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Hallin, C.; Almström, B.; Larson, M., and Hanson, H., 2019. Longshore transport variability of beach face grain size: Implications for dune evolution. Journal of Coastal Research, 35(4), 751–764. Coconut Creek (Florida), ISSN 0749-0208. This study investigates grain-size sorting through longshore transport processes and how it influences dune evolution. The analysis is based on a data set of 58 sediment samples distributed alongshore over a 6.5-km-long sandy beach in Ängelholm, Sweden. Grain size differs significantly from north to south, where median grain size varies from about 0.4–0.15 mm. The long-term coastal evolution is derived from shoreline change analysis of a series of aerial photos from the 1940s until today and from longshore sediment transport rates calculated on the basis of wave data simulated by the SWAN wave model employed in the Coastal Engineering Research Center (CERC) formula. The results show an almost unidirectional longshore transport from north to south; the beach is eroding in the northern part and accreting in the southern part. The McLaren model, a grain size–based model to predict transport direction, was tested against the grain size data. The test indicated transport in the opposite direction. This result supports previous studies suggesting that the McLaren model has limited applicability for sandy beaches with a dominant longshore transport. The sediment samples were collected at the mid–beach face position in an area where sediment is supplied to the beach during accreting conditions. Sediment in the appropriate grain size to build dunes—at this beach, 0.2–0.3 mm—was found in the parts of the beach where the dunes are growing. In the eroding parts, the sediment was coarser, suggesting that the longshore transport influences the supply of sediment for aeolian transport. The gradients in longshore transport rate were also found to affect dune morphology; the dunes were higher in the eroding and stable parts of the beach and lower in the accreting parts. [ABSTRACT FROM AUTHOR]

Williams, H.; Van Hoang, L.; Elliott, P.; Nguyen, H.H., and Manh, H., 2019. A tentative record of mid-Holocene sea-level highstand and barrier overwash from the Cam River mouth, Vietnam. Journal of Coastal Research, 35(4), 852–860. Coconut Creek (Florida), ISSN 0749-0208. A freshwater coastal marsh near the mouth of the Cam River in Northern Vietnam stands 2–3 m above mean sea level and is bordered by a coastal barrier that reaches about 6 m above mean sea level. A core from the marsh contains a 14-cm-thick sand and shell layer. The presence of abundant shell fragments suggests inland transport of littoral sediment, and the sand layer is tentatively identified as a washover deposit. The coast of the study area contains a beachrock standing above the modern beach and reaching to ∼4 m above mean sea level. A tentative explanation of this beachrock is that it represents a beach that formed during a mid-Holocene 2–3-m highstand, evidence for which has been reported from Thailand, Malaysia, Singapore, and Vietnam. Possible explanations of the sand and shell layer include the following: it is a late-Holocene tropical cyclone washover deposit, formed by a large storm surge that overtopped the coastal barrier; or it is a late-Holocene tsunami deposit formed when a tsunami wave, probably from a nearby source, overtopped the coastal barrier. The lack of other distinctive washover deposits in the core suggests that overwash of a magnitude that formed the relatively thick sand and shell layer is a rare event at this site within the last 3000 years. Given the tentative but intriguing results of this study, further research at this site is warranted to better define the stratigraphy and age of the apparent washover deposit. [ABSTRACT FROM AUTHOR]

Coasts vary in their composition and the physical processes that affect them. However, their nature and behavior have similarities. Presently, the majority of coasts worldwide are eroding. The rapidly increasing threat of global warming and the resulting rise in sea level can accelerate coastal erosion. The nearly 2 km coastline in the port city of Puerto Cabello in Venezuela, to the west of the island Goaigoaza, was taken as a case study. The long-term state of the beach was assessed by considering the credits and debits of sand that pass through the coastal system. In the study, the net longshore sediment transport rate in the west of the salient was westward and Qin < Qout, denoting that beach erosion will occur in this particular area. Through field investigations and theoretical analysis, it can be preliminarily concluded that the beaches in the study area are slightly eroded. However, a long-term study on the current profile is essential to arrive at a decisive conclusion. [ABSTRACT FROM AUTHOR]

Thomas, J.; Velamala, S.N., and Prasad, K.V.S.R., 2019. Numerical simulation of tidal constituents in Thane Creek and the Ulhas estuary, west coast of India. Journal of Coastal Research, 35(2), 376–388. Coconut Creek (Florida), ISSN 0749-0208. Complex tidal progression in creeks and estuaries attract a large number of researchers around the globe. The main motive of the present work is to study the complex tidal variation of Thane Creek and the Ulhas estuary on the west coast of India. A Delft3D model was applied to simulate its depth-averaged hydrodynamics and tidal propagation along the system, and the calibration and validation of this model revealed its accuracy. The system was classified as hyposynchronous; a gradual decrease in the amplitude was noticed from mouth to upstream in all seasons. The interpretation of the major tidal constituents amplitude and phase, shallow water constituents, form number, and tidal asymmetry showed the dynamic nature of the system. The form number results revealed that the tide in Thane Creek and the Ulhas estuary is mixed semidiurnal. The tidal asymmetry parameter indicated a seasonal variation of ebb and flood current in Thane Creek and the Ulhas estuary, which favors sedimentation processes in the system with consequent erosion and deposition. For the future, these results will help in understanding sediment transport and the corresponding shoreline changes and the biogeochemical processes of this dynamic system and help to establish its sustainability. [ABSTRACT FROM AUTHOR]

Carassai, J.J.; Lavina, E.L.C; Chemale, F., Jr., and Girelli, T.J., 2019. Provenance of heavy minerals for the Quaternary coastal plain of southernmost Brazil (Rio Grande do Sul State). Journal of Coastal Research, 35(2), 295–304. Coconut Creek (Florida), ISSN 0749-0208. During the Quaternary, an extensive barrier system was developed in southern Brazil and northern Uruguay. The patterns of variation in the distribution and behavior of heavy minerals present in the aeolian and marine (upper shoreface-foreshore) facies of the four barriers formed in the Rio Grande do Sul costal plain were identified. Minerals were analyzed by scanning electron microscopy, including epidote, tourmaline, zircon, magnetite/ilmenite, polymorphs of aluminum silicates (andalusite, kyanite, and sillimanite), staurolite, rutile, amphibole, pyroxene, corundum, perovskite, chromite, garnet, apatite, monazite, xenotime, spinel, and titanite. In all of the barriers, zircon, magnetite, and ilmenite are the most important, followed by chromite, garnet, rutile, tourmaline, staurolite, and epidote. In total, heavy minerals indicate two primary sources in the coastal plain: (a) direct feeding from the rocks of Uruguay and Rio Grande do Sul Shield and Paraná Basin, drained by Rio Camaquã and Rio Jacuí; and (b) indirect feeding from rocks of the Andean province, drained by Rio Paraná and Rio La Plata estuary in northern Argentina. During low sea level, rivers flowed directly into the continental shelf, and their deposits were reworked during subsequent transgressive stages. Throughout this region, the atmospheric circulation pattern forms a NW oceanic swell, generating a longshore current with dominant northward direction. Thus, several transgressive-recessive pulses associated with Pleistocene glacial events pushed large volumes of sediments northward, giving rise to the present southern Brazil coastal plain. [ABSTRACT FROM AUTHOR]

