BAART, F.; VAN KONINGSVELD, M., and STIVE, M., 2012. Trends in sea-level trend analysis.

Discussions on sea-level rise trend estimates as, for example, the one recently published in this Journal of Coastal Research, reveal different perspectives on proper methods of deriving sea-level trend estimates. This editorial discusses various methodological considerations and proposes a number of best practices for sea-level trend analysis.

WOODWORTH, P.L., 2012. A note on the nodal tide in sea level records.

This note discusses the likely amplitude and spatial dependence of the nodal (18.61 year) tide in mean sea level (MSL) records. The period of this signal is comparable to the length of many MSL records and so could conceivably affect estimates of secular trends and accelerations. However, it is shown that sufficient knowledge of the nodal tide exists to enable “correction” of the records, should that be required. This approach is likely to yield more reliable estimates of trends from medium-length records than a suggested alternative approach of using nodal terms computed from the individual records.

HILL, D., 2012. The lessons of Katrina, learned and unlearned.

Originally planned to evaluate storm surge barriers, the New York City Panel on Climate Change (NPCC) instead developed a process for government agencies and private stakeholders to adapt critical infrastructure in New York City to the effects of climate change. In its influential 2010 report, the NPCC ignored the literature documenting the lessons learned from Hurricane Katrina striking New Orleans in 2005. A report by the American Society of Civil Engineers (ASCE) sums up these lessons in 10 calls to action. An examination of the NPCC report suggests that half of these lessons have been learned and half have not. Essentially, the ASCE makes public safety, health, and welfare, not adapting critical infrastructure, its top priorities. The NPCC report fails to quantify the risks, does not address the question of an acceptable level of risk, and does not evaluate the consequences of severe coastal flooding. Although storm surge barriers have been found to be hydrologically and technically feasible, they are dismissed as mere contributions to the discussion that are not needed for at least the next several decades, despite the report's own accounting of the extreme uncertainty and possible effects of severe hurricanes and nor'easters. The NPCC report features Flexible Adaptation Pathways to plan and revise adaptation measures over time, which ignore the possibility of hedging strategies and the well-established precautionary principle. Without an engineering presence, the NPCC also overlooks consideration of lead times in planning major projects. It is concluded that the NPCC report is delaying regional measures against severe coastal flooding, discouraging hedging and the precautionary principle, and deterring adequate measures to protect public safety, health, and welfare.

Nebel, S.H.; Trembanis, A.C., and Barber, D.C., 2012. Shoreline analysis and barrier island dynamics: Decadal scale patterns from Cedar Island, Virginia.

Aerial photography, topographic maps, high-resolution satellite imagery, and global positioning system (GPS) data were compiled in ArcMAP™ and analyzed using the Digital Shoreline Analysis System (DSAS) to determine decadal trends of shoreline movement on Cedar Island, Virginia. Shoreline retreat rates for Cedar Island had an alongshore average of −4.1 m/y based on simple endpoint analysis (1852–2007), while the short-term (1994–2007) retreat rates increased to −12.6 m/y. Retreat statistics were further calculated for the time intervals 1852–1910 (−5.1 m/y), 1910–62 (−3.5 m/y), 1962–80 (−3.9 m/y), 1980–94 (−6.5 m/y), 1994–2002 (−12.4 m/y), and 2002–06 (−13.8 m/y). This analysis indicates that retreat of the Cedar Island shoreline has been accelerating with a notable increase in rate within the years 1980 to 1994. Additionally, the shoreline data confirms that the orientation of the Cedar Island shoreline has rotated through time.

AIDONA, E. and LIRITZIS, I., 2012. Magnetic susceptibility and radioactivity changes of Aegean and Ionian Sea sediments during last glacial/interglacial: Climatic and chronological markers.

