Finkl, C.W. and Makowski, C., 2020. Latitudinal and situational zonation of coastal catenary sequences observed from satellite images using the Biophysical Cross-shore Classification System (BCCS). Journal of Coastal Research, 36(2), 205–217. Coconut Creek (Florida), ISSN 0749-0208.

The Biophysical Cross-shore Classification System (BCCS) was devised as a means for assessing shore-normal ecological and geomorphological successions from offshore to onshore transects within a coastal belt (Finkl and Makowski, 2020). The three-dimensional transects were parameterized in terms of alongshore length, cross-shore width, and depth below or elevation above sea level to codify environments and habitats in the framework of the BCCS. Repetitive ecological successions were so prominent that they were identified as archetypes, which included Barrier, Beach, Beach Ridge, Cliff, Coral Reef, Delta, Dune, Flat, Ice, Lagoon, Mountain, Rock, Till (glacial material), Upland, and Wetland. By sequentially linking together several archetypes based on a cross-shore ecological interpretation of the satellite imagery, a common master sequence is generated and referred to as a Dominant Catenary Sequence (DCS; e.g., Beach-Dune-Wetland). The more detailed Coastal Ecological Sequence (CES) of a coastal belt, which is defined by a discrete codification sequence built up from the DCS, is formulated by cognitive geovisual-analytics to link the dominant catena with a numbered shore-parallel shape distinction and subscripted sub archetypes to refine the sequential composite archetypes in a DCS. Once the CES has been established, a more thorough header and extended caption can then be composed to disseminate details of the geomorphological-ecological zonation within the geographical purview of latitude, elevation, and situational aspects that can be site-parameterized in terms of intensity of precipitation, temperature, humidity, exposure, windiness, presence of flora and fauna, etc. Examples of the BCCS on coastal belts dominated by cliff archetypes are provided in this study through a three-tiered process: Level I: DCS creation; Level II: CES formulation; and Level III: header and extended caption composition. Different latitudes and geographical-biophysical positions illustrate the ubiquity and applicability of identical DCS for broadscale cross-shore characterization of coastal belts, while more detailed ecological definitions are provided by larger-scale (smaller-area) observation of the same types of catenary cross sections for comparative purposes. Derivation of variable CES within identical DCS emphasizes the utility of this cross-shore classification system as it pertains to latitudinal and situational zonation. In this way, variable manifestations of coastal zonation are accommodated in the BCCS for both alongshore and cross-shore coastal belts worldwide.

Guo, J.; Sun, Y.; Mi, D., and Qin, C., 2020. Differential responses of bacterial communities inhabiting pristine and industrially polluted sediment from oil spills along Dalian, China. Journal of Coastal Research, 36(2), 218–227. Coconut Creek (Florida), ISSN 0749-0208.

Several studies have compared bacterial communities between polluted and unpolluted areas, but few have investigated the responses of bacterial communities in different habitat types to oil spills. This work monitored the responses of bacterial communities inhabiting pristine area (PA) and chronically industrially polluted (CI) sites in Dalian, China, and compared them with background samples at other sites through next-generation sequencing. The PA site had a significantly lower Shannon index than the CI site before the oil spill, but it significantly increased after the oil spill. The community structure also dramatically changed after the oil spill, with the abundance of several classes significantly increasing within 3 weeks, although these differed between the PA and the CI sites. By two calculation strategies, 15 oil-induced genera were identified, most of which have been proved in other studies. However, these genera had inconsistent responses depending on the background pollution level. Alcanivorax, Cycloclasticus, Erythrobacter, Glaciecola, Granulosicoccus, and Maribacter were the majorly induced taxa at the PA site, whereas Granulosicoccus and Maribacter were the predominantly induced taxa at the CI site after the oil spill. These findings will help develop niche-targeting bioremediation strategies for oil spills in different habitat types.

Xi, H.; Zhang, Z., and Lu, Y., 2020. A quasi-decadal oscillation of sea-level variation in the South China Sea. Journal of Coastal Research, 36(2), 228–237. Coconut Creek (Florida), ISSN 0749-0208.

