likely due to the adjustment of the sediment transport rate to the instantaneous changes in the local beach slope, which could successfully control the erosion/accretion process in the swash zone more realistically. [ABSTRACT FROM AUTHOR]

In this study, a swash-zone model, using Larson and Wamsley formula (LW07), was combined into the Telemac-2D model system to examine the performance of modeling swash-zone processes through comparisons with field observation data. The experimental site was the Haeundae Beach in South Korea where Typhoon Phanfone occurred in October 2014, and bathymetric surveys were performed before and after the typhoon. Hydrodynamic data were also measured to validate the modeled data. The performance of LW07 was tested by running the model in two modes, with and without LW07. First, the model was run to simulate the shoreline response to an imaginary coastal breakwater. The result showed a clear discrepancy between the two modes as the sediments were considerably cumulated behind the breakwater in the case with the swash-zone formula (LW07) in the wide range along the shoreline behind the breakwater, indicating that the sediments more actively and rapidly responded to the shadowing by the breakwater with LW07. The model was also run for a realistic case from August to October 2014, which included the typhoon’s period during 2–6 October. The results showed that the morphological changes at both ends of the beach in the swash zone were simulated with higher accuracy with LW07, supporting the effectiveness of LW07 in simulating the short-term morphological changes induced by the typhoon attack. In particular, the successful simulation of the sand accumulation at the end sides of the beach’s swash zone indicates that LW07 was effective in estimating not only the cross-shore transport but also longshore transport, which was likely due to the characteristics of LW07 that calculated sand transport in both directions. The enhanced modeling performance with LW07 was likely due to the adjustment of the sediment transport rate to the instantaneous changes in the local beach slope, which could successfully control the erosion/accretion process in the swash zone more realistically.

Lee, J. and Hong, S., 2023. Morphodynamics of rip current systems at Haeundae Beach, Korea. Journal of Coastal Research, 39(1), 199–206. Charlotte (North Carolina), ISSN 0749-0208. Rip current generation and beach morphodynamics were measured for about 60 days at Haeundae Beach, Busan, Korea, using various instruments comprising co-located velocity and pressure sensors, ADCPs, and kinematic GPS surveys. Rip currents are narrow currents initiated close to the shoreline that flow strongly in a seaward direction through the surf zone and beyond. It is generally accepted that rip currents arise mostly from the variation of wave height alongshore attritutable to wave refraction over inhomogeneous bathymetry. Field measurement was performed to clarify the generation mechanism of rip currents at Haeundae Beach, Korea. The creation and destruction of sandbars could be identified clearly using data from a photogrammetric survey taken from the roof of a high building during the summer season. In this study, a surf-zone depth survey was performed periodically using Network Real-Time Kinematic GPS, a device that can provide a detailed topographic survey of the surf-zone region. Using these data, we perform a correlation analysis between rip current generation and surf-zone morphological variation. [ABSTRACT FROM AUTHOR]

This study aimed to isolate wild yeasts from seawaters and soils samples of the Haeundae and Mongdol beaches on the southern coast of Korea, and to characterize these unrecorded wild yeast strains. In total, 41 strains, representing 37 different species of wild yeast were isolated from 70 samples collected from the beaches. Among these, 14 strains were isolated from the alkalophilic medium of yeast extract-peptone-dextrose (YPD) medium (pH 9.0), and 27 strains were isolated concurrently on general YPD medium (pH 6.5). Among the 41 isolated wild yeast strains, Candida insectorum HUD 16-3(JSL-KSS-002) and Metschnikowia citriensis HUD 12-5(JSL-KSS-001) had not previously been recorded. We investigated the microbiological characteristics of these two unrecorded yeast strains and three other strains-, Cystobasidium lysinophilum JSC 52-2(JSL-GGU-019), Candida takata NMD 11-1(JSL-GGU-017) and Candida panamensis ASG 58M-2(JSL-GGU-018) from Jangseoncheon in Jellabuk-do and Jangtaesan in Deajeon city. All five previously unrecorded yeasts were oval and did not form spores. All strains grew well in YPD and yeast extract-malt extract media in a vitamin-free medium. Two strains, including C. insectorum HUD 16-3(JSL-KSS-002) grew well in a 15% NaCl-containing YPD medium. Three strains, including Cys. lysinophilum JSC52-2(JSL-GGU-019) assimilated lactose, and all strains assimilated starch.