Five marine sediment boreholes from the Aegean and Ionian Sea have been measured here for their magnetic susceptibility and (in an earlier work) by alpha- and beta-particle radioactivity. The corresponding borehole cores cover the Holocene period and closely spaced data have been sampled from all cores. The obtained depth data series have been converted here to the time series by using appropriate conversions on the basis of sedimentation rates derived from dating of selected samples of each core. The spectral characteristics of the new statistical elaboration for the final time series exhibit a significant correlation of the magnetic susceptibility and radioactivity data. This correlation is prominent especially for intermediate periods (typically 1–10 ky) of the examined spectra and tends to disappear for higher frequency variations (<1 ky), suggesting that mainly long-period climatic and other changes are the ones that affect the examined quantities in a similar manner. This pattern is verified by the band-pass filtered time series for intermediate periods, which reveals well-correlated susceptibility and radioactivity changes. In addition, specific time markers are observed in the filtered time series, and comparison of their variation to certain climatic phases within the Holocene is recognized.

SAITOH, T. and KOBAYASHI, N., 2012. Wave transformation and cross-shore sediment transport on sloping beach in front of vertical wall.

An experiment was conducted in a wave flume to examine cross-shore sand transport on a sloping beach in front of a vertical wall located above the still water level (SWL). The irregular wave transformation and beach profile change were measured using eight wave gauges, four velocimeters, a laser line scanner, and three ultrasonic transducers. An initial semi-equilibrium beach accreted slightly above SWL where approximately 5% of incident waves reached the vertical wall. The cross-shore numerical model CSHORE is calibrated and used to predict the cross-shore variations of the maximum free surface elevation and horizontal velocity that are needed for coastal flood hazard mapping. The cross-shore variations of the suspended sand and bedload transport rates predicted by CSHORE are examined to explain the accretion in front of the vertical wall. The experiment in this study was very limited but indicated that accretion could occur in front of the vertical wall exposed to infrequent wave action.

CHEN, Y.-Y.; CHEN, G.-Y., and LIN, C.-H. 2012. The slip factor and slip velocity on a permeable bed.

In the present study, a new, simple method for determining the slip velocity (also called the bed velocity) at the solid-fluid interface in the wave boundary layer is proposed. Based on experimental and numerical results, when waves travel over a rigid permeable seabed, a nonzero slip velocity exists at the interface. The defect of a small slip velocity has been found to occur in previous studies and is usually encountered in fluid–porous layer problems. In the wave–rigid permeable seabed problem, the slip effect depends on the properties of the seabed. The slip velocity boundary condition (SVBC) is one specification of the slip conditions and is usually applied to explain the slip phenomenon in a fluid–porous layer problem. However, the traditional SVBC or the slip velocity is only considered in a single flow, and application of SVBC in harmonic motion is still an open problem that necessitates a simple formula for determining the slip velocity in realistic cases.

The Stokes' second problem and the slip length model (SLM) are applied to derive a new slip velocity and a slip factor in this paper. Both the permeability and the roughness of the seabed are chosen as the slip length. The analytical solution shows that the new slip velocity depends on the wave period and the pressure gradient, and the slip factor is related to the wave Reynolds number, the permeability, and the roughness of the seabed. The resultant slip velocity exhibits good agreement with the experimental results, and the slip factor formula obtained by this present study can be applied to a real seabed.

CHANG, H.-K.; LIOU, J.-C., and CHEN, W.-W., 2012. Protection priority in the coastal environment using a hybrid AHP-TOPSIS method on the Miaoli Coast, Taiwan.

Coastal erosion often happens around the island of Taiwan because of strong waves from typhoons in the summer. The problem of beach erosion cannot be completely solved at this time due to insufficient government budgets. Prioritization of coastal protection should be made yearly to match engineering requirements and annual official budgets. This paper proposes both analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS) methods to prioritize the protection of the coastal environment on the Miaoli Coast of Taiwan. The weights of three main criteria (engineering safety, ecology, and coastal landscape) and their subcriteria are determined through the AHP method. Twenty-two segments of the Miaoli Coast are ranked according protection priority by the TOPSIS method. This multipart methodology can help decision makers prioritize coastal engineering and environmental efforts. This procedure also enables researchers to put more expert knowledge together, allowing more precise decisions and moderating personal judgments.

