International Coastal Symposium Research Articles

Monthly Variations of Phytoplankton Community in Geoje-Hansan Bay of the Southern Part of Korea Based on HPLC Pigment Analysis

Kang, J.J.; Lee, J.H.; Kim, H.C.; Lee, W.C.; Lee, D.; Jo, N.; Min, J.-O., and Lee, S.H., 2018. Monthly variations of phytoplankton community in Geoje-Hansan bay of the southern part of Korea based on HPLC pigment analysis. 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. 356–360. Coconut Creek (Florida), ISSN 0749-0208.Seasonal variations in environmental parameters such as temperature, salinity, and nutrients can significantly affect the community structure of phytoplankton, the primary food source of a marine ecosystem. To understand the influences of environmental factors on phytoplankton community structure, phytoplankton pigments analysis were conducted in the Geoje-Hansan bay situated at the southern part of Korea during January to December, 2016 on monthly basis. Salinity in the water was observed to be fairly stable throughout the study period except for the rainy periods during the summer season (August: 30.3 ± 0.3 and September: 31.1 ± 0.2 psu). Water temperature showed typical seasonal patterns similar to the temperate oceans with maximum values during summer seasons (24.9 ± 0.9 °C). Major nutrients (nitrogen, phosphate, and silicate; hereafter N, P, Si) showed similar patterns of seasonal variation with averages of 3.677 ± 2.707μM, 0.338 ± 0.270μM, and 17.614 ± 9.287μM, respectively, with peak values during December. Phytoplankton community composition estimated using the CHEMTAX program showed distinctive seasonal variations during the study period. The results showed a dominance of dinoflagellates during November – March (>64%) with an exception in December whereas diatoms appeared to be dominant during May – October (60.1%). Dinoflagellates exhibited a negative correlation with temperature, whereas diatoms showed a positive correlation with temperature based on principal components analysis (PCA). Given these findings, a diatom-dominant ecosystem would be expected throughout the year under ongoing ocean warming conditions, which could provide different food qualities to upper trophic levels in the Geoje-Hansan bay.

Climate Change Effects on Suspended Sediment Dynamics in a Coastal Lagoon: Ria de Aveiro (Portugal)

ABSTRACT Costa, S.; Picado, A.; Vaz, N.; Coelho, C.; Portela, L., and Dias, J.M., 2018. Climate change effects on suspended sediment dynamics in a coastal lagoon: Ria de Aveiro (Portugal). 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. 521–525. Coconut Creek (Florida), ISSN 0749-0208. Coastal systems are very important interface areas between land and sea, subject to constant changes motivated by both natural and anthropogenic factors. In addition to the increasing modifications imposed by human activities, natural processes are also being altered as a result of climate change. Important consequences of climate change in coastal systems are sea level rise (SLR) and changes in freshwater discharge, due to modifications in rainfall patterns and air temperature. The aim of this work was to assess the impact of climate changes on the suspended sediment dynamics i...

Implementation of a Numerical Model of Metals for Total Maximum Daily Loads (TMDLs) in Onsan Harbor, Korea

Kim, Y.H.; Sugarman, D.E.; Kim, H.C.; Son, S.; Ha, H.K.; Chang, W.K.; Han, K.W., and Ryu, J., 2018. Implementation of a Numerical Model of Metals for Total Maximum Daily Loads (TMDLs) in Onsan Harbor, 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. 1506–1510. Coconut Creek (Florida), ISSN 0749-0208.Accumulation of heavy metals has been one of fundamental environmental concerns for many coastal and estuarine systems, which can be directly influenced by contaminants loading from land. Onsan Harbor, Korea, surrounded by Onsan National Industrial Complex, shows high concentration of heavy metals in the seabed sediments. In order to establish proper environmental management plan for Onsan Harbor, the implementation of a Total Maximum Daily Loads (TMDL) was proposed. As a part of TMDL for metals, numerical model has been developed to evaluate metal fluxes into the Onsan harbor.A bathtub model for four different metals, including Copper, Zinc, Lead, and Mercury, was implemented in Onsan harbor. To supply data for boundary conditions and model calibration, extensive monitoring programs were conducted in the study area for past three years, between 2014 and 2016. The data from the monitoring programs includes freshwater discharge rate, load of metals from streams and tributaries, concentration of dissolved and particulate metals in water and sediments, sedimentation rates, and current velocities. The model was calibrated and validated with these monitoring data and other public data sets, and the results confirm high performance of the metal TMDL model in Onsan Harbor system. To evaluate numeric targets of the TMDL for metals, more than 100 scenarios were simulated with the well-calibrated model. The results show that (1) after the reduction of 10% loading from the present level, the copper concentration in sediments will be lower than Probable Effects Level (PEL) within 12 years, and (2) after the reduction of 10% zinc loading, the zinc concentration in sediments will be lower than PEL in 17 years.

