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Journal articles on the topic 'Seabed'

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Published: 4 June 2021

Last updated: 10 March 2023

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1

Krutilla, Kerry, David Good, Michael Toman, and Tijen Arin. "Addressing Fundamental Uncertainty in Benefit–Cost Analysis: The Case of Deep Seabed Mining." Journal of Benefit-Cost Analysis 12, no. 1 (2021): 122–51. http://dx.doi.org/10.1017/bca.2020.28.

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AbstractMineral deposits of base metals, precious metals, and rare earth elements have been discovered on deep seabeds, and the commercial exploitation of these resources seems poised to begin after faltering for many years. The development of seabed resources could be socially beneficial if all goes well, but the industry faces daunting challenges and uncertainties. Emerging regulations and contracting mechanisms are the principal means for managing these uncertainties. This article recommends a complementary approach: the use of ex ante benefit–cost analysis of proposed seabed mining contracts that incorporates a fundamental uncertainty evaluation. We argue that such an ex ante evaluation will improve the state of information for the decision-making, reducing the risk of regulatory noncompliance or costly contract disputes after seabed mining begins.

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2

Barnett, Anna. "Seabed seepage." Nature Climate Change 1, no. 909 (August 27, 2009): 99. http://dx.doi.org/10.1038/climate.2009.81.

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3

Dyer, KR. "Seabed mechanics." Marine and Petroleum Geology 2, no. 4 (November 1985): 377. http://dx.doi.org/10.1016/0264-8172(85)90037-6.

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4

BROADUS, J. M. "Seabed Materials." Science 235, no. 4791 (February 20, 1987): 853–60. http://dx.doi.org/10.1126/science.235.4791.853.

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5

Lodge, Michael. "The International Seabed Authority and deep seabed mining." UN Chronicle 54, no. 2 (May 26, 2017): 44–46. http://dx.doi.org/10.18356/ea0e574d-en.

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6

Yang, Wenxian, and Wenye Tian. "Concept Research of a Countermeasure Device for Preventing Scour around the Monopile Foundations of Offshore Wind Turbines." Energies 11, no. 10 (September 28, 2018): 2593. http://dx.doi.org/10.3390/en11102593.

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Scouring has long been considered to be a major issue affecting the reliability of the monopile foundations of offshore wind turbines (OWTs) on sandy seabeds. To reduce the impact of scouring, several tons of rock/stone are usually placed around the foundations shortly after the installation of them. Such a measure is costly. Moreover, rock and stone may spread widely on the seabed during the long-term service period of OWTs. It has no doubt that recycling these rock and stone on the seabed is quite difficult in future decommission. For this reason, a new scour-countermeasure device (SEMCD) is proposed and studied in this paper. Considering that the major driver of scouring is horseshoe vortices around the monopile foundation, a hollow horn-like SEMCD with an arc surface profile is designed for weakening the horseshoe vortices. The SEMCD is made of either cement or other kinds of corrosion resistant materials. It is light in weight, and easy to install and decommission. In the paper, the working mechanism of the SEMCD is first explained. Then, its scouring mitigation effect (SME), i.e., its contribution to the reduction of horseshoe vortices and the mitigation of seabed erosion around the foundation, is studied through investigating its influences on down/up-flow and seabed shear stress. Finally, the optimal size of the SEMCD is discussed through investigating the impact of its size on the speeds of up and down flows and the shear stress on seabed surface. The calculation results have shown that the proposed SEMCD has great potential to prevent scouring and seabed erosion, so that it is of significance to improve the reliability of the monopile foundations of OWTs.

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7

Riddell-Dixon, E., and Roderick Ogley. "Internationalizing the Seabed." International Journal 40, no. 3 (1985): 548. http://dx.doi.org/10.2307/40202253.

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8

Lodge, Michael W. "International Seabed Authority." International Journal of Marine and Coastal Law 26, no. 3 (2011): 463–80. http://dx.doi.org/10.1163/157180811x576929.

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9

Jaeckel, Aline. "International Seabed Authority." International Journal of Marine and Coastal Law 31, no. 4 (November 22, 2016): 706–19. http://dx.doi.org/10.1163/15718085-12341416.

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10

Pace, N. G., and H. Gao. "Swathe seabed classification." IEEE Journal of Oceanic Engineering 13, no. 2 (April 1988): 83–90. http://dx.doi.org/10.1109/48.559.

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11

Sibbald, Joanna, and Kirsten Wick. "Foreshore and seabed." International Journal of Entrepreneurship and Small Business 2, no. 2 (2005): 188. http://dx.doi.org/10.1504/ijesb.2005.006814.

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12

Hutnak, Michael. "Seabed Fluid Flow." Geofluids 7, no. 4 (November 2007): 468–69. http://dx.doi.org/10.1111/j.1468-8123.2007.00189.x.

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13

MacKenzie, Debora. "Danger – radioactive seabed." New Scientist 224, no. 2999 (December 2014): 14. http://dx.doi.org/10.1016/s0262-4079(14)62372-1.

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14

Gross, Michael. "Seabed search boost." Current Biology 21, no. 3 (February 2011): R94—R95. http://dx.doi.org/10.1016/j.cub.2011.01.021.

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15

Fredsøe, Jørgen. "Pipeline–Seabed Interaction." Journal of Waterway, Port, Coastal, and Ocean Engineering 142, no. 6 (November 2016): 03116002. http://dx.doi.org/10.1061/(asce)ww.1943-5460.0000352.

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16

Brown, E. D. "Internationalizing the seabed." Marine Policy 9, no. 3 (July 1985): 243–44. http://dx.doi.org/10.1016/0308-597x(85)90024-7.

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17

Woodliffe, J. C. "Internationalizing the seabed." International Review of Law and Economics 5, no. 1 (June 1985): 124–27. http://dx.doi.org/10.1016/0144-8188(85)90025-0.

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18

Guo, Zhen, Wenjie Zhou, Congbo Zhu, Feng Yuan, and Shengjie Rui. "Numerical Simulations of Wave-induced Soil Erosion in Silty Sand Seabeds." Journal of Marine Science and Engineering 7, no. 2 (February 20, 2019): 52. http://dx.doi.org/10.3390/jmse7020052.

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Silty sand is a kind of typical marine sediment that is widely distributed in the offshore areas of East China. It has been found that under continuous actions of wave pressure, a mass of fine particles will gradually rise up to the surface of silty sand seabeds, i.e., the phenomenon called wave-induced soil erosion. This is thought to be due to the seepage flow caused by the pore-pressure accumulation within the seabed. In this paper, a kind of three-phase soil model (soil skeleton, pore fluid, and fluidized soil particles) is established to simulate the process of wave-induced soil erosion. In the simulations, the analytical solution for wave-induced pore-pressure accumulation was used, and Darcy flow law, mass conservation, and generation equations were coupled. Then, the time characteristics of wave-induced soil erosion in the seabed were studied, especially for the effects of wave height, wave period, and critical concentration of fluidized particles. It can be concluded that the most significant soil erosion under wave actions appears at the shallow seabed. With the increases of wave height and critical concentration of fluidized particles, the soil erosion rate and erosion degree increase obviously, and there exists a particular wave period that will lead to the most severe and the fastest rate of soil erosion in the seabed.

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19

Hansen, Signe Schilling, Verner Brandbyge Ernstsen, Mikkel Skovgaard Andersen, Zyad Al-Hamdani, Ramona Baran, Manfred Niederwieser, Frank Steinbacher, and Aart Kroon. "Evaluation of Boulder Characteristics for Improved Boulder Detection Based on Machine Learning Techniques." Geosciences 12, no. 11 (November 16, 2022): 421. http://dx.doi.org/10.3390/geosciences12110421.

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Detailed maps of the seabed and knowledge of its habitats are critical for a wide range of tasks, such as sustainable development, and environmental protection. Boulders on the seabed form an important environment for ecosystems, but the detection of them is challenging. In this study, we aim to improve the understanding of boulder predictors and to determine connections between predictors and boulder environments on different spatial scales. The Relief-F filter feature selection algorithm was used on four 30 m × 30 m areas in Rødsand lagoon, containing one boulder each, to determine the most relevant predictors. The predictors could be divided into four groups detecting different boulder characteristics: colour contrast, height, boulder boundaries, and spherical geometry. Twelve different types of boulder environments were evaluated. Bare, spherical boulders on sandy seabeds can be predicted from all four predictor groups. It is not possible to detect non-spherical boulders on seabed covered by vegetation. The best predictors for boulder detection depend on the shape and size of the boulder and the surrounding sediment and vegetation. The predictors were evaluated on a larger 400 × 2500 m area. When up-scaling the boulder detection area, larger seabed structures may affect the results. Therefore, knowledge about these structures can be used to remove errors and uncertainties from machine learning input data.

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20

Zhang, H., and D. S. Jeng. "An integrated three-dimensional model for wave-induced seabed response in a porous seabed. I. A sloping seabed." Ocean Engineering 32, no. 5-6 (April 2005): 701–29. http://dx.doi.org/10.1016/j.oceaneng.2004.08.009.