MILNE, F.D.; DONG, P., and DAVIDSON, M., 2012. Natural variability and anthropogenic effects on the morphodynamics of a beach–dune system at Montrose Bay, Scotland.

Beach–dune systems are valuable geomorphic assets providing a buffer between the coastal hinterland and the sea. Sustained coastal erosion can diminish the protective capability of the beach–dune system with potentially negative implications for coastal amenities, infrastructure, ecology, and archaeology. To develop suitable management solutions in response to erosion, it is necessary to ascertain spatiotemporal variations in the processes that affect site-specific coastal morphology. This study examines a beach–dune system at Montrose Bay in eastern Scotland that is undergoing severe erosion, threatening the current layout of the Montrose Medal Golf Course. Sediment eroded from the golf course frontage is deposited at the northern end of the bay where contemporaneous accretion has occurred. Analysis of sediment transport rates, time-series aerial photography, and historical maps indicate that the current spatial distribution of erosion and accretion at Montrose Bay is likely due to a strengthening of northerly drift, driven by wave–climate change during the 1980s. This natural variability was examined further through assessment of earlier changes in coastal morphology apparent in historical mapping and from archaeological evidence of shoreline change reflecting the temporal dynamism of soft sedimentary coasts. The removal of sediment dredged from the South Esk estuary in the closed coastal system is shown to be a major anthropogenic influence on the beach–dune system in recent decades based on a simple quantitative analysis of dune erosion due to removal of beach sediments during dredging operations.

EL-GAMAL, A.A., 2012. New approach for erosion and accretion coasts discrimination.

Erosion and accretion are considered as the main coastal processes. The Nile Delta is suffering from erosion due to the construction of dams and barrages across the Nile River. Detection of the coastal erosion and accretion has been carried out using different indicators. Most of these indicators require historical records for comparison. Some of these are not valid to use in front of cliffs or seawalls. Thus, the implementation of new indicators would be beneficial for coastal zone management. The aim of this work is to show that chemical indicators may be used to differentiate between eroding and accreting coasts. Dissolved inorganic silicate and suspended particulate material concentrations in seawater were selected as indicators. Data from three successive years of silicate and suspended particulate material values were evaluated for the Rashid area as an example of an erosional coast and El-Gamil as an accretionary coast. Statistically significant differences were detected between Rashid and El-Gamil according to their respective silicate and suspended particulate material values. Cluster analysis segregates the values into two separate groups (clusters). Relatively small values were contributed to the coastal erosional area (Rashid) and relatively higher values to the coastal accretionary area (El-Gamil). Validation of this method was carried out using a third location (Damietta), which is known to be another erosional coast. Cluster analysis assembled the two erosion locations (Rashid and Damietta) together and well separated from the accretionary coast. Seasonal variations in these parameters have been detected, and autumn appeared the best season for this type of differentiation.

NAYAK, S.R.; HEGDE, V.S.; SHALINI, R.; RAJAWAT, A.S.; ALI, M.; VENKATESHWARLU, B., and RAMANA, I.V., 2012. Application of satellite remote sensing for investigation of suspended sediment dispersion pattern in the near shore region: A case study from the Central West Coast of India.

Indian Remote Sensing -P4 (IRS P4) Ocean Color Monitor (OCM) data is used to understand seasonal variations in suspended sediment (SS) dispersal pattern in the near-shore waters of the Central West Coast of India. Four distinct patterns of sediment dispersion are observed. (1) During monsoon, plume-like sediment dispersion seaward is observed especially in the mouths of rivers. (2) As the monsoon progresses, there is northerly transport of sediments with anticlockwise pattern within the plumes. (3) During NE monsoon, sediment concentration is less and its transport is southward. (4) During premonsoon, SS concentration is high in the near-shore water and transport is landward. Sequential OCM data analyses indicated the influence of tidal currents, especially during premonsoon in the vicinity of the river mouths on sediments dispersion. During rising tide, sediments move into the estuary, and during falling tide they flow seaward resulting in erosion and formation of shoals. Sediment-dispersal patterns largely follow wind and wave patterns, a characteristic feature of the mesotidal coast. Presence of a number of mudflats within the estuary along with the siltation in the channels suggests that a net landward transport of sediments occur in the region.