An Improved Contaminant Source Identification Method for Sudden Water Pollution Accident in Coaster Estuaries

Jing, L.; Kong, J.; Wang Q., and Yao Y.T., 2018. An improved contaminant source identification method for sudden water pollution accident in coaster estuaries, China. 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. 946–950. Coconut Creek (Florida), ISSN 0749-0208.This paper presents a method for quickly and accurately identifying contaminant source in estuary region, characterized by decoupling solving releasing time, location and density of source problems, respectively. The method firstly gets the rough source releasing time by analyzing the typical double peak phenomenon in tidal estuary region, and then presents the rough position of source by using Lagrange tracing scheme. The rough position makes up the deficiency of priori information in traditional Genetic Algorithm (GA). And then, according to the correlation between the measured and calculated concentration at measuring point, a high resolution mass transportation and an optimization models are operated repeatedly and alternatively. In order to increase the efficiency of searching optimal parameters, the Genetic Algorithm is improved by introducing a weighting factor based on the precision improvement trend. Such an optimization model can effectively reduce the calculation burden when parameters are increased in demand. This model has been successfully applied in an accident case in Quanzhou Bay of China. Simulated results confirm the model's merits in reasonably identifying relevant unknown parameters. The convergence of present model is more efficient in searching for the optimal parameters with less iteration times nearly half the traditional Genetic Algorithm. This model is high efficiency and has great practical significance in dealing with emergent water pollution in estuary and coastal areas.

Accuracy Improvement of Particle-tracking Simulation Considering Wind Speed using Various Drift Objects

ABSTRACT Choi, J.-W.; Kwon, J.-I.; Heo, K.-Y.; Park, K.-S., and Choi, J.-Y., 2018. Accuracy improvement of particle-tracking simulation considering wind speed using various drift objects. 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. 901–905. Coconut Creek (Florida), ISSN 0749-0208. The simulation accuracy of the particle-tracking model (PTM) primarily depends on wind and current, among various parameters. This study explored the effect of wind on particle tracking using drift objects (drift buoy and mannequin). For numerical experiments, wind and current generated from the weather research and forecasting model (WRF) and Modelo Hidrodinâmico (MOHID) were used in the PTM. Furthermore, a field experiment was conducted using a surface drift buoy nearby Gageo Island, which is located on the south-western coast of the Korean Peninsula. Drifting buoy data from Ju...

Flood Hazard Prevention Appraisal in Europe: Training Key Stakeholders on the Benefits and Costs of Efficient Protection and Response

Navas, F.; Malvarez, G.; Penning-Rowsell, E., and Parker, D.J., 2018. Flood Hazard Prevention Appraisal in Europe: Training Key Stakeholders on the Benefits and Costs of Efficient Protection and Response. 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. 1546–1550. Coconut Creek (Florida), ISSN 0749-0208.Coastal floods in the European Union member states produce massive costs in environmental loss but also as flood damage property, infrastructure and economic activity. These costs will increase in the future due to Climate Change. The appraisal of benefits and costs are of key importance in the current economic situation in which Europe's resources need to be distributed with great prudence. In this context the implementation of European Directives, such as the EU Floods Directive (2007/60/EC) require that decision makers need to base their assessments of flood prevention measures on Cost-Benefit analysis studies. But despite this requirement EU member states are basing their implementation in a variety of approaches. In this article the results of the implementation of a new e-learning and face to face training approach based on flood prevention appraisal methodologies (e.g. cost-benefit, multicriteria analyses) is presented. The training programme used significant resources from web-based knowledge platform developed during relevant EU projects including extensive databases with legislative framework, a toolkit with resources on cost benefit analysis calculators and links with spatial data which were deemed essential for flood hazard prevention appraisal. The lessons learnt from the implementation of the training programme are of significance to assess the success or failure of the implementation of key legislative frameworks such as the EU Floods Directive in the future. A prior and post consultation process carried out with the participants showed that a) trainees were successful in developing the step by step procedure using a dedicated calculator; b) trainees also had a more contextualized general picture at EU level of the main issues regarding flood hazard prevention; and c) the trainees found the e-learning and face to face material and the resources very easy to follow and easy to understand, and explicitly recognised the pedagogic value of online availability of course materials.

