Johnson, M.E.; Baarli, B.G.; da Silva, C.M.; Cachão, M.; Ramalho, R.S.; Santos, A., and Mayoral, E.J., 2016. Recent rhodolith deposits stranded on the windward shores of Maio (Cape Verde Islands): Historical resource for the local economy.

Maio is a volcanic island with an area of 269 km² in the Cape Verde archipelago off the west coast of Africa. Although considered a leeward island, it absorbs NE trade winds that typically register 5 to 6 on the Beaufort Scale (moderate to fresh breeze). The trade winds produce ocean swells commonly 3.5 m in height that scour the island's north coast but also generate eastern longshore currents. Outcrops with Pleistocene rhodoliths occur on the SE and south shores and include lithified dunes mainly composed of crushed rhodolith debris. In contrast, the modern beaches and Pleistocene dunes on the more sheltered west coast are practically devoid of rhodoliths. Present-day rhodolith banks off the north coast would seem to be precluded by intense wave action. This study examines rhodoliths from overwash and beach-rock deposits around Ponta Cais in the far north. Lumpy rhodoliths (likely Lithothamnion sp.) are concentrated in a sheltered corner on the bay south of Ponta Branca. A more extensive overwash deposit covers an area of 27,000 m² that is 1 m above mean sea level with a surface exposure of 450 rhodoliths/m². A unique specimen nucleated around a ceramic fragment indicates that the deposit is historical in context. Rhodolith beach rock extends all along Praia Real east of Ponta Cais. A northern bank clearly exists, but it does so at a water depth normally adequate to protect larger rhodoliths from all but major storms. Abandoned limekilns behind Praia Real demonstrate that the local economy on a volcanic island used rhodoliths as a source of mortar and whitewash.

Ezer, T.; Haigh, I.D., and Woodworth, P.L., 2016. Nonlinear sea-level trends and long-term variability on western European coasts.

Nonlinear trends and long-term variability in sea level measured on the U.K. and western European coasts with long tide-gauge records (∼100–200 y) were investigated. Two different analysis methods, a standard quadratic regression and a nonparametric, empirical mode decomposition method, detected similar positive sea-level accelerations during the past ∼150 years: 0.014 ± 0.003 and 0.012 ± 0.004 mm/y², respectively; these values are close to the sea-level acceleration of the global ocean over the same period, as reported by several studies. Ensemble calculations with added white noise are used to evaluate the robustness of low-frequency oscillations and to estimate potential errors. Sensitivity experiments evaluate the impact of data gaps on the ability of the analysis to detect decadal variations and acceleration in sea level. The long-term oscillations have typical periods of 15–60 years and ranges of 50–80 mm; these oscillations appear to be influenced by the North Atlantic Oscillation and by the Atlantic Multidecadal Oscillation. Analysis of altimeter data over the entire North Atlantic Ocean shows that the highest impact of the North Atlantic Oscillation is on sea-level variability in the North Sea and the Norwegian coasts, whereas the Atlantic Multidecadal Oscillation has the largest correlation with sea level in the subpolar gyre and the Labrador Sea, west of the study area.

Coch, N.K., 2016. Sediment dynamics in the Upper and Lower Bays of New York Harbor.

A long-term geologic and oceanographic study has provided the first holistic picture of sediment dynamics in the estuaries of SW New York state. Oceanographic data indicates that the east (Brooklyn) part of the Upper Bay is flood dominant, while the western (Staten Island) side is ebb-dominant. Bedform analysis indicates a net northerly (flood) orientation on the eastern side of the Lower Bay. The west side, in contrast, has fine sediment similar to that supplied by the Hudson River to the Upper Bay. The numerous sand borrow pits on the nearshore shelf also reflect a difference in net flow. The eastern pits are filled with shelf sands while the western ones are filled with mixtures of fine Hudson derived sediments and shelf sands. These patterns suggest flood dominant transport of shelf sands from the Lower Bay into the Upper Bay and ebb dominant supply of Hudson-derived fine material into the Lower Bay on the western side. The shelf and Hudson River Estuary are not the only suppliers of sediment to New York Harbor. The East River and Harlem Rivers have supplied significant amounts of coarse sediment to the northern part of the Upper Bay. This continued until massive stream changes in the 19th Century cut off sediment supply. The East and Harlem River sediments were deposited in a delta extending south and west of the Battery in Manhattan. Part of the relict East River material is now being reworked and moved northward by flood dominant nontidal flow along the eastern shore of the Hudson.