GALVÁN, K.: BARGU, S.; WHITE, J.R.; LI, C.; SULLIVAN, M., and WEEKS, E., 2012. The effects of two consecutive hurricanes on basal food resources in a shallow coastal lagoon in Louisiana.

Short-term effects of two consecutive hurricanes on physical, chemical, and biological factors were examined in a Louisiana coastal lagoon (Bay Champagne) with a focus on effects to basal food resources. Hurricanes Gustav and Ike made landfall on Louisiana's coast on 1 and 13 September 2008, respectively. Water column and sediment chlorophyll a (Chl a), phytoplankton, and benthic microalgal (BMA) community composition, phytoplankton toxin production, sediment organic matter (SOM), sand ∶ mud ratio, and water column nutrients were measured at one prehurricane and three posthurricane sampling dates. Additional samples were taken 1 year later to address relative long-term effects on sediment characteristics. After Hurricane Gustav, the sand ∶ mud ratio of sediment significantly increased, whereas SOM and water depth decreased likely because of sediment transport of the beach and nearshore sands. This continued after the storm because of multiple breaches in the beach. Water column Chl a decreased over time; sediment Chl a did not significantly change. Phytoplanktonic diatoms increased in sediments after hurricanes relative to benthic assemblages, resulting in a BMA community more closely resembling the water-column phytoplankton community. The sand ∶ mud ratio remained high for most stations, whereas SOM decreased after Gustav and remained low 1 year after the hurricanes. Thus, sediment nutritional quality decreased with decreases in SOM and reduced BMA species; however, phytoplankton may have replaced BMA as a food resource within sediments. Additionally, the abundance of phytoplankton in the domoic acid (DA)–producing genus Pseudo-nitzschia increased in the water column and benthos after the hurricanes, and particulate DA increased significantly in the water samples. Our results suggest that hurricanes substantially affect food resources (e.g., phytoplankton, BMA, and SOM) on Louisiana's coast, and posthurricane production of DA, in this case, could increase ecosystem stress during recovery. To our knowledge, this is the first study to address the effects of hurricanes on DA concentrations.

ST-HILAIRE-GRAVEL, D.; FORBES, D.L., and BELL, T., 2012. Multitemporal analysis of a gravel-dominated coastline in the central Canadian Arctic Archipelago.

This study assesses the stability of Arctic gravel coasts across a range of timescales, based on field and remote-sensing studies of three coastal sites near Resolute Bay, Nunavut. It considers shore-zone sensitivity to ice, wind, and wave forcing at storm-event and annual timescales within a longer-term context, including coastal emergence resulting from postglacial isostatic uplift partially counteracted by accelerating sea-level rise. Another long-term factor associated with climate change is the potential for increased seasonal depth of thaw in the beachface and nearshore. The coast in this area is ice bound on average for 10 months of the year, but the annual duration of ice cover has decreased over the past 30 years (1979–2009) by 0.95 d/y. A longer open-water season has implications for the number and timing of storm-wave events, with increased probability of storms impacting the coast later in the season when the seasonal thaw layer is approaching maximum thickness. Overall, shoreline progradation surpassed erosion in the Resolute area between 1958 and 2006, reflecting a combination of sediment supply and emergence. The coastal impacts of storms were found to be short lived and not necessarily indicative of longer-term trends. Gravel shorelines can be resilient in the face of intermittent storm impacts, but thresholds of stability in this high-latitude setting are poorly understood. If current trends of rising sea level, increasing open-water duration, and more frequent effective wave events continue, there is a heightened potential for more rapid coastal change in the region.