ABSTRACT Lee, J.; Kim, I., and Lee, J.L., 2018. Improving the performance of rip current forecasting index with a focused on Haeundae Beach, Korea. 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. 1556–1560. Coconut Creek (Florida), ISSN 0749-0208. Rip currents can potentially drag swimmers into deep water, beyond seaward sand bars, and hence pose great threat to beach visitors worldwide. The primary aim of this study was to develop a method for improving the performance of rip current forecasting indices to more effectively, demonstrate a rip current warning level. The previous rip current forecasting index was established with four predictive levels: notice, watch, warning, and danger. The new index is based on a numerical model, using wave and wind data as well as forecast information. Through this study, standardization of rip current occurrence levels has been achieved, by using CCTV images recorded during the summer of 2015. Better forecasting accuracy was obtained given the improvement in predicting the rip current index for Haeundae, and was established in association with the Korean Meteorological Administration. The usefulness of the rip current predictive index on Haeundae Beach was determined through a matrix correlation analysis between the observed and predicted rip current levels. In addition, the accuracy of the prediction results was calculated using the new rip current forecasting index during the summer of 2016. It is necessary to continue the development of predictive studies for risk mitigation in a variety of coastal environments. [ABSTRACT FROM AUTHOR]

ABSTRACT Lee, H.J.; Do, J.-D.; Kim, S.S., and Lim, H.S., 2018. Sands Escaping Haeundae Beach. 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. 1006–1010. Coconut Creek (Florida), ISSN 0749-0208. Haeundae Beach has been hypothesized to lose sands from the nearshore of the western extremity of its pocket-beach system with a tidal range of 0.5 – 1.2 m. To test the hypothesis, a measurement station was located in this area to observe a suspended transport of sands near the seabed. The hydrodynamic measurements included water level, wave, currents and suspended sediment concentration with a benthic tripod for longer than one month of the 2013–2014 winter. In addition, a Telemac-2D tide model was run to simulate tidal currents for the same period of time as the measurements. A total of 6 events of two tidal cycles each were selected and analyzed to represent a variety of combinations of tidal phase, wave energy and wave direction. The results show that the suspended sand transport occurred continuously and was controlled predominantly by ebb-dominant tidal currents. Thus it was always directed offshore. Waves higher than 1 m sporadically took place during the measurements. However, high waves could just reorient the offshore suspended sand transport from obliquely to normal to the shoreline. This is because they created residual currents flowing roughly parallel to the shoreline. Neither offshore wave direction nor tidal phase evidently influenced the characteristics of residual currents. Therefore, the escape of the Haeundae sand from the area of interest has been proven to occur year round intrinsically by tidal currents. Waves intermittently contribute much to enhancing the suspended sand flux offshore by vigorous resuspension processes. [ABSTRACT FROM AUTHOR]

Song, D.S; Kim, G.Y., and Lee, J.L., 2016. Quantitative behaviour characteristics analysis of GPS buoy in rip current generation. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1242 - 1246. Coconut Creek (Florida), ISSN 0749-0208. GPS buoys have been used to acquire sea level change data, current measurements and other oceanic variables in sea for the purposes of vertical datum determination, tide correction, radar altimeter calibration, ocean environment and marine pollution monitoring. The occurrence of rip currents in the Haeundae beach, which is one of the most famous beaches in South Korea, has been threatening beach-goer security in summer season annually. Therefore, we adopted a GPS buoy system for an experiment which is to investigate rip current velocity; it is sporadic and may quickly upsurge within minutes due to larger arriving wave groups or nearshore flow uncertainties. In this study, for high accurate positioning of buoy equipment, a Satellite Based Argumentation System DGPS data logger was deployed to investigate within floating object, and it can be acquired three-dimensional coordinate or geodetic position of buoy with continuous NMEA-0183 protocol during 24 hours. The wave height and current profile measured by in-situ Acoustic Doppler Current Profilers in a cross-shore array were compared with the GPS-derived current velocity, it is being clearly increased before and after generation of rip current, and wave period also was lengthened when a rip current generated. The results presented in this study indicate that by using the GPS buoy system is a reasonable alternative for the measuring of rip current behaviour. [ABSTRACT FROM AUTHOR]