Chen, J.; Oseji, O.; Mitra, M.; Waguespack, Y., and Chen, N., 2016. Phytoplankton pigments in Maryland coastal bay sediments as biomarkers of sources of organic matter to benthic community.

In this study, the sources of pelagic organic matter and their transport to the surface sediment in the Maryland Coastal Bays (MCB), part of the U.S. mid-Atlantic coastal lagoon system, were examined. Photosynthetic pigments (chlorophylls a and b), accessory pigments (peridinin, fucoxanthin, zeaxanthin, alloxanthin, etc.), and chlorophyll a decomposition products (chlorophyllide a, pheophorbide a, pheophytin a, and pyropheophytin a) from surface sediments collected at 13 sites in the MCB in March 2013 were analyzed using high performance liquid chromatography. The spatial distributions of diagnostic pigments in surface sediments indicated that organic matter was mainly derived from nano- and picophytoplankton (i.e. cyanobacteria, cryptophytes, and chlorophytes) at sites characterized by high nutrient input, although diatoms dominated the standing phytoplankton biomass throughout the MCB except at one site. We attribute this phenomenon to selective microzooplankton grazing on nano- and picophytoplankton in the cold season and low grazing pressure on large phytoplankton species of diatoms and dinoflagellates resulting in the diatom bloom in early spring. At sites characterized by strong tidal current and mixing of bay waters and ocean waters, information from pigment data supports the deposition of dead/senescent diatoms. Results from this study indicate that nano- and picophytoplankton may play a crucial role in supplying organic matter to the benthic community, although their standing stock is low in the cold season.

Cornwell, J.C.; Owens, M.S.; Boynton, W.R., and Harris, L.A., 2016. Sediment-water nitrogen exchange along the Potomac River estuarine salinity gradient.

Observations of N₂ efflux in estuarine sediments across the salinity gradient of the tidal Potomac River, a eutrophic subestuary of the Chesapeake Bay, were used to evaluate environmental controls of microbial denitrification. Rates of denitrification were measured using N₂:Ar ratios in core incubations and were similar to other nitrogen-enriched estuaries, with summer and spring N₂-N efflux rates averaging 54 ± 47 and 153 ± 97 μmol m⁻² h⁻¹, respectively. The paradigm of higher denitrification rates at lower salinities was not supported by observations during summer and spring conditions along this estuarine salinity gradient. Low bottom water oxygen concentrations in the lower, more saline part of the estuary resulted in low rates of coupled nitrification/denitrification. The most favorable region for denitrification in the tidal Potomac River occurred where changes in salinity were most rapid and oxygen concentrations were not depleted, with high rates observed within the estuarine turbidity maximum (ETM) zone. Overall, the key role of salinity in the tidal Potomac River in controlling denitrification appears to be in the focusing of materials into ETM and providing stratification in the lower estuary that restricts the vertical exchange of oxygen necessary for coupled nitrification/denitrification.

Palinkas, C.M.; Barth, N.; Koch, E.W., and Shafer, D.J., 2016. The influence of breakwaters on nearshore sedimentation patterns in Chesapeake Bay, USA.

This study describes nearshore Chesapeake Bay sedimentation at sites adjacent to and landward of 24 segmented breakwaters, varying in age (1–19 years) and physical setting. Grain-size and organic-content profiles are examined at the breakwater-protected sites to assess potential changes induced by breakwater installation as well as at the adjacent-exposed sites to establish historical trends. Sedimentation rates at all sites are calculated with ²¹⁰Pb (half-life 22.3 years). At the breakwater-protected sites, these rates largely reflect preconstruction sedimentation because of the long half-life of ²¹⁰Pb relative to breakwater ages. Determining the postconstruction sedimentation rate can be more difficult because the signature of breakwater influence in the sedimentological record can be obscured. For example, if the source of sediment is not affected dramatically by construction, down-core profiles may not have obvious changes. The depth of breakwater influence, however, can be interpreted by considering all the sedimentological evidence at a given location, and the postconstruction rates are calculated from this depth. In general, the sedimentological response to breakwater construction is fairly unique for each location but depends on such factors as breakwater age and geometry, shoreline sediment composition, and construction technique.