To investigate the sea-level variation (SLV) in the South China Sea (SCS), independent multisource datasets, including observations from satellite altimetry and satellite gravity missions, sea-level reconstruction data, tide gauge data, and ocean model and oceanographic temperature and salinity observation, are used. Fast Fourier transform analysis indicates that the SLV and its steric component appear to exhibit significant quasi-decadal oscillation. Cross wavelet and wavelet coherence analysis show that high common power and significant antiphase coherence appear between the Pacific decadal oscillation (PDO) and steric SLV at the decadal scale. High common power also exists between the sunspot cycles and the steric SLV, but with in-phase coherence. Further analysis shows that the impacts of both PDO and sunspot activity on the sea surface temperature are more significant than those on the sea surface salinity. As a result, the quasi-decadal oscillation in the SLV of the SCS is associated with PDO and with the solar activity represented by the sunspot. It is useful to understand the mechanism of the rising sea level.

Dodge-Wan, D. and Nagarajan, R., 2020. Boring of intertidal sandstones by isopod Sphaeroma triste in NW Borneo (Sarawak, Malaysia). Journal of Coastal Research, 36(2), 238–248. Coconut Creek (Florida), ISSN 0749-0208.

Sphaeromatid isopods are known for their ability to bore into wood and friable rock and to cause damage to mangrove plant roots, wooden structures, and polystyrene dock floats in the intertidal zone. The ability of isopods to bore extensively into rock and accelerate coastal erosion is less well known and has not been previously reported in Malaysia. This study investigated the presence, the identity, and the erosive effect of rock-boring isopods in sandstones of the NW Borneo coastal region (Sarawak, East Malaysia). A multidisciplinary approach was used, including field and laboratory observations (geological and biological) of rocks and wood. This study revealed that abundant cylindrical borings in soft intertidal rock are created by the boring isopod Sphaeroma triste (S. triste). Bioerosion by this species can result in the direct removal of up to 50% of the exposed surface of the rock and penetrate the rock up to a few centimeters depth. This has a significant but localised impact on coastal erosion, contributing to the development of concavities in the rock, enlargement of joints, deepening of wave cut notches, widening of rock pools, and erosion of fallen blocks and sea-cave walls. There is evidence of modification of the isopods' mandible incisor processes by abrasion during rock boring. Although several Sphaeromatid species are known to bore into soft rocks, this is the first report and comprehensive description of boring into sandstone substrates by S. triste. The S. triste borings are compared with those made by other species reported elsewhere. In terms of neoichnology, the borings belong to deep-tier Trypanites ichnofacies, and fossil equivalents may be useful in palaeogeographic reconstructions of ancient shorelines, although they may have poor preservation potential.

Mylroie, J.; Lace, M.; Albury, N., and Mylroie, J., 2020. Flank margin caves and the position of mid- to late Pleistocene sea level in the Bahamas. Journal of Coastal Research, 36(2), 249–260. Coconut Creek (Florida), ISSN 0749-0208.

The Bahamian Archipelago has abundant fossil coral reefs and related subtidal deposits as evidence of the last interglacial (marine isotope stage [MIS] 5e) sea-level highstand; evidence of earlier highstands from the mid-Pleistocene is limited and controversial (excepting Mayaguana Island). Data from flank margin cave elevations, used as a sea-level proxy, were initially interpreted to demonstrate an MIS 5e origin derived from ∼60 mapped caves across the archipelago. A new analysis of cave morphologies and distribution has now produced 363 maps of flank margin caves, demonstrating for the first time that 26 caves with associated elevations between +8 and +24 m above modern sea level are found spanning the northwest to the southeast boundaries of the archipelago. Flank margin caves are the primary remaining evidence of past sea-level position, because almost all mid-Pleistocene subtidal deposits, and related sea-level indicators such as subtidal facies, sea caves, and bioerosion notches, have been removed by karst denudation. Cave elevations up to 24 m (above sea level) indicate that prior assumptions as to the rate of subsidence of the Bahama Banks at 1–2 m per 100 ka may not be correct. The activity of MIS 5e was recent enough, and its subtidal deposits voluminous enough, to survive to the present, along with the majority of flank margin caves formed at that time. Karst denudation may have created sufficient mass loss that isostatic subsidence stopped, or was possibly reversed, as has been demonstrated for the Florida peninsula. If true, then mid-Pleistocene flank margin caves may not represent eustatic sea-level position at the time of speleogenesis.