Estimates of Sediment Pickup Rate induced by Surge Wave within a Multilevel Bayesian Regression Framework

Jeong, S.I.; Kwon, H.-H., and Lee, S.O., 2018. Estimates of Sediment Pickup Rate Induced by Surge Wave Within a Multi-level Bayesian Regression Framework. 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. 286–290. Coconut Creek (Florida), ISSN 0749-0208.A coastal erosion was caused by the tractive force of wave, and is accelerating in some areas. In this study, a hydraulic experiment considered the pickup concept was carried out to understand this phenomenon. Since existing methods for deriving suspended sediment concentrations (SSC) were likely to affect the results, image processing techniques was used. Preliminary experiments were conducted for this process. Because relevant data necessarily involves uncertainty, a two-step Bayesian Markov Chain Monte Carlo method (MCMC) was used to quantitatively derive it. The first step was about the relationship between image grayscale and turbidity, and then relationship between SSC and turbidity was presented for quantative analysis to show sediment pickup rate. A sluice gate was designed for rapid openning to generate a solitary wave, and the optimum opening speed was derived. The experimental result indicated that the physical characteristics of wave and suspended sediment pickup rate were closely related, and this relationship was changed according to wave breaking. And solitary wave pickup function was presented by adapting Einstein (1950)'s essential concepts. More precise pickup rate can be used as basic data for prevention of coast erosion and management of shoreline.

Numerical Study on Optimization of the Float in a Shoreline Wave Energy Converter

Peng, W.; Fan, Y., and Zhang, J., 2018. Numerical study on optimization of the float in a shoreline wave energy converter.. 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. 1296–1300. Coconut Creek (Florida), ISSN 0749-0208.In this paper, the hydrodynamic performance of the float in a shoreline wave energy converter is investigated under regular waves. A numerical model is built based on the Navier-Stokes solver coupled with immersed boundary method, volume of fluid method and the mechanics model of float. Making use of the laboratory measurements, the numerical model has been proved to be a reliable tool in reproducing wave deformations and the dynamics of the float. Then, the model is employed to test the sensibility of float performance to changes in some variables under various waves: spacing between breakwater and float, length of float. From numerical estimations, it can be concluded that the nondimensional motion amplitude of float will decrease with the increasing float length or spacing between breakwater and float. With different loads, the dynamic of float shows different variation trend against the length of float, which implies further investigations may be needed in the future on the effect of power take-off damping load. Last but not the least, the interactions between water waves and two types of floats (rectangle and convex) are simulated and discussed. With the help of snapshots of water particle velocity field and the water surface profile from numerical calculation, the flow pattern and external forces from the fluid field acting on the float can be estimated. Then, the motion amplitudes of floats are computed and compared, and the convex floats are proved to capture more power than the rectangular ones.

Coastal Flood Disaster in Sri Lanka-May 2017: Exploring Distributional Changes in Rainfall and Their Impacts on Flood Risk

ABSTRACT S.S.K, Chandrasekara.; Uranchimeg, S.; Kwon, H-H., and Lee, S-O., 2018. Coastal Flood Disaster in Sri Lanka-May 2017: Exploring Distributional Changes in Rainfall and Their Impacts on Flood Risk. 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. 1476–1480. Coconut Creek (Florida), ISSN 0749-0208. Coastal communities, their livelihoods, and the coastal ecosystems of Sri Lanka are vulnerable to extreme rainfall events. In May 2017, the southern and southwestern coastal regions of Sri Lanka experienced devastating floods, which caused nearly 122 deaths. In light of this, exploring distributional changes in extreme rainfall series recorded across Sri Lanka are crucial to understand flood risk in the context of climate variability and change. This study was focused on investigating possible distributional changes in annual maximum daily rainfall (ADMR) over ...

