Van Wellen, E., 2019. Global Engineering Congress (GEC): Notes and goals from the 2018 conference. Journal of Coastal Research, 35(3), 485–488. Coconut Creek (Florida), ISSN 0749-0208.

From 22 October 2018 to 26 October 2018, the Institution of Civil Engineers (ICE) in London hosted the Global Engineering Congress (GEC). The GEC formed part of the ICE 200 bicentenary programme, the 50th anniversary of the World Federation of Engineering Organizations, and the UK Government's Year of Engineering. The Congress focused on five of the 17 global United Nations (UN) Sustainable Development Goals set in 2015. These five goals are inextricably linked with the world's coastal community and its environment. Using the numbering system of the UN, these five goals are: Clean Water and Sanitation (Goal 6); Affordable and Clean Energy (Goal 7); Industry, Innovation, and Infrastructure (Goal 9); Sustainable Cities and Communities (Goal 11); and Climate Action (Goal 13). They are absolutely vital for all of us, who as a global community, urgently need to take action on climate change and address issues such as delivering clean water to all, sustainable energy, and connectivity. This communication reports on the GEC and the role that the global coastal community can play and has to play in addressing the major issues at stake.

Xi, H.; Zhang, Z.; Lu, Y., and Li, Y., 2019. Long-term and interannual variation of the steric sea level in the South China Sea and the connection with ENSO. Journal of Coastal Research, 35(3), 489–498. Coconut Creek (Florida), ISSN 0749-0208.

Multisource observation and model data sets, including satellite altimetry, satellite gravimetry (the Gravity Recovery and Climate Experiment mission [GRACE]), ocean model (Estimation of the Circulation and Climate of the Ocean [ECCO]), and oceanographic reanalysis data (Ishii), are used to explore the long-term and interannual sea-level variation (SLV) in the South China Sea (SCS) and the connection with El Niño–Southern Oscillation (ENSO). From 1993 to 2012, the sea level rose at a rate of 4.7 ± 0.3 mm/y, and the steric component contributed approximately 40–55% of the increase shown in the Ishii data (1.9 ± 0.3 mm/y) and the ECCO model (2.6 ± 0.3 mm/yr). Using the GRACE observations from 2003 to 2012 for independent validation, the ECCO-derived steric trend was consistent with the mass-corrected altimetry result, whereas the Ishii data failed to capture the sea-level rise in the central basins. On the interannual scale, both the empirical orthogonal function (EOF) and the wavelet coherence (WTC) analysis indicate that the total SLV and the steric SLV have positive correlations with ENSO. The correlation is stronger between the Southern Oscillation index (SOI) and the ECCO-derived steric SLV than it is between the SOI and the Ishii-based steric SLV. In the time-frequency domain, the WTC shows a clear in-phase coherence in the 2-year cycle between the SOI and the ECCO-derived steric SLV over the entire time span; no significant coherence appears between the SOI and the Ishii-based steric SLV after 2003. The abnormal northerly winds and the increasing intrusion of low-temperature Kuroshio water into the SCS through the Luzon Strait during El Niño years may explain the connection between ENSO and the interannual steric SLV.

Wang, L.; Bianchette, T.A., and Liu, K.-b., 2019. Diatom evidence of a paleohurricane-induced coastal flooding event in Weeks Bay, Alabama, USA. Journal of Coastal Research, 35(3), 499–508. Coconut Creek (Florida), ISSN 0749-0208.