BUJALESKY, G.G., 2012. Tsunami overtopping fan and erosive scarps at Atlantic Coast of Tierra Del Fuego.

The Ensenada de la Colonia embayment, NE Tierra del Fuego, presents an extensive and wide Holocene beach ridge plain composed of gravel and coarse sand. These deposits have revealed a regressive behavior since 6000 years BP. A Pleistocene gravel beach ridge plain was recognized in the area. Several erosive scarps are present at the embayment, indicating strong and episodic erosive events. Seaward and immediately behind the present storm berm, a high and unique overtopping fan develops.

Tierra del Fuego is a seismic area, and the subduction zone of the South Sandwich Islands constitutes a potential source of tsunamis. The abrasion platform of embayment shows a glacifluvial carved paleomorphology. This feature conditions the wave refraction pattern, concentrating the orthogonal rays in its central section. In this setting, a tsunami backwash could generate megavortexes in the nearshore zone of the bay linked to the depressed areas of the abrasion platform. The combined action of large seepage, tsunami backwash currents, and tangential currents of the vortex applied on saturated gravel beaches would cause carving of the lower section of the beach and instability of the entire profile. Then collapses of relevant volumes of gravel and sand would lead to the formation of semicircular erosive scarps.

The overtopping fan architecture displays a sequence of three to five landward onlapping radar facies of overwashing and overtopping events. The semicircular erosive scarps and the overtopping fan were created by tsunamis that reached the Atlantic coast of Tierra del Fuego. At least three pulses of a unique tsunami episode constructed the overtopping fan.

RAMSEY, E. III; WERLE, D.; SUZUOKI, Y.; RANGOONWALA, A., and LU, Z., 2012. Limitations and potential of satellite imagery to monitor environmental response to coastal flooding.

Storm-surge flooding and marsh response throughout the coastal wetlands of Louisiana were mapped using several types of remote sensing data collected before and after Hurricanes Gustav and Ike in 2008. These included synthetic aperture radar (SAR) data obtained from the (1) C-band advance SAR (ASAR) aboard the Environmental Satellite, (2) phased-array type L-band SAR (PALSAR) aboard the Advanced Land Observing Satellite, and (3) optical data obtained from Thematic Mapper (TM) sensor aboard the Land Satellite (Landsat). In estuarine marshes, L-band SAR and C-band ASAR provided accurate flood extent information when depths averaged at least 80 cm, but only L-band SAR provided consistent subcanopy detection when depths averaged 50 cm or less. Low performance of inundation mapping based on C-band ASAR was attributed to an apparent inundation detection limit (>30 cm deep) in tall Spartina alterniflora marshes, a possible canopy collapse of shoreline fresh marsh exposed to repeated storm-surge inundations, wind-roughened water surfaces where water levels reached marsh canopy heights, and relatively high backscatter in the near-range portion of the SAR imagery. A TM-based vegetation index of live biomass indicated that the severity of marsh dieback was linked to differences in dominant species. The severest impacts were not necessarily caused by longer inundation but rather could be caused by repeated exposure of the palustrine marsh to elevated salinity floodwaters. Differential impacts occurred in estuarine marshes. The more brackish marshes on average suffered higher impacts than the more saline marshes, particularly the nearshore coastal marshes occupied by S. alterniflora.

RAO, A.M.F. and CHARETTE, M.A., 2012. Benthic nitrogen fixation in an eutrophic estuary affected by groundwater discharge.