Run-up Heights of Tsunamis for Geometric Variables

ABSTRACT Kang, C.; Park, K.-Y., and Cho, Y.-S., 2018. Run-up Heights of Tsunamis for Geometric Variables. 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. 731–735. Coconut Creek (Florida), ISSN 0749-0208. Since many islands are located in the South Sea of the Korean Peninsula, unexpected tsunamis could cause devastating damage. To investigate the effects of geometric variables on the maximum run-up heights of tsunamis, a numerical model is first employed. The model is based on the nonlinear shallow-water equations with a moving boundary treatment along the shoreline. The numerical model is then applied to simulation of maximum run-up heights of tsunamis approaching on islands with variable geometric conditions. The obtained numerical results can be used to a defense plan of islands in the case of real tsunami attacks.

Influence of Kuroshio Path on Salinity Distribution in Seto Inland Sea

Nakashita, S.; Woo, H.; Kim, K.; Kim, K.; Lee, I.-C.; Kim, D.-S., and Hibino, T., 2018. Influence of Kuroshio path on Salinity distribution in Seto Inland Sea. 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. 21–25. Coconut Creek (Florida), ISSN 0749-0208.This study analyzes residual current and salinity distribution in Seto Inland Sea induced by Kuroshio Path variation. The salinity ranged 30 - 34 PSU and it decreased by approximately 1 - 2 PSU at near center of Bisanseto during non-meandering period. Sea level height variations at both boundary of Seto Inland Sea which induces residual current mainly depends on distance between boundaries and Kuroshio Path because of higher sea level hight at Kuroshio path than than that at northern part of Kuroshio path approximately 1 m. Westward residual flow during the non-meandering period (year 1997) was estimated to be faster than that during the meandering period with maximum relative velocity of 4.5 cm/sec. Decrease of salinity at near center of Bisanseto is due to the westward movement of the river water plume from the eastern Bisanseto. From the results obtained above, it is concluded that location of low salinity water at Bisanseto is mainly depends on the residual current due to variation of Kuroshio Path.

Numerical Simulation and Large-Scale Physical Modelling of Coastal Sand Dune Erosion

Do, K.; Shin, S.; Cox, D., and Yoo, J., 2018. An international comparison of drowning in South 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. 196–200. Coconut Creek (Florida), ISSN 0749-0208.Coastal sand dune system is important in the nearshore environment for sand supply, ecosystem, and hazard mitigation. In this study, a process-based morphological model was performed and the results were compared with large-scale laboratory experimental data. Two-dimensional large-scale laboratory experiments were conducted with 1:6 geometric scale in the large wave flume (104m (L) × 3.7 m (W) × 4.6 m (D)) of the Hinsdale Wave Research Laboratory at Oregon State University (Maddux et al, 2006). Several different wave conditions were used with different water levels in this experiment including pre-storm, storm, and post storm based on random wave time series by using TMA spectrum. The data set included cross-shore Wave heights, fluid velocities, and the profile changes of the beach and dune. The process based model, XBeach (Roelvink et al., 2009) was used to simulate the nearshore hydrodynamics and bed level change during storm wave condition. Several semi-empirical parameters were used in the XBeach model to predict morphodynamic process (Roelvink et al., 2009) and recently the updated parameters (WTI settings) were suggested based on the results of field observations. The present study ran the XBeach model by using both default and WTI settings and compared with the results from the experiments. The results showed that the model results with WTI settings showed good agreement with the measured beach profile while the model results with default settings over-predicted the offshore sediment transport and dune erosion. Especially, the wave skewness (facSk) and asymmetry (facAs) gave the highest contribution to predict dune erosion.

Study of High Waves caused by Slanting-fetch Effects along the Coast

ABSTRACT Lee, J.H. and Kim, T.R., 2018. Study of High Waves caused by Slanting-fetch Effects along the Coast. 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. 831–835. Coconut Creek (Florida), ISSN 0749-0208. Design wave height estimation for the ports and coastal structures are mainly based on the waves from offshore wind which have long fetches enough to develop high waves. The waves generated by short fetched land wind are usually neglected because they are thought to be small and short period waves. However, in case of land wind oblique to the long coast line with short fetch, unexpected long period high waves are developed along the coast by slanting-fetch effects. These high waves can damage human lives as well as coastal structures, but are difficult to predict using offshore wave measurement system. Therefore, it is important to understand the character...