Sand layers deposited in coastal backbarrier lakes and marshes have been taken as indicators of overwash processes generated by hurricane landfalls, but sand layers discovered in sediments from non-backbarrier estuarine settings have not been as thoroughly investigated. Sedimentological and diatom analyses of a 44-cm core (WB 08-04) taken from a seep forest on the north shore of Weeks Bay in southern Alabama contains an 8-cm-thick sand layer embedded in dark gray peat. As an aid to determining the provenance of the sand layer, diatoms were also analyzed from eight surface samples taken from five nearby environments representing different salinity conditions. The diatom assemblage in the sand layer is dominated by acidophilous (Eunotia spp., Frustulia krammeri) and freshwater (Pinnularia neomajor, Pinnularia latevittata) species, suggesting that they were transported by fluvial processes from the acidic and freshwater bogs above the banks of Fish River. The sand layer also contains small percentages of brackish and marine diatoms (Tryblionella marginulata, Planothidium delicatulum), suggesting that incursion of seawater and brackish water from Weeks Bay and Mobile Bay also played a role in its deposition. It is inferred that the sand layer was deposited by a hurricane that brought both intense precipitation to coastal Alabama and a storm surge into Weeks Bay. Heavy rainfall caused overbank flooding of Fish River, which transported sand from the river banks and diatoms from nearby bogs to the coring site. Concurrently, storm surge waters also deposited marine and brackish diatoms at the site. Historical records suggest that the Bernard Romans' Gulf Coast Hurricane in AD 1772 may have been responsible for the flooding that resulted in the deposition of the sand layer.

Amos, C.L.; Christian, H.; Buckley, D.E., and Daborn, G.R., 2019. The stability, settling character, and strength of seabed sediments in the Miramichi estuary, Canada. Journal of Coastal Research, 35(3), 509–523. Coconut Creek (Florida), ISSN 0749-0208.

A survey of seabed stability was undertaken in the Miramichi estuary, New Brunswick, Canada: a region subject to intense industrial pollution, channel dredging and maintenance, and the passage of commercial ships. The estuary has a diverse fauna that has been described. The impact of natural and industrial activities on the indigenous fauna is largely unknown. Reworking of dredge spoil tailings has been considered the main cause of sediment dispersal in the system, yet there have been no direct measurements of this. As a result, a study was undertaken to determine the character and stability of dredge spoils and the natural estuarine sediments in which they sit, using the benthic flume Sea Carousel over the years 1991, 1993, and 1994. As well, a limited program of seabed and water column sampling and monitoring was undertaken using a variety of techniques in order to provide a setting for the measurements of stability. Results showed that tidal influence on resuspension was small compared with storm (and ship) waves and other “events” that appeared to be anthropogenic in origin. The erosional and depositional character of natural (control) sites were similar to those from other estuaries described in the literature despite the strong anthropogenic influences. Surprisingly, the strength of disposed dredge spoils (collected using a clam-shell bucket) was similar to the natural sediments at the control site, even after only a few hours of disposing. The stability of the disposed material did not change measurably after 1 year. The erosion flux (E) was found to be a power function of the excess bed shear stress: E = 1.9 × 10^-3(τ₀ – τ_c,z)^0.71 kg/m^2/s. The settling of eroded material took place as aggregates at a mean rate of 1.1 × 10^-3 m/s, which corresponds to a mean sedimentation diameter of 75 microns (very fine sand). The fluid mud potential of the system is low: laboratory settling experiments showed that suspended silts/clays underwent free settling at a rate proportional to initial concentration to a maximum concentration of 18 g/L; hindered settling (and fluid mud development) was evident above this value.

Xu, M.; Meng, K.; Zhao, Y., and Zhao, L., 2019. Sedimentary environment evolution in East China's coastal tidal flats: The North Jiangsu radial sand ridges. Journal of Coastal Research, 35(3), 524–533. Coconut Creek (Florida), ISSN 0749-0208.