Anthropogenic nutrient loading of coastal aquifers has resulted in the discharge of nutrient-enriched groundwater to the coastal zone, with sweeping repercussions on aquatic community structure and ecosystem function. Groundwater-derived nutrient loading is known to initiate coastal eutrophication, hypoxia, and harmful algal blooms. However, most land-derived inputs of nitrogen to the coastal ocean are thought to be removed in heterotrophic estuarine and coastal sediments, which have traditionally been considered net fixed nitrogen sinks, reducing nutrient export to the oceans. Here, we provide evidence of net N₂ fixation in heterotrophic estuarine sands affected by submarine groundwater discharge based on N₂ ∶ Ar measurements in benthic flux chamber incubations. Below the surface sediments, we observed efficient removal of fixed N. Together, these results suggest that net N₂ fixation in sandy estuarine sediments is promoted by N limitation because of efficient fixed N removal in subsurface aquifer sediments and in muddy sediments elsewhere in this estuarine system. Our observations suggest that estuarine sediments in some anthropogenically affected ecosystems may not represent a net fixed N sink, limiting the potential attenuation of increased N loads and permitting increased N export to the open ocean.

GAO, J.; BAI, F.; YANG, Y.; GAO S.; LIU, Z., and LI, J., 2012. Influence of Spartina colonization on the supply and accumulation of organic carbon in tidal salt marshes of northern Jiangsu Province, China.

Two species of cordgrass (Spartina anglica Hubbard and Spartina alterniflora Loisel.) were artificially introduced to the intertidal zone of Jiangsu Province, China, in 1963 and 1982, respectively. However, as alien species, the impact of Spartina on the tidal flat ecosystem remains largely unknown. Suaeda salsa and Phragmites australis, two native plants in the intertidal zone of northern Jiangsu Province, China, are C3-type plants, whereas the Spartina species are C4-type plants. In this article, we investigate the vertical distribution of total organic carbon, total nitrogen, and organic carbon isotope ratios in different ecosystems associated with the northern Jiangsu tidal flats; analyze changes in the organic carbon sources in the tidal flat sediments after Spartina colonization; compare carbon burial patterns at different evolutionary stages in the tidal flats; and discuss the effects of Spartina on organic carbon cycling over the intertidal flats on the Jiangsu, China, coast. Before the introduction of Spartina, the organic material in the intertidal sediments of the study area mainly came from a combination of marine and C3 plants. After the introduction of Spartina, the contribution of S. alterniflora to the organic carbon content in the salt-marsh strata exceeded those made by marine sources and other C3 plants. On the S. anglica flat, the quantity of organic carbon originated from S. anglica was lower than from S. alterniflora but was still greater than the contribution made by native C3 plants. The introduction of Spartina not only had a significant effect on primary productivity throughout the tidal flats but also enhanced the organic carbon accumulation rate in the sediment.

WANG, P.; WU, T.; WANG, X., and ZHANG, Y., 2012. Novel method for in situ investigation of PAH adsorption onto mangrove leaves.

A synchronous solid-surface fluorimetry (S-SSF) method combined with an optical fiber and a fluorescence spectrophotometer was established for in situ determination of anthracene and pyrene adsorbed onto Kandelia candel (L.) Druce and Aegiceras corniculatum (L.) Blanco leaves as single components and in mixture. Using the established approach, the linear dynamic ranges and detection limits for determination of anthracene and pyrene adsorbed onto the leaves of two mangrove species as single components and in mixture were investigated. The relative standard deviations were all less than 10% (n  =  6), and the experimental recoveries with S-SSF of adsorbed anthracene and pyrene on K. candel and A. corniculatum leaves as single components and in mixture were between 82.9% and 116.5%. Furthermore, with the established method, the spectroscopic behavior of anthracene adsorbed on the living K. candel leaves were studied in situ, and gas chromatography–mass spectrometry was also used to verify the accuracy of the S-SSF approach. The results demonstrated that in a certain period of exposure time to anthracene, the trends for quantity of adsorbed anthracene on the upper side of living K. candel leaves determined by the two methods were similar. The S-SSF approach proved to be a simple, fast, and easy method, without the necessity of sample pretreatment with a large amount of organic solvent. Therefore, the S-SSF method has great potential for use in the field, and experimental conditions were further optimized and the sensitivity of the method improved.