Song, Y.; Li, D., and Hou, X., 2020. Characteristics of mainland coastline changes in Southeast Asia during the 21st century. Journal of Coastal Research, 36(2), 261–275. Coconut Creek (Florida), ISSN 0749-0208.

Based on multitemporal Landsat images covering the entire coastal zone, a visual interpretation method was adopted to extract the coastlines of mainland Southeast Asia (MSA) in 2000 and 2015 referencing Google Earth images and global distribution of mangrove data. Coastline structures, coastline fractal dimensions, coastline change rates, and patterns of land–sea interchange were analyzed to reveal the spatial–temporal characteristics of mainland coastline changes in the 21st century. The results showed that (1) during the past 15 years, the length and percentage of natural coastline decreased from 15,440.24 km (83.33%) to 14,909.75 km (78.91%) and artificial coastlines increased at an average growth rate of 29.04% from 3088.79 to 3985.89 km; (2) the fractal dimensions of most areas in MSA tended to increase under interference driven by human activities, and the coastline morphology became more complex overall; (3) coastlines had obvious evolution, in which 18.54% of the coastline advanced toward the sea and 11.25% retreated toward land at average rates of +20.36 and –15.41 m.a^–1, respectively; and (4) the number of patches representing land–sea interchange reached 6607 so that the net land expansion area was 534.25 km² and among these regions, those larger than 1 km² accounted for only a small percentage (2.54%) of the total number but 79.41% of the total area. These hot spots were mainly concentrated in Myanmar, followed by Vietnam and Malaysia. Overall, the coastline of MSA was characterized by rapid artificial growth but still had a high percentage of naturalization. When it comes to developing the marine economy and addressing the ecological risk, the intensity of utilization and hardening of the coastline will likely increase.

Dye, B.; Jose, F., and Allahdadi, M.N., 2020. Circulation dynamics and seasonal variability for the Charlotte Harbor Estuary, Southwest Florida coast. Journal of Coastal Research, 36(2), 276–288. Coconut Creek (Florida), ISSN 0749-0208.

A hydrodynamic model was developed and validated for the Charlotte Harbor estuarine system, located in SW Florida, to elucidate freshwater fluxes within the system's various inlets during diverse hydrologic conditions. Fresh water entering the system not only varies seasonally but also, because of regulatory fresh water, releases controlling water levels within an upstream lake. The unnatural freshwater releases have been found to negatively affect the system's ecology, in particular within the Caloosahatchee River portion of the system. Neither the flood nor ebb phase exhibits uniform dominance in flushing the system's four major passes. Boca Grande Pass and Big Carlos Pass were mostly ebb dominant, whereas San Carlos Bay was largely flood dominant; neither phase dominated at Captiva Pass. The similarities and/or contradictions of these results in comparison to former field and modeling results are mainly attributed to the differences between the freshwater sources and environmental forces corresponding to each study that forces a different mass-balance condition over the estuary-bay system and, thereby, at each individual inlet. A Lagrangian particle tracking study revealed particles released within the Peace River during different hydrological conditions were comparably transported regardless of freshwater inputs and predominate wind direction. In contrast, particles released within the Caloosahatchee River were flushed into the Gulf of Mexico within 10 days during a usually wet El Niño, dry (November–April) season period whereas during the summer wet (May–October) season released particles remained in the estuary for a longer period (13 days), ultimately resulting in their further transport into Pine Island Sound and Matlacha Pass. The results also demonstrate the effect of freshwater river inputs and wind on the travel time of the neutrally buoyant particles within the estuarine system. The hydrodynamic and coupled particle tracking model serve as the first step in a forthcoming larval transport modeling study.

Kim, S.; Pyeon, Y.; Lee, K.; Kim, P.; Oh, W., and Choi, J.H., 2020. Visualization of rotational swimming patterns in oblate jellyfish. Journal of Coastal Research, 36(2), 289–294. Coconut Creek (Florida), ISSN 0749-0208.