The North Jiangsu radial sand ridges (NJRSR) are a unique sedimentary system comprising the largest silt and mud coastal tidal flat in China. Many factors influence its tidal geomorphology sensitivity when responding to the marine environment and human activities. In this study, three typical core samples were collected from sampling points near Xinyang Gang (XYG), Chuandong Gang (CDG), and Xiaoyangkou Gang (XYK). ²¹⁰Pb and ¹³⁷Cs radionuclide dating was used to estimate the sedimentation rate of the tidal flat. On the basis of combined sediment grain size and reclamation history over the last 50 years, the evolution of the NJRSR coastal tidal flat sedimentary environment under the impact of human activities and the changing coastal environment was examine. The result indicated that the predominant type of sedimentary deposition is sandy silt; however, sediment composition varies because of coastal reclamation activities extending into the sea and with changes in sediment source and depositional forces. Average sedimentation rates of the three core samples were 1.27, 1.85, and 2.43–3.3 cm/y, respectively, reflecting increasing sedimentation rates from north to south. However, sedimentation rates over the past century have gradually declined in core XYG because of a reduced supply of materials from northern sources. Moreover, sand content has increased in the north since the 1980s, and grain size has become coarser. In the middle sample, a sudden change in sediment composition occurred in the 1950s–60s, exhibited by a significant reduction in sand content but an increase in silt content and finer grain sizes. In the south, grain size coarsened initially before becoming finer, likely because of a reduction of eroded material from the Yellow River in the north, increased coastal reclamation activities, and changes in sedimentary dynamics.

Ajedegba, J.O.; Perotto-Baldivieso, H.L., and Jones, K.D., 2019. Coastal dune vegetation resilience on South Padre Island, Texas: A spatiotemporal evaluation of the landscape structure. Journal of Coastal Research, 35(3), 534–544. Coconut Creek (Florida), ISSN 0749-0208.

Vegetation is critical for coastal dune building and stabilization. However, dune vegetation can suffer significant damage from coastal hazards such as hurricanes, anthropogenic disturbances, and tidal flooding. The goal of this study was to evaluate the spatiotemporal dynamics of dune vegetation at South Padre Island, Texas, and to use changes in the landscape structure to better understand dune vegetation recovery from the impact of the 2008 Hurricane Dolly and overall dune vegetation resilience. Remotely sensed imagery was used in the format that was publicly available as Digital Orthophoto Quarterly Quadrangles captured from 1996 to 2016. Landscape metrics were used to quantify dune vegetation spatial structure and changes in the amount of and spatial distribution of dune vegetation. Results from classified images before and after Hurricane Dolly showed only a 5% decrease in dune vegetation cover in the 0.5-km² study area; however, there was a 48% decrease in patch density (from 6890 patches/100 ha to 3589 patches/100 ha) and a 25% decrease in edge density (from 2035 m/ha to 1521 m/ha), respectively. The less aggregated vegetation on the seaward side was more vulnerable to hurricane impact than the larger and more aggregated patches shielded by the crests of foredunes. Despite the disturbance of the 2008 Hurricane Dolly, vegetation cover in this dune region gradually increased by 38% from 1996 to 2016. Aggregation and the largest patch indices also increased during this period. Patch density decreased between 2004 (10,075 patches/100 ha) and 2016 (3605 patches /100 ha) after an initial increase from 1996 (3594 patches/100 ha). Growth trends pre– and post–Hurricane Dolly were strongly correlated, suggesting dune vegetation recovery and resilience. Overall, South Padre Island dune vegetation has appeared to maintain a steady increase in productivity over the last two decades regardless of routine tidal incursions.

Ragan, A.N. and Wozniak, J.R., 2019. Linking hydrologic connectivity in salt marsh ponds to fish assemblages across a heterogenous coastal habitat. Journal of Coastal Research, 35(3), 545–558. Coconut Creek (Florida), ISSN 0749-0208.

In estuarine systems, inundation regime plays a vital role in shaping the physical and chemical characteristics of salt marsh ponds. Along the Texas Gulf Coast, salt marsh ponds are scattered across the coastal marsh landscape, with each pond possessing a varying degree of hydrological connectivity to adjacent estuarine waters. The timing, frequency, and magnitude of connection events can directly influence both the abiotic and biotic components of the ponds. To determine how the degree of hydrological connectivity impacts these systems, discriminant function analysis (DFA) was used to test the ability of environmental variables (e.g., pond size, vegetation, soil type, water column salinity, pH, dissolved oxygen, etc.), fish presence–absence data, and fish relative abundances to predict the level of connectivity of a subset of ponds. In addition, canonical correspondence analysis (CCA) was used to determine whether fish assemblage data (collected via seine and minnow traps) could determine whether pond conditions affect the composition of fish assemblages. Results from the DFA for environmental parameters showed that the model classified ponds correctly to their a priori connectivity classifications; however, no more accurately than random chance. Fish presence–absence data were the least accurate for predicting degree of connectivity, but the relative abundances of those species proved to be an accurate method for pond connectivity classification. Many efforts to understand how an altered hydroperiod impacts marsh complexes along the Texas Gulf Coast have focused on tidal creeks and the vegetated portions of open marshes rather than salt marsh ponds, which can be key habitats for both primary and secondary productivity. This study concentrates on salt marsh ponds to provide a better understanding of how these ecosystems function within the greater marsh landscape.