Ning, D.; Chen, L.; Zhao, M., and Teng, B., 2016. Experimental and numerical investigation of the hydrodynamic characteristics of submerged breakwaters in waves.

The interactions between nonlinear, regular waves and submerged breakwaters with rectangular or trapezoidal cross-sections were investigated both experimentally and numerically in this article, with emphasis on the effect of the shape of the breakwater on its hydrodynamic behavior. A series of experiments was carried out and used to validate a numerical model based on a fully nonlinear, two-dimensional boundary-element method. Comparisons among the numerical results of both wave elevations and wave pressures on the structure and the measured data indicate that the present numerical model is very capable of accurately predicting the hydrodynamic characteristics of submerged breakwaters in waves. Furthermore, parametric studies were conducted to investigate the influence of the existence of the seaward and rearward slopes on the effectiveness of the breakwater in reflecting the wave energy.

Zhang, H.-S.; Zhou, E.-X.; Dai, S., and Zhang, Y., 2016. Comparison of the calculated and measured wave heights in inland lakes.

Knowledge of the wave climate of inland lakes is important for a wide range of issues, including the appropriate design of dikes and pollution monitoring. The measured wind and wind wave data for two inland lakes in southeast China (Lake Taihu and Lake Dianshan) were collected along with predicted wind data for Lake Taihu. The wave heights in the two lakes were calculated using a wave model, Simulating WAves Nearshore (SWAN), and an empirical formula. Then, the calculated results were compared to measured data. The SWAN model cannot effectively simulate wave fields near lateral boundaries; therefore, detailed studies were carried out on how to set appropriate boundaries for calculation domains. Lake Taihu is a large water body with wind fields that vary at different locations; hence, it is an ideal location for detailed studies of the effects of measured wind fields on wave fields. It was shown that when wave fields of a large lake are simulated with the SWAN model, measurement stations should be arranged carefully, and proper wind field input is crucial. The accuracy of results calculated with the empirical formula was similar to that of the results calculated with the SWAN model, provided that appropriate care was taken during the input of measured wind fields. In contrast, the accuracy of SWAN model results was greater than that of empirical formula results if forecasted wind fields were used as inputs. Overall, the wind wave fields in the two inland lakes of different sizes were effectively simulated in this study.

Fan, R.; Wei, H., and Zhao, L., 2016. Linking suspended particulate material characteristics to the plankton distribution in summer in the Yellow Sea and East China Sea.

Identifying particle characteristics through in situ observations can be beneficial for understanding local sediment dynamics. This study analyzed the suspended particulate material (SPM) characteristics in the Yellow Sea and East China Sea, as well as the hydrological structure and chlorophyll a (Chl a) concentration in summer during a cruise conducted from 16 August 2013 to 31 August 2013. This study identifies two significant particle size (PS) peaks ranging between approximately 12 < diameter (d) < 63 and 280 < d < 390 μm, defined as small and large particles, respectively, by using the SPM PS spectrum. In the surface layer, the main part of small SPMs is composed of phytoplankton, whereas large SPMs are primarily dominated by mesozooplankton. High concentrations of SPM in the surface layer located on Subei Shoal and off the Changjiang River estuary overlap with the high Chl a concentration. High total SPM concentrations, maximum levels of Chl a, and large particle concentrations were observed in the pycnocline in the central Yellow Sea and at the middle shelf of the East China Sea. The high SPM subsurface concentration is primarily influenced by plankton, particularly mesozooplankton. Small particles are dominant in the bottom layer and consist mainly of inorganic particulate matter.

Isla, F.I. and Angulo, R., 2016. Tectonic processes along the South America coastline derived from Quaternary marine terraces.

South America is overriding the Nazca, Antarctic, and Cocos plates, and at the same time is moving along the Caribbean and Scotia plates. Quaternary sea-level highstands are ideal benchmarks to estimate tectonic uplifts considering altitude differences along the coast. The Sangamonian highstand, corresponding to the Marine Isotopic Stage 5, is the most helpful indicator for these purposes as it is more easily preserved and spanning a record of 120,000 years. The Mid-Holocene highstand leads to errors assigned to tidal-range variations, estuarine floods, and meteorological effects; however, its maximum altitudes could confirm faster uplifting rates. The major uplifting trends were estimated in relation to the subduction of seismic or aseismic ridges along the Pacific Ocean coast. The Quaternary uplifted terraces of the Atlantic coast at Patagonia were explained by the decreasing uplift induced by the subduction of the Chile Ridge, and related to a very modern volcanic field.