Alcántara-Carrió, J.; Caicedo, A.; Hernández, J.C.; Jaramillo-Vélez, A., and Manzolli, R.P., 2019. Sediment bypassing from the new human-induced lobe to the ancient lobe of the Turbo Delta (Gulf of Urabá, Southern Caribbean Sea). Journal of Coastal Research, 35(1), 196–209. Coconut Creek (Florida), ISSN 0749-0208. Artificial river diversions cause intense and unpredictable changes in the geomorphological evolution and sedimentary dynamics of deltas. This study analyzes the effects of the 1958 course diversion of the Turbo River delta, Gulf of Urabá, southern Caribbean Sea. Recent satellite images were analyzed and beach topography was monitored to obtain the shoreline migration and sediment budget; surface sediments were seasonally sampled, and their grain size parameters were determined; and seasonal sediment transport directions were deduced according to grain size trends. It was concluded that the bimodal wave regime controls the seasonal sedimentary patterns associated with southward longshore transport during both the dry and rainy seasons, and the northward longshore transport occurs in the midsummer drought. Beach morphodynamics of Yarumal Point, close to the present-day river mouth, show that this is the most exposed sector to waves, whereas fluvial sediment inputs are evidenced by a decrease in mean grain size and by poorly sorted sediments in the rainy season. A new spit is forming in Yarumal Point, with an intense increase in area and a westward progradation related to high fluvial sediment inputs from the La Niña event of 2010–12 and low erosion from the El Niño events of 2009–10 and 2015–16. In the central sector, longshore drift has formed the Yarumal barrier spit with a southeastward progradation that recently closed the interdistributary El Uno Bay. Consequently, a humaninduced sand barrier–lagoon system resulted with a stable or slightly regressive shoreline. Moreover, the Yarumal barrier spit has generated a new sediment bypass to Barajas Beach in the northern limit of the Las Vacas spit (i.e. the ancient delta lobe). Therefore, there is an unusual accretion of the abandoned delta lobe by sediment supply from the new lobe. [ABSTRACT FROM AUTHOR]

Li, H.; Beck, T.M.; Moritz, H.R.; Groth, K.; Puckette, T.; Marsh, J., and Sánchez, A., 2019. Sediment tracer tracking and numerical modeling at Coos Bay inlet, Oregon. Journal of Coastal Research, 35(1), 4–25. Coconut Creek (Florida), ISSN 0749-0208. An investigation was conducted on transport of dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to the Coos Bay inlet, Oregon. A sediment tracer release/sampling and field data collection program was carried out and a numerical hydrodynamic, wave, and sediment transport model, the Coastal Modeling System, was developed to perform the analysis of sediment transport around the inlet system and the ODMDS. The data were used to calibrate and validate model calculations, and the model was set up to calculate sediment fluxes and to simulate the process of sediment tracer release and movement, and determine the pathways of sediment tracer under combined wave, current, and wind conditions within and around the immediate vicinity of the Coos Bay ODMDS. The calculations and the measurements indicate that sediment tracer movement is primarily controlled by tidal current inside Coos Bay and at the inlet entrance, and responding to wave and storm conditions in the open coastal area. A divergence in net sediment transport directions in the adjacent nearshore beach was apparent in the results of the tracer release and numerical simulations. This methodology may be used to determine sediment bypassing pathways and optimal placement of sediment within a nearshore environment adjacent to tidal inlets. [ABSTRACT FROM AUTHOR]

Li, S. and Liu, Y., 2018. Analytical and explicit solutions to implicit wave friction-factor equations based on the Lambert W function. Calculation of the friction factor of turbulent oscillatory fluid flow is a significant issue in accessing bed shear stress and sediment entrainment in coastal areas. A fast, robust calculation is necessary for intensive scientific simulations. However, some widely used friction-factor equations belong to the group of implicit and transcendental equations. Common procedures for obtaining accurate solutions are based on root-solving techniques such as the Newton–Raphson iterative method, with substantial computation cost and potential failure of solution convergence. The present note offers a simple and highly accurate procedure for explicitly calculating the friction factors. First, explicit analytical solutions of the friction-factor equations are derived using the Lambert W function, which is a newly recognized elementary transcendental function. Then, the analytical solutions are numerically calculated by simply calling the fast algorithms of the Lambert W function that is available in the libraries of many kinds of software of widely applied numerical computing environments. For practical purposes, this note also compares several fast algorithms of the function. [ABSTRACT FROM AUTHOR]

Li, C.; Fu, X.; Xiao, Q.; Pan, X., and Cao, H., 2018. Vertical distribution of sediment concentration in offshore waters. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 167–171. Coconut Creek (Florida), ISSN 0749-0208. The existing formulae of vertical distribution of sand concentration are difficult to integrate. Based on the formula of vertical distribution of the flow velocity obtained in the previous study and the suspended sediment diffusion equation in equilibrium, a formula of the distribution of suspended sediment is deduced. It can effectively avoid the phenomena that the Rouse formula equals zero at the water surface. The field measurement data of Jiangsu Sea is used to verify and analyze the deuced formula. And results show that it has a high accuracy and it solve the difficulties caused by lack of data in engineering, such as only the sediment concentration on the surface is given. [ABSTRACT FROM AUTHOR]

Duy, D.V.; Tanaka, H.; Mitobe, Y.; Anh, N.Q.D., and Viet, N.T., 2018. Sand spit elongation and sediment balance at Cua Lo Inlet in Central Vietnam. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 32–39. Coconut Creek (Florida), ISSN 0749-0208. Erosion is significant on the downdrift beach of Cua Lo Inlet, which is located in Central Vietnam. The elongation of Cua Lo Inlet's updrift sand spit together with severe erosion of the downdrift bank is raising numerous social problems such as flood safety and land loss. In this study, a series of Landsat and Google Earth images were used to analyze and investigate the inlet recent morphological changes and evolution. Since 1970 the inlet has constantly migrated towards the sediment transport pathway, and its traveling distance has reached 1700 m. In order to quantitatively investigate such characteristics, the tip coordinates and the area of the sand spit updrift of the inlet were calculated. In particular, the area of the sand spit has increased remarkably, and the increasing rate is almost constant. Using this value, the rate of sand volume transported along the updrift sand spit by the waves was estimated and it is in good agreement with the longshore sediment transport rate of the surrounding beach. [ABSTRACT FROM AUTHOR]

Thanh, T.M.; Tanaka, H.; Mitobe, Y.; Viet, N.T., and Almar, R., 2018. Seasonal variation of morphology and sediment movement on Nha Trang Coast, Vietnam. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 22–31. Coconut Creek (Florida), ISSN 0749-0208. The Nha Trang beach, an embayed sandy beach located in the southeast of Vietnam, is a tropical touristic coastal environment that is being threat by persistent shoreline retreat. In order to investigate the processes underlying this erosive pattern, 1.5-years of video imagery, obtained from a local video system, was analyzed. Video products such as shoreline position and surf zone width (extracted from time-averaged images) were used to identify patterns of shoreline variability (using empirical orthogonal function – EOF) and investigate the link between the seasonal variations in the wave forcing and longshore sediment transport. Results indicate that shoreline retreat occurs essentially during the winter season, when energetic northeast monsoon waves dominate. The recovery phase (shoreline advance) was found to occur during the summer season, when milder south/southeast wind waves dominate. Shoreline variability was further investigated using EOF analysis and results show that the first mode, which explains 89% of the observed variance, corresponds to the seasonal longshore shoreline variations. This EOF mode was found to strongly related to the winter and summer monsoon seasons, thus reinforcing the role that seasonal changes in the wave climate play on the shoreline variations. Finally, the net of longshore sediment transport in Nha Trang beach was investigated using seasonal and monthly depth of closure (Dc) information, rather than a single fixed value of this parameter. The results highlight that the use of monthly or seasonal Dc values allow to capture the seasonal variations in the wave climate, thus providing more realistic patterns of sediment transport in this coastal area. [ABSTRACT FROM AUTHOR]

Appeaning Addo, K., 2018. Assessing ocean wave dynamics, potential sediment transport, and coastal erosion along Accra coast in Ghana. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 76–85. Coconut Creek (Florida), ISSN 0749-0208. This study assessed wave dynamics and sediment transport along the coast of Accra in Ghana and compared the results with coastal erosion trend. Wave data from NOAA global wave model and measured buoy wave data were analysed as well as the potential sediment transport using the CERC's equation. The estimated mean significant wave height was 1.40 m and the period was between 10 and 15 seconds. The potential sediment transport rate was between 4.1 ×105 m3/yr and 4.1 ×105 m3/yr, while coastal erosion rate was 1.13 m/yr. Potential sediment transport rate increases from west to east. Coastal erosion is relatively high along the eastern and western coasts of Accra, while the central coast is relatively stable. Wave heights increased gradually from 1.00 m in January to a peak of 1.73 m in August, and eventually decreased to 1.10 m in December. The shape of the nearshore profile is significantly different along the eastern coast relative to the western and central coasts. This indicates that sediment transport intensity and nearshore bathymetry interaction in part explain the rate of erosion observed along the Accra coast in Ghana. [ABSTRACT FROM AUTHOR]