To identify the swimming mechanism of jellyfish, the present study conducted observational experiments using particle image velocimetry in a relatively flat and oblate-shaped jellyfish, the moon jellyfish (Aurelia aurita). The formation of vortices around the left and right edges of the jellyfish's bell and the associated vorticity structures that formed during rotational swimming were analyzed. The effects of variation in the width-to-height ratio of the jellyfish during rotational swimming were also investigated. Moon jellyfish generated locomotor structures with velocities faster than their neighboring flow velocities by producing paddling motions at the left and right edges of the bell at width-to-height ratios more than 0.531. Faster locomotor structures were not observed at width-to-height ratios less than 0.496. Moreover, jellyfish tended to rotate in a counterclockwise direction from the central axis of the body. With respect to paddling speed, and according to changes in the width-to-height ratio, the left edge was, on average, 25% faster than the right edge. The left edge, where the central axis of rotation is located, exhibited a 40% reduction in its rotational angle when paddling speed was decreased by 87%. This study lays the methodological foundation for further studies to investigate how variation in environmental conditions affect jellyfish locomotion and how locomotion varies among species.

Dai, W.; Bilal, A.; Xie, Q.; Ahmad, I., and Joshi, I., 2020. Numerical modeling for hydrodynamics and near-surface flow patterns of a tidal confluence. Journal of Coastal Research, 36(2), 295–312. Coconut Creek (Florida), ISSN 0749-0208.

Because of the flow influx of tributaries, a confluence forms a unique environment carrying interesting hydrodynamic features and other attributes. The understanding of flow behavior here is important, particularly if it is on a tidally influenced channel in a harbor metropolitan. Because of communal requirements, there is a possibility of building wading structures, which may interplay with the flow in this zone. The knowledge of unidirectional river or flume confluences so far is not readily applicable for similar features in channels near coastal areas that have tidal flow in addition to river runoff. In this study, a tidal confluence that has a highly dynamic bidirectional flow is investigated. Near-surface flow patterns in a tidal cycle are simulated by using a numerical model. A field survey provides the bathymetry, time-series boundary conditions, and corresponding verification data. Good agreement is reached between calculated and measured results. Based on the condition of tidal current, four scenarios are selected for which confluence flow patterns are observed, both spatially and temporally. The results indicate that at least one recirculation is always in the tidal confluence for all flow conditions, which rotates counterclockwise for the ebb flow and clockwise for the flood flow. In addition, there is no absolute slack water condition at the tidal junction in the study area. The study also finds that the flows of all three connected channels at the confluence change in a looped pattern with respect to one another. Furthermore, the study reports unique relationships among the ratios of different flows.

Nagdee, M.R.M.S.; Nurse, L.; Inniss, L.; Chadwick, A., and Johnson, T., 2020. Historical shoreline mapping: Application of the Digital Shoreline Analysis System to the evolution of Worthing Beach, Barbados, following Hurricanes Allen (1980) and Ivan (2004). Journal of Coastal Research, 36(2), 313–318. Coconut Creek (Florida), ISSN 0749-0208.

This paper examines the application of the Digital Shoreline Analysis System (DSAS), developed by the U.S. Geological Survey, to a test site at Worthing Beach, Barbados. The system calculates shoreline rates-of-change statistics from historical shoreline positions by casting transects perpendicular to a common baseline and observing where each transect intersects with beach width. DSAS was applied using four historical aerial photographs (1973, 1982, 1991, and 2004) to project its 50 year trend (1973–2023). Following the impact of Hurricane Allen (1980), Worthing Beach, contrary to expectations, exhibited a rapid accretion rate of 7.0 m/y. Subsequently, the passage of Hurricane Ivan (2004) led to the removal of approximately 110 m of shoreline while the hurricane impacted the island. The linear methodology used by DSAS, however, projected continued accretion over the central spur up to the base of the coral rubble reef within the nearshore, which was in contrast to the actual shoreline trend. It was hypothesized that both rapid accretion and erosion were initiated by changes in the height of the coral rubble reef introduced by each of the hurricanes, respectively. The statistical projections were used to assess the accuracy of the computed shoreline positions prior to the implementation of engineering works in 2006 by the Barbados Coastal Zone Management Unit, since erosion continued to threaten infrastructure along the back beach long after Hurricane Ivan (2004). It was concluded that it is essential to identify the underlying causes of accretion and erosion to assist in designing any engineering interventions.