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21

Rona, Peter A. "Seabed authority implements regime for mining marine minerals from deep seabed." Eos, Transactions American Geophysical Union 93, no. 49 (December 4, 2012): 514–16. http://dx.doi.org/10.1029/2012eo490005.

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22

NISHIO, Shinya, Eiji OGISAKO, and Atsushi DENDA. "Seabed Deformation during Methane Hydrate Production : Mechanical Properties of Seabed Sediments." Proceedings of the JSME annual meeting 2003.3 (2003): 335–36. http://dx.doi.org/10.1299/jsmemecjo.2003.3.0_335.

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23

Dettmer, Jan, Charles W. Holland, and Stan E. Dosso. "Analyzing lateral seabed variability with Bayesian inference of seabed reflection data." Journal of the Acoustical Society of America 126, no. 1 (July 2009): 56–69. http://dx.doi.org/10.1121/1.3147489.

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24

Dettmer, Jan, Stan E. Dosso, and Charles W. Holland. "Resolving spatial seabed variability by Bayesian inference of seabed reflection inversions." Journal of the Acoustical Society of America 125, no. 4 (April 2009): 2618. http://dx.doi.org/10.1121/1.4808757.

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25

Anderson, John T., D. Van Holliday, Rudy Kloser, Dave G. Reid, and Yvan Simard. "Acoustic seabed classification: current practice and future directions." ICES Journal of Marine Science 65, no. 6 (April 29, 2008): 1004–11. http://dx.doi.org/10.1093/icesjms/fsn061.

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Abstract Anderson, J. T., Holliday, D. V., Kloser, R., Reid, D. G., and Simard, Y. 2008. Acoustic seabed classification: current practice and future directions. – ICES Journal of Marine Science, 65: 1004–1011. Acoustic remote sensing of the seabed using single-beam echosounders, multibeam echosounders, and sidescan sonars combined and individually are providing technological solutions to marine-habitat mapping initiatives. We believe the science of acoustic seabed classification (ASC) is at its nascence. A comprehensive review of ASC science was undertaken by an international group of scientists under the auspices of ICES. The review was prompted by the growing need to classify and map marine ecosystems across a range of spatial scales in support of ecosystem-based science for ocean management. A review of the theory of sound-scattering from seabeds emphasizes the variety of theoretical models currently in use and the ongoing evolution of our understanding. Acoustic-signal conditioning and data quality assurance before classification using objective, repeatable procedures are important technical considerations where standardization of methods is only just beginning. The issue of temporal and spatial scales is reviewed, with emphasis on matching observational scales to those of the natural world. It is emphasized throughout that the seabed is not static but changes over multiple time-scales as a consequence of natural physical and biological processes. A summary of existing commercial ASC systems provides an introduction to existing capabilities. Verification (ground-truthing) methods are reviewed, emphasizing the difficulties of matching observational scales with acoustic-backscatter data. Survey designs for ASC explore methods that extend beyond traditional oceanographic and fisheries survey techniques. Finally, future directions for acoustic seabed classification science were identified in the key areas requiring immediate attention by the international scientific community.

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26

Zhai, Hualing, Dong-Sheng Jeng, and Zhen Guo. "The Role of 2D Seepage on Sediment Incipient Motion around a Pipeline." Journal of Marine Science and Engineering 9, no. 6 (May 27, 2021): 580. http://dx.doi.org/10.3390/jmse9060580.

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Pipelines have been used as one of the main transportation methods for the offshore industry, with increasing activities in marine resources recently. Prediction of seabed instability is one of key factors that must be taken into consideration for an offshore pipeline project. As the first step of the scour process, sediment incipient motion has been intensively studied in the past. Most previous investigations didn’t consider the wave-induced seepage in the elevation of sediment motion. In this paper, two-dimensional seepage was considered to modify the conventional Shields number and its associated impact on sediment incipient motion around the trenched pipeline was investigated. Both flat and sloping seabeds are considered. The numerical results indicated that a peak or valley of the modified Shields number was formed below the pipeline and horizontal seepage flow tremendously impact the sediment motion in the vicinity of the pipeline. Parametric analysis concludes: the influence of the seepage around the pipeline becomes more significant in a large wave, shallow water in a seabed with large shear modulus and permeability, and larger pipeline diameter and smaller flow gap ratio. This will make soil particles be more easily dragged away from the seabed.

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27

Chen, Linya, Dong-Sheng Jeng, Chencong Liao, and Dagui Tong. "Wave-Induced Seabed Response around a Dumbbell Cofferdam in Non-Homogeneous Anisotropic Seabed." Journal of Marine Science and Engineering 7, no. 6 (June 19, 2019): 189. http://dx.doi.org/10.3390/jmse7060189.

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Cofferdams are frequently used to assist in the construction of offshore structures that are built on a natural non-homogeneous anisotropic seabed. In this study, a three-dimensional (3D) integrated numerical model consisting of a wave submodel and seabed submodel was adopted to investigate the wave–structure–seabed interaction. Reynolds-Averaged Navier–Stokes (RANS) equations were employed to simulate the wave-induced fluid motion and Biot’s poroelastic theory was adopted to control the wave-induced seabed response. The present model was validated with available laboratory experimental data and previous analytical results. The hydrodynamic process and seabed response around the dumbbell cofferdam are discussed in detail, with particular attention paid to the influence of the depth functions of the permeability K i and shear modulus G j . Numerical results indicate that to avoid the misestimation of the liquefaction depth, a steady-state analysis should be carried out prior to the transient seabed response analysis to first determine the equilibrium state caused by seabed consolidation. The depth function G j markedly affects the vertical distribution of the pore pressure and the seabed liquefaction around the dumbbell cofferdam. The depth function K i has a mild effect on the vertical distribution of the pore pressure within a coarse sand seabed, with the influence concentrated in the range defined by 0.1 times the seabed thickness above and below the embedded depth. The depth function K i has little effect on seabed liquefaction. In addition, the traditional assumption that treats the seabed parameters as constants may result in the overestimation of the seabed liquefaction depth and the liquefaction area around the cofferdam will be miscalculated if consolidation is not considered. Moreover, parametric studies reveal that the shear modulus at the seabed surface G z 0 has a significant influence on the vertical distribution of the pore pressure. However, the effect of the permeability at the seabed surface K z 0 on the vertical distribution of the pore pressure is mainly concentrated on the seabed above the embedded depth in front and to the side of the cofferdam. Furthermore, the amplitude of pore pressure decreases as Poisson’s ratio μ s increases.

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28

Gordon, Angus D. "Offshore Sydney Seabed Mapping." Journal of Coastal Research 101, sp1 (August 26, 2020): 116. http://dx.doi.org/10.2112/jcr-si101-024.1.

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29

Jermy, Andrew. "Electricity blankets the seabed." Nature Reviews Microbiology 8, no. 4 (April 2010): 248. http://dx.doi.org/10.1038/nrmicro2343.

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30

Dalton, Rex. "Seabed images create waves." Nature 457, no. 7233 (February 2009): 1065. http://dx.doi.org/10.1038/4571065a.

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31

Jayaraman, K. S. "Seabed mining for India." Nature 329, no. 6135 (September 1987): 94. http://dx.doi.org/10.1038/329094c0.

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32

Small, Andrew, and Greg Cook. "Overcoming seabed design obstacles." Renewable Energy Focus 15, no. 3 (May 2014): 34–35. http://dx.doi.org/10.1016/s1755-0084(14)70070-5.

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33

Holland, Charles W. "Seabed reflection measurement uncertainty." Journal of the Acoustical Society of America 114, no. 4 (October 2003): 1861–73. http://dx.doi.org/10.1121/1.1605388.

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34

Holland, Charles W., and Peter L. Nielsen. "Seabed reflection measurements from an autonomous undersea vehicle: Probing seabed spatial variability." Journal of the Acoustical Society of America 126, no. 4 (2009): 2315. http://dx.doi.org/10.1121/1.3249548.

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35

Hamilton, L. J. "Acoustic seabed segmentation for echosounders through direct statistical clustering of seabed echoes." Continental Shelf Research 31, no. 19-20 (December 2011): 2000–2011. http://dx.doi.org/10.1016/j.csr.2011.10.004.

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36

Nugroho, Arif Satrio, and Ika Riswanti Putranti. "International Seabed Regime in Southeast Asia: The Lack of ASEAN Member States’ Role in Seabed Mining." Indonesian Perspective 3, no. 1 (September 6, 2018): 37. http://dx.doi.org/10.14710/ip.v3i1.20177.

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International Seabed Authority (ISA) as a part of implementation of UNCLOS Part XI has main objective is to foster healthy economic development especially for developing states and to minimize the negative environmental impacts derived from activities in the area. Although ISA had facilitated states to provide legal procedure to establish seabed explorations, the role of developing states are still lacking. For instance, the role of ASEAN member states are still minimum though some of its states rely on maritime resources such as Indonesia and Philippines. This paper argues that there are two main factors that cause minimum roles of ASEAN states in the development of seabed mining; lack of awareness of government officials, academics and its people in development of law of sea, mainly in seabed mining matters and the excessive cost and high technology requirements to explore and later to exploit seabed materials. To overcome the issue, ASEAN states should increase its stakeholder awareness in law of sea progress and the importance of seabed mining. In addition, ASEAN states could wait the Enterprise as an economic arm of The Authority to come into account to facilitate developing states in seabed exploitation for commercial value. In order to overcome environmental issue regarding seabed mining, ASEAN should maximize its own body of institution which already been built.Keywords: International Seabed Authority, seabed mining, ASEAN

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37

Abdullah, Faizal Ade Rahmahuddin, and Elvi Syukrina Erianto. "Modeling a Wave on Mild Sloping Bottom Topography and Its Dispersion Relation Approximation." KUBIK: Jurnal Publikasi Ilmiah Matematika 7, no. 1 (September 30, 2022): 1–10. http://dx.doi.org/10.15575/kubik.v7i1.18419.

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Linear wave theory is a simple theory that researchers and engineers often use to study a wave in deep, intermediate, and shallow water regions. Many researchers mostly used it over the horizontal flat seabed, but in actual conditions, sloping seabed always exists, although mild. In this research, we try to model a wave over a mild sloping seabed by linear wave theory and analyze the influence of the seabed’s slope on the solution of the model. The model is constructed from Laplace and Bernoulli equations together with kinematic and dynamic boundary conditions. We used the result of the analytical solution to find the relation between propagation speed, wavelength, and bed slope through the dispersion relation. Because of the difference in fluid dispersive character for each water region, we also determined dispersion relation approximation by modifying the hyperbolic tangent form into hyperbolic sine-cosine and exponential form, then approximated it with Padé approximant. As the final result, exponential form modification with Padé approximant had the best agreement to exact dispersion relation equation then direct hyperbolic tangent form.

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38

Mortenson, Michael C., Tracianne B. Neilsen, Mark K. Transtrum, and David P. Knobles. "Learning both a value and uncertainty label for seabed parameters from ship noise data." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A49. http://dx.doi.org/10.1121/10.0015502.

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Because the seabed impacts sound propagation in the ocean, machine learning is being used for both seabed classification and to obtain estimates of individual seabed properties. This paper proposes a method to simultaneously estimate these properties and an associated uncertainty label. A residual neural network is trained and validated using synthetic ship noise spectrograms generated with a range-independent normal mode sound propagation model and a ship noise source spectrum. The data set includes 140 seabeds: In each, the top sediment layer has a random thickness and properties randomly chosen from five sets of bounds, which roughly correspond to clay, mud, sand, silt, and gravel. For each of the 140 sediments, a random selection of 405 combinations of ship speed, closest-point-of-approach range, and source depth are used resulting in 22k data samples. Each data sample is labeled with the true values of the sediment parameters as well as a label for the uncertainty level of each. The uncertainty levels are obtained from the Fisher information and qualify of the information content in the ship spectrogram about each parameter. Examples of how the residual neural network learns to perform regression for the parameter value and the uncertainty level will be presented.

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39

Sui, Titi, Yu Jin, Zhaojun Wang, Chi Zhang, and Jian Shi. "Effects of the Soil Property Distribution Gradient on the Wave-Induced Response of a Non-Homogeneous Seabed." Journal of Marine Science and Engineering 7, no. 8 (August 20, 2019): 281. http://dx.doi.org/10.3390/jmse7080281.

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The seabed is usually non-homogeneous in the real marine environment, and its response to the dynamic wave loading is of great concern to coastal engineers. Previous studies on the simulation of a non-homogeneous seabed response have mostly adopted a vertically layered seabed, in which homogeneous soil properties are assumed in the governing equations for one specified layer. This neglects the distribution gradient terms of soil property, thus leading to an inaccurate evaluation of the dynamic response of a non-homogeneous seabed. In this study, a numerical model for a wave-induced 3D non-homogeneous seabed response is developed, and the effects of the soil property distribution gradient on the wave-induced response of a non-homogeneous seabed are numerically investigated. The numerical model is validated, and the results of the present simulation agree well with those of previous studies. The validated model is applied to simulate an ideal two-dimensional (2D) vertical non-homogeneous seabed. The model is further applied to model the practical wave-induced dynamic response of a three-dimensional (3D) non-homogeneous seabed around a mono-pile. The difference in pore pressure and soil effective stresses due to the soil distribution gradient is investigated. The effects of the soil distribution gradient on liquefaction are also examined. Results of this numerical study indicate that (1) pore pressure decreases while soil effective stresses increase (the maximum difference of the effective stresses can reach 68.9 % p 0 ) with a non-homogeneous seabed if the distribution gradient terms of soil properties are neglected; (2) the effect of the soil property distribution gradient terms on the pore pressure becomes more significant at the upper seabed, while this effect on the soil effective stresses is enhanced at the lower seabed; (3) the effect of the soil distribution gradient on the seabed response is greatly affected by the wave reflection and diffraction around the pile foundation; and (4) the soil distribution gradient terms can be neglected in the evaluation of seabed liquefaction depth in engineering practice.

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40

Asumadu, Richard, Ji-Sheng Zhang, Osei-Wusuansa Hubert, and Alex Baffour Akoto. "Two-dimensional model of wave-induced response of seabed around permeable submerged breakwater." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401983080. http://dx.doi.org/10.1177/1687814019830809.

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This article focuses on a two-dimensional numerical model established to determine the seabed dynamic response in the region of a permeable submerged breakwater. The wave motion in this article is governed by the volume-averaged Reynolds-averaged Navier–Stokes equation, whereas Biot’s poro-elastic equation determines the seabed foundation. The water surface is recorded using the volume of fluid technique. In this study, the results for the two-dimensional seabed dynamic response for both the consolidation status and the dynamic wave-induced response status for the seabed foundation coupled with submerged breakwater are illustrated. The numerical results examined from the dynamic pore pressure, the effective stresses, the shear stress, and the seabed soil displacements revealed that the impact of dynamic response at the offshore zone/seaward on the seabed foundation is more developed than at the onshore zone/harbor side. Parametric results analysis as regards the effect of the wave, the seabed, and the submerged breakwater structure variation significantly affected the seabed foundation response coupled with the breakwater structure. The numerical outcome on the liquefaction potential shows that the seabed foundation is more seemingly to liquefy and happen approximately at the toe of the submerged breakwater under the wave loading.

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41

Fenollosa, Carlos, Marcel Otón, Pau Andrio, Jorge Cortés, Modesto Orozco, and J. Ramon Goñi. "SEABED: Small molEcule activity scanner weB servicE baseD." Bioinformatics 31, no. 5 (October 27, 2014): 773–75. http://dx.doi.org/10.1093/bioinformatics/btu709.

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Abstract Motivation: The SEABED web server integrates a variety of docking and QSAR techniques in a user-friendly environment. SEABED goes beyond the basic docking and QSAR web tools and implements extended functionalities like receptor preparation, library editing, flexible ensemble docking, hybrid docking/QSAR experiments or virtual screening on protein mutants. SEABED is not a monolithic workflow tool but Software as a Service platform. Availability and implementation: SEABED is a free web server available athttp://www.bsc.es/SEABED. No registration is required. Contact: ramon.goni@bsc.es Supplementary information: Supplementary data are available atBioinformatics online.

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42

Han, C., J. Liu, and P. Yi. "Adaptivity of plate anchors to restrain the impact of seabed trenching." Géotechnique Letters 13, no. 1 (March 1, 2023): 1–26. http://dx.doi.org/10.1680/jgele.21.00160.

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The seabed trenching due to chain-soil-water interaction in deepwater moorings is disadvantageous to the holding capacity of the anchor, which threatens the safety of the whole floating system. A measure is proposed in this study to restrain the adverse impact of seabed trenching by utilizing the diving potential of plate anchors. Model tests were conducted to verify the stability and further keying behaviour of the plate anchor in trenched seabed. Test results show that the plate anchor automatically dives deeper and hence develops higher resistance to balance the uplift load with the progressive development of the seabed trenching. This indicates that the plate anchor adapts to the seabed trenching automatically and the holding capacity of the plate anchor is largely unaffected in trenched seabed.

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43

Maeno, Yoshihiko, and Takashi Hasegawa. "PREDICTION OF PROPERTIES OF MARINE SAND BY IN-SITU MEASUREMENT OF WAVE INDUCE PORE PRESSURE." Coastal Engineering Proceedings 1, no. 20 (January 29, 1986): 101. http://dx.doi.org/10.9753/icce.v20.101.

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The purpose of this paper is to predict the physical and mechanical properties of deposits near the surface of the seabed by in-situ measurements of the wave-induced pore pressure. First, the wave-induced pressure both at the surface of the seabed and inside the seabed are examined by frequency analysis, to clarify the propagation characteristics of pressure in the seabed. Secondly, a theoretical equation which gives the relationship between pore pressure fluctuation and wave pressure fluctuation is proposed. Thirdly, the porosity of the seabed is predicted by the propagating characteristics of the pore pressure within the seabed based on the results of both the model tests by wave tank and the field measurements of the wave-induced pore pressure. Finally, by fitting the theoretical equation to the spectral ratio of the in-situ measured pore pressure fluctuation to wave pressure fluctuation, the bulk modulus of the seabed and the degree of saturation are predicted.

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Dingwall, Joanna. "International Investment Protection in Deep Seabed Mining Beyond National Jurisdiction." Journal of World Investment & Trade 19, no. 5-6 (October 15, 2018): 890–929. http://dx.doi.org/10.1163/22119000-12340114.

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Abstract The deep seabed beyond national jurisdiction comprises almost three-quarters of the entire surface area of our oceans. It boasts an array of mineral resources, including valuable metals and rare earth elements. Acting under the United Nations Convention on the Law of the Sea, the International Seabed Authority is responsible for regulating this area and granting mining contracts to allow investors to explore for and exploit deep seabed minerals. As yet, deep seabed mining activities have been confined to the exploratory stage. However, recently, there has been a marked growth in deep seabed investment by private corporate actors. As technology advances and commercial appetite increases, extraction of deep seabed minerals may soon commence. In this context, this article seeks to address crucial legal issues facing pioneers of deep seabed mining. What is the extent of investment protection within the existing regime? And are there dispute resolution options to enforce such protection?

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45

Cafaro, Valentina, Dario Angeletti, Bruno Bellisario, Armando Macali, Claudio Carere, and Jessica Alessi. "Habitat overlap between bottlenose dolphins and seabirds: a pilot study to identify high-presence coastal areas in the Tyrrhenian Sea." Journal of the Marine Biological Association of the United Kingdom 96, no. 4 (September 9, 2015): 891–901. http://dx.doi.org/10.1017/s0025315415001447.

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The identification of foraging hotspots able to support the co-existence of multiple top predators provides a potential approach to addressing protection measures for marine ecosystems. In this study, we conducted visual surveys in the central Tyrrhenian Sea to determine areas with simultaneous presence of bottlenose dolphins, four species of seabirds (Audouin's gull, Yellow-legged gull, Yelkouan shearwater and Cory's shearwater), and baitballs occurring at the surface, indicating the presence of potential prey items. We also analysed their occurrence in relation to topography (depth, slope and distance from the shore) and seabed types. Kriging analysis identified areas with simultaneous presence of several marine top predators. Dolphin distribution appeared to be linked to gentle slope (6–10 m) and muddy seabed, possibly associated with prey distribution, whereas the four seabird species were more frequent in areas with a water depth of 100–150 m, gentle slope and muddy seabed, apart from Audouin's gull, which preferred a depth of 10–20 m. Baitball distribution was linked to depth (20–40 m), gentle slope (6–10 m) and muddy seabed. The overlapping presence of bottlenose dolphins, seabirds and baitballs allowed the identification of foraging areas, presumably representing biodiversity and productivity hotspots, located in waters of 50–100 m depth at the mouths of two rivers. This approach provides a promising tool for identifying highly productive coastal areas, and should also be recommended for wider-scale surveys.

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Nik Fuad, Nik Munirah, Wan Izatul Asma Wan Talaat, and Mohd Hazmi Mohd Rusli. "Mining the Deep Seabed: Is Malaysia Ready?" Asian Social Science 13, no. 2 (January 19, 2017): 107. http://dx.doi.org/10.5539/ass.v13n2p107.

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The mineral industry is expanding fast coinciding with the increase in demands. The depleting land-based minerals has led to the seeking of mineral resources especially from deep sea. Deep seabed minerals have high concentration of precious metal in comparison to land-based minerals. A lot of countries have started to explore and exploit the deep seabed minerals. Thus, it is necessary for Malaysia to commence on deep seabed mining exploration to reap its economic and technological benefits. Similarly, like land mining, the marine environment will face environmental degradation from deep seabed mining exploration. Being a State-party to the United Nations Convention on the Law of the Sea 1982 (UNCLOS 1982) and Convention of Biological Diversity 1994 (CBD), Malaysia has yet to develop a set of policies, regulations and laws related to deep seabed mining to mitigate its effect to the marine environment coinciding to the requirements of these conventions. The purpose of this study is to explore the preparedness of Malaysia to embark on exploration of deep seabed mining in areas beyond the national jurisdiction while observing the effects of deep seabed mining to the marine environment. The challenges in exploring the deep seabed mining as well as the relevant international and national laws related to deep seabed mining will also be observed in this study.

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47

Housner, Stein, Ericka Lozon, Bruce Martin, Dorian Brefort, and Matthew Hall. "Seabed bathymetry and friction modeling in MoorDyn." Journal of Physics: Conference Series 2362, no. 1 (November 1, 2022): 012018. http://dx.doi.org/10.1088/1742-6596/2362/1/012018.

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This paper presents the implementation and verification of a seabed bathymetry feature and seabed friction feature to the open-source, lumped-mass mooring system dynamics modeler, MoorDyn, which is part of the National Renewable Energy Laboratory’s aero-hydro-servo-elastic simulation tool, OpenFAST. Variations in seabed slope, as well as the frictional effects of mooring lines moving along the seabed, will affect the mooring line tensions of a floating platform and the consequent platform response. These new features are especially relevant for modeling mooring systems in deep-water coastal areas where seabed depth can change significantly over an entire mooring footprint. The bathymetry feature models the seabed as a rectangular grid of variable water depths in place of the existing, uniform water depth in MoorDyn. The friction force is primarily represented as a Coulombic friction force, or the product of a kinetic friction coefficient and the seabed contact normal force, with the ability to differentiate between transverse and axial motion of a line node on the seabed in any bathymetry grid. These capabilities were tested by running MoorDyn and OpenFAST simulations over a variety of seabed and environmental conditions; the resulting fairlead tensions, node tensions, and mooring line kinematics were verified against equivalent OrcaFlex simulations. The results match closely, meaning the features are verified, which will increase the overall fidelity of OpenFAST and FAST.Farm simulations.

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Yue, Z. Q., A. P. S. Selvadurai, and K. T. Law. "Excess pore pressure in a poroelastic seabed saturated with a compressible fluid." Canadian Geotechnical Journal 31, no. 6 (December 1, 1994): 989–1003. http://dx.doi.org/10.1139/t94-113.

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This paper presents an analytical investigation on the excess pore-fluid pressure in a finite seabed layer by taking into account the influence of a compressible pore fluid. The seabed layer is modeled as a poroelastic layer saturated with a compressible pore fluid and resting on a rough, rigid impermeable base. The surface of the poroelastic seabed layer is either completely pervious or completely impervious, and subjected to a normal surface traction induced by offshore structures. The paper presents analytical and numerical results to illustrate the time-dependent behaviour of excess pore pressure in the poroelastic seabed. The results demonstrate that the presence of a compressible pore fluid reduces the generation of excess pore pressure in the poroelastic seabed layer. Key words : excess pore pressure, poroelastic seabed layer, soil consolidation, compressible pore fluid, integral transforms.

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49

Jeng, D. S. "A New Wave Dispersion Equation: Effects of Soil Characteristics." Journal of Offshore Mechanics and Arctic Engineering 123, no. 4 (June 27, 2001): 177–81. http://dx.doi.org/10.1115/1.1408612.

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The evaluation of wave characteristics has been widely studied by ocean engineers in the past. However, conventional investigations for determining wave characteristics have been focused on the nonlinear wave effects in a rigid seabed. On the other hand, most previous investigations for the wave-induced seabed response in a porous seabed have been only concerned with the soil response after wave pressure penetrate into seabed. In this paper, employing a complex wave number, the whole wave-seabed interaction problem will be re-examined. Based on the new closed-form analytical solution, a new wave dispersion equation is derived, including the seabed characteristics. The numerical results indicate that the wave characteristics (such as the wavelength, wave pressure and wave profile) are affected by the soil permeability and shear modulus in a shallow water.

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Ma, Jingxin, Haisen Li, Jianjun Zhu, Weidong Du, Chao Xu, and Xinyang Wang. "Design and Experiments of a Portable Seabed Integrated Detection Sonar." Sensors 21, no. 8 (April 9, 2021): 2633. http://dx.doi.org/10.3390/s21082633.

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The integrated observation of seabed topography, sediment geomorphology and sub-bottom profile information is very important for seabed remote sensing and mapping. To improve the efficiency of seabed detection and meet the needs of portable development of detection equipment, we developed a portable seabed feature integrated detection sonar (PSIDS) with whcih a single sonar device can simultaneously detect the above three types of seabed information. The underwater transducer is mainly composed of the following three components: a parametric emission array as the sound source, a high frequency receiving linear array for multibeam echo signal collection, and a two-dimensional vector hydrophone for receiving the low-frequency sediment echo signal. Field experiments were conducted to validate the performance of the PSIDS on 11–17 January 2018 in Jiaozhou Bay, China. (1) PSIDS could perform the functions of both multibeam sonar and sub-bottom profiler; (2) The synchronously and integrated measurement of various seabed information was achieved by alternately emitting multibeam echo-sounding and sub-bottom profiling signal using parametric source. The detection results proved the feasibility and practicability of PSIDS to achieve multiple seafloor characteristics. PSIDS provides a new idea for developing integrated seabed detection sonar. In terms of convenience and data fusion, it is a good option to use this equipment for integrated seabed detection.

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