Chien, N.Q. and Tung, T.T., 2018. Recent sedimentation of a mesotidal wave-dominated river mouth: Lach Van, Vietnam. In: Almar, R.; Almeida, L.P.; Viet, N.T., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 50–56. Coconut Creek (Florida), ISSN 0749-0208 The sedimentation of a wave-dominated river mouth in Tonkin Gulf, Vietnam, has been investigated for the time period 2005–2017. Deepwater wave statistics and the potential longshore sediment transport (LST) has been determined, which shows a net LST rate of ~105 m3/yr southward. A one-line model is used to estimate the change in local coastline; the model is verified against shoreline position data obtained from satellite images. It is apparent that the accretion occurs on both sides of the river mouth with a rate of ~10 m/yr. Coastline evolution trend is then predicted for the aforementioned time period, and results show evidences that accretion is intensifying in recent years, which is most probably due to slight variation in local wave climate. Results of this study can be used as a scientific basis to propose solutions for stabilizing the river mouth entrance and its channel. [ABSTRACT FROM AUTHOR]

ABSTRACT Zuckerman, S. and Anderson, S., 2018. Bathymetry and water-level estimation using X-band radar at a tidal inlet. Knowledge of bathymetry in coastal areas is a key factor for maintaining shipping channels, identifying hazards to navigation, and measuring sediment transport processes. Remote-sensing techniques are crucial for this purpose, because in situ methods are often costly, time-consuming, and less frequent in occurrence. This paper presents a derived bathymetry and water-level retrieval algorithm that operates on time-series X-band marine radar data. The algorithm is designed to operate on a long-term continuous data stream, generating updated water-level measurements and bathymetry maps as new data are collected. In step 1, individual data sets are first processed to retrieve dominant wave numbers over a pyramid of overlapping tiles. In step 2, depths are estimated at each pixel location in the domain using the shallow-water wave dispersion relation. Last, results from step 2 are used to estimate the current water level. Updated water levels are used to tide correct a series of individual depth estimates, which are averaged together to produce an updated bathymetry map. In this way, no a priori or external data sources from the survey area are required. A 2-month-long experiment was conducted at Beaufort, North Carolina, to test the algorithm and quantify the frequency at which adequate signal levels were present for valid retrievals. Derived bathymetry and water-level results are presented and compared against ground truth. Derived measurements agree well with ground truth, although bathymetry accuracy degrades in areas of the domain with large bottom gradients or strong tidal currents. [ABSTRACT FROM AUTHOR]

ABSTRACT Jara, M.S.; González, M.; Medina, R., and Jaramillo, C., 2018. Time-varying beach memory applied to cross-shore shoreline evolution modelling. A new cross-shore Shoreline Evolution Model Based on the Equilibrium Wave Energy—the SE-WE Model—is presented in this article. This simple model predicts the shoreline position S as the equilibrium shoreline response under a specific wave forcing, i.e. the proposed Equilibrium Wave Energy (Eeq) is computed as a weighted average of antecedent wave conditions, according to a new formulation. This new approach allows for the prediction of S at any time from a small fragment of the incident wave-energy time series as the only input of the model. In contrast, previous, similar models needed to evaluate the entire time series from an initial shoreline position to the target time. The proposed model addresses shoreline changes derived from wave-driven, cross-shore sediment transport. Consequently, the SE-WE Model has limited applicability in beaches in which the gradient in the longshore sediment transport or the longshore sediment transport itself are not negligible. The time frame considered for the computation of Eeq refers to the set of antecedent wave conditions having significant influence on the current shoreline position and, therefore, alludes to a certain beach memory (BM). In contrast to existing, similar models, the SE-WE Model BM varies over time. This time-varying BM is in agreement with observations in which high wave energy events erase all trace of past configurations of the beach (“short beach memory”), whereas at the same beach, the effects of past events usually remain after long periods of calm conditions (“long beach memory”). Results from the SE-WE Model applied at the beach of Nova Icaria, Spain, show a good agreement with observations. Additionally, the new model is compared with existing similar models, showing remarkably similar skills in spite of the differences in model approach and model input. [ABSTRACT FROM AUTHOR]

ABSTRACT Kolokythas, G.A.; Grigoriadis, D.G.E., and Dimas, A.A., 2018. Dynamic friction coefficient in formulas of bed-load transport induced by waves over vortex orbital ripples. Empirical formulas for the computation of bed sediment transport induced by wave propagation over sand ripples often depend on, among other parameters, the dynamic friction coefficient, μd, of the sand grain motion. Here, a new approach is presented for the determination of μd based on the physics of the interaction between flow and sediment transport. Specifically, the correlation of μd to the wave, ripple, and sand grain characteristics was obtained using coupled numerical simulations of the flow over the rippled bed, the bed-load transport, and the bed morphology evolution. Flow results were obtained by two different numerical methods, one for wave boundary layer flow and one for purely oscillatory flow, both based on the solution of the Navier-Stokes equations. The bed-load transport rate, which drives the bed morphology evolution, was computed using three different empirical formulas. The value of μd that leads to an equilibrium of the rippled bed profile after many wave periods was found to depend almost linearly on (Lr/ao)·(hr/ao), where, Lr is the ripple length, hr is the ripple height, and ao is the wave orbital motion amplitude. [ABSTRACT FROM AUTHOR]

Zhang, J., 2018. Estimating sediment moving into the Yellow River based on moving process analysis. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 163–168. Coconut Creek (Florida), ISSN 0749-0208. The sediment moving into the Yellow River has decreased in recent years. For instance, the measured annual mean sediment amount at Tongguan station showed a sharp decreasing trend from 15.9 × 108 t/a during 1919–1960 to only 2.5 × 108 t/a during 2000–2015, a change of 84%. This led to an increased interest in the movement of sediments into the Yellow River. However, the results and conclusions were quite different due to different data and methods used in different studies. Consequently, no widely acceptable understanding existed regarding the sediment movement into the Yellow River. In this study, firstly the main process of sediment moving into the Yellow River was analyzed in the area where the sediments mainly yielded due to hydraulic erosion, gravitational erosion, and sediment transport by water flow in the riverbed. Then, referring to soil erosion as the "three lines of defense", the effects of water and soil conservation projects were discussed to estimate the amount of sediment moving into the Yellow River. Considering the effects of water and soil conservation projects, climate change, and human activities, the sediment in the Yellow River used in engineering design should be between 8 × 108 and 12 × 108 t/a for safety purpose, and at least 10 × 108 t/a for suggestion. [ABSTRACT FROM AUTHOR]

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]

ABSTRACT Solari, S.; Alonso, R., and Teixeira, L., 2018. Analysis of Coastal Vulnerability Along the Uruguayan Coasts. 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. 1536–1540. Coconut Creek (Florida), ISSN 0749-0208. The objective of this work is to identify the most vulnerable areas to coastal erosion on the Uruguayan coast. To this end, global wind and local waves and sea level reanalysis were used to estimate the littoral and aeolian sand transport rates (cross- and long-shore), the response of the beach profile to extreme events (by means of X-Beach model) and the supply of sand from rivers all along the Uruguayan coast, obtaining 18 years of three-hourly data. For each estimated variable, its intra- and inter-annual variability and its correlation with relevant climatic indexes were calculated. Using this information the sediment budget of the coast was analyzed at different scales: global (all the Uruguayan coast; O(100 km)), regional (physiographic units, O(10km)) and local (beach nodes; O(1km)). In turn, the above information was combined with a qualitative assessment of the coastal uses, obtaining a vulnerability index used to identify priority areas to undertake detailed studies. [ABSTRACT FROM AUTHOR]