Montes, J.M.; Lavín, M.F., and Parés-Sierra, A.F., 2016. Seasonal heat and salt balance in the Upper Gulf of California.

The salinity and heat balance, as well as the seasonal variation of the average absolute salinity (⟨S_A⟩) and conservative temperature (⟨Θ⟩), were described by using data from 24 cruises within four domains in the Upper Gulf of California (UGC). Monthly values of S_A and Θ, and surface fluxes obtained from ERA-Interim reanalysis data sets were fitted to a seasonal signal, and the horizontal fluxes of salinity and heat content were calculated by using balance equations. The UGC exports salt and heat to the Northern Gulf of California (NGC) almost all year, with an annual mean of 1.6 g/kg per year for the salinity flux and 0.16 terawatts (TW) for the heat flux. The results suggest that the net excess of evaporation (∼0.8 m/y) and heat gain by the surface (∼70 W/m²) are the main factors controlling the exchange of salinity and heat between the UGC and the NGC. To help identify the relevant dynamic factor involved in the heat and salinity balances, a high-resolution numerical model, the regional ocean modeling system (ROMS), was implemented for the region. The main feature of the UGC circulation consists of a cyclonic surface flow that extends downward as a laterally sheared flow pattern, with inflow at the Sonora coast side and outflow at the Baja California coast side. Although the cyclonic circulation pattern remains most of the year, the maximum velocities (∼0.20 m/s) are reached in June. The results indicate that the major exchange between the UGC and the NGC occurs in June and July when the net volume transport (∼0.9 Sverdrups) is dominated by the horizontal overturning transport.

Vieira da Silva, G.; Muler, M.; Prado, M.F.V.; Short, A.D.; Klein, A.H.F., and Toldo, E.E., Jr., 2016. Shoreline change analysis and insight into the sediment transport path along Santa Catarina Island north shore, Brazil.

This paper presents a shoreline change analysis applied to identify the sediment transport path involving nine adjoining beaches, including dunes and spits, located along the microtidal eastern and northern shores of Santa Catarina Island (Brazil) and extending 50 km from Barra-Moçambique to Daniela. A data set was comprised of aerial images from 1957, 1978, 1998, 2002, 2007, and 2010, and the 2012 shoreline position measured with real-time kinematic GPS, topobathymetric data set, and a 60-year water-level time series. The images were rectified and the shoreline position for each year was extracted. The average errors (ranging from 1 to 9.8 m) of the rectification process as well as the horizontal tide-related errors (varying from 8.3 ± 2.6 m to 14.9 ± 0.6 m) were calculated within a confidence level of 95%. Two complementary approaches were used: (1) general trends analysis using linear regression rate method and (2) shoreline behaviour statistically analysed by Euclidean distance and year-to-year analysis. The results indicate an anticlockwise longshore transport between a series of beaches with variable orientation and separated by headlands, including a dune overpassing from Santinho delivering ∼10,000 m³ y⁻¹ to Ingleses, and headland bypassing leading to the development of three spits along the protected part of the study area that have possibly been nourished by subaqueous sand transport from the updrift beaches. During its development the Ponta das Canas spit grew ∼7000 m³ y⁻¹, controlling the sediment availability downdrift. As the spit grows it traps sediment and the downdrift area retreats; on the other hand, when the spit merges to the coast the sand spreads and the downdrift beaches prograde.

Crowe, S.E.; Bergquist, D.C.; Sanger, D.M., and Van Dolah, R.F., 2016. Physical and biological alterations following dredging in two beach nourishment borrow areas in South Carolina's coastal zone.

Dredging of nearshore subtidal sand deposits as a source for beach fill is a common practice in the SE United States, but the long-term effects of this practice on benthic environments are not well documented. Two borrow areas used to nourish the shoreface of Folly Beach, South Carolina, in 2005 (borrow area A) and 2007 (borrow area B) were sampled for sediment characteristics (silt and clay, calcium carbonate, total organic matter content, and sand phi size) and macrobenthic infaunal community composition using a before–after, control–impact design over periods of 8 and 6 years postdredging, respectively. Following dredging, surficial sediment characteristics within both borrow pits shifted toward finer materials and showed little evidence of recovering 8 and 6 years after impact. Changes in the benthic community occurred with respect to faunal density, number of species, and changes in composition at the species level, largely reflecting recolonization by opportunistic taxa within the disturbed seafloor. Benthic community changes consisted largely of the loss of species associated with coarser sands and shell and recolonization by species associated with finer sands and silt and clay. The similar responses of two nearby borrow areas dredged 2 years apart may be partly because of their location and the depth they were dredged below the seafloor. Borrow site location and the depth at which sediments are mined below grade may be important considerations for improving the sustainable reuse of limited sand resources in many areas and avoiding long-term changes in benthic infaunal community composition.