Choi, Y.H.; Jeong, D.U.; Lee, Y.G.; Choi, J.U.; Kim, S., and Lee, J.S., 2019. Opportunistic species and seasonal variation in epiphytic foraminiferal assemblages in abalone farm nets. Journal of Coastal Research, 35(3), 559–573. Coconut Creek (Florida), ISSN 0749-0208.

Monitoring of dissolved oxygen (DO), temperature, and epiphytic foraminifera on seagrass in the nets of abalone farms in three areas (Haenam, Pyeongildo, Soando) with different seawater movement was conducted between April 2016 and January 2017. The aim was to identify the opportunistic species, seasonal variation, relationships with DO, and temperature of epiphytic foraminiferal assemblages under environmental conditions affected by the biodeposits discharged from abalone farming. The results showed that the highest relative abundance of epiphytic foraminifera occurred in September (22.96°C), although the temperature was highest in August (24.37°C); this may be related to the consistently stable high temperatures during this time (22–23°C). There was no direct relationship between DO and epiphytic foraminiferal assemblages. Rosalina bradyi (frequency: 78.6%; species diversity: 0.96; distributed across three areas in July) was found to be an opportunistic species for nutrient enrichment discharged from abalone farming. Epiphytic foraminiferal assemblages of the three areas were varied, from the R. bradyi assemblage in July, to the R. bradyi–Cornuspira involvens or R. bradyi–Murrayinella minuta assemblages in August and September, and to the Glabratella sp.–R. bradyi or Epistominella naraensis–R. bradyi assemblages of January. Species diversity was also increased. It is thought that this seasonal variation in epiphytic foraminiferal assemblages may be a process needed to maintain a stable epibiosis in epiphytic foraminifera.

Narra, P.; Coelho, C.; Sancho, F.; Escudero, M., and Silva, R., 2019. Coastal hazard assessments for sandy coasts: Appraisal of five methodologies. Journal of Coastal Research, 35(3), 574–589. Coconut Creek (Florida), ISSN 0749-0208.

The acceptable development of coastal areas requires thorough and comprehensive management processes. In this context, the evaluation and identification of areas endangered by coastal hazards is fundamental for an appropriate implementation of coastal zone management plans, in which coastal hazard assessment methodologies become a vital tool for the identification and classification of the littoral lands. This work presents an overview of five coastal hazard assessment methods that are currently available. The objective is to provide coastal managers an understanding of the most adequate approaches to apply in specific areas, taking into consideration the basis of each method and the user purpose. Furthermore, this work also aims to be a guide for the application of the featured methodologies. The work focuses on coastal erosion; therefore, all methods discussed (coastal erosion risk assessment, coastal vulnerability index, Smartline, Coastal Hazard Wheel, and the RISC-KIT Coastal Hazard Assessment module) include coastal erosion in their assessments. A total of nine coastal hazard assessments were performed in three different study areas (Aveiro, Portugal; Macaneta, Mozambique; Quintana Roo, Mexico). The procedure for each appraisal and the data collected for each study area are presented here, as well as the results obtained. Each methodology has an ideal set of conditions for its application, varying in the ease of application and the data requirements. Despite that, most methods agree in the identification of the most endangered areas in each study site.