Chen, Q. and Chen, P., 2020. Short-term effects of artificial reef construction on surface sediment and seawater properties in Daya Bay, China. Journal of Coastal Research, 36(2), 319–326. Coconut Creek (Florida), ISSN 0749-0208.

The degradation and modification of habitats are dominant drivers of biodiversity fluctuation, which is increasingly threatened in marine ecosystems (especially coral reefs) and can be mitigated by the construction of artificial reefs (ARs). Environmental indices are considered excellent indicators of how disturbances affect organisms, but the effects of AR construction on nearby sediment and seawater environments remain unclear. In the current study, changes in the properties of surface sediment and seawater (surface and bottom) for 2 years following AR construction were investigated in Daya Bay, China. The reef habitat and the nearby nonreef habitat were sampled. The results indicated that surface sediment organic matter significantly increased but sediment texture did not change following AR construction, regardless of habitat. The pH, dissolved oxygen, and salinity significantly declined, but chemical oxygen demand, inorganic nitrogen, and suspended particulate organic matter significantly increased in both surface and bottom seawater, regardless of habitat; temperature, nitrogen/phosphorus ratio, and available phosphate were not consistently altered by AR construction. Considering the intimate relationships between abiotic factors and organisms, these results indicate that long-term assessment of multiple environmental properties is needed to evaluate and predict the effects of AR construction on marine wildlife.

Zhu, W.; Zhang, M.; Yu, G.; Petukhov, V.; Mymrin, V., and Gidarakos, E., 2020. Flow resistance in dredged soil under a vacuum preloading system with vertical drainage boards. Journal of Coastal Research, 36(2), 327–338. Coconut Creek (Florida), ISSN 0749-0208.

Vacuum preloading combined with prefabricated vertical drains is one of the most widely applied methods to improve soft-ground loading capacity in coastal engineering projects. The resistance of solid particles to the pore-water flow in vacuum-preloaded soil plays an important role in the soil consolidation and pore-water dissipation. However, the flow resistance is still not clearly known during the vacuum drainage process. It is not clear whether the formulae for calculating the flow resistance factor for flow in uniform non-deformational porous media are applicable for flow in vacuum-preloaded soils or not. Because of a lack of knowledge on flow resistance in the vacuum-preloaded soil, coastal engineers only rely on their experience to select vacuum pumps. In this paper, the hydraulic resistance to flow in vacuum-preloaded soils was investigated. Energy conservation in the vacuum preloading system during the drainage process was analyzed. Sixteen laboratory tests were conducted, in which the vacuum pressure, flow rate, seepage velocity, and particle Reynolds number were observed or calculated. Results showed that particle size, uniformity coefficient, and porosity of the soil have important effects on resistance in dredged soils under vacuum preloading condition. The flow resistance in the vacuum-preloaded soil behaved quite differently from that in uniform porous medium. The formulae for calculating the flow resistance factor for flow in uniform packed beds were not applicable for flow in vacuum-preloaded soils. A new formula was proposed to calculate the flow resistance factor in vacuum-preloaded soils with acceptable accuracy. Because the vacuum preloading system with fixed pump power consumes much energy, new vacuum preloading systems with low energy consumption are necessarily developed in future work.

Rodríguez Paneque, R. and Finkl, C.W., 2020. Erosion of carbonate beaches on the northeastern coast of Cuba. Journal of Coastal Research, 36(2), 339–352. Coconut Creek (Florida), ISSN 0749-0208.