Deng, H.; Zhang, Z.-H.; Gu, J.-N., and Liu, J.-B., 2016. Hydrodynamic pressure field caused by a ship sailing near the coast.

Based on the shallow-water wave-potential flow theory and the assumption of a slender ship, a mathematical model, whose dispersion relation is improved, has been established for the ship hydrodynamic pressure field (SHPF), which is suitable for a wider speed range. The finite difference method is used for calculating the SHPF, and the artificial viscous terms are added in the boundary conditions to ensure the stability of the nonlinear equation solution. The comparison between the calculated results and the experimental ones shows that the calculation method is feasible and the improved mathematical model is more accurate and effective. The calculation and analysis of the SHPF caused by ships deviating from the channel centre line or sailing near the coast in shallow water indicate that the narrower the distance between the ship and the coastal sidewall the greater will its effects be on the coast, the seabed, and the coastal architecture around the ship at the subcritical speed, which will cause effects on the coast, seabed, and coastal architectures of a wider water area behind the ship to a large extent at supercritical speed.

Chun, H. and Suh, K.-D., 2016. Wave-induced Reynolds stress in three-dimensional nearshore currents model.

This paper presents the formulation of the wave-induced Reynolds stress (WIRS), i.e. the correlation of horizontal and vertical water particle velocities, based on the Airy's wave theory. Even though the correlation of the velocities is zero in a constant-depth water, it has a nonzero value if there are slopes on the bottom and mean water level. Comparison of the vertical gradient of the WIRS term with the horizontal gradient of wave-forcing terms shows that the two terms have the same order of magnitude, which in turn is comparable to that of the radiation stress in the surf zone. For the three-dimensional computation of nearshore currents, the WIRS term is incorporated into a three-dimensional ocean model in the σ coordinates. The numerical model is then applied to two laboratory experiments. To see the effect of the WIRS term on the mean flow, numerical simulations without this term are also carried out. The numerical simulations show that the WIRS term influences the flow properties such as mean water level, longshore current, and undertow.

Luo, W.; Guo, C.; Wu, T.; Dai, S., and Su, Y., 2016. Numerical simulation of viscous flow field around ships in ballast.

In this study, a numerical method based on the solution of the unsteady Reynolds-averaged Navier–Stokes equation was used to evaluate the hydrodynamic performance (wave pattern, limiting streamlines, nominal wake, and axial velocity contours) of the hull of a Korean Research Institute of Ships and Ocean Engineering container ship under in-ballast and design conditions. The results obtained under the design conditions were validated against model test data, and good agreement was observed between the computational and experimental fluid dynamics results. Numerical calculations were performed under the in-ballast condition using the same method. The results indicated that the bulbous bow protruded above the surface of the water and generated high wave cresting at the front of the bulbous bow and high wave troughs at the rear, causing significant variations in the flow fields. Additionally, calculations revealed that when the ship was in ballast, its resistance was poor because of a 1.069° trim by the stern.

Mallin, M.A.; Turner, M.I.H.; McIver, M.R.; Toothman, B.R., and Freeman, H.C., 2016. Significant reduction of fecal bacteria and suspended solids loading by coastal best management practices.