ABSTRACT Shim, W.J. and Kim, C.W., 2018. The necessity of coastal management in Busan Considering human and natural conditions: The case of barrier islands in Nakdong-estuary. 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.1501–1505. Coconut Creek (Florida), ISSN 0749-0208. The Busan coasts have complex natural and human conditions including dynamic coastal, river processes and human activities. These complex natural and human factors have had direct and indirect impacts on the coastal areas of Busan, so a spatially integrated approach for management is required. Especially, the barrier islands located in the Nakdong River estuary are proper examples that show the effect of the sediment budget as natural and human conditions. This research aims to identify the effects of natural and human conditions on the barrier islands. The area of the barrier islands, sediment budget from the watershed, the amount of dredging at Nakdong-Estuarine-Dam and land use coverage were compared using correlation analysis. The more sediment eroded from watershed and the less sediment was dredged at Nakdong-Estuarine-Dam, the larger area of the barrier islands. This indicates that boundary conditions such as the supply of sediment from the rivers are related to the barrier islands; thus river and watershed management are important. Regarding land use, used and barren areas are positively correlated with the barrier islands, but water, forests and agricultural lands are negatively correlated. Internal factors within Busan, such as coastal modifications and urban growth, are affecting coastal dynamics, which change the sediment budget. These results show that the barrier islands sensitively respond to boundary conditions from the river and watershed and to internal conditions such as shoreline management and development. Therefore, for the effective management of Busan's coasts, it is necessary to consider how natural and human conditions interact spatially. [ABSTRACT FROM AUTHOR]

ABSTRACT Fernández-Fernández, S.; Silva, P.A.; Ferreira, C.; Ribeiro, A.S.; Abreu, T.; Romão, S.; Baptista, P.; Fontán-Bouzas, A.; Dias, J.M..; Coelho, C., and Bernardes, C. 2018. Assessment of Dredging/Dumping Scenarios for Figueira da Foz Coastal Region (W 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. 1266–1270. Coconut Creek (Florida), ISSN 0749-0208. Figueira da Foz coastal region (W Portugal), that comprises sandy beaches and the Mondego estuary-inlet, is exposed to the high energetic wave climate of the North Atlantic Ocean, which induces important local morphological changes. These changes entail shoaling problems as the formation of a submerse sandbar at the inlet which can block navigation towards local harbor. Therefore, coastal dredging is a non-structural temporal solution for this problem. Nevertheless, dredging activities have an impact on local hydrodynamic processes that should be known beforehand. The aim of this study is to clarify this issue using modeling tools dedicated to help stakeholders in decision making process. For that purpose, Delft3D-WAVE module propagates the most representative regional wave conditions under four dredging scenarios including the respective dump areas. Additionally, Delft3D-FLOW module simulates tidal flows along spring and neap tides. The hydrodynamic parameters, significant wave height, orbital velocity, wave-induced currents, tidal current velocity and total sediment transport are analyzed in comparison with numerical solutions obtained in reference scenario (no dredging and no dumping). The results highlight changes in these hydrodynamic parameters in dredging and dumping areas as well as in surrounded areas. Different scenarios draw a similar change pattern for different parameters, namely a reduction of flow velocity intensity within dredged areas and their increase in adjacent areas. Furthermore, hydrodynamic alterations intensify in response to the increase in significant wave height and wave direction considered. These findings are the basis for understanding the influence of dredging and dumping operations on the hydrodynamic of this coast. [ABSTRACT FROM AUTHOR]

ABSTRACT Lee, S.; Kim, H.; Park D., and Lim, H.S., 2018. Modelling shoreline evolution at Anmok Beach by using CST3D-WA, 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. 1241–1245. Coconut Creek (Florida), ISSN 0749-0208. Anmok Beach suffered heavy morphological and shoreline position changes since a submerged breakwater was constructed in October 2014. Straight shoreline changed into a S-shape shoreline after about 3 months, and mostly returned back towards the initial straight line after typhoon Goni in August 2015. Previous wave-average type flow and sediment transport equations cannot reproduce shoreline evolution due to their “wave-average” properties. A wave-average flow and sediment transport model, CST3D-WA, adopt the “beachface slope adjustment method” to enable shoreline evolution in area morphological modelling. The modelling system simulated the morphological change for two periods, and reproduced the changes in morphology and shoreline shape of the two periods reasonably well. [ABSTRACT FROM AUTHOR]

ABSTRACT Wang, J.; Qu, Z.; Xu, Z.; Shim, J.S.; Liang, B., and Lee, D.Y., 2018. Measurement of Sediment Concentration of the Oscillatory Flow in the Surf- and Swash-zone.. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1231–1235. Coconut Creek (Florida), ISSN 0749-0208. The sediment transports near the bed need to be accurately observed to validate the existing models that are based on the empirical formula for the sediment flux and to develop more realistic morphology prediction model. One of the essential tasks for the evaluating the existing models and developing new one is the precise measurement of the sediment transport at swash zone without disturbing flow. Different methods in estimating the sediment transport rates at the surf-zone and swash-zone such as measuring the time evolution of the bed profile, sand ripple volume and migration speed are investigated and evaluated. To develop more reliable estimation of the sediment flux by measuring the vertical profiles of sediment concentration and velocity without disturbing the flow conditions, method of estimation of the vertical sediment concentration profile by detecting the backscattered light intensity using high quality camera was tested and evaluated. The problems of different methods in estimating the sediment flux are identified and discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Xu, C.Y.; Chen, Y.P., and Yu, L.L., 2018. Numerical Studying on The Sedimentary Processes at A Mudflat Near Yangtze River. 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. 1201–1205. Coconut Creek (Florida), ISSN 0749-0208. A two-phase model for studying the sedimentation processes is presented. The simple flocculation model is incorporated in the two-phase model to take account the flocculation effects on the settling velocity and thus the distribution of suspended sediment concentration. The model is applied to study the sedimentation processes at a mudflat and the suspended sediment concentration is presented and compared with measured data. The results show that it is important to include the flocculation effects in predicting the vertical profile of sediment concentration. [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]

ABSTRACT Park, D.; Kim, H.; Lee, S.; Lee, J., and Yoo, J., 2018. Simulation of storm-induced cross-shore sediment transport at Anmok Beach with wave-resolving CST3D-WR. 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. 1001–1005. Coconut Creek (Florida), ISSN 0749-0208. An intensive field survey was carried out before and after a typhoon Goni at Anmok Beach, east coast of Korea, where a submerged breakwater exists. Survey items include offshore wave height, direction, and period; nearshore wave height, direction, and period, current and water level, bed load and suspended sediment load; bathymetry; and shoreline position. Interesting bathymetric change was observed after the typhoon: offshore sediment transport and consequent bathymetric change happened along the most coastline. The data exhibit the impact of the typhoon clearly, A wave-resolving numerical modelling system CST3D-WR was applied to the site for the typhoon situation, and qualitatively well reproduced the field bathymetric change. [ABSTRACT FROM AUTHOR]

ABSTRACT 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]

ABSTRACT Chu A.; Wang Z.B.; de Vriend H.J., and Tai J.A., 2018. Parallel morphodynamic modelling for the Yangtze Estuary. 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. 641–645. Coconut Creek (Florida), ISSN 0749-0208. Model input reduction and morphological acceleration techniques to bridge the large time scale of morphological evolution and the small time scale of hydrodynamically driven sediment transport is investigated for the Yangtze Estuary morphodynamic model. The discharge series of the river is schematized into a set of multi-discharge levels. Each discharge level coupled with the spring-neap tide forms one morphodynamic model for the estuary with bed stratigraphy approach applied. These models are used to simulate the bathymetry change of the estuary in parallel with the results merged together base on the Mor-Merge (MM) method. The morphological factor is used to accelerate the bathymetry change during hydrodynamic simulation. The modelled bathymetry change based on MM method is compared with the Quasi Real Time (QRT) simulation result. It shows that the results of the MM model with more discharge levels correlate more significantly with that of the QRT model. Therefore, the MM approach with multi discharges, which achieves an acceptable acceleration for morphological change, results in the feasibility of the medium term morphodynamic model of the Yangtze Estuary. [ABSTRACT FROM AUTHOR]