Childers, D.P.; Madsen, J.A.; Krantz, D.E., and Deliberty, T.L., 2019. Constraining the geometry of subsurface paleochannels beneath Delaware Bay and the Mid-Atlantic inner continental shelf. Journal of Coastal Research, 35(3), 590–599. Coconut Creek (Florida), ISSN 0749-0208.

This study improves the understanding of paleochannels underlying Delaware Bay and the Mid-Atlantic inner continental shelf. Major surfaces interpreted from analog seismic profiles were used in ArcGIS™ to create a three-dimensional (3D) model in ArcScene™ that constrains the geometry and relative age relationships of the paleochannels. Interpolation with kriging in the Geostatistical Analyst tool in ArcGIS was used to generate spatial models that were imported into ArcScene to create 3D perspective views of the primary subsurface features. The results better constrain the geometry of previously mapped paleochannels. These revisions enhance the understanding of the Quaternary geologic evolution of the region in response to sea-level fluctuations. A new nomenclature for previously named paleochannels is proposed based on their relative age relationships. The Central (renamed as Q_c1) paleochannel in Delaware Bay is identified as the youngest and continues onto the inner shelf trending SE approximately 50 km across the shelf and then eastward toward Baltimore Canyon. The next oldest Delaware Bay paleochannel, the Southern (Q_c2) paleochannel, correlates with the previously identified Orange (Q_c2) paleochannel and also trends toward Baltimore Canyon. The oldest paleochannel in the Bay, the Northern (Q_c3) paleochannel, is projected beneath the tip of Cape May, New Jersey, and continues on the inner shelf as the earlier defined Green (Q_c3) paleochannel.

Zhou, Y. and Voyiadjis, G.Z., 2019. Finite element modeling of production-induced compaction and subsidence in a reservoir along coastal Louisiana. Journal of Coastal Research, 35(3), 600–614. Coconut Creek (Florida), ISSN 0749-0208.

Subsidence has caused significant wetland losses in coastal Louisiana because of various anthropogenic and geological processes. Releveling data from the National Geodetic Survey show that one of the governing factors in subsidence in coastal Louisiana is hydrocarbon production, which has led to the acceleration of spatial- and temporal-dependent subsidence. The production-induced reservoir compaction and land subsidence are investigated for a typical reservoir in the Valentine field in coastal Louisiana, for three cases within the framework of homogeneous poroelasticity, inhomogeneous poroelasticity, and inhomogeneous poroplasticity. The observed subsidence is first interpreted by the Geertsma analytical model for a disk-shaped reservoir embedded in a semi-infinite homogeneous elastic medium and then by an analytical inhomogeneous poroelastic model that considers layered stratigraphy. A three-dimensional uncoupled finite element model is set up and validated against the two analytical poroelastic models. A modified Cam-Clay model is then adopted to account for the plastic compaction of the reservoir in an inhomogeneous poroplastic case. The material properties are calibrated based on the subsidence in the field and available geomechanical data in other reservoirs in the Gulf of Mexico. The observed trend and magnitude of subsidence in the Valentine field can be approximately interpreted through finite element modeling in all the three cases after calibration. It is inferred that the governing compaction mechanism is plastic deformation instead of elastic deformation during fluid production in the Valentine field. The ratio of subsidence over compaction generally varies with different compaction mechanisms. The finite element models presented in this study can be applied to evaluate the production-induced compaction and subsidence in other reservoirs, and the results could be potentially useful to coastal restoration and management.

Li, D.; Tang, C.; Hou, X., and Zhang, H., 2019. Rapid morphological changes caused by intensive coastal development in Longkou Bay, China. Journal of Coastal Research, 35(3), 615–624. Coconut Creek (Florida), ISSN 0749-0208.