Lee, G.; Hong, S.; Lee, C.; Kim, J., and Lee, J., 2016. Rip current zoning map to manage safety at Haeundae Beach, Korea. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue No. 75, pp. 1452-1456. Coconut Creek (Florida), ISSN 0749-0208. Rip currents are well-known in South Korea. Between July and August 2012, rescue workers covering Busan's beaches were on high alert for rip currents. Rescuers pay particular attention to Haeundae Beach near the Paradise Hotel because it is the frequent site of these currents. In July and August of 2012, 62 fast-moving rip currents were observed with maximum speeds of 2.5 m/s. During this period 187 people were rescued at Haeundae Beach after being dragged into deeper waters by these currents; fortunately, no casualties were reported. Authorities caution that ideal weather conditions for rip currents will persist, so this phenomenon could occur again at any time. In response to this public safety threat, the Korean Meteorological Administration plans to implement automatic monitoring systems for forecasting rip current generation at Haeundae Beach. In this study, we propose an approach for mapping the rip current risk to improve safety management at Haeundae Beach. First, we determine the spatial occurrence rate of rip currents using a field monitoring system based on closed-circuit television (CCTV) images and the Haeundae Current Model (HAECUM) rip current prediction system; the velocity and direction of the rip currents are also considered. This information is then combined with vulnerability factors such as the distribution of beachgoers and the capacity of lifeguards to produce a risk assessment map of rip currents at Haeundae Beach. [ABSTRACT FROM AUTHOR]

Strong wave-induced currents frequently develop at Haeundae Beach, Korea. Rip currents at the beach have threatened safety of swimmers in water. Near-shore currents at Haeundae Beach during a high wave time were measured on 4 June 2008 by using drogues equipped with GPS. The current field during measurement period showed westward flow along shoreline. Major driving force of the measured currents is thought to be the wave-induced force, and the tide-induced force was the second important driving force at the time. The wave-induced current field at the time is quantitatively described by using a numerical modelling system CST3D which adopts rearrangement of driving wave-induced forces, and the PESM for computation of advection terms. The computed wave-induced current field agrees reasonably well with the drogue measurements. The numerical model predicts development of rip current around the beach centre for S wave case, the result of which could be used for warning of possible rip current development at the site. [ABSTRACT FROM AUTHOR]

Kim, I.; Lee, J.L.; Hwang, J.S.; Lee, S., and Lee, J., 2014. Vertical structure of rip current observed at Haeundae Beach. On 4 and 7 August, 2012, more than 200-300 people were swept away by the fast moving seaward current at Haeundae Beach, which is located on the southeastern corner of the Korean Peninsula, and they then had to be rescued Beach patrons were carried away 50 to 100 meters away from the shore by rip currents, to an area where swimming is restricted due to safety reasons. Rip currents are narrow currents that begin close to the shoreline and strongly flow seaward through the surf zone and beyond. Although rip currents can cause tragic accidents and are of considerable interest to scientists and to the general public, our current understanding of the spatial and temporal behavior of rip currents is limited. As a result, the Korean Meteorological Administration installed monitoring equipment that can assess weather conditions and issue rip current warnings on Haeundae beach starting from 2010. Rip current kinematics and beach morphodynamics were measured for 50 days at Haeunadae beach using several instruments, including velocity and pressure sensors, such as an Aquadopp profiler for shallow water, and the morphology consisted of a low-tide terrace with incised quasi-periodic rip channels, which are representative of transverse bars. The spatial distribution of the sediment is reflected in the background rip current flow field with mean velocity magnitudes within the rip channel that increase offshore both with a decrease in the tidal elevations and with an increase in the sea-swell energy. The vertical velocity profile on the bar indicated that the flow was predominantly shoreward. The Aquadopp profiler is a high-resolution current profiler that operates at sub-cm scales and collects data at up to 8 Hz. The instrument is generally used in boundary layer studies at the bottom 1-2 meters of the ocean and in low energy environments. In addition, the HR profiler excels at providing flow details that are not attainable with any other instrument. In this study, the data from the Aquadopp profiles was used to investigate the detailed vertical structure of dangerous rip currents at Haeundae beach, and we were able to quantitatively understand the mechanism of a rip current. [ABSTRACT FROM AUTHOR]