Beaches on the northeastern coast of Cuba have made this area one of the most important tourist destinations in the Caribbean, despite the fact that many beaches are visibly eroded. In this study, the causes and magnitude of coastal erosion on the northeastern coast of Cuba were evaluated using the Digital Shoreline Analysis System (DSAS 4.3) application, satellite images, and beach profiles. Time frames between 7 and 14 years were considered from 2003 to 2017 using satellite images and between 11 and 18 years using beach profiles. Results of this investigation showed that 56% of northeastern coast beaches tend to erode at a rate of less than 1.2 m/y. An increase in the recurrence of extreme events (hurricanes and tropical storms) during the last 39 years induced more beach erosion. It was furthermore observed that El Niño–Southern Oscillation events enhanced the sedimentary balance of the beaches by returning sand volumes that were transported in a westerly direction to their original shoreline locations. Possibly due to sea-level rise, which may be occurring in response to global warming, beaches on the northeast coast will retreat on average about 0.17 m/y. At this rate of shoreline recession, by the end of the twenty-first century, 14% of the beaches on this littoral will be lost, and the width of 27% of the other beaches will be significantly reduced.

Shalini, G.; Hegde, V.S.; Soumya, M., and Korkoppa, M.M., 2020. Provenance and implications of heavy minerals in the beach sands of India's central west coast. Journal of Coastal Research, 36(2), 353–361. Coconut Creek (Florida), ISSN 0749-0208.

The heavy mineral assemblage and mineral chemistry of the beach sands of Mulki, Karnataka, central west coast of India, are discussed in this paper to understand their provenance. The study is based on the seasonal modification in shoreface profiles and identification of heavy minerals under binocular microscope followed by electron probe micro-analysis. The heavy mineral assemblage of the Mulki estuarine beach sands includes ilmenite, magnetite, zircon, rutile, hornblende, epidote, kyanite, and tremolite. There are two generations of ilmenite. The older generation is characterized by porous ilmenite that shows TiO₂/FeO between 1.32 and 8.09. The second generation of ilmenite is characterized by fresh, rounded to angular grains that have relatively lower TiO₂/FeO ratios (<1.25). Rutile also shows two types: one with TiO₂ >97% and another with TiO₂ <94%. The presence of two generations of ilmenite and rutile suggests reworking of the older generation, probably derived from the offshore region or a paleobeach brought by the combined action of alongshore current and waves to the present beach, and a second generation brought by the modern drainage system. The heavy mineral assemblage and mineral chemistry suggest mixed provenance consisting of basic igneous rocks, acidic rocks, and high-grade metamorphic rocks. Mafic and acidic source rocks are indicated by the presence of two types of ilmenite, one with Cr₂O₃ and the other devoid of Cr₂O₃, and two types of hornblende, one rich in MgO and the other poor in MgO. High-grade metamorphic source rocks are indicated by the presence of rutile, kyanite, and tremolite. The Mulki-Pavanje River drains from a low-grade metamorphic terrain. Therefore, high-grade metamorphic minerals are attributed to an external source brought by alongshore drift.

Yan, X. and Mohammadian, A., 2020. Evolutionary modeling of inclined dense jets discharged from multiport diffusers. Journal of Coastal Research, 36(2), 362–371. Coconut Creek (Florida), ISSN 0749-0208.

Multiport diffusers are becoming popular for discharging wastewaters into the receiving water. In this work, an approach based on multigene genetic programming (MGGP) is presented and applied to model the mixing properties of inclined dense jets discharged from multiport diffusers. Explicit mathematical models were formulated for the nondimensional terminal rise height, the nondimensional impact distance, and the nondimensional impact dilution, which are the most important parameters for describing effluent mixing properties. The developed model can be employed to predict mixing parameters as functions of the densimetric Froude number, the nondimensional port spacing, and the nondimensional current speed. The models were trained and tested with experimental data for three different ambient flow conditions: stationary, coflowing, and counterflowing. Therefore, these models are generally valid for these different scenarios. Sample Pareto-optimal MGGP models were compared, and the best ones are identified. The single-gene genetic programming (SGGP) algorithm was also utilized to develop models for the same parameters. It was found that the best MGGP models outperformed the best SGGP models and the existing empirical formulations. A confidence analysis for the best MGGP models is also reported. On the basis of a detailed evaluation of the performances of the MGGP models, the MGGP technique was proved to be a useful tool in developing models for predicting the mixing properties of inclined dense discharges from multiport diffusers.