The Town of Wrightsville Beach, North Carolina, is a resort island that has periodic stormwater runoff problems, affecting local swimming and shellfishing waters from excessive fecal bacteria loading. In 2013–15, the planning, installation, and before-and-after monitoring of several types of best management practices (BMPs) designed to reduce pollutant loading to estuarine waters occurred. A straight pipe carrying runoff directly into estuarine Banks Channel was replaced by a buried infiltration chamber. The infiltration chamber did not reduce fecal bacteria concentrations but caused 93% stormwater discharge reduction, 96% fecal bacteria, 90% Enterococcus load reductions, and a 99% total suspended solids (TSS) load reduction to Banks Channel. Near the town's municipal area a number of curb cuts, reversed stormwater inlets, and regraded grassed swales were constructed to encourage infiltration of stormwater into the sandy soils of the island. Also in that area a large rain garden was constructed to collect and infiltrate stormwater that formerly drained directly into estuarine Lee's Cut. The set of stormwater volume reduction and treatment BMPs in the municipal area caused fecal coliform bacteria and Enterococcus concentration reductions of 57% and 71%, respectively, 50% stormwater discharge reduction, 28–55% fecal bacteria load reductions, and 99% TSS load reduction. The pollutant concentration and load decreases in the municipal area of Wrightsville Beach are particularly striking because the BMPs only capture about 50% of the runoff from the drainage area that enters the outfall into Lee's Cut. The BMPs installed and tested would be applicable to developed coastal areas in numerous locations.

López Royo, M.; Ranasinghe, R., and Jiménez, J.A., 2016. A rapid, low-cost approach to coastal vulnerability assessment at a national level.

Vulnerability is defined as the system's potential to be damaged by a certain climate change (CC) hazard, and ideally, it has to be assessed by accounting for the different factors controlling the coastal response both in negative (susceptibility) and positive (resilience) terms to changing climatic and/or geomorphic conditions. The lack of an easy-to-use assessment method that requires only readily available data has severely hampered efforts to assess national-scale coastal vulnerability to the potential impacts of CC and population growth in the coastal zone, particularly when project budgets are limited. This study presents a modified version of the Coastal Vulnerability Index (CVI) approach. The main modifications are (1) the introduction of a more physically meaningful representation of the wave effect where storm erosion will only occur when the wave height exceeds a certain threshold value, and (2) an aggregated coastal-vulnerability classification method that comprises exactly the same number of vulnerability classes as that of the individual components of the CVI. As a demonstration, the method is applied to the 4996-km-long peninsular coastline of Spain. Under the worst-case scenario considered (sea-level rise [SLR] of 1 m by 2100), 50% of the Spanish coastline is classified as highly or very highly vulnerable. Given that tourism contributes 10% of the Spanish gross domestic product (GDP), it is noteworthy that high/very high vulnerability (both under low and high emissions scenarios) is indicated for very popular touristic areas along the Mediterranean Coast. These outcomes are likely to enable coastal managers/planners to identify high priority areas for further, more-detailed coastal vulnerability/hazard/risk quantification studies.

Williams, H.E.; Briganti, R.; Pullen, T., and Dodd, N., 2016. The uncertainty in the prediction of the distribution of individual wave overtopping volumes using a nonlinear shallow water equation solver.

This work analyses the uncertainty of the prediction of individual overtopping volumes using the nonlinear shallow water equations. A numerical model is used to analyse the variability from seeding. The effect of the incident wave height distribution on the distribution of individual overtopping volume is also considered. The numerical results are then compared with both the laboratory tests and available empirical methods. A large variability was found across the distributions, which produced some results showing significant diversion from the empirical prediction methods. The magnitude of that departure was directly related to the accuracy of the numerical model in reproducing the incident wave height distribution at the toe of the structure in the physical model.

Karimpour, A. and Chen, Q., 2016. A simplified parametric model for fetch-limited peak wave frequency in shallow estuaries.

A study was conducted on the wave energy and peak wave frequency in Breton Sound, Louisiana. A bottom-mounted Acoustic Doppler Velocimeter was used to measure waves and currents. The results of the study indicate that the asymptotic limits for the wave energy and peak wave frequency can be defined accurately, while the integral properties of the wave field estimated by the existing parametric wave models, particularly the peak wave frequency, suffer from a lack of accuracy. Based on the observed dependency of peak frequency on the ratio of wind fetch to water depth, a simplified parametric model is proposed in an effort to increase the accuracy of the estimated peak wave frequency. The physical boundaries between water depth and wind fetch for proper estimation of the peak frequency are introduced. The model was evaluated for the goodness of fit against measured data that had been collected at a different study site. The proposed model proved to be more accurate in comparison to previous methods. Further assessment of the new relationship, along with the measured data, revealed that water depth had a more significant effect on the peak wave frequency in the fetch-limited shallow water than did wind fetch. The simplicity of the proposed model, with fewer unknown coefficients compared to other existing models, makes it convenient for practical applications and requires less effort to be calibrated for shallow estuaries of differing bottom roughness.

