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Lee, J.K.; Lee, I., and Kim, J.O., 2017. Analysis on tidal channels based on UAV photogrammetry: Focused on the west coast, South Korea case analysis. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 199-203. Coconut Creek (Florida), ISSN 0749-0208. In the coastal waters of the Republic of Korea, the incidence of marine vessel accidents has been increasing in recent years, due to increased maritime traffic and complex terrain conditions. With the proliferation of marine leisure activities and the maritime conditions such as tides, rocks, typhoons, tsunamis, there are various types of marine accidents that have not been experienced before. Therefore, it is imperative to establish an information based system (like digital map or 3D distribution map) that can be utilized in marine safety fields such as accident and disaster prevention. In this investigation, it will be discussed the safety mapping for tidal channel connected directly with human life. A tidal channel is a waterway where occurs by the process of ebb tide and flood tide in the tidal flats. Since the shape (included exact depth) of tidal channel cannot be identified when a tide comes in, it must be considered as the main causes of the summer drowning fatalities. A map for tidal channel has been proposed by a 3D distribution map that can be identified the shape and location of tidal channel, and also, this map should be offered to marine tourist and maritime safety authority. A cartography based on image collected by manned aerial Photogrammetry or satellite has the insoluble limitations in terms of economy, time constraint and periodic for measurement. Due to temporary erratic overflow through the tidal amplitude, the information for tidal channel cannot be monitored in real time. Therefore, in the present investigation, a UAV (Unmanned Aerial Vehicle) recently been actively used in the field of spatial information is considered in analyzing the status of tidal channel. First of all, the DEM (Digital Elevation Model) of tidal flats generates through UAV based auto-image, the distribution map for tidal channel expresses different colors by the height of topographic. A tidal channel encoding specific color (normally red) can be provided dangerous signal to the user. It can be identified the sea leveling at the certain time that can be measured whole shape of tidal channels, and also, provided a more realistic and readable information on tidal flats. The information provided through the tidal channel map was verified by comparison with the VRS GPS positioning solution. Since information such as the exact distribution location and shape should be considered as the first priority, the coordinates of the tidal channel was compared with the previously proven method, VRS GPS. As a result, it is determined that the location of attribute information and the 3D shape analysis value analyzed by UAV image can fully provide information within the convergence range. In this investigation, UAV image can be estimated on the location and shape of tidal channel by observing exactly at the time zone for flood tide. It can be fully expected that the UAV is contributed to preventing the marine accident in advance by maximizing the latent properties with regards to periodicity, accuracy, operation convenience and economy. [ABSTRACT FROM AUTHOR]

Hung, N.T.; Vinh, B.T.; Nam, S.Y., and Lee, J.L., 2017. Cause analysis of erosion-induced resort washout on Cua Dai Beach, Vietnam. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 214-218. Coconut Creek (Florida), ISSN 0749-0208. On an eroding beach, high waves can completely wash out beaches, swimming pools, and resorts. Cua Dai shore, which is located immediately north of Thu Bon river mouth in central Vietnam, has eroded on the order of hundreds of meters in beach width. The present study estimated the erosion rate of sediment volume into the estuary through the Thu Bon river mouth by using recent satellite images, and utilized a shoreline change model to reproduce the erosion of shoreline near the river mouth. Results are in good agreement with observed data. The numerical model is modified by including the equilibrium angles that were obtained from a static shoreline equation of parabolic shape. Through the sediment conservation rule, the main cause of shore retreat is found to be sediment loss in the Thu Bon river estuary with the reduction in river sediment. The possible causes for this type of sediment loss are mining in the estuary and reduction of river flow action against waves in the river mouth with the reduced sediment supply. Proper management of Cua Dai beach requires the development of a monitoring system to fully understand beach dynamics and to mitigate the further resort washout owing to background erosion. [ABSTRACT FROM AUTHOR]

Shin, S.; Nam, J.; Son, S.; Kim, I.H., and Jung, T.-H., 2017. Field observation and numerical modelling of rip currents within a pocket beach. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 229-233. Coconut Creek (Florida), ISSN 0749-0208. Understanding the occurrence mechanism of rip currents are very important in terms of the sediment transport and the water safety issues. In order to investigate the rip current occurrence mechanism, field observations were carried out at Chunjin beach and a numerical model was employed to simulate rip currents by using the field observation data. The collected data set includes the beach topography, bottom bathymetries, shoreline, sand sample, and incident waves for each season. The field observation data showed the spatiotemporal variations of shoreline and sand bars. The results also showed that the rip currents were generated near the crescentic sand bar. For better understanding the mechanism of rip currents, numerical simulation using phase- resolving, three-dimensional 3D Non-Hydrostatic WAVE Model (NHWAVE) was also carried out. The model considered incoming wave conditions collected from the field observation to look at the nearshore current generation patterns. Through this numerical model, this study could have investigated vertical profiles of nearshore wave-induced current while the field observation data represent depth uniform currents. The numerical simulation showed a good agreement with the field observation and provided useful information for nearshore circulation. [ABSTRACT FROM AUTHOR]

Chen, Y.; Xu, Z., and Lee, D.-Y., 2017. Numerical test on the impacts of submerged breakwaters for different design parameters. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 299-303. Coconut Creek (Florida), ISSN 0749-0208. With the improvement of the living standards, the recreational use of the beach is gradually valued in China. There was a need of the development of artificial beach to meet the need of increased recreational use of the beach. Submerged breakwaters (SBW) is a widely used coastal protection measure, especially for the beach for tourist and water sports, which is constructed to reduce the wave condition to a required level to protect the beach from erosion and also to increase the recreational value of the beach. Understanding the impacts of the SBW on the transformation of the waves and the circulation induced by wave setup behind the SBW is important both for the proper design of the SBW for the protection of beach from erosion and also for water safety for the people enjoying water sports at artificial beach. There are so many design parameters including the dimensions of the SBW and wave conditions that impact the performance of the SBW. During carrying out a beach restoration project in China, it was recognized that there is a strong demand for the efficient method that the engineers can use in designing the SBW to predict the response of the SBW for different design parameters considering the detailed wave-structure interaction. An intensive numerical experiment had been carried out using wave resolving model for the evaluation of the impacts of the SBW on the wave transformation behind the SBW and also to develop an efficient tool to predict the wave tramsmission coefficients for various SBW design parameters. The development of such tool using intensive numerical experiment is discussed in this paper. [ABSTRACT FROM AUTHOR]