Analyses of the evolution of subaqueous topography in coastal water provide an understanding of the effects of intensive coastal development on bays and estuaries. Analysis of a series of historical bathymetric acoustic surveys has revealed large changes in morphology from the 1960s to 2010s in Longkou Bay, China. Water depths were extracted from digitized admiralty charts to explore the accretion-erosion characteristics in a geographical information system environment, providing quantitative estimates of morphological changes. Multibeam echosounders were used to map and analyze the geomorphologic features caused by the construction of artificial islands. Results illustrated that the shoreline and bathymetry of Longkou Bay have changed rapidly in recent decades. The subaqueous area decreased by about 15%, while land area increased by more than 13 km² in the study area during the last 50 years. From the 1960s to 1990s, the evolution of Longkou Bay was mainly governed by natural processes with a patchy distribution of deposition and erosion, and there were few signs of change related to large-scale human activities. During the period from the 1990s to 2010s, intensive coastal developments, including large port engineering projects, channel dredging, and construction of artificial islands, became the main processes affecting morphological changes in Longkou Bay. The high-resolution bathymetric results near the artificial island showed that the seafloor was dredged at many sites, leaving large areas of borrow pits. The sudden change of the underwater topography will lead to the destruction of local benthic habitat, and effective measures need to be taken to protect and remediate the heavily disturbed subaqueous environment.

Duan, L.; Jeng, D.-S.; Wang, S., and Zhu, B., 2019. Numerical investigation of the wave/current–induced responses of transient soil around a square mono-pile foundation. Journal of Coastal Research, 35(3), 625–636. Coconut Creek (Florida), ISSN 0749-0208.

A mono-pile foundation is a commonly used supporting base for marine infrastructure in shallow water, such as offshore wind turbine foundations and cross-sea bridges and platforms. Sea floor instability around a pile foundation has attracted much attention among offshore geotechnical engineers. In this paper, a three-dimensional numerical model for wave–seabed–structure interactions is proposed using open field operation and manipulation (OpenFOAM). Unlike previous studies, currents are included in the proposed model and applied to a square cross-section mono-pile foundation. In the model, the flow motion is described by the Reynolds-averaged Navier–Stokes (RANS) equation and k–ϵ turbulence model, and the water free surface is tracked using the volume of fluid (VOF) method. Meanwhile, the soil response is determined by the Biot's poro-elastic equation (u–p approximation), in which the accelerations of the soil displacements are included. After the model is validated with the previous laboratory experiments, it is further used to investigate the transient soil response around the square mono-pile foundation. Numerical results demonstrate that the cross-section shape has significant influence on the distribution of wave/current–induced transient pore pressure but little influence on the maximum soil liquefaction depth. On the other hand, both the current velocity and the seabed permeability can greatly affect the maximum soil liquefaction depth and slightly affect the distribution of pore pressure. Furthermore, the cross-section dimension significantly affects both the maximum soil liquefaction depth and the distribution of the pore pressure around a mono-pile foundation.

Bong, T.; Son, Y., and Kim, K.-S., 2019. Experimental modeling of suspended sediment transport considering the flow rate and grain size. Journal of Coastal Research, 35(3), 637–647. Coconut Creek (Florida), ISSN 0749-0208.

In this study, laboratory sediment disposal tests were performed using an open channel, and the behavior of soil particles underwater was analyzed according to flow rate and grain size. For each grain size, the deposition distributions of soil particles were demonstrated to have log-normal distributions regardless of the flow rate. The relationships between the average and standard deviation of the deposition distance and the flow rate can be expressed using a quadratic regression equation, and the relationships between the average and standard deviation of deposition distance and the grain size can be expressed using a two-term exponential decay equation. As a result, a simple experimental model was proposed for predicting the soil transportation and deposition distribution considering the flow rate and grain size. The proposed model was validated by comparison with the test results for each grain size and a mixed soil, which was collected from another area, and the proposed model showed good agreement with the experimental results.

Williams, A.T. and Rangel-Buitrago, N., 2019. Marine litter: Solutions for a major environmental problem. Journal of Coastal Research, 35(3), 648–663. Coconut Creek (Florida), ISSN 0749-0208.

A current major environmental problem is that marine litter is being deposited in increasing amounts on the world's beaches and oceans. This is especially true for plastics, which form the bulk of the litter and which can last for an unknown number of years in the oceans. This article concerns itself with some solutions that can be applied to this problem. The standard responses involve cutting down plastic waste at the source, beach cleanups, use of the circular economy, education, and a reduction in packaging, among other solutions. Knowledge, prevention, mitigation, removal, and behavioural change are the key mandates involving a host of measures, ranging from politics, behaviour change, and radiation of plastic by gamma rays in order to strengthen concrete, to turning plastics into fashion items, furniture, bedding, and clothes, amongst many others. Collaboration is the key.

Jin, G.; Mo, Y.; Li, M.; Tang, H.; Qi, Y.; Li, L., and Barry, D.A., 2019. Desalinization and salinization: A review of major challenges for coastal reservoirs. Journal of Coastal Research, 35(3), 664–672. Coconut Creek (Florida), ISSN 0749-0208.

Coastal reservoirs are a possible solution to water supply and management issues in coastal zones. However, salinization can degrade the utility of such reservoirs. Two related major challenges affecting the operation of a coastal reservoir are desalinization and seawater intrusion. The former arises mainly during the period following reservoir construction, while the latter is ongoing. This review discusses the salt dynamics of coastal reservoirs under the influence of surface-water flows, river inflows, reservoir water level, and tides. Various salt transport processes are examined in relation to water salinity changes in coastal reservoirs. The methods and limitations of existing numerical models for coastal reservoirs are also discussed. Given the difficulty in reproducing realistic boundary conditions for laboratory experiments, further research needs to focus on investigations that consider salinization in real coastal reservoirs. More broadly, there remains a need to unravel the impacts of coastal reservoirs on the surrounding environment, as they can significantly change the hydrodynamics and chemical transport pathways in coastal waters. A comprehensive understanding of coastal reservoir salinization will improve water management and thus contribute to alleviating overexploitation of water resources in coastal zones.

Nahirnick, N.K.; Hunter, P.; Costa, M.; Schroeder, S., and Sharma, T., 2019. Benefits and challenges of UAS imagery for eelgrass (Zostera marina) mapping in small estuaries of the Canadian West Coast. Journal of Coastal Research, 35(3), 673–683. Coconut Creek (Florida), ISSN 0749-0208.

Seagrasses are a fundamental component of nearshore marine habitats, and as such, concerted effort has been put into developing remote sensing methods to assess the spatial coverage of these important habitats. However, in small coastal bays, traditional aerial or satellite remote sensing can be cost-prohibitive or lack sufficient spatial resolution to detect the small, fringing, and often patchy eelgrass (Zostera marina) meadows. This paper presents a method for collection and processing of unoccupied aerial system (UAS) imagery used to map eelgrass at three small coastal estuaries in the Salish Sea of British Columbia. A low-cost, consumer-grade UAS platform equipped with a GoPro Hero 3+ was used to acquire images with a ground resolution of 2 cm, which were postprocessed using structure-from-motion techniques into georeferenced orthomosaics. A manual classification approach incorporating segmented image objects was used to classify eelgrass on a presence or absence basis, resulting in overall mapping accuracies of 96.3%, 86.5%, and 89.7%, as determined by field validation using kayak videography. The major benefit of this method was fine spatial resolution that allowed for textural discrimination between spectrally similar species. However, eelgrass detection and overall accuracy was found to be highly influenced by the environmental conditions at the time of image acquisition.

Sun, Z.-l.; Gao, Y.; Xu, D.; Hu, C.-h.; Fang, H.-w., and Xu, Y.-p., 2019. A new formula for the transport capacity of nonuniform suspended sediment in estuaries. Journal of Coastal Research, 35(3), 684–692. Coconut Creek (Florida), ISSN 0749-0208.

A new formula for calculating the sediment transport capacity is developed as a function of the time-dependent Froude number and the particle Reynolds number. Considering the relation between suspension and transport of sediment, a critical condition for suspension is introduced into the formula. The proposed formula provides a consistent formulation for the fractional and total transport capacity of nonuniform sediments and leads to an expression for the mean fall velocity that makes physical sense. The coefficients in the proposed formula were determined with laboratory data of uniform sediment, and it is verified by field data measured from alluvial rivers. The concept of instantaneous equilibrium was proposed so that applicability of the formula extended to estuaries. The results show that the present formula performs well in conditions of laboratories, rivers, and estuaries. This can provide a key parameter or bottom boundary condition for two-dimensional/three-dimensional mathematical models of nonuniform sediment.

