Littérature scientifique sur le sujet « Nearshore characterization »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Nearshore characterization ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Nearshore characterization"
1
Khalsa, Noah S., Kyle P. Gatt, Trent M. Sutton et Amanda L. Kelley. « Characterization of the abiotic drivers of abundance of nearshore Arctic fishes ». Ecology and Evolution 11, no 16 (22 juillet 2021) : 11491–506. http://dx.doi.org/10.1002/ece3.7940.
Texte intégral
2
Goodbody-Gringley, Gretchen, Emma Strand et Joanna M. Pitt. « Molecular characterization of nearshore baitfish populations in Bermuda to inform management ». PeerJ 7 (4 juillet 2019) : e7244. http://dx.doi.org/10.7717/peerj.7244.
Texte intégralRésumé :
Small-bodied marine fishes play an important role in the food web, feeding both larger fishes and seabirds. Often referred to as baitfishes, they concentrate seasonally in coastal areas in large, often heterospecific assemblages that are targeted by both commercial and recreational fishers. Given apparent declines in at least some of Bermuda’s baitfish species over the past 40 years, it is useful to determine the species composition of baitfish assemblages, and how it varies among sites, in order to inform management. Using genetic barcoding of the Cytochrome c oxidase 1 gene (COI), we confirm species identity, assess intraspecific genetic diversity locally, and determine rates of broader genetic connectivity for baitfish assemblages in Bermuda. Species analyzed includedHypoatherina harringtonensis,Anchoa choerostoma,Jenkinsia lamprotaenia,Harengula humeralis,Opisthonema oglinumandSardinella aurita. Species identification based on molecular barcoding revealed some misidentification of individuals based solely on gross morphological characteristics, with an error rate of 11%, validating the usefulness of this approach. Interestingly, sequence results for the endemic Bermuda anchovy,A. choerostoma, were within 1% similarity to the more broadly distributed big-eye anchovy,A. lamprotaenia, and thus additional analyses are warranted to evaluate the genetic basis for endemism. Estimates of genetic diversity within and among baitfish assemblages in Bermuda were high, indicating high rates of local connectivity among sites for all species. As such, management should consider Bermuda’s baitfish species as single, highly mixed populations. However, with the exception ofH. humeralisand the endemicA. choerostoma, significant genetic differentiation and population structure were found when comparing Bermuda’s baitfish populations with those from other regions, suggesting limited gene flow between other regions and Bermuda for these species. Limited regional connectivity has implications for management, as strong genetic divergence suggests that populations in Bermuda are predominantly self-seeding and thus not likely to be replenished from distant populations. These results therefore support precautionary management of baitfish species in Bermuda.
3
Nie, Ding, Ning Li, Min Zhang, Wangqiang Jiang et Xin Wang. « Characterization of Electromagnetic Scattering From Water-Depth-Changed Nearshore Sea Surface ». IEEE Antennas and Wireless Propagation Letters 15 (2016) : 472–75. http://dx.doi.org/10.1109/lawp.2015.2453336.
Texte intégral
4
Raubenheimer, Britt. « DEVELOPMENT OF A NEARSHORE EXTREME EVENTS RECONNAISSANCE COMMUNITY ». Coastal Engineering Proceedings, no 36v (31 décembre 2020) : 12. http://dx.doi.org/10.9753/icce.v36v.keynote.12.
Texte intégralRésumé :
Extreme events have significant impacts on the nearshore water-land system - where ocean, sound, and estuary processes interact with the nearby land - that pose high risk to society. Observations before, during, and after these events are critical to improve understanding of the interactions and feedbacks among the natural and built environments during major storms, and the corresponding human actions and reactions. The goal of the Nearshore Extreme Events Reconnaissance (NEER) Association is to organize and coordinate a national network of scientists spanning many disciplines to perform rapid, pre-and post-event site characterization, to deploy instruments to observe event processes, and to gather virtual data about the event and provide support to field teams. This presentation provides information about NEER's motivation, event-response and coordination activities, data-distribution plans, and lessons learned to date. Funding for NEER is provided by the U.S. National Science Foundation Coastlines and People Program.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/9I9Z3OLGszU
5
Gonzalez, Raul, Qingping Zou et Shunqi Pan. « MODELLING OF THE IMPACT OF A WAVE FARM ON NEARSHORE SEDIMENT TRANSPORT ». Coastal Engineering Proceedings 1, no 33 (9 octobre 2012) : 66. http://dx.doi.org/10.9753/icce.v33.sediment.66.
Texte intégralRésumé :
This paper presents the results from an integrated modelling system investigating the effects of a wave farm on nearshore sediment transport. Wave Hub project is a large scale demonstration site for the development of the operation of arrays of wave energy generation devices located at the southwest coast of the UK where multiple field measurements took place. The two-way coupled SWAN and ROMS models with nested modelling system were set up at the Wave Hub site and run with and without a wave farm. The model results show that the presence of the wave farm has significant impacts on the nearshore circulation, bed shear stresses and sediment transport. The morphological changes are also altered by the wave farm. The study is the key element for the wave resource characterization and environmental impact assessment of the wave farm.
6
Tsai, Chia-Cheng, et Chun-Hung Lin. « Review and Future Perspective of Geophysical Methods Applied in Nearshore Site Characterization ». Journal of Marine Science and Engineering 10, no 3 (1 mars 2022) : 344. http://dx.doi.org/10.3390/jmse10030344.
Texte intégralRésumé :
Seabed surveying is the basis of engineering development in shallow waters. At present, geophysical survey methods mainly utilize sonars for qualitative surveying, which requires the calibration of the results found through in situ drilling and sampling. Among them, the parameters required for engineering designs are obtained from either in situ tests or laboratory experiments of soil samples retrieved from drilling. However, the experience from onshore applications shows that the physical quantities obtained through quantitative geophysical survey methods for shallow waters can be indirectly used to estimate engineering parameters or directly as parameters for engineering evaluation, which has high application potential. This review analyzes various geophysical survey methods for nearshore site characterization (i.e., side-scan sonar, single/multi- beam sonar, sub-bottom profiler, seismic reflection method, and underwater magnetometer) and challenges in their application, and introduces quantitative geophysical survey methods (including the underwater seismic refraction method, seismic surface wave method and underwater electrical resistivity tomography) that are worth focusing on for future development. Three application difficulties have been identified, namely, the lack of operational efficiency, appropriate operational equipment and systems, and sufficient guidance for experimental shallow sea applications. It is hoped that comprehensive discussion of these challenges will increase awareness leading to engineering improvements in the surveying and measuring capabilities in shallow waters, further reducing the risk of geotechnical hazards.
7
Lowe, Alexander T., Aaron W. E. Galloway, J. Sean Yeung, Megan N. Dethier et David O. Duggins. « Broad sampling and diverse biomarkers allow characterization of nearshore particulate organic matter ». Oikos 123, no 11 (17 juin 2014) : 1341–54. http://dx.doi.org/10.1111/oik.01392.
Texte intégral
8
Ahn, Seongho, Vincent S. Neary, Mohammad Nabi Allahdadi et Ruoying He. « Nearshore wave energy resource characterization along the East Coast of the United States ». Renewable Energy 172 (juillet 2021) : 1212–24. http://dx.doi.org/10.1016/j.renene.2021.03.037.
Texte intégral
9
Waples, James T., Robert Paddock, John Janssen, David Lovalvo, Boris Schulze, Jerry Kaster et J. Val Klump. « High Resolution Bathymetry and Lakebed Characterization in the Nearshore of Western Lake Michigan ». Journal of Great Lakes Research 31 (janvier 2005) : 64–74. http://dx.doi.org/10.1016/s0380-1330(05)70290-2.
Texte intégral
10
Hotto, A. M., M. F. Satchwell et G. L. Boyer. « Molecular Characterization of Potential Microcystin-Producing Cyanobacteria in Lake Ontario Embayments and Nearshore Waters ». Applied and Environmental Microbiology 73, no 14 (25 mai 2007) : 4570–78. http://dx.doi.org/10.1128/aem.00318-07.
Texte intégralRésumé :
ABSTRACT The distribution and genotypic variation of potential microcystin (MC) producers along the southern and eastern shores of Lake Ontario in 2001 and 2003 were examined using a suite of PCR primers. Cyanobacterial, Microcystis sp., and Microcystis-specific toxin primer sets identified shoreline distribution of cyanobacterial DNA (in 97% of the stations) and MC synthetase genes (in 50% of the stations). Sequence analysis of a partial mcyA amplicon targeting Microcystis, Anabaena, and Planktothrix species indicated that the Microcystis sp. genotype was the dominant MC genotype present and revealed a novel Microcystis-like sequence containing a 6-bp insert. Analysis of the same samples with genus-specific mcyE primers confirmed that the Microcystis sp. genotype was the dominant potential MC producer. Genotype compositions within embayments were relatively homogenous compared to those for shoreline and tributary samples. MC concentrations along the shoreline exhibited both temporal and spatial differences as evidenced by the protein phosphatase inhibition assay, at times exceeding the World Health Organization guideline value for drinking water of 1.0 μg MC-LReq liter−1. MC genotypes are widespread along the New York State shoreline of Lake Ontario, appear to originate nearshore, and can be carried through the lake via wind and surface water current patterns.
Thèses sur le sujet "Nearshore characterization"
1
Albatal, Ali Hefdhallah Ali. « Advancement of Using Portable Free Fall Penetrometers for Geotechnical Site Characterization of Energetic Sandy Nearshore Areas ». Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/94608.
Texte intégralRésumé :
Portable Free Fall Penetrometers (PFFPs) are lightweight tools used for rapid and economic characterization of surficial subaqueous sediments. PFFPs vary in weight, shape and size with options for using add-on units. The different configurations enable deployments in various environments and water depths, including the nearshore zone where conventional methods are challenged by energetic hydrodynamics and limited navigable depth. Moreover, PFFPs offer an opportunity to reduce the high site investigation costs associated with conventional offshore geotechnical site investigation methods. These costs are often a major obstacle for small projects serving remote communities or testing novel renewable energy harvesting machines. However, PFFPs still face issues regarding data analysis and interpretation, particularly in energetic sandy nearshore areas. This includes a lack of data and accepted analysis methods for such environments. Therefore, the goal of this research was to advance data interpretation and sediments characterization methods using PFFPs with emphasis on deployments in energetic nearshore environments.
PFFP tests were conducted in the nearshore areas of: Yakutat Bay, AK; Cannon Beach, AK; and the U.S. Army Corps of Engineers' Field Research Facility's beach, Duck, NC. From the measurements, the research goal was addressed by: (1) introducing a methodology to create a regional sediment classification scheme utilizing the PFFP deceleration and pore pressure measurements, sediment traces on the probe upon retrieval, and previous literature; (2) investigating the effect of wave forcing on the sediments' behavior through correlating variations in sediment strength to wave climate, sandbar migration, and depth of closure, as well as identifying areas of significant sediment mobilization processes; and (3) estimating the relative density and friction angle of sand in energetic nearshore areas from PFFP measurements. For the latter, the field data was supported by vacuum triaxial tests and PFFP deployments under controlled laboratory conditions on sand samples prepared at different relative densities.
The research outcomes address gaps in knowledge with regard to the limited studies available that investigate the sand geotechnical properties in energetic nearshore areas. More specifically, the research contributes to the understanding of surficial sediment geotechnical properties in energetic nearshore areas and the enhancement of sediment characterization and interpretation methods.PHD
2
Varing, Audrey. « Wave characterization for coastal and nearshore marine renewable energy applications : focus on wave breaking and spatial varaibility of the wave field ». Thesis, Brest, 2019. http://www.theses.fr/2019BRES0105.
Texte intégralRésumé :
Les énergies marines renouvelables (EMR) sont soumises aux vagues générées par le vent. Une caractérisation précise de ces vagues est nécessaire dans les zones côtières et littorales où les vagues interagissent fortement avec le fond, générant de la réfraction et du déferlement parmi d’autres processus.Une étude approfondie sur l’initiation du déferlement est développée. La validité du critère de déferlement conventionnel uc/c (rapport entre la vitesse orbitale horizontale à la crête et la vitesse de phase) est examinée numériquement. Cette étude nous mène à définir un nouveau critère cinématique basé sur le rapport entre la vitesse orbitale maximale ||um|| et c. Ce nouveau critère améliore la détection de l’initiation du déferlement, car la position d’où s’initie l’instabilité conduisant au déferlement est mieux capturée à partir de ||um||. La variabilité spatiale du champ de vagues en zone côtière est majoritairement étudiée à partir de modèles spectraux. La capacité d’un modèle à phase-résolue (type Boussinesq BT) à fournir des informations complémentaires pour les EMR est étudiée. Les modèles spectraux et BT produisent des résultats très différents en termes de hauteur de vagues et de puissance en présence d’une forte réfraction causée par la variabilité de la bathymétrie. On définit une méthode innovante pour extraire des informations liées aux vagues à partir d’images satellites, issues d’un radar à synthèse d’ouverture (SAR), et les comparer aux sorties des modèles. Nos résultats montrent des similitudes encourageantes entre le modèle BT et les données SARSince Marine Renewable Energy (MRE) systems are submitted to wind generated waves. Accurate wave characterization is required in the coastal and nearshore environment where the waves are strongly modified by their interaction with the sea bottom, inducing refraction and wave breaking among other processes.A comprehensive study regarding the wave breaking initiation process is developed. The conventional kinematic criterion uc/c (ratio between the horizontal orbital velocity at the crest and the phase velocity) validity is numerically investigated. Our study leads us to a new kinematic wave breaking criterion based on the ratio between the maximum fluid velocity ||um|| near the wave crest and c. This new criterion improves the detection of the breaking initiation, since ||um|| accurately captures the location of the fluid instability leading to breaking.The wave field spatial variability in coastal areas is mostly studied with spectral wave models. We explore the ability of a phase-resolving model (Boussinesq-type, BT) to provide additional wave information for MRE applications.Spectral and BT models lead to significantly different spatial wave height and power patterns in the presence of strong bottom-induced refraction. We define an innovative methodology to extract wave information from satellite Synthetic Aperture Radar (SAR) images for comparison with models’ outputs. Our results highlight encouraging similarities between the BT model and SAR data
3
VANNUCCHI, VALENTINA. « Wave energy harvesting in the Mediterranean Sea ». Doctoral thesis, 2013. http://hdl.handle.net/2158/797871.
Texte intégralRésumé :
ITALIANO. Gli obiettivi principali di questa tesi sono la caratterizzazione sottocosta della potenza ricavata dal moto ondoso in aree italiane non ancora studiate o poco studiate e l'ottimizzazione di dispositivi per la conversione dell’energia disponibile dal moto ondoso (WEC - Wave Energy Converters), nei due punti maggiormente energetici di ciascuna area. I dispositivi studiati sono un corpo oscillante (il caso di studio più semplice) fissato al fondale marino per mezzo di un sistema di conversione di energia e di un dispositivo galleggiante a colonna d'acqua oscillante chiamato Spar Buoy OWC e studiato presso l'Istituto di Ingegneria Meccanica (IDMEC) dell’Istituto Superiore Tecnico (IST) di Lisbona. La caratterizzazione sottocosta è stata ottenuta mediante simulazioni numeriche effettuate con il MIKE21- Spectral Wave, un modello spettrale di onda che permette la simulazione di fenomeni come l'interazione non lineare onda-onda, la dissipazione dovuta all’attrito con il fondale, la dissipazione indotta dal frangimento delle onde, la rifrazione e lo shoaling dovuti alla variazione della profondità. Come condizioni al contorno in mare aperto sono stati utilizzati i valori di altezza d'onda, periodo di picco, direzione media e fattore di diffusione estratti dal modello PREVIMER MENOR-4000M. Le aree analizzate sono: la Toscana Settentrionale (La Spezia - Livorno), la Toscana Centrale (Livorno - Piombino), la Liguria Occidentale (Ventimiglia - Imperia), la Sardegna Nord-Occidentale (Stintino - Alghero). Per i due climi d’onda corrispondenti ai punti maggiormente energetici di ciascuna area sono stati ottimizzati i due dispositivi studiati (corpo oscillante ancorato al fondale e Spar Buoy OWC) in base alla geometria e al sistema di conversione dell’energia. L’ottimizzazione è stata effettuata massimizzando delle funzioni obiettivo che tenessero conto del costo, dell'efficienza e delle prestazioni del dispositivo.
INGLESE. The main purposes of this thesis are the nearshore wave energy characterization in Italian areas not yet analysed or little analysed and the optimization, in the two locations with the highest wave power of each area, of devices for the Wave Energy Conversion (WEC). The analysed devices were a single floating body linked to the seabed by means of a Power Take Off (PTO) mechanism (the simplest case of study) and of the Spar Buoy Oscillating Water Column (OWC), an axisymmetric floating OWC that was studied at Institute of Mechanical Engineering (IDMEC) of the Instituto Superior Técnico (IST) in Lisbon. The nearshore characterization is computed with numerical simulations that were carried out by the MIKE21-Spectral Wave, a spectral wind-wave model based on unstructured mesh that allows the simulation of the phenomena as non-linear wave-wave interaction, dissipation due to white-capping, dissipation due to bottom friction, dissipation due to depth-induced wave breaking, refraction and shoaling due to depth variations. As offshore boundary conditions the values of wave height, peak period, average direction and spreading factor, of the points extracted by the MENOR-4000M PREVIMER model on a depth of 100 m, were used. This methodology is applied to four selected areas: the North of the Tuscany coast (La Spezia – Livorno), the centre of the Tuscany coast (Livorno – Piombino), the Western part of Liguria coast (Ventimiglia – Imperia) and the North-West of the Sardinia coast (Stintino – Alghero). The device optimization was performed for the geometry and for the PTO system in local wave climates selected for each area. The optimization procedure followed different criteria that consisted in maximizing objective functions, in order to consider the cost, particularly useful in the fully commercial stage, the efficiency and the performance of the devices.
4
Caulkins, Joshua Lee. « Characterization and investigation of submarine groundwater discharge from a coastal aquifer into the nearshore environment ». Thesis, 2004. http://hdl.handle.net/2429/15434.
Texte intégralRésumé :
The current trend of global populations moving increasingly to high density,
coastal cities places a greater emphasis upon the water quality of aquifers supplying those
cities. Problems that affect coastal aquifers (e.g. saltwater intrusion, non-point source
pollution) will be amplified as this trend increases. The goal of this research project is to
understand the processes that control freshwater/saltwater interactions in the coastal zone,
specifically in areas of high submarine groundwater discharge (SGD). A site in NW
Florida along the Gulf Coast is a well-documented SGD locale and provides an excellent
opportunity to examine how tidal fluctuations, differential pressure in the seabed and
groundwater seepage rates are interrelated. Experiments at the site focus on
characterization of the nearshore aquifer, submarine groundwater discharge at the seabed
and numerical modeling of the system. New onshore wells at the field site show that
hydraulic conductivities in onshore region are similar to those in the offshore region. Slug
tests and water level monitoring of the onshore wells are used to measure a seaward,
horizontal hydraulic gradient. Direct measurements of discharge are conducted with an
automated seepage meter, which shows that peak discharge rates tend to occur at the
transition between high and low tides. A new apparatus called a differential piezometer
system (DPS) is designed and used to measure differential hydraulic head in the seabed
created by seepage and tidal interactions. This system failed to accurately portray
differential head fluctuations in the seabed as a result o f calibration error. Salinity
samples are collected from on and offshore wells and from a newly installed multi-level
well, the data of which are made into salinity profiles. These profiles define the boundaries of a saline wedge and mixing zone in the nearshore region. FRAC3DVS is
flow and transport groundwater model that is used to design and run a 1-dimensional
numerical model. The model results confirm the temporal effects of tidal elevation on
discharge rates observed in the seepage meter.
Livres sur le sujet "Nearshore characterization"
1
Thomson, Denis H. Identification and characterization of Arctic nearshore benthic habitats. Winnipeg, Man : Western Region, Dept. of Fisheries and Oceans, 1986.
Trouver le texte intégralActes de conférences sur le sujet "Nearshore characterization"
1
Plant, Nathaniel G., et Rob A. Holman. « Nearshore Morphology Characterization Based on a Predictive Model for Sandbar Migration ». Dans Fourth Conference on Coastal Dynamics. Reston, VA : American Society of Civil Engineers, 2001. http://dx.doi.org/10.1061/40566(260)54.
Texte intégral
2
Tseng, Y., C. Ko, C. Chien, P. Tseng, H. Hsu et T. Shiao. « A Preliminary Site Characterization of Geological Carbon Storage Projects in Western Nearshore Taiwan ». Dans EAGE GET 2022. European Association of Geoscientists & Engineers, 2022. http://dx.doi.org/10.3997/2214-4609.202221117.
Texte intégral
3
Flaum, Jason, Stanley T. Paxton et Justin Birdwell. « FACIES CHARACTERIZATION AND STRATIGRAPHIC RELATIONS OF A NEARSHORE TO OFFSHORE MUDSTONE SUCCESSION OF THE LOWER EAGLE FORD FORMATION IN THE EAST TEXAS BASIN ». Dans GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-378926.
Texte intégral
4
Cabezas-Rabadán, Carlos, Josep E. Pardo-Pascual, Jesús Palomar-Vázquez et Alfonso Fernández-Sarría. « Monitoring the spatiotemporal variability of beach mesoforms by analyzing Sentinel-2 images ». Dans 5th Joint International Symposium on Deformation Monitoring. Valencia : Editorial de la Universitat Politècnica de València, 2022. http://dx.doi.org/10.4995/jisdm2022.2022.13822.
Texte intégralRésumé :
Beaches are extremely dynamic natural environments that experience significant variations at different spatial and temporal scales. The processes of appearance and maintenance of morphological features as the beach mesoforms, as well as their characterization, may provide useful information on the morphodynamic evolution of a beach and the spatial variability of nearshore processes. The high availability of Sentinel-2 satellite images together with the development of tools such as the system SHOREX allows the automatic extraction of the position of the shore. The high accuracy of the resulting satellite-derived shorelines (SDS) offers high potential for the definition of relatively detailed morphological features. This work assesses the ability to apply the SDS for characterizing beach mesoforms appearing at Cala de Mijas, in Málaga (S Spain) as well as characterising their changes over time. The extraction of the SDS enables the characterisation of rhythmic coastal forms through the undulations described by the shoreline position along the beach face by using a sinuosity index and to start to address the study of their relationship with the registered wave conditions. This proves that the information derived from mid-resolution satellite images can become a key source of information to characterize the morphological dynamics of beach environments.
5
Armenio, Elvira, Domenico Laforgia, Marco Milanese et Michele Mossa. « Wind and Wave Study for Off-Shore Wind Farm Applications ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49219.
Texte intégralRésumé :
The study focuses on wind-waves-bottom characterization as first step in the feasibility evaluation of an offshore windfarm in the offing of Apulian coast - Italy. Planning offshore windfarm, hydrodynamic and aerodynamic fields, and their interaction, must be investigated. Waves studies and their transformation due to diffraction, shoaling, refraction, etc. are fundamental to predict the effects that sea could have on turbine’s foundation, especially for floating turbine, mooring lines, structural stress and moreover to consider the influence that frequently high waves may have on installation, operation and maintenance. In this study, starting from wind data and a nautical map, a good determination of the wave motion has been obtained. Particularly, three-hours measurements of wind intensity and direction, by on-land anemometer, have been used. Wind data of a period of time of 45 years, from 1951 to 1996, have been statistically processed to extract the most relevant winds with velocity and duration bigger than 10 knots and 6 hours respectively. Using the nautical map of the area under investigation, the sea bottom morphology has been reconstructed to obtain a model of bathymetry. After that, the bathymetric curves have been traced on the map, converted in a depth matrix and then transformed into an interpolated grid point. Subsequently, the assessment of waves propagation has been obtained through both Jonswap Spectrum and SPM method and the results have been compared. Finally, the wave heights and peak periods were calculated with reference to return period of fifty years and used as input in two model: Nearshore Spectral Waves (NSW) model and Parabolic Mild Slope Spectra Waves (PMS) model. In conclusion, this study can represent a useful approach to plan an offshore windfarm.
6
Stark, Nina, Brandon Quinn, Katerina Ziotopoulou et Hugues Lantuit. « Geotechnical Investigation of Pore Pressure Behavior of Muddy Seafloor Sediments in an Arctic Permafrost Environment ». Dans ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41583.
Texte intégralRésumé :
Herschel Island, Yukon, Canada, is made of ice-rich permafrost and is affected by high rates of coastal erosion, likely to increase with decreasing summer sea ice extent. During an interdisciplinary expedition to Herschel Island in July 2014, geotechnical investigations were carried out in shallow water environments of up to 20 m water depth and at different beaches. The free-fall penetrometer BlueDrop was deployed at 299 positions. Apart from obtaining vertical profiles of sediment strength and the pore pressure response upon impact, the pore pressure evolution over a period of one hour after deployment was investigated. The focus area for these tests was Pauline Cove, located at the south-eastern side of the island, being sheltered by a spit from the open Beaufort Sea and affected by a number of old and young retrogressive thaw slumps, delivering large amounts of mud. The sediment resistance profiles revealed up to three distinct layers of sediment strength, expressing different consolidation states, or possibly changes in sediment composition. This stratification was supported by the pore pressure results, including pore pressure evolution “on-the-flight” during penetrometer penetration as well as pore pressure evolution at maximum penetration depth with the penetrometer being at rest. The sediment surface layer 1 was characterized by a thickness of 5–20 cm depending on the respective location, low sediment resistance and predominantly hydrostatic pressure. It most likely has frequently been reworked by wave action, and exhibited similar geotechnical signatures as fluid mud. Layer 2 reached sediment depths of 30–60 cm, showed an increase in sediment resistance and distinct subhydrostatic pore pressures during penetration, while pore pressures increased in an asymptotic manner to suprahydrostatic (160–180% of hydrostatic pressure) over an observation period of 30–50 minutes. Based on comparison to other examples from the literature, it was hypothesized that layer 2 was composed of overconsolidated mud. Layer 3 featured a significant increase in sediment resistance as well as pore pressure during penetration. As soon as the probe came to rest, the pressure decreased significantly to subhydrostatic conditions, before swinging back to being suprahydrostatic and then slowly dissipating. A similar behavior has been associated to silty sands and high bulk densities. Here, it may suggest a change in sediment composition, likely influenced by coarser nearshore and beach sediments, representing also a denser sediment matrix. The pore pressure results will complement the geological and geotechnical characterization of the coastal zone of Hershel Island, and contribute to the investigation of erosion and deposition processes.