Zhang, S.; Jia, Y.; Lu, F.; Zhang, Y.; Zhang, S., and Peng, Z., 2020. Effects of upward seepage on the resuspension of consolidated silty sediments in the Yellow River Delta. Journal of Coastal Research, 36(2), 372–381. Coconut Creek (Florida), ISSN 0749-0208.

Strong seepage flows in coastal zones could significantly change seabed properties, even leading to seepage failure. With respect to the effect of seepage flows on sediment resuspension, available literature has presented conflicting results, indicating that the influence appears to vary for different locations. In the present study, a seepage-scouring, annular flume was designed and employed to evaluate the influence of a sequence of seepage gradients on the resuspension of silts derived from the Yellow River Delta. The experimental results indicated that upward seepage slightly increases the suspended sediment concentration (SSC) level by 4.9–11.1% before the occurrence of seepage failure; however, the occurrence of seepage failure dramatically increases the SSC by at least 64% by pumping massive sediments out of the seabed into the overlying water column. Strong seepage flow and the resultant loss of sediments from the internal seabed are potential mechanisms for the formation of numerous collapse depressions in the Yellow River Delta.

Zhao, S.; Zhang, J.; Wang, Z.; Huang, H.; Hu, J., and Guo, C., 2020. Improving Scholte-wave vibration signal recognition based on polarization characteristics in coastal waters. Journal of Coastal Research, 36(2), 382–392. Coconut Creek (Florida), ISSN 0749-0208.

Scholte waves on the underwater interface provide a lot of information, which can be employed to identify the target in coastal water and speculate the coastal underwater medium. However, as the practical acquired signals are the superposition of multiple wave fields, it is necessary to separate the Scholte wave and to improve its signal-to-noise ratio. The LS-DYNA software was used to simulate the underwater acoustic field to analyze the excitation mechanism and particle trajectory law of Scholte waves and to obtain the propagation characteristic of Scholte waves. The results showed that Scholte waves attenuate according to r^–0.5 on the underwater interface and according to exponent in the depth direction. The amplitude of Scholte waves mainly concentrates below 25 Hz, and the corresponding particle trajectory makes a counterclockwise elliptical shape by filtering the acquired signals of particle vibration velocity below 25 Hz on and below the underwater interface. This method was applied to separate Scholte waves from the acquired complex signals of the wave field in the lake experiment to obtain the pure signals of the Scholte wave. This research can provide significant knowledge to better take advantage of resourceful information provided by Scholte waves in the coastal environment.

Dodds, R. and Holmes, M.R., 2020. Preferences at city and rural beaches: Are the tourists different? Journal of Coastal Research, 36(2), 393–402. Coconut Creek (Florida), ISSN 0749-0208.

Visiting a beach is one of the most popular tourist activities and one that draws people to the surrounding area. Although much literature has been written on tourism, little examines preferences for visitor behavior in a rural versus urban setting or whether that behavior is linked to environmental management of the setting. To this end, this paper examines tourists' motivations to visit beaches, as well as their experiences, perceptions, demographics, and desires, all within the context of the tourists' geographic orientation (i.e. urban vs. rural). Drawing on responses from 1664 quantitative surveys from Ontario beaches in Canada, this research found that beachgoers to rural beaches were more likely to have higher income levels but lower levels of education than city beachgoers. Rural beachgoers were also more likely to spend more per trip, as well as having higher levels of overall satisfaction. Findings also show that beachgoers to both rural and city beaches would be more willing to make the Blue Flag environmental management designation a component of their future beach going decision if they were aware of which beaches had the certification. The outcomes of this research have implications for beach destinations, tourism organizations, and municipalities, enabling them to better understand beachgoers and derive targeted marketing strategies.

Liang, B.; Han, G.; Liu, M.; Yang, K.; Li, X., and Liu, J., 2020. Source identification and water-quality assessment of dissolved heavy metals in the Jiulongjiang River, Southeast China. Journal of Coastal Research, 36(2), 403–410. Coconut Creek (Florida), ISSN 0749-0208.

