Stability of Temporary Submarine Slopes

2011 ◽  
Author(s):  
Julian Bubel ◽  
Christina Rudolph ◽  
Ju¨rgen Grabe
Keyword(s):  
North Sea ◽  
Critical State ◽  
Slope Angle ◽  
Friction Angle ◽  
Shallow Foundation ◽  
Offshore Wind ◽  
Coarse Grained ◽  
Sea Floor ◽  
The North ◽  
The North Sea

Shallow foundation structures for offshore wind turbines offer ecological benefits compared to pile foundations as less noise is emitted at sea floor level during construction process. On the other hand, shallow offshore foundations can rarely be placed on top of the sea floor. Weak soils usually need to be excavated to place the foundation structure on more stable ground and thus, anthropogenic submarine slopes result. Steep but stable slopes meet both economic and ecologic aims as they minimise material movement and sediment disturbance. After Terzaghi [1] the angle β between slope and the horizontal of the ground surface of coarse-grained soil is at most equal to the critical state friction angle φc. However, it can be observed that natural submarine slopes of sandy soils are always much more shallow. Particularly fine-grained, cohesionless or almost cohesionless soils failed in the past, although the slope angle was much smaller than the critical state friction angle φc. Artificial (temporary) slopes do not appear and behave as natural submarine slopes, since the latter are already shaped by perpetual loads of waves, tide and mass movements. Physical simulations of different scales are used to analyse the stability of artificial submarine slopes with sandy soil of the North Sea. The study focuses on gravitational forces and impacts from the excavation processes. The simulations and theoretical considerations result in suggested slope angles for future shallow offshore foundations of wind farms in the North Sea.

Accessibility assessment for operation and maintenance of offshore wind farms in the North Sea

Wind Energy ◽  
2016 ◽  
Vol 20 (4) ◽  
pp. 637-656 ◽  
Author(s):  
Michele Martini ◽  
Raúl Guanche ◽  
Iñigo J. Losada ◽  
César Vidal
Keyword(s):  
North Sea ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The North ◽  
Operation And Maintenance ◽  
The North Sea

scholarly journals Evidence for the effects of decommissioning man-made structures on marine ecosystems globally: a systematic map protocol

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Anaëlle J. Lemasson ◽  
Antony M. Knights ◽  
Murray Thompson ◽  
Gennadi Lessin ◽  
Nicola Beaumont ◽  
...  
Keyword(s):  
North Sea ◽  
Evidence Synthesis ◽  
Marine Ecosystem ◽  
Offshore Wind ◽  
Systematic Map ◽  
Management Options ◽  
The North ◽  
Ecosystem Effects ◽  
Published Evidence ◽  
The North Sea

Abstract Background Numerous man-made structures (MMS) have been installed in various parts of the ocean (e.g. oil and gas structures, offshore wind installations). Many are now at, or nearing, the end of their intended life. Currently, we only have a limited understanding of decommissioning effects. In many locations, such as the North Sea, regulations restrict decommissioning options to complete removal, with little consideration of alternative management options might offer. To generate a reliable evidence-base to inform the decision-making processes pertaining to marine MMS management, we propose a wide-encompassing systