المؤلفون: Breili, Kristian

المصدر: Ocean Dynamics; Feb2022, Vol. 72 Issue 2, p115-136, 22p

مصطلحات موضوعية: GLACIAL isostasy, SEA level, WIND pressure, COASTS, NORWEGIANS, COASTAL processes (Physical geology)

مستخلص: A first national analysis of the evolution of sea-level rates along the Norwegian coast for the period 1960–2100 has been accomplished by exploring tide-gauge records, relative sea-level projections, and detection techniques for acceleration. Firstly, sea-level rates for the two study periods 1960–2020 and 1991–2020 were estimated. Along the Norwegian coast, relative sea-level rates show significant spatial variation due to glacial isostatic adjustment. Moreover, the coastal average sea-level rate for the period 1991–2020 is significantly higher than for the period 1960–2020. Accelerations were then estimated for all combinations of start years and study periods longer than 30 years by including quadratic coefficients in regression models. It was found that the estimates strongly depend on the study period and do not provide confident estimates of climate change driven variation in the sea level along the Norwegian coast. Secondly, non-linear trends in relative sea level were reconstructed from Singular-Spectrum Analysis, which at several tide gauges revealed low rates in the 1970s, maximum rates around 1990, and declining rates thereafter. From the reconstructed trends, significant positive acceleration in the relative sea level was estimated for the period 1960–2020, while accelerations less than zero were detected for the period 1991–2020. However, the estimates for the recent period appear not robust due to the influence of decadal and multidecadal variation characterizing Norwegian tide-gauge records. Finally, by artificially extending the tide-gauge records by projections, the time when unprecedented high sea-level rates emerge was identified. With projections calculated for the intensive emission scenario RCP8.5, the climate signal of the relative sea level emerges at earliest in the late 2030s. The time of emergence is typically 5 to 10 years later if reanalysis of sea-level pressure and wind speed are used to reduce decadal variation in the tide-gauge records. This is because the meteorological regressors, as a side effect, introduce serial correlations that lead to rate estimates with enlarged standard errors. An important implication of the findings is that a possible absence of record high sea-level rates in the 2020s and 2030s does not falsify that relative sea level along the Norwegian coast is consistent with projections of RCP8.5. [ABSTRACT FROM AUTHOR]

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المؤلفون: Lauzon, Rebecca, Murray, A. Brad

المصدر: Journal of Geophysical Research. Earth Surface; Feb2022, Vol. 127 Issue 2, p1-19, 19p

مصطلحات موضوعية: DELTAS, VEGETATION & climate, COASTAL processes (Physical geology), HYDRAULICS, SEDIMENT analysis

مستخلص: The dynamics and morphological evolution of deltas and their channel networks involve interactions between many factors, including water and sediment discharge and cohesion from fine sediment and vegetation. These interactions are likely to affect how strongly vegetation influences deltas. Altering water or sediment discharge may affect channel mobility, magnitude of deposition and erosion events, and may result in the delta being less suitable for vegetation colonization. Using the numerical model DeltaRCM Vegetation, we explore how water and sediment discharge affects delta evolution and under which conditions vegetation exerts a stabilizing effect on the channel network. We propose new insights into delta evolution under different discharge conditions. First, we observe a regime shift in avulsion dynamics, driven by delta‐scale water surface slopes, with increasing water discharge: from a few active channels undergoing occasional complete, global avulsions (with low discharge) to many active channels experiencing frequent partial, local avulsions (with high discharge). Second, with vegetation, increased sediment discharge results in more frequent switching of the dominant channels but also prevents vegetation from establishing in non‐dominant channels, resulting in more frequent channel reoccupation and therefore greater stability in channel network planform. These insights have important implications for understanding the distribution of water, sediment, and nutrients on deltas in the face of future changes in climate and human modifications of fluxes of sediment and water to the coast, especially for restored or engineered deltas with controlled water or sediment discharges. Plain Language Summary: Delta restoration projects may take the form of building new land through diverting water and sediment from a river or channel to a chosen location. The presence or absence of vegetation changes how deltas respond to different volumes of water (discharge) and different amounts of sediment in the water (sediment input). We study the effect that the discharge and sediment input have on the behavior of channels on river deltas using a simple model. We find that deltas with lower discharge have few channels and experience occasional large changes in channel location. However, with higher discharge, deltas have many channels and experience frequent but small changes in channel location. On deltas with vegetation the same patterns in channel behavior with low and high discharge occur but channel locations are more stable, as vegetation makes creation of a new channel unlikely, by confining water in channels and making the land outside of channels difficult to erode. Increasing the sediment discharge also increased channel stability on deltas by burying young plants and preventing vegetation from growing in small channels. This study will help us better understand how water and sediment discharge influences delta shape and channel behavior. Key Points: Different avulsion regimes for high and low water discharge driven by patterns in delta‐wide water surface slopesDeltas undergo shift from few to many channels and global to local avulsions with increasing water dischargeVegetation confines flow to and stabilizes channel networks under high sediment or water discharge via frequent channel reoccupation [ABSTRACT FROM AUTHOR]

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المؤلفون: Mortimore, Rory N.

المصدر: Quarterly Journal of Engineering Geology & Hydrogeology; Feb2022, Vol. 55 Issue 1, p1-28, 28p

مصطلحات موضوعية: CHALK, SHEAR zones, CORE drilling, PETROLOGY, MARL, COASTAL processes (Physical geology)

مصطلحات جغرافية: SUSSEX (England)

مستخلص: Chalk fracture logging is reviewed in the context of the broader geology needed to build conceptual ground models. Examples of drilling damaged core illustrate the many issues faced by core loggers including identification of marker beds (marl seams, hardgrounds, flint bands, fossil shell beds) and the 'interpretations' necessary to complete a fracture log. Stratabound fractures impart a special style of fracturing to each Chalk formation. Lithology is a key factor in development of fracture style where marl seams control inclined conjugate fracture sets, development of listric growth faults and interbed slides. Lateral changes in lithology and thickness and consequent controls on fracture evolution are related to intra-Chalk tectonic episodes and tectonic setting with onshore interpretations supported by offshore seismic profiles. Strike-slip faults are illustrated in the Chalk cliffs of the Sussex coast. Fracture log reports should highlight special features such as shear zones and use annotated core photographs to illustrate issues requiring discussion. [ABSTRACT FROM AUTHOR]

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المؤلفون: Dimitriu, Radu George¹, Stanciu, Irina-Marilena¹, Barbu, Marius-Bogdan¹, Dobrev, Nikolai², Dumitru, Paul Daniel³

المصدر: Proceedings of the International Multidisciplinary Scientific GeoConference SGEM. 2017, Vol. 17 Issue 1-4, p149-157. 9p.

مصطلحات موضوعية: *GEODYNAMICS, *COASTAL processes (Physical geology), *GLOBAL Positioning System, *ELECTRONIC data processing

مصطلحات جغرافية: BLACK Sea

مستخلص: The north-western and western coast of the Black Sea, corresponding to Romania and Bulgaria, is subject of crustal deformations due to remote effects produced by geological processes ran at planetary (e.g. plate tectonics in the Atlantic and Eastern Mediterranean-Anatolia realms) and regional (e.g. the tectonic coupling of the Black Sea basin and Vrancea seismogenic area) scales as well as due to relatively local geological processes (e.g. subsidence of sedimentary basins, young sediments compaction, etc.). The geodynamic researches, systematically carried out for decades in Romania and Bulgaria, in the past were able to highlight the predominance of descending vertical movements (-1 to -2 mm/yr) of Earth crust within the Danube Delta, along the Romanian coast and around Burgas bay. The same researches indicate an ascendant geodynamic regime (+1 to +2 mm/yr) for the eastern sector of the Moesian Platform's Wallachian Compartment (the so-called North Bulgarian Uplift or Arch). Recent geodynamic studies, carried out based on satellite geodetic data, generally indicate horizontal velocity vectors heading towards south and south-east, with amplitude ranging from 1 to 2.5 mm/yr for the eastern Romania and Bulgaria. These studies also seem to indicate a subsiding regime of the coastal zone, at least for the Romanian territory. One of the main goals of the cross-border cooperation project MARINEGEOHAZARD, financed between 2010 and 2013 by the European Commission, is the implementation along the Romanian and Bulgarian coastline of a permanent GNSS stations network able to highlight and monitor the deformations of the Earth crust. This transborder geodynamic network, called GeoPontica, was commenced in 2013, it comprises 18 permanent GNSS stations (13 in Romania, 5 in Bulgaria) and is now part of the Black Sea Security System and of the National Centre for Marine Natural Hazards Monitoring-Early Warning-Alarming Euxinus operated from Constanta and Varna. Each station of the network consists of a geodynamic pillar monumentalized by the "deep drilled braces" UNAVCO solution on which GNSS receivers and other instruments operate 24/7. The advanced processing of satellite raw data logged on Euxinus servers since 2013 allowed us to establish a reference epoch for the observed velocity vectors. It corresponds to March, 01-05, 2016 timespan and is considered as a "zero" reference for all previous and subsequent data processing. The early and until now preliminary results of these advanced processing carried out for different epochs are already able to confirm the predominance of subsidence movements along the coast, except for the southern half of the Bulganian shore, and also to separate distinct geodynamic behavior for the main tectonic blocks that make up the Earth crust in the study area. [ABSTRACT FROM AUTHOR]

المؤلفون: Vergara Dal Pont, Iván P.¹, Caselli, Alberto T.², Moreiras, Stella M.^1,3, Lauro, Carolina¹

المصدر: Journal of Coastal Research. Nov2017, Vol. 33 Issue 6, p1367-1375. 9p. 2 Charts, 2 Graphs, 3 Maps.

مصطلحات موضوعية: *COASTAL processes (Physical geology), *GEOMORPHOLOGICAL research, *HYDRODYNAMICS, *COASTS

مصطلحات جغرافية: NEGRO River (Rio Negro, Argentina), ARGENTINA

مستخلص: Vergara Dal Pont, I.P.; Caselli, A.T.; Moreiras, S.M., and Lauro, C., 2017. Recent coastal geomorphological evolution in the Negro River's mouth (41°S), Argentinean Patagonia. This paper analyzes the geomorphological evolution of the Negro River's mouth to understand how aerodynamic and hydrodynamic states of the Atlantic coast have developed to this date. Accordingly, the morphometry of the beach and the historical river flow record were studied. The results indicate a dichotomous state for this coast. The SW area is characterized by cliffs with an average recession rate of 0.69 m/y during the 1959-2011 period, whereas the NE area is characterized by beaches in stable and accretion states. In the latter zone, a relatively fast coastal accretion was corroborated with the advance of a berm of up to 170 m between 1986 and 2014; furthermore, the beach extension grew to 760 m during 1986-2004. Since 1936, a completely new phenomenon was observed at the Negro River's mouth: the displacement and accretion of intertidal banks toward the coast provoked the closure of the channels of fluvial discharge and tidal currents. This activity at the Negro River's mouth could be due to the reduction of river discharge during the 20th century, which increased the preponderance of littoral current over the river discharge. [ABSTRACT FROM AUTHOR]

المؤلفون: Clark, K.J.¹ K.Clark@gns.cri.nz, Nissen, E.K.², Howarth, J.D.¹, Hamling, I.J.¹, Mountjoy, J.J.³, Ries, W.F.¹, Jones, K.¹, Goldstien, S.⁴, Cochran, U.A.¹, Villamor, P.¹, Hreinsdóttir, S.¹, Litchfield, N.J.¹, Mueller, C.¹, Berryman, K.R.¹, Strong, D.T.¹

المصدر: Earth & Planetary Science Letters. Sep2017, Vol. 474, p334-344. 11p.

مصطلحات موضوعية: *COASTAL processes (Physical geology), *DEFORMATIONS (Mechanics), *SATELLITE geodesy, *EARTHQUAKES, *PLATE tectonics, *PALEOSEISMOLOGY

مستخلص: Coseismic coastal deformation is often used to understand slip on offshore faults in large earthquakes but in the 2016 M W 7.8 Kaikōura earthquake multiple faults ruptured across and sub-parallel to the coastline. Along ∼110 km of coastline, a rich dataset of coastal deformation comprising airborne lidar differencing, field surveying and satellite geodesy reveals highly variable vertical displacements, ranging from −2.5 to 6.5 m. These inform a refined slip model for the Kaikōura earthquake which incorporates changes to the slip on offshore faults and inclusion of an offshore reverse crustal fault that accounts for broad, low-amplitude uplift centered on Kaikōura Peninsula. The exceptional detail afforded by differential lidar and the high variability in coastal deformation combine to form the highest-resolution and most complex record of coseismic coastal deformation yet documented. This should prompt reassessment of coastal paleoseismic records that may not have considered multi-fault ruptures and high complexity deformation fields. [ABSTRACT FROM AUTHOR]

المؤلفون: Sadovskii, Vladimir M.¹ sadov@icm.krasn.ru, Sadovskaya, Oxana V.¹ o_sadov@icm.krasn.ru, Lukyanov, Alexander A.² aalukyanov1@gmail.com

المصدر: Journal of Computational Physics. Sep2017, Vol. 345, p834-855. 22p.

مصطلحات موضوعية: *COASTAL processes (Physical geology), *MATHEMATICAL models, *MECHANICAL behavior of materials, *TENSILE strength, *POROUS materials

مستخلص: The wave processes in blocky media are analyzed by applying different mathematical models, wherein the elastic blocks interact with each other via pliant interlayers with the complex mechanical properties. Four versions of constitutive equations are considered. In the first version, an elastic interaction between the blocks is simulated within the framework of linear elasticity theory, and the model of elastic–plastic interlayers is constructed to take into account the appearance of irreversible deformation of interlayers at short time intervals. In the second one, the effects of viscoelastic shear in the interblock interlayers are taken into the consideration using the Poynting–Thomson rheological scheme. In the third option, the model of an elastic porous material is used in the interlayers, where the pores collapse if an abrupt compressive stress is applied. In the fourth case, the model of a fluid-saturated material with open pores is examined based on Biot's equations. The collapse of pores is modeled by the generalized rheological approach, wherein the mechanical properties of a material are simulated using four rheological elements. Three of them are the traditional elastic, viscous and plastic elements, the fourth element is the so-called rigid contact, which is used to describe the behavior of materials with the different resistance to tension and compression. It was shown that the thermodynamically consistent model is provided, which means that the energy balance equation is fulfilled for an entire blocky structure, where the kinetic and potential energy of the system is the sum of the kinetic and potential energies of the blocks and interlayers. Under numerical implementation of the interlayers models, the dissipationless finite difference Ivanov's method was used. The splitting method by spatial variables in the combination with the Godunov gap decay scheme was applied in the blocks. As a result, robust and stable computational algorithms are built and tested. Using MPI technology, the parallel software was designed for the modeling of wave processes in 2D setting. The numerical results are presented, discussed and future studies are outlined. [ABSTRACT FROM AUTHOR]

المؤلفون: Robertson, Bryson¹ bryson@uvic.ca, Gharabaghi, Bahram² bgharaba@uoguelph.ca, Power, Hannah E.³ Hannah.power@newcastle.edu.au

المصدر: Coastal Engineering Journal. Sep2017, Vol. 59 Issue 3, p1-14. 14p.

مصطلحات موضوعية: *COASTAL processes (Physical geology), *GENE expression, *OCEAN engineering, *MATHEMATICAL models, *WAVELENGTHS, *WATER depth

مستخلص: The forces and loading resulting from shallow water breaking waves are one of the most important drivers in coastal engineering design and morphological change. The importance of accurately and precisely predicting breaking wave conditions cannot be overstated. Using a novel dataset of laboratory and field scale breaking wave conditions, this study assesses the performance of widely applied empirical relationships for breaking waves and uses newly available artificial neural networks and gene expression programming (GEP) numerical methods to develop an accurate and easily applied predictor of breaking conditions for coastal engineers and planners. A novel GEP model is developed and shown to: provide excellent predictive ability at all scales, greatly improve prediction compared with previous works at laboratory scale and clearly identify the relevant importance of seafloor slope and the water depth to wavelength ratio. [ABSTRACT FROM AUTHOR]