With the aggravation of ecological deterioration, dissolved heavy metals in coastal rivers do not only affect the quality of local drinking water, but also pose ecological risks to the ocean. To identify the sources and ecological effects of dissolved heavy metals in the Jiulongjiang River water, concentrations of six dissolved heavy metals (Al, Fe, Mn, Cu, Zn, and Ba) were measured using an inductively coupled plasma mass spectrometer. The results showed that the dissolved heavy metals can be categorized into three groups: the dominant elements (Mn and Fe, >100 µg/L), moderately abundant elements (Ba and Al, 10–100 µg/L), and less abundant elements (Zn and Cu, <10 µg/L), of which Mn was the dominant pollutant in the drainage basin by comparing with the guidelines for drinking water. The Pearson correlation matrix exhibited a similar result for Fe, Cu, and Ba. The principal component analysis explained that Ba, Zn, and Cu were attributed to agricultural inputs affected by upland cultivation; Al, Fe, and Cu were controlled by input of crustal materials and agricultural contribution; Mn and Zn were affected by a mixed source of natural weathering and anthropogenic activities. The water-quality index suggested that water in the Xixi Stream was worse than in the Beixi Stream and the Nanxi Stream. The health risk assessment results indicated that there were no health risks or potential carcinogenic concern via daily intake and dermal absorption. The fluxes of dissolved heavy metals in this study were lower than other worldwide rivers during the dry season, of which Mn and Fe were the dominant elements pouring into the ocean through Xiamen Bay. The fluxes of dissolved heavy metals between the wet season and the dry season in the Jiulongjiang River might be controlled by different water discharge quantity.

Palalane, J. and Larson, M., 2020. A long-term coastal evolution model with longshore and cross-shore transport. Journal of Coastal Research, 36(2), 411–423. Coconut Creek (Florida), ISSN 0749-0208.

This study encompasses the development of a long-term coastal evolution model with enhanced capabilities to simulate simultaneously the cross-shore and longshore evolution of the coast. The paper starts by reviewing the theory related to cross-shore and longshore sediment transport, which are the major components integrated in the model. Major advances were made by introducing modules to better account for dune erosion and overwash, dune buildup by wind, and exchange of sediment between the berm and the bar into an existing coastal evolution model. Then, the model performance was tested by simulating the evolution for a stretch of coastline corresponding to the conditions at Westhampton Beach (United States), first for a case with open boundaries representing a situation of dynamic equilibrium and then for the placement of a terminal groin causing advance of the shoreline, berm crest, and dune foot. Subsequently, the model was employed to simulate the combined cross-shore and longshore evolution along Macaneta Spit (Mozambique), and the results were compared with available data. Overall, the model succeeded in reproducing the expected combined cross-shore and longshore evolution at the selected case study sites. For the Westhampton Beach case, the model was able to qualitatively simulate the observed advance of the cross-shore dune system, following the placement of the terminal groin. For Macaneta Spit, the model reproduced the alongshore variation in cross-shore profile shape in response to the incident waves and water levels, as well as the net longshore sand transport pattern as identified in previous studies. In summary, the model produced reliable and robust predictions, showing the capability of running simulations for a period of decades in a few minutes on a personal computer.

Guo, T.; Song, D.; Li, K.; Li, C., and Yang, H., 2020. Pitch angle control with model compensation based on active disturbance rejection controller for underwater gliders. Journal of Coastal Research, 36(2), 424–433. Coconut Creek (Florida), ISSN 0749-0208.

As the pitch angle control system of an underwater glider is nonlinear, multivariate, and has strong coupling, active disturbance rejection control (ADRC) was applied in the pitch angle control loop. To improve the control precision and responsiveness, a model compensation (MC) was presented to alleviate the estimation pressures for the extended state observer in the ADRC. The vast majority of parameters in the MC were estimated and identified so that the ADRC controller can work better. Simulation experiments illustrated that the MC based on ADRC was effective. For the pitch angle control, the overshoot was reduced by 4.5% and the settling time dropped to 90 seconds compared with the traditional ADRC. It demonstrated a more accurate motion trajectory control effect for an underwater glider. Besides, the MC-ADRC controller has better dynamic characteristics and antidisturbance ability, which ensure that the underwater glider is more anti-interference and flexible.