ABSTRACT Kim, D.-H,; Kim, B., and Choi, B., 2018. Adaptability of suspended sediment transportmodel for sandbar migration simulation. 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. 661–665. Coconut Creek (Florida), ISSN 0749-0208. Adaptability of a nonequilibrium suspended sediment transport model to flow and morphological conditions was studied. Under dispersive and unsteady flow conditions, four sets of numerical simulations were conducted using a morphodynamic model. The flow fields were modeled using the Boussinesq equation and the bottom evolutions were modeled using the transport equation for the suspended load and the bed load formulae. Numerical simulations using a constant suspended parameter and variable bed load parameters within a multiple of reference values yielded very similar predictions. These similarities resulted from the adaptability of the suspended sediment transport model which considered the flow and morphological conditions; although the use of different values of bed load parameters resulted in different individual contributions to the bed load fluxes by the parameters, the suspended sediment model adjusted the suspended load flux and made total fluxes converged. The same results were observed in the bottom evolution rates. On the other hand, successful results could not be obtained in the opposite cases: with fixed bed load parameter and variable suspended load parameter. [ABSTRACT FROM AUTHOR]

ABSTRACT Gómez, M.; Villagrán, M.; Martínez, C., and Belmonte, A., 2018. Characterizing the Longshore Sediment Transport Pattern on Beaches in the Gulf of Arauco, Chile, to Assess Morphological Shoreline Evolution. 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. 656–660. Coconut Creek (Florida), ISSN 0749-0208. Coastal evolution is an important research topic worldwide and has become increasingly relevant due to growing anthropogenic pressure on the coast and a climate change scenario (Masselink et al., 2016). The Gulf of Arauco covers an area of roughly 40,000 km2 and has a sandy-rocky coastline located in a very seismic environment. The area has suffered several major earthquakes during the last century (Valdivia 1960, Maule 2010) and seismic displacement has widely affected the coastline (Béjar-Pizarro et al., 2010). Despite these findings, the morphological evolution of sandy coastlines is mainly caused by wave-driven littoral processes. In this paper, using numerical modeling (Delft3D), we aim to characterize the longshore sediment transport (LST) direction at several spots (7 beaches) spread along the coastline of the Gulf of Arauco. Wave patterns were identified at each study site, revealing the importance of Santa Maria Island, located at the entrance to the gulf, despite the approach direction of deep water waves. The island acts as a moderator of wave patterns, softening the highly energetic swell that comes from the Antarctic Ocean and sorting the wave propagation inside the gulf. Moreover, LST patterns were characterized at each site for dominant wave conditions (SW swell and NW winter storms) and it was possible to explain how each condition has a different response at each spot, even under similar co-seismic displacements. Adaptation capabilities differ from site to site, suggesting a dynamic equilibrium of beaches in the area. [ABSTRACT FROM AUTHOR]

ABSTRACT Woo, S.-B. and Yoon, B.I., 2018. Numerical simulation of fortnightly modulations of the convergence zone by residual volume transport in a macrotidal estuary. 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. 606–610. Coconut Creek (Florida), ISSN 0749-0208. This study examines the fortnightly modulation of convergence zone by residual volume transport of main channel using a numerical model in the tidally dominated Han River estuary (HRE), South Korea. The numerical model, EFDC (Environmental Fluid Dynamics Code), was simulated for 124 days, from May to August 2009, and used observed freshwater discharge for major rivers of HRE. The residual volume transport discharged into the HRE from the Yeomha channel and Seokmo channel had a ratio of 44:56 over thirty days under normal freshwater conditions. The model results show that a temporal variation of the residual volume transport (Lagrangian transport = Eulerian transport+Stokes transport) is formed near the Yeongjong Bridge with spring-neap variability, and net transport is outflowed to the west through the channel between Ganghwa and Yeongjong. Due to magnitude change of the residual volume transport by fortnightly (spring-neap) modulation, convergence zone (junction location of residual volume transport) show upward and downward spatial variation. We found that the convergence zone moves downstream during the spring period because of; 1) strong net downward barotropic flow by increased sea level difference between upstream and downstream during the spring tide; 2) decreased baroclinic flow towards the upstream of the main channel, caused by intensified tidal mixing during the spring period; and 3) increased outflow through the tidal flat channel between Ganghwa and Yeongjong during the spring period. [ABSTRACT FROM AUTHOR]

ABSTRACT Birchler, J.J.; Harris, C.K.; Kniskern, T.A., and Sherwood, C.R., 2018. Numerical model of geochronological tracers for deposition and reworking applied to the Mississippi subaqueous delta. 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. 456–460. Coconut Creek (Florida), ISSN 0749-0208. Measurements of naturally occurring, short-lived radioisotopes from sediment cores on the Mississippi subaqueous delta have been used to infer event bed characteristics such as depositional thicknesses and accumulation rates. Specifically, the presence of Beryllium-7 (7Be) indicates recent riverine-derived terrestrial sediment deposition; while Thorium-234 (234Th) provides evidence of recent suspension in marine waters. Sediment transport models typically represent coastal flood and storm deposition via estimated grain size patterns and deposit thicknesses, however, and do not directly calculate radioisotope activities and profiles, which leads to a disconnect between the numerical model and field observations. Here, observed radioisotopic profiles from the Mississippi subaqueous delta cores were directly related to a numerical model that represented resuspension and deposition using a new approach to account for the behavior of short-lived radioisotopes. Appropriate selection of parameters such as the biodiffusion coefficient, sediment accumulation rate, and radioisotopic source terms enabled a good match between the modeled and observed cores. Comparisons of modelled profiles with geochronological analytical models that estimate accumulation rate and flood layer thickness revealed potential avenues for refining these tools, and highlight the importance of constraining the biodiffusion coefficient. [ABSTRACT FROM AUTHOR]

ABSTRACT Choi, T.-J.; Choi, J.-Y.; Park, J.-Y.; Um, H.-Y., and Choi, J.-H., 2018. The Effects of Nourishments Using the Grain-Size Trend Analysis on the Intertidal Zone at a Sandy Macrotidal 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. 426–430. Coconut Creek (Florida), ISSN 0749-0208. Byeonsan Beach is a typical macrotidal beach located at the west coast of Korea, which has been eroded continuously over the past decade since the construction of Saemangeum Dike. Starting from 2011, beach nourishment has been conducted annually on the Beach, with about 8 × 103 m3 of well sorted medium sands over the intertidal flat area. Primary purposes of this study are to understand the pattern of sediment transport using the grain-size trend analysis (GSTA) proposed by Gao and Collins (1992), and to evaluate the effect of nourishment procedures. Because of the monsoonal climate, nourishments were carried out just before the rainy summer season between late May and early Jun. 120 surficial-sediment samples were carefully collected each time in March before nourishment and also in September about 3-month after nourishment. The results of sediment grain-size analysis showed the equilibrium status of transport pattern in the previous winter season and during summer after nourishment, respectively. Beach morphology was also made monthly by using RTK-GPS system. The result showed that most of the nourished sands remained within the intertidal zone of the beach, and thus the nourishment procedures conducted on Byeonsan Beach were considered as successful. Nourishment sediments were transported predominantly landward direction, resulting in 20-cm increase in mean elevation along the upper sand beach. Subsequent amounts of nourished sand were considered to be transported seaward direction showing different transport patterns between 2013 and 2014, especially at the northern and southern parts of the beach. Local factors influencing the transport pattern were the amount of rainfalls and the resulting freshwater discharge from sluice gates, and the climatic conditions such as typhoon events in summer and strong northwesterly winds during winter. [ABSTRACT FROM AUTHOR]

ABSTRACT Shi, H.Y.; You, Z.J.; Yin, B.S., and Bai, Y.C., 2018. Critical Depths Derived for Three Distinct Modes of Coastal Sediment Transport. 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. 271–275. Coconut Creek (Florida), ISSN 0749-0208. A unified criterion is developed for three distinct modes of coastal sediment transport: incipient movement of sediment (only bedload), initiation of bedripple formation (bedload and suspended load), and inception of bed ripple disappearance or sheet flow (mainly bed load) based on three unique laboratory datasets collected on a horizontal bed of sediment under regular waves. The onset velocity criterion on the three distinct sediment transport modesis derived to be of the same simple form, U0 = 2πC (1 − T0/T), where U0 is the maximum on set wave orbital velocity close to the bed, T is the wave period, and C and T0 are the coefficients dependent of sediment property only. The newly developed criterion is then extended to calculate critical depths for the distinct modes of sediment transport under coastal waves by replacing regular wave height H and period T with statistical wave height Hrms and period Trms according to the recently developed “zero-crossing and energy balance” wave analysis method and linear wave theory. The critical depth calculated from this unified criterion is shown to be a function of sediment grain size and density, and wave height and period, but more sensitive to wave period. The critical depth estimated for the initiation of bed sediment ripple formation is found to be much larger than the depth of closure derived for beach-fill designs. [ABSTRACT FROM AUTHOR]