Wang, G.; Liang, Q.; Zheng, J., and Wan, P., 2019. A new multilayer nonhydrostatic formulation for surface water waves. Journal of Coastal Research, 35(3), 693–710. Coconut Creek (Florida), ISSN 0749-0208.

This work presents a new multilayer nonhydrostatic formulation for surface water waves. The new governing equations define velocities and pressure at an arbitrary location of a vertical layer and only contain spatial derivatives of maximum second order. Stoke-type Fourier and shoaling analyses are carried out to scrutinize the mathematical properties of the new formulation, subsequently optimizing the representative interface and the location to define variables in each layer to improve model accuracy. Following the analysis, the one-layer model exhibits accurate linear and nonlinear characteristics up to kd = π, demonstrating similar solution accuracy to the existing second-order Boussinesq-type models. The two-layer model with optimized coefficients can maintain its linear and nonlinear accuracy up to kd = 4π, which boasts of better solution accuracy a larger application range than most existing fourth-order Boussinesq model and two-layer Boussinesq models. The three-layer model presents accurate linear and nonlinear characteristics up to kd = 10π, effectively removing any shallow water limitation. The current multilayer nonhydrostatic water wave model does not predefine the vertical flow structures, and more accurate vertical velocity distributions can be obtained by considering the velocity profiles in coefficient optimization.

Yin, Z.; Wang, Y., and Yang, X., 2019. Regular wave run-up attenuation on a slope by emergent rigid vegetation. Journal of Coastal Research, 35(3), 711–718. Coconut Creek (Florida), ISSN 0749-0208.

Coastal vegetation can reduce wave run-up on a beach so as to protect coastal structures and humans. The regular wave run-up attenuation on a slope with emergent rigid vegetation idealized by vertical cylinders was investigated experimentally and numerically. A series of physical experiments and a mathematical model coupling the Reynolds-averaged Navier-Stokes equations, the renormalization group k-ϵ equations, and the volume of fluid technique were conducted, and the numerical wave surface exhibited good agreement with the experimental data. The relationships of relative maximum wave run-up R_sc/H and the cylinder effect of wave attenuation on slope K were examined with the slope ratio, wave steepness, and relative distance from cylinders to slope toe. It was found that R_sc/H and K increased with increasing slope ratio, respectively, and increased with decreasing incident wave steepness, respectively. In addition, R_sc/H (K) decreased (increased) with an increase in relative horizontal distance between the closest cylinders and the slope toe. Simple formulas for R_sc/H and K were proposed using dimensional analysis and least squares methods validated well with the experimental data.

Park, Y.H.; Oh, Y.-M.; Ahn, S.M.; Han, T.H.; Kim, Y.-T.; Suh, K.-D., and Won, D., 2019. Development of a new concrete armor unit for high waves. Journal of Coastal Research, 35(3), 719–728. Coconut Creek (Florida), ISSN 0749-0208.

Hundreds of new concrete armor units (CAUs) have been developed since 1950, but only a few have been used because of their low price and familiarity. Because the design wave height has been increasing as a result of climate change, the Korean government decided to develop a new CAU for protection against high waves. Therefore, a new research project to develop a new CAU that considers stability, structural strength, economic feasibility, casting efficiency, and constructability was started. The new CAU was called Chi Block. The hydraulic stability achieved a Hudson stability coefficient of more than 13 at a significant wave height of 10 m by adopting a conservative approach. Chi Block can be installed in both uniform and random placements and can be used as an overlay for repair. A new placement for Chi Block was invented, and it features the advantage of functioning like a 1.5 layer. Although a single layer generally has a higher overtopping rate than a double layer, Chi Block, on uniform placement, has a performance near that of the Tetrapod.