Cheng, Y.; Xu, Q., and Zhang, Y., 2016. Tidal estimation from TOPEX/Poseidon, Jason primary, and interleaved missions in the Bohai, Yellow, and East China seas.

In this study, response analysis of 18 years of TOPEX/Poseidon–Jason-1–Jason-2 (T/P-Jason) primary mission and 4 years of TOPEX–Jason-1 (TOPEX-Jason) interleaved mission along-track data is performed to derive four principal tidal constituents (M₂, S₂, K₁, and O₁) in the Bohai, Yellow, and East China seas (BYE). The intercomparison at crossover points and comparison with the ground truth show that the combination of T/P-Jason primary with TOPEX-Jason interleaved mission data are suitable for estimating the four principal tidal constituents in the regions. Three data sets of harmonic constants determined from tide-gauge records are used to investigate the impacts of TOPEX-Jason interleaved mission data on tidal constituent estimation over the BYE regions. The accuracy of estimated tidal constituents using 18 years of T/P-Jason data is slightly better than that using 10 years of T/P data in comparison with tide-gauge data over the coastal regions. However, comparisons with 116 tide-gauge data show that the root-mean-square differences in amplitude are reduced by 31%, 38%, 7%, and 7% (M₂, S₂, K₁, and O₁) when using primary mission and interleaved mission data to replace the T/P-Jason primary mission data for tide estimation in the study area. Moreover, the cotidal charts of the major tide constituents are well produced because the satellite altimetry recovers the tidal signal twice with dense ground tracks and more available measurements available in the regions.

Tsai, C.-C.; Lin, Y.-T., and Hsu, T.-W., 2016. Propagating of obliquely incident weakly viscous waves over variable bathymetry.

A linear theory for weakly viscous waves propagating obliquely over variable topographies is introduced without considering the boundary layers. Using an eigenfunction-matching method, which involves including the evanescent modes that satisfy the matching conditions, the present problem can be transformed into a system of linear equations. Furthermore, by using a weak-viscosity hypothesis, the proposed method can be degenerated to the traditional eigenfunction-matching method of the potential flow if both the molecular viscosity and the bottom friction are discarded. The applicability of this model was confirmed by comparing it with available theoretical, numerical, and experimental results for both of the normal and oblique incidences.

Houston, J.R., 2016. Discussion of: Boon, J.D. and Mitchell, M., 2015. Nonlinear change in sea level observed at North American tide stations. Journal of Coastal Research, 31(6), 1295–1305.

Boon and Mitchell determined sea-level acceleration using monthly averaged relative mean sea-level data from 45 U.S. tide stations and 1 Canadian station for 1969–2014. Their methods of analyzing tide gauge data are interesting and useful. However, they then projected sea-level change for 58 years from 1992–2050 based on constant accelerations calculated from these 46-year records. Calculations of acceleration based on records as short as 40–50 years are well known to be heavily corrupted by decadal variations in sea level. For example, Boon and Mitchell showed that 3–6 year variations in record length or time period resulted in what they said were “dramatic change” in calculated acceleration. Therefore, the accelerations they calculated did not even remain constant for a few years, making long-term projections based on them untenable. Boon and Mitchell projected significant sea-level falls from 1992 to 2050 on the coasts of California, Oregon, and Washington, in stark contrast with projections of significant rises by the National Research Council. Similarly, their projections on the U.S. Atlantic and Pacific coasts differ remarkably from projections of the Intergovernmental Panel on Climate Change. Acceleration calculated from 46-year records varies significantly through time, and it is not valid to fix an acceleration value and project it into the future as if it were a constant.

Williams, S.D.P.; Woodworth, P.L., and Hunter, J.R., 2016. Commentary on ‘Coastal planning should be based on proven sea level data' by A. Parker and C.D. Ollier (Ocean & Coastal Management, 124, 1–9, 2016).

A recent paper by A. Parker and C.D. Ollier (Ocean & Coastal Management, 124, 1–9, 2016), concerned with the use of ‘proven' sea-level data for coastal planning, contained a number of incorrect or misleading statements about sea-level data sets and measurement methods. In this commentary, we address aspects of sea-level records that could have been misunderstood by readers of that paper. While we agree with the main point made by the authors, that the best possible sea-level data are required by coastal planners, we suggest that planners should base their work on wider and better informed sources of sea-level information.