ABSTRACT Santos, M.I.; Oliveira, F.S.B.F., and Trigo-Teixeira, A., 2018. Characterization of Maritime Storms and Analysis of their Effect on the Beaches South of the Mondego River (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. 266–270. Coconut Creek (Florida), ISSN 0749-0208. In the study of coastal processes and coastal dynamics, the analysis of the storms impact is one of the most discussed topics in terms of management and defense of the coastal sector. The Portuguese west coast is exposed to the energetic wave climate that characterizes the North Atlantic, thus requiring permanent care as regards the efficient coastline management and planning. Indeed, the risk associated with erosion and flooding of vulnerable areas is a constant concern, making it imperative to predict the impact of these events and the response of the beach-dune systems. This study focuses on maritime storms and on the morphological response of the beach to these short-term events. The two main objectives are to characterize the storms regime in the coastal stretch between the Mondego and the Lis rivers' inlets based on the wave time series (hindcast) from the period 1952–2010, and to evaluate the impact of the storms duration on erosive events, using a short-term morphodynamic numerical model, LITPROF. This model is used for the analysis of the effect of storms on the beach morphology and thus, for comparing the erosive effect of events with the same relative storm power and different duration. The statistical analysis of the wave climate time series showed a coastal storms regime with high inter-annual and intra-annual variability in number, duration and relative storm power of events, characterized by a strong seasonality, with an average duration and relative storm power of 3 days and 2654 m2.h, respectively. The most frequent events are simultaneously in the classes [1–2[ days and [800–1600[ m2.h (36% of occurrences). The numerical model, applied to several scenarios, predicted the dominance of the duration factor for storms with similar relative storm power, leading to the conclusion that longer duration storms always generate larger erosive effects (and higher transport rates) in the cross-shore profile, when compared with storms of shorter duration. [ABSTRACT FROM AUTHOR]

ABSTRACT Xu, B.B.; Gong, Z.; Zhang, Q.; Zhang, C.K., and Zhao, K., 2018. Non-equilibrium suspended sediment transport on the intertidal tidal flats of Jiangsu coast, 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. 251–255. Coconut Creek (Florida), ISSN 0749-0208. Accurate modelling of instantaneous sediment transport processes in coastal environments has been a great challenge for many decades. One of the difficulties comes from the existence of time lag between flow and sediment transport, termed as “the non-equilibrium transport effect”. To better understand and simulate the sediment transport processes, field observations were conducted on the middle intertidal flats of Jiangsu coast. Water depths, current velocity profiles, wave parameters, stratified suspended sediment concentrations (SSC), as well as grain sizes of both suspended sediment and bed sediment were measured. Results show that suspended sediment has an average grain size of 11.2 μm, the percentage of cohesive suspended sediment can be up to 97%. The bed load has an average grain size of 40 μm, the percentage of cohesive sediment is only 76%. The measured maximum SSC occurs at the beginning and the end of each tidal cycle. It is well-mixed during flood and ebb peak, but stratified during slack period. The vertical equilibrium SSC profiles were calculated based on the advection-diffusion theory. Calculated equilibrium SSC is well-mixed during whole tidal cycle and is controlled by the local hydrodynamics. The difference between calculated equilibrium SSC and real ones indicates that the contribution of advection is dominant. Thus the non-equilibrium suspended sediment transport processes should be taken into account for intertidal flat evolution. [ABSTRACT FROM AUTHOR]

ABSTRACT Bastos, A.P.; Ponte Lira, C.; Calvão, J.; Catalão, J.; Andrade, C.; Pereira, A.J.; Taborda, R.; Rato, D.; Pinho, P., and Correia, O., 2018. UAV Derived Information Applied to the Morphological Study of Slow-changing Dune Systems. 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. 226–230. Coconut Creek (Florida), ISSN 0749-0208. São João da Caparica (Portugal) slow-growing dune system was investigated using field-based GPS and UAV surveying methods. Here, vegetation may preclude straightforward extraction of ground surface data from DSM and low sedimentation rates demand high accuracy. The approach used comprised acquisition of UAV-derived DSM and RGB orthomosaics at flight-heights of 30 and 60 m. Results were compared with DTM derived from traditional RTK-GPS ground surveys. Two methods (M1 and M2) where used to convert UAV-derived DSM into a DTM, both departing from supervised classification of land cover. In M1, vegetation areas are removed from the original DSM, which is then re-interpolated. M2 redefines elevation of pixels corresponding to vegetation by subtracting a mean height parameter defined for each vegetation class. It was found that DTM derived from UAV and RTK-GPS data exhibit errors in the same order of magnitude, regardless of the higher resolution of the former. M2 yielded the best compromise when considering deviations in both profile and surface analysis. M2 is strongly dependent on vegetation classification and on parametrization of the vertical correction affecting each vegetation class. UAV methodology presents the best cost-benefit ratio relative to traditional RTK-GPS surveys, providing additional image information (RGB orthomosaic) synchronous of the topographic data. [ABSTRACT FROM AUTHOR]

ABSTRACT Yuhi, M. and Umeda, S., 2018. Characteristics of systematic migrations of multiple sandbars and related cross-shore sediment transport at Chirihama and adjacent coasts, Japan. 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. 231–235. Coconut Creek (Florida), ISSN 0749-0208. Characteristics of systematic migration of multiple bar system on the Chirihama and adjacent coasts, Japan, have been investigated based on a set of annual field surveys collected over 11 years. The morphological variations were first separated into time-averaged profiles and deviation components. An EOF analysis was conducted on the deviation components in order to extract the principal modes of periodic bar migration. The migration cycle consisting of generation, migration and degeneration were well reproduced by the combination of first and second modes. The cross-shore sediment transport and sediment volume variation related to bar migration were then examined. An integration of the equation for sediment volume conservation revealed that the principal modes of cross-shore sediment transport was characterized by the spatial integration of spatial eigen-functions and the temporal derivative of the temporal eigen-functions. Corresponding to the cyclic behaviors of sandbar system, the direction of sediment transport changed alternatively between seaward and landward directions. On short-term, cyclic exchange of sediment occurred between the bar migration zone and foreshore, but on long-term the principal modes of bar migration made little contribution to overall sediment volume variation. [ABSTRACT FROM AUTHOR]

ABSTRACT Tao, J.; Xu, F.; Yao, P.; Zhou, Z., and Zhang, C., 2018. The variations of sediment transport patterns in the radial sand ridges along the Jiangsu coast, China over the last 30 years. 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. 216–220. Coconut Creek (Florida), ISSN 0749-0208. The research objective is to clarify the primary factors lead to the variations of the suspended sediment transport in the radial sand ridges (RSRs) along the Jiangsu Coast over the last 30 years. The suspended sediment concentration (SSC) fields measured in several field surveys from 1980 to 2010 were analyzed. The field data indicate that the SSCs in 1980 are higher than those 2010. A two-dimensional numerical model was developed to simulate the inter-annual variations of the suspended sediment transport. Generally, the magnitude of the SSC is highly relevant with the current speed, which peaks around the Old Yellow River Delta (OYRD) and in the central RSRs. However, the northern part of the RSRs indicates higher SSC than the southern part, which is attributed to their different bed sediment composition. The net suspended sediment flux was calculated. In the north of the RSRs, the sediments are transported in the south direction, which implies a sediment input from the OYRD to the RSRs. In the south of the RSRs, a net sediment loss was observed, which is consistent with the decreasing of the sediment flux from the Yangtze River. The simulated suspended sediment transport in 1980 and 2010 mutually show similar spatial patterns, while SSCs in 1980 are overall larger than those in 2010. It is concluded that the decrease of the SSCs from 1980 to 2010 is attributed to the reduction of the OYRD and the large-scale reclamation along the Jiangsu coast, while the sediment fluxes from the Yangtze River is less important. [ABSTRACT FROM AUTHOR]