Three-dimensional Numerical Simulation of Airflow in Oscillating Water Column Device

Lee, K.H. and Kim, T.G., 2018. Three-dimensional Numerical Simulation of Airflow in Oscillating Water Column Device. 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. 1346–1350. Coconut Creek (Florida), ISSN 0749-0208.An Oscillating Water Column (OWC) is a wave energy converting technology that uses the compressed and decompressed airflow induced by the vertical oscillations of water column inside the chamber as a driving force of an airflow turbine. In this study, three-dimensional numerical simulations of a bottom-fixed OWC are performed to understand the interaction of an OWC device with regular waves. The open-source CFD model REEF3D is used, which is able to consider immiscible two-phases (air and water) using the Reynolds-averaged Navier-Stokes equations. The simulation capability of REEF3D is validated by comparison with experimental data for wave deformations caused by the OWC and air-flow fields and the airflow velocity in the chamber. The numerical results revealed that the CFD numerical tool REEF3D can successfully simulate wave deformations caused by wave-OWC interactions, and directly estimate an air velocity inside the chamber. In addition, it was found that a phase difference occurs between time series of free surface evolution and air velocity evolution.

Climate Change, Coastal Management and Acceptable Risk: Consequences for Tourism

Phillips, M.R.; Jones, A., and Thomas, T., 2018. Climate Change, Coastal Management and Acceptable Risk: Consequences for Tourism. 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. 1411–1415. Coconut Creek (Florida), ISSN 0749-0208.An evaluation of the present day status of a coastline is fundamental in deciding whether to actively manage or to refrain from intervention. Unfortunately, with climate change and assessments of acceptable risk based on ongoing costs to defend, decisions need to be taken that reduce difficult and expensive decisions for future generations, i.e. sustainable management of the shoreline. The coastline provides economic opportunities, and tourism is one of the main stakeholders at risk from managed retreat and no active intervention decisions. Therefore, which aspect of risk takes priority, as barriers to effective Integrated Coastal Zone Management (ICZM) are inadequate capacity and finance? This paper shows the consequences of taking ‘managed retreat’ and ‘no active intervention’ decisions with no implementation strategy in place. The economic consequences for coastal stakeholders does not only include loss of tourism income but also assets and residential properties. Established processes for establishing risk and evidence gathering are questioned with recommendations for future strategies made. Subsequently, arguments are put forward that initial large scale assessments should be supplemented by smaller scale studies when decisions of ‘managed retreat’ and ‘no active intervention’ are proposed. Assessments should also include costs of lost business and infrastructure.

Monitoring of the Changjiang River Plume in the East China Sea using a Wave Glider

Moh, T.; Cho, J.H.; Jung, S.-K.; Kim, S.-H., and Son, Y.B., 2018. Monitoring of the Changjiang River plume in the East China Sea using a wave glider. 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. 26–30. Coconut Creek (Florida), ISSN 0749-0208.Most water from the Changjiang River discharges into the East China Sea (ECS), and affects the sea's oceanographic environment, even near Jeju Island, Korea. However, most research conducted using vessels, buoys, and satellite systems has a limited capacity for continuous direct measurement over a wide area. To overcome these spatial and temporal limitations, an autonomous wave-powered glider equipped with a fluorometer, a conductivity-temperature-depth, and an acoustic Doppler current profiler was deployed. Over 34 days from August 19 to September 22 in 2016, the wave glider navigated 985 km in the ECS near Jeju Island, and sensed 34,500 continuous water columns every minute. The glider transmitted the data via the Iridium satellite communication system, even under severe weather conditions. The wave glider detected low salinity and high turbidity of the surface water southwest of Jeju Island. Comparison of the surface turbidity and back-scattered echo intensity revealed that the surface turbid water migrated from west to south of Jeju Island. It descended slightly through chaning of the mixed layer depth. The observations from this study suggest that wave gliders can provide reliable sensing and maneuvering capabilities for monitoring of the Changjiang River plume in the ECS.