HEGDE, V.S.; NAYAK, S.R.; SHALINI, G.; KRISHNAPRASAD, P.A.; RAJAWAT, A.S.; GIRISH, K.H., and TEJASWINI, B., 2012. Spit dynamics along the central west coast of India: Implications for coastal zone management.

Spit growth is observed across many rivers of the central west coast of India. Studies on the seasonal dynamics of the spits of the central west coast of India on the basis of the multidate satellite images LISS III, landsat™ data, panchromatic camera (PAN) data etc. in a geographic information system (GIS) environment using ERDAS imagine 9.0 version followed by field-check and wave data analysis have been discussed in this paper. All types of spits such as paired spits, winglike spits, single spits, etc. are observed along the coast of Karnataka, central west coast of India. Spit growth is responsible not only for shifting of the river mouths, but also for rapid changes in estuarine morphology and in turn on the sedimentation process. It is observed that river mouths with a spit across them have a submerged bar in front of them, whereas rivers devoid of spits are also devoid of submerged bars in front of them. This spatial association of spit and submerged bar is believed to have a genetic relationship. Along the coast many perpendicular faults and uplifts have been observed. Rate of spit growth, along with their direction and inland drainage pattern, suggest a role of sea-level changes and tectonic control in addition to alongshore currents. Rapid spit growth is observed near the inferred tectonic axis. Seasonal dynamics and modification in the spit configuration are related to alongshore drift as well as the wave refraction around the mouth of the rivers.

BAART, F.; VAN GELDER, P.H.A.J.M.; DE RONDE, J.; VAN KONINGSVELD, M., and WOUTERS, B., 2012. The effect of the 18.6-year lunar nodal cycle on regional sea-level rise estimates.

Sea-level rise rates have become important drivers for policy makers dealing with the long-term protection of coastal populations. Scenario studies suggest that an acceleration in sea-level rise is imminent. The anticipated acceleration is hard to detect because of spatial and temporal variability, which consequently, have become important research topics. A known decadal-scale variation is the 18.6-year nodal cycle. Here, we show how failing to account for the nodal cycle resulted in an overestimation of Dutch sea-level rise. The nodal cycle is present across the globe with a varying phase and a median amplitude of 2.2 cm. Accounting for the nodal cycle increases the probability of detecting acceleration in the rate of sea-level rise. In an analysis of the Dutch coast, however, still no significant acceleration was found. The nodal cycle causes sea level to drop or to rise at an increased rate; therefore, accounting for it is crucial to accurately estimate regional sea-level rise.

ISLA, F. I.; QUEZADA, J. F.; MARTÍNEZ, C.; FERNÁNDEZ, A.; and JAQUE, E. 2012. The evolution of the Bío Bío delta and the coastal plains of the Arauco Gulf, Bío Bío region: The Holocene sea-level curve of Chile.

Mid-Holocene highstands are characteristic of the Southern Hemisphere. The Chilean coast extends from 17°S to 56°S in a dominant microtidal regime; thus, it is an ideal place to test ages and altitudes of this highstand with minimal errors. However, coseismic events, the dynamic phenomena they triggered (tsunamis), and the behaviour of land in relation to the overriding of the South American Plate over the oceanic Nazca Plate, make it necessary to distinguish these effects from purely eustatic changes. To the south, the glacioisostatic uplift has been approximately measured. At 37°S, the Coronel coastal plain extends several kilometres inland. Its sediment availability has been related to the supplies of the Bío Bío River. From this beach-ridge plain, shell remains gave a radiocarbon age of 4370 ± 90 years before present (YBP), indicating a highstand not higher than 5 m. Further south, at the Carampangue coastal plain, southern coast of the Arauco Gulf, a radiocarbon age of 8010 ± 90 YBP marks the oldest age of this transgression. Some consequences of the earthquake and tsunami of February 27, 2010, are reported here. The radiocarbon ages of these plains permit completion of a Holocene sea-level curve. These Holocene sea-level data were compared to other regions of South America.