ABSTRACT Talavera, L.; Del Río, L.; Benavente, J.; Barbero, L., and López-Ramírez, J.A., 2018. UAS & SfM-based approach to Monitor Overwash Dynamics and Beach Evolution in a Sandy Spit. 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. 221–225. Coconut Creek (Florida), ISSN 0749-0208. The role of overwash processes is of great relevance in the long-term evolution of sandy barriers, and it can also affect coastal infrastructures in the short term. In this work, a 10-month monitoring program based on the use of Unmanned Aerial Systems (UAS) in combination with Structure from Motion (SfM) algorithms was performed in order to monitor morphological changes and ulterior evolution at Camposoto beach, an overwash-prone coastal spit located in SW Spain. This UAS&SfM approach allowed the reconstruction of 6 Digital Elevation Models (DEMs) of the area with high temporal and spatial resolutions (RMS vertical errors spanning from 5 to 8 cm). The morphological changes occurred were detected using Geomorphic Change Detection Software in ArcGIS, and they were correlated with the oceanographic conditions that prevailed during the analysed period. The results obtained provided insight into the response of the system against storm-induced overwash, which caused significant erosion/accretion patterns over a pre-existing washover fan, as well as the landward migration of the system. In addition, this methodology captured the progressive partial recovery of the system, which included onshore transport of sand, fore-beach accretion, and berm reconstruction. Despite the partial recovery observed, spring tides also triggered non-storm overwash in the area during fair-weather conditions, allowing to rethink the actual vulnerability state of the spit against rollover processes. [ABSTRACT FROM AUTHOR]

ABSTRACT Montreuil, A-L.; Chen, M.; Brand, E.; Strypsteen, G.; Rauwoens, P.; Vandenbulcke, A.; De Wulf, A.; Dan, S., and Verwaest, T., 2018. Dynamics of surface moisture content on a macro-tidal 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. 206–210. Coconut Creek (Florida), ISSN 0749-0208. Surface moisture content is a significant factor controlling aeolian sand transport. It is influenced by atmospheric, marine and sub-surface processes. Although several studies reported direct links in surface moisture content with the processes responsible for those variations, there is still a lack of understanding of its dynamic on a macro-tidal beach. This study aims to investigate spatial and temporal dynamics in the surface moisture content of a macro-tidal beach, and to determine the relative importance of factors controlling these. A field experiment was performed on a dissipative and non-barred beach at Mariakerke (Belgium) during an aeolian sand transport event in March 2017. Surface moisture content was measured from the backshore to the tidal zone using a video monitoring system. Simultaneous measurements of grain size, volumetric moisture content, groundwater level, atmospheric conditions, wind parameters, water level and topography were carried out. The hourly generated moisture maps indicate a clear cross-shore gradient of decreasing surface moisture content from the intertidal zone (ranging from 4–18%) to the backshore (none–8%), while it is more complex in the alongshore dimension. The backshore experienced the most rapid reduction of moisture content below 4% with a dryness rate of the surficial zone reaching 29% per hour in the late morning. It progressively continued to dry in the afternoon when sand strips, mobile aeolian bedforms, were well developed. Changes in moisture content over the beach surface reflect the atmospheric (solar radiation and wind) and marine (tidal elevation, wave and groundwater level) conditions and internal beach characteristics such as bedforms produced by aeolian sand transport and topography. Thus the continuous combinations of direct and indirect interactions between all these factors contribute to the spatial and temporal dynamics of surface moisture content. A better knowledge of the dynamics of the surface moisture content is a necessary prerequisite for the development of models and to compute budgets of aeolian sand transport. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. [ABSTRACT FROM AUTHOR]

ABSTRACT Alonso, R.; Solari, S., and Teixeira, L., 2018. Erosion Problem on a Fluvial Beach. The Case Study of “La Concordia” in the Uruguay River. 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. 131–135. Coconut Creek (Florida), ISSN 0749-0208. A case study of beach erosion at “La Concordia” is presented. It is a fluvial beach located in the most downstream stretch of the Uruguay River. Despite it is a fluvial environment, the 10 km width that the river has in this zone allows for the generation of wind-waves that play an important role in the morphological processes that shape its sandy margins. This was initially proven by assessing the evolution of the coastline from satellite images and aerial photos, since the main change observed in the coastline is the expected one when groins are built on a sea coast. After that, the predominant influence of waves was confirmed by: 1) a good agreement between the geometry of the system (i.e. plan-shape and profiles) with the one predicted by formulations conceived from wave dominated marine environments, 2) a cross–section river flow velocity distribution, calculated for an historical maximum discharge, that shows that outside of the river channels velocities are lower than the critical expected for bottom sediment transport, 3) an estimation of the littoral transport in agreement with the historical coastline evolution. This verification supports the use of models and methods commonly employed in coastal engineering for the study of this type of fluvial beaches. In this case, the numerical model XBeach was used to simulate the response of the system to extreme events, in order to provide an input to a beach nourishment design. [ABSTRACT FROM AUTHOR]

ABSTRACT Rollnic, M.; Costa, M.S.; Medeiros, P.R.L., and Monteiro, S.M., 2018. Tide Influence on Suspended Matter in an Amazonian Estuary. 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. 121–125. Coconut Creek (Florida), ISSN 0749-0208. The aim of this study is to check which tidal component (dispersive or diffuse) dominates suspended particulate matter transport (SPM) in the Mojuim River estuary. This estuary comprises the eastern sector of the Amazon coast, characterized by mangrove-vegetated tidal flats. Measurements of current intensity and direction, SPM, and tide level over a tidal cycle (13 h) were performed in a section of the lower estuary. Samplings were conducted in March (wet season) and September (dry season), 2014, during spring tide. The resulting transport and relative contribution of advective transport (SPM diffusion and dispersion) were calculated. Mojuim estuary has a macrotidal regime, with mean height of 4.9 m during spring tide and 3.2 m during neap tide. As it is a shallow environment, the water column is homogeneous, and hydrological parameters do not significantly vary along the water column. SPM ranged from 12 to 92 mg.L−1 during dry season and from 20.4 to 94.8 mg.L−1 during wet season. The highest SPM concentrations occurred during ebb tide, and this determined the maximum instantaneous transport, both during wet season (127.8 kg.s−1) and dry season (159 kg.s−1). This estuary is characterized as an exporter environment. During dry season, it had a residual transport of 4.1 kg.s−1 and a total transport of 191.9 tons downstream of the estuary. However, during wet season, it showed an inversion in advective transport due to equinoctial tidal influence, which caused a higher tidal prism thus resulting in a residual transport of 1.92 kg.s−1 and a total transport of 90 tons upstream of the estuary. The dominant SPM transport component downstream of the estuary was river discharge, whereas SPM transport upstream of the estuary was dominated by Stokes Transport. [ABSTRACT FROM AUTHOR]