Relative Contribution of Wave Setup to the Storm Surge: Observations and Modeling Based Analysis in Open and Protected Environments (Truc Vert beach and Tubuai island)

Pedreros, R.; Idier, D.; Muller, H.; Lecacheux, S.; Paris, F.; Yates-Michelin, M.; Dumas, F.; Pineau-Guillou, L., and Senechal, N., 2018. Relative contribution of wave setup to the storm surge: observations and modeling based analysis in open and protected environments (Truc Vert beach and Tubuai island). 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. 1046–1050. Coconut Creek (Florida), ISSN 0749-0208.Recent events like the Xynthia (2010, France) storm illustrate the potentially devastating effect that storm surges can have on the coasts. Nearshore storm surges at the result mainly from two processes: atmospheric surges and wave setup. This paper investigate the relative wave setup contribution in the storm surge signal for energetic events and focusing on two cases: an open beach (Truc Vert beach, France) and a high island protected by a reef lagoon (Tubuai, French Polynesia). The two selected events are the Johanna storm (March'08), for the Truc Vert site, and the Oli cyclone (February'10), for Tubuai. The data analysis shows that the maximum total storm surge reaches 1.2 m on the Truc Vert site and 1.1 m in the Tubuai lagoon. On the Truc Vert beach, the ECORS'08 in-situ measurements allow estimating a wave setup contribution of 80% of the total storm surge, at the time of maximum storm surge. The relative contribution of the wave setup is investigated a bit further, using the modeling approach. The modeling relies on the joint use of a shallow-water (MARS 2DH) and wave (SWAN) models. It shows an heterogeneous distribution of the wave setup in the Tubuai lagoon and a longshore variability close to the waterline for Truc Vert (~ 30%). In both cases, the wave setup contribution to the whole storm surge is predominant, with relative values ranging from 71 to 120% of the total maximal storm surge. Values larger than 100% occur on the Tubuai site when the atmospheric storm surge is negative.

Improved Hypothetical Typhoon Generation Technique for Storm Surge Frequency Analyses on the Southwest Korean Coast

Kim, H.-J. and Suh, S.-W., 2018. Improved hypothetical typhoon generation technique for storm surge frequency analyses on the Southwest Korean Coast. 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. 516–520. Coconut Creek (Florida), ISSN 0749-0208.In coastal disasters storm surges accelerate damages. To establish appropriate countermeasures, a probabilistic approach to storm surge prediction is required, particularly in case of the historical record of cyclone populations is slim. Among historical typhoons that affected the southwest coast of Korea, some arrived by passing through the Yellow Sea after landfall on southeast mainland China. This study aims to incorporate resurgence and the mid-latitude transition effect to generate more realistic synthetic storms. Synthetic typhoon simulations and surge analyses were performed by taking probability density function parameters from historical storm data, and the simulations were automated as batches using the Perl script. The results showed that the proposed synthetic generation scheme, which models the resurfacing effect, can produce realistic storm frequency results for the Korean coasts. This work can be applied in further vulnerability analyses of coastal zone management.

An Assessment of Swash Excursion Predictors using Field Observations

ABSTRACT Passarella, M.; De Muro, S.; Ruju, A., and Coco, G., 2018. An assessment of swash excursion predictors using field observations. 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. 1036–1040. Coconut Creek (Florida), ISSN 0749-0208. Accurate predictions of swash excursion are fundamental for improving the understanding of swash zone dynamics and for coastal management and hazard applications. Researchers have provided several formulas for predicting the swash excursion on sandy beaches. However, the problem of the universality of these formulas is still open. In fact, it is not clear whether the existing formulations are applicable to a wide range of beaches and wave conditions. This study verifies 13 existing swash (total, incident and infragravity) formulations using 13 published experiments (636 swash measurements). The experiments were carried out on ...

Evaluation of Mixing and Stratification in an Estuary of Korea

Kim, N.-H.; Hwang, J.H., and Kim, D.H., 2018. Evaluation of Mixing and Stratification in an Estuary of 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. 96–100. Coconut Creek (Florida), ISSN 0749-0208.In the estuary, flow structures depend on the relative contributions of the tidal current and the released freshwater, which determine the mixing and the stratification. To understand how artificially discharged freshwater affect the flow structure in an estuary of Korea, flow velocities, temperature, and salinity were measured in the field. During the field campaign, discharged freshwater cyclically forms the stratified layers during ebb tide and relatively well mixed water column during flood tide as in the conventional estuarine process. The gradient Richardson number evaluated such cyclic patterns quantitatively with the field measurement data, which were sampled following the tidal cycle and after the release of freshwater. In the early stage of the freshwater discharge, stratification dominates due to the large density difference, which overcomes the mixing by shear at the interface. As time goes on, the momentum of the released flow weakened and tidal modulation becomes significant and the discharged freshwater advected back and forth along the tidal currents. Different from the conventional mixing during flood, the stratification breaks down not by vertical mixing caused by the shear generated turbulence but by the vertical advection in the front of the gate.