المؤلفون: Amadio, Mattia, Essenfelder, Arthur H., Bagli, Stefano, Marzi, Sepehr, Mazzoli, Paolo, Mysiak, Jaroslav, Roberts, Stephen

المصدر: Natural Hazards & Earth System Sciences; Jan2022, Vol. 22 Issue 1, p265-286, 22p

مصطلحات موضوعية: RELATIVE sea level change, COST effectiveness, FLOOD damage, SEA level, LAND subsidence, FLOODS, FLOOD risk, COASTAL processes (Physical geology)

مصطلحات جغرافية: RIMINI (Italy), ITALY

مستخلص: The combined effect of global sea level rise and land subsidence phenomena poses a major threat to coastal settlements. Coastal flooding events are expected to grow in frequency and magnitude, increasing the potential economic losses and costs of adaptation. In Italy, a large share of the population and economic activities are located along the low-lying coastal plain of the North Adriatic coast, one of the most sensitive areas to relative sea level changes. Over the last half a century, this stretch of coast has experienced a significant rise in relative sea level, the main component of which was land subsidence; in the forthcoming decades, climate-induced sea level rise is expected to become the first driver of coastal inundation hazard. We propose an assessment of flood hazard and risk linked with extreme sea level scenarios, under both historical conditions and sea level rise projections in 2050 and 2100. We run a hydrodynamic inundation model on two pilot sites located along the North Adriatic coast of Emilia-Romagna: Rimini and Cesenatico. Here, we compare alternative extreme sea level scenarios accounting for the effect of planned and hypothetical seaside renovation projects against the historical baseline. We apply a flood damage model to estimate the potential economic damage linked to flood scenarios, and we calculate the change in expected annual damage according to changes in the relative sea level. Finally, damage reduction benefits are evaluated by means of cost–benefit analysis. Results suggest an overall profitability of the investigated projects over time, with increasing benefits due to increased probability of intense flooding in the near future. [ABSTRACT FROM AUTHOR]

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المؤلفون: Ryang, Woo Hun, Simms, Alexander R., Yoon, Hyun Ho, Chun, Seung Soo, Kong, Gee Soo

المصدر: Earth System Science Data; Jan2022, Vol. 14 Issue 1, p117-142, 26p

مصطلحات موضوعية: OPTICALLY stimulated luminescence, PENINSULAS, TIDAL flats, CYCLOSTRATIGRAPHY, SEA level, COASTAL processes (Physical geology)

مصطلحات جغرافية: KOREA

مستخلص: Like most of the world's coastlines, the Korean Peninsula experienced higher-than-present sea levels during the last interglacial (LIG), otherwise known as Marine Isotope Stage (MIS) 5e. However, the expression of that highstand in the geological record differs across the eastern and western Korean Peninsula. The tectonically active east coast of the Korean Peninsula is characterized by broad uplifted marine terraces, while the stable west coast is characterized by tidal flats and rias. In this study, we used a standardized database template to review and extract the existing constraints on LIG sea levels along both the east and west coasts of the Korean Peninsula. A total of 62 LIG constraining data points were compiled including 34 sea-level indicators, 22 marine limiting records, and 6 terrestrial limiting records. The ages from these data points are based on 61 optically stimulated luminescence (OSL) measurements and 1 paleomagnetic-based age. Along the uplifted east coast, LIG sea-level indicators based on marine terraces are at elevations ranging from + 9 to + 32 m. The uplifted marine terraces are cut or otherwise deformed by faults developed under a compressional regime due to back-arc closing of the East Sea since the early Pliocene. As a result, tectonic uplift likely has affected the elevations of the east coast LIG shorelines. In contrast, LIG sea-level records on the west coast of the Korean Peninsula are found at heights of between + 3 and + 6 m and include marine and terrestrial elevation limiting records as well as true sea-level indicators. The LIG sea-level constraints along the west coast of the Korean Peninsula are likely unaffected by vertical movement or experienced minor subsidence during the Quaternary. The database is available open access at 10.5281/zenodo.4974826 (Ryang and Simms, 2021). [ABSTRACT FROM AUTHOR]

: Copyright of Earth System Science Data is the property of Copernicus Gesellschaft mbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)