ABSTRACT Lu, C.Z.; Li, H.; Dai, W.Q.; Tao, J.F.; Xu, F.; Cybele, S.; Zhang, X.Y., and Guo, H.T., 2018. 3-D Simulation of the Suspended Sediment Transport in the Jiaojiang Estuary: Based on Validating by Remote Sensing Retrieval. 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. 116–120. Coconut Creek (Florida), ISSN 0749-0208. Suspended sediment concentration (SSC) in Jiaojiang Estuary is characterized by high concentration and significant diurnal dynamics. The large-scale reclamation will influence the sediment transport in Jiaojiang Estuary. At present, ship-borne data, remote sensing observations, and numerical modeling technique are the main technological methods to acquire the distributions of SSC. However, every method has its own limitations in application. Conventional ship-borne survey requires a lot of manpower and resources to obtain sediment distribution of an estuary although its accuracy is high. The cloudy and rainy environment has been the bottle-neck for monitoring the land and ocean surface. With the influence of land-use by human activities (such as tidal flats reclamation) being strengthened gradually, previous numerical models are not suitable for the new environment. This paper aims to combine numerical modeling technique with remote sensing observations to acquire a higher-resolution surface suspended sediment field in time and space. MIKE3 3D model was used to simulate the suspended sediments and it is composed of hydrodynamic module and mud transport module. The surface-layer sediment distribution was calculated using suspended sediment dynamic mathematical model in MIKE 3. Based on Geostationary Ocean Color Imager (GOCI) and the simultaneous surface layer sediment concentration data, a remote sensing model was developed to retrieve the distribution of SSC in the Jiaojiang Estuary. The degree of matching between the remotely sensed SSC and the numerically simulated SSC is up to 72%, both of which reveal temporal-spatial variation of the SSC. The research provides a reference for real-time monitoring and forecasting the dynamic variation of the SSC. [ABSTRACT FROM AUTHOR]

ABSTRACT Simionato, C.G. and Moreira, D., 2018. Modeling the processes that control fine sediments transport in the Río de la Plata Estuary. 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. 31–35. Coconut Creek (Florida), ISSN 0749-0208. Numerical models are excellent tools for conducting process studies and testing hypotheses based on observations. They constitute a “virtual laboratory” in which the forcings can be set “on” or “off”, or even the environmental conditions can be modified. The Rio de la Plata (RdP) is one of the most turbid estuaries in the world and the one most important in terms of continental discharge and drainage area. Observations of suspended fine sediments, particularly those remote and in situ collected on recent studies, have driven to the statement of several hypotheses about the processes that would determine the concentration of suspended sediments in the different parts of the estuary. Nevertheless, the relative scarcity of data do not allow to demonstrate the validity of those hypothesis and the role of several physical processes and of the morphology remain unknown. The objective of this work is, therefore, to analyze the role of the different forcing and the environmental conditions in the determination of the distribution of suspended fine sediments in the RdP applying processes oriented numerical simulations. [ABSTRACT FROM AUTHOR]

Ferreira, C.; Silva, P.A.; Fernández-Fernández, S.; Baptista, P.; Abreu, T.; Romão, S.; Fontán-Bouzas, A.; Bertin, X., and Garrido, C. 2018. Wave Climate Definition on Modeling Morphological Changes in Figueira da Foz Coastal System (W 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.1256–1260. Coconut Creek (Florida), ISSN 0749-0208. Field surveys at Figueira da Foz coastal system, a jettied river-mouth located to the W of Portugal, show a high impact of storm events on the morphological evolution of the ebb-tidal delta, with formation of a submerged sandbar and the quick infill of dredged areas. Non-stormy wave conditions produce minor morphological changes. The morphodynamic modeling of this system is being done to support coastal management. The methodology uses Delft3D modeling system that was previously calibrated for this coastal region. Modeling scenarios are set by considering two initial bathymetric situations, i.e., with or without an excavation site resulting from dredging operation. In order to investigate the relations between the computational efficiency and the time series of the input wave data, some tests were performed including a month with a total of 70% of storms and other with 10%, approximately. For each period it was studied the whole month period and only the storms. Numerical results disclose similar patterns of morphological evolution for both complete and storm periods simulated. Nevertheless, the omission of lower wave energy conditions slightly covers up the volume of sediment accretion in the area. This volume of sediment accretion masking effect is higher in the dredging case study, since dredged area acts as a sink of sediment. The results demonstrated that morphodynamic simulations should include the whole set of waves recorded to achieve more accurate estimations of sediment transport rates and corresponding sediment balance. [ABSTRACT FROM AUTHOR]

Park, W.K.; Moon, Y.H.; Chang, S.Y.; Jeong, W.M.; Chae, J.W.; Ryu, K.H.; Chang, Y.S., and Jin, J.Y., 2018. Nonlinear Transformation of Storm Waves and Impacts on Nearshore Mound in 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. 1131–1135. Coconut Creek (Florida), ISSN 0749-0208. Haeundae beach is the most popular beach in South Korea which has been suffered from serious erosion problem. To protect the beach erosion, various countermeasures such as beach nourishments, submerged breakwaters and nearshore mound have been conducted. However during typhoon Chaba (1618), extreme storms caused significant beach erosions. Extensive field measurements have been made to monitor the storm impacts on the beach changes. This study focuses on (i) the nonlinear transformation of the very high waves over the submerged shoals in coastal waters and nearshore mound placed parallel to the shoreline, and (ii) the consequent morphological changes. For numerical modeling, SWAN was used for offshore wave propagation and XBeach of non-hydrostatic mode for hydrodynamics and sediment transport simulations. It is found that the storm waves were significantly transformed by submerged shoals through wave breaking due to the shallow water depth and generation of super harmonics with significant amount of wave energy transferred from the primary waves, and similar process occurred around the nearshore mound. Specifically, the impacts of the nearshore mound on beach evolution were pronounced for the beach erosion control with respect to wave energy dissipation, onshore sediment transport, and sediment trap in the lee of the mound. [ABSTRACT FROM AUTHOR]

Kim, H.J.; Cho, S.M., and Cho, W.C., 2018. Numerical analysis of beach erosion at Jeongdongjin Beach in South Korea using field survey and measurement data. 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. 596–600. Coconut Creek (Florida), ISSN 0749-0208. Recently, Jeongdongjin Beach in Gangneung, Gangwon–do, in the eastern part of South Korea, has been seriously eroded, and several parts of the revetments along the coast were subsided due to frequent high wave attacks. Thus, several parts of the Jeongdongjin rail bike track and facility in the southern part of Jeongdongjin station were damaged and washed out. In this study, field surveys and measurements (including waves, current, water depth, seabed material, beach profile, and shoreline) at Jeongdongjin Beach 2014–2015 were conducted to analyze and determine the erosion process. From the surveys and measurements, it reveals that longshore currents moving to the south and north are generated in winter and summer season due to dominant NE and ENE wave directions, respectively. Rip currents are also generated in several points near the coast due to waves coming from various directions and morphological characteristics. Beach erosion at the front of Jeongdongjin station has repeatedly occurred due to high wave attacks. Numerical simulations on the generation of long-shore current, sediment transport, and shoreline change were conducted using field data, and the erosion process at Jeongdongjin Beach was analyzed to determine the characteristics of seasonal longshore sediment transport and the effect of the construction of revetments to beach erosion. From these monitoring data and numerical results, the process of Jeongdongjin Beach erosion was predicted and beach maintenance and protection plans at Jeongdongjin Beach are established. [ABSTRACT FROM AUTHOR]

Ha, H.K.; Seo, J.Y.; Jung, Y.H.; Ha. H.J.; Kim, S.B.; Kang, J.W.; Kim, Y.H., and Ryu, J., 2018. Dynamics of sediment resuspension in the inner harbor under different forcing conditions: A case study of Ulsan, 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. 451–455. Coconut Creek (Florida), ISSN 0749-0208. Bottom mooring data of currents and backscatter strength derived from a 1200-kHz acoustic Doppler current profiler were collected in the inner Onsan Harbor, Ulsan during the summer season (July 5 to August 5, 2016). The mean volume backscattering strength (MVBS), which is a proxy of suspended sediment concentration (SSC), continued to exhibit distinct signatures of sediment erosion (or resuspension) under different forcing conditions such as tides, winds, and precipitation. Results exhibit the different patterns of sediment resuspension between spring and neap tides. During spring tide, the extensive tidal forcing provided a favorable condition to resuspend sediments trapped near the bed. The MVBS with high SSC was consistently recorded. During neap tide, on the other hand, the MVBS with high SSC was intermittently recorded, which was related to the strong wind events. While the flow was being intensified by winds, the short-lasting (2–4 hours) sharp spikes of MVBS were observed. The stratification developed by increased precipitation might cause to block the upward transport of sediments near the bed, even though the strong winds (>13.6 m s−1) lasted over 4 days. These outcomes could give insight into the complexity of hydrodynamics and sediment transport occurring in the harbor where various natural and artificial forcings are combined. [ABSTRACT FROM AUTHOR]