Shin, C.H.; Noh, H.K.; Yoon, S.B., and Choi, J., 2014. Understanding of rip current generation mechanism at Haeundae Beach of Korea: Honeycomb waves. Many studies have proposed the generation mechanism of rip currents observed at Haeundae beach. Most of them suspect the rip channels as a rip current generating mechanism at this beach. This study focuses on the understanding of rip current generation mechanism in a different point of view based on the CCTV images and the numerical simulations. The CCTV images captured when the rip currents occurred show that the rip currents are accompanied by the waves of honeycomb pattern. The rip currents are developed along the nodal lines of honeycomb waves. To confirm the new mechanism of rip current generation at Haeundae Beach a series of numerical experiments are conducted using a phase resolving numerical model based on the nonlinear Boussinesq equations. The numerical results with the simplified beach topography and the incident honeycomb waves similar to real ones show that the rip currents can be generated without the rip channels. The rip currents generated by the honeycomb waves can grow much faster and the intensity of the rip currents is much stronger than those generated by the unidirectional waves over the rip channels. The magnitude of rip currents agrees reasonably well with that observed using CCTV image analyses. The role of rip channels developed by the rip currents is also discussed. [ABSTRACT FROM AUTHOR]

Kim, H.; Jin, J.Y.; Jang, C.; Yoo, H.J., and Hwang, D.H., 2014. Simulation of seasonal bathymetric change at Haeundae Beach with two representative wave settings. Long-term shoreline position of Haeundae Beach has been quite stable notwithstanding seasonal oscillatory movement. Bathymetry around Haeundae Beach was surveyed on 7 August 2007 and 12 November 2007 by using an echo-sounder, while wave, tide, and tidal current were measured between the two survey days, so that bathymetric change at Haeundae Beach was obtained from the two surveys. According to the surveys the east part of the beach was eroded, and the west part of the beach was accreted. Measured waves from SSE, SE, ESE, E during the period were stronger than measured waves from S, SSW, SW, WSW. A numerical model system CST3D was adopted to reproduce the bathymetric change at Haeundae Beach during the period. Two representative wave settings are chosen for the period as a minimum number to represent the time-series of wave record, based on equivalent sediment flux concept contained in the CERC formula. Wave field, wave-induced force field, wave-induced current field, sediment transport field, and bathymetric change are computed from individual modules, SWAN, WIF, FLOW, SED in CST3D, respectively. Computed bathymetric change agrees reasonably well with measured one. It is believed that selection of two representative wave settings is useful for simulation of seasonal bathymetric change for fairly straight morphology like Haeundae. CST3D is thought to effectively describe overall seasonal sediment transport pattern and consequent bathymetric change at Haeundae Beach. [ABSTRACT FROM AUTHOR]

Bae, J.S., Yoon, S.B., Choi, J., 2013. Boussinesq Modelling of a Rip Current at Haeundae Beach. The rip current occurring at Haeundae beach in Busan, South Korea was numerically investigated under directional random wave environment. The numerical simulations were performed using a fully nonlinear Boussinesq equation model, FUNWAVE which is capable of resolving phase interaction and simulating nearshore circulation since it includes the effect of wave-induced momentum flux and horizontal turbulent mixing. To examine the modelling, the rip current occurred on the 12th of June, 2011 at Haeundae beach was simulated by using observations. The results of numerical simulation showed the time-dependent evolution of the wave-induced nearshore circulation that was caused by transformation of random waves due to the unique topography of Haeundae beach. And, it was found that the rip current was well generated and developed through the region where relatively lower wave heights were caused by refraction and diffraction of waves due to the topographical characteristics (i.e., submerged shoal). In addition, we found that a narrow-banded spectral wave (i.e., a swell spectrum) close to a regular wave generates stronger rip current than a broad-banded spectral wave under an equivalent wave height and period condition. [ABSTRACT FROM AUTHOR]

Choi, D.-L.; Shin, D.-H.; Jin, J.-Y.; Lee. Y.-K., and Kum, B.-C., 2020. High-resolution seismic stratigraphy offshore Haeundae beach in Busan, South Korea. 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. 187-193. Coconut Creek (Florida), ISSN 0749-0208. The stratigraphic architecture of the Haeundae shallow sea was evaluated using numerous high-resolution single-channel seismic profiles and drilled cores. Two major seismic units over the basement, the lower Unit II and upper Unit I, as well as two subunits (Units Ia and Ib) in the upper Unit I were identified in the study area. Unit II shows numerous chaotic diffraction hyperbolic seismic reflection patterns overlying high amplitude, and irregular reflection of the bedrock surface, corresponding well with the gravel-dominated deposits. Unit II is interpreted as nonmarine alluvial deposits in the Quaternary glaciations. Unit I is present over Unit II with two distinct subunits at different locations: Unit Ia, distributed inshore within ∼10 m depth, and Unit Ib, offshore beyond ∼13 m depth. Unit Ia, which is accumulated more in the western inshore section, exhibits an acoustically semi-transparent and sigmoidal clinoform wedge and is well correlated with sand-dominated deposits from core data. Unit Ib, which pinches out landward but gradually thickens seaward, is generally characterized by transparent seismic facies, likely made up of very fine sandy to muddy sediments from surface sediments. The depositional environments of Units Ia and Ib are categorized as shoreface settings and the landward innermost part of the Nakdong distal delta system during late Holocene sea-level highstand, respectively. Due to severe weather conditions associated with winter storms and summer typhoons as well as human interventions, the sediment morphology and its distribution are thought to have constantly been reactivated and modified. [ABSTRACT FROM AUTHOR]

Yoon, H.S., Kang, T.S., Nam, S.Y., Kim, J.T., and Park, J.H., 2007. Measuring coastline morphodynamics using video-based techniques at Haeundae Beach, South Korea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1106 – 1111. Gold Coast, Australia, ISSN 0749.0208 In this study, video-based monitoring systems were installed at three locations on high-rise buildings in Haeundae, Busan, South Korea and beach image data were obtained from September, 2003 to December, 2005. Through quantitative analyses (statistical and time-series analyses) of the observed video image data, areal changes in Haeundae Beach and the shoreline were identified and summarised as follows. 1) Shoreline changes varied according to season and could be divided into four sections (east side section I: 250 m; II: 350 m; III: 300 m; west side section IV: 250 m). The biggest change in beach width occurred in section III; the change pattern at section IV differed from that at the other sections. The shoreline usually regressed (eroded) during the typhoon period (summer) but progressed (by sedimentation) during other seasons. 2) The overall change in beach width was correlated with the frequency of typhoons during the same period with abrupt beach erosion occurring between July and September, when typhoons struck. However, beach erosion and sedimentation at both ends of the beach during winter and summer were opposite of that at the centre of the beach. 3) During the video-monitoring period the maximum beach area was approximately 42,689 m2 and the minimum area was approximately 36,100 m2. The beach area was reduced due to typhoons and high waves by about 15.4%. 4) The beach area decreased by 6,400 m2 in summer during the typhoon period but rose by 5,300 m2 through winter resulting in an 82.8% recovery. As a result, the total beach area declined by approximately 17.2% during the observation period. [ABSTRACT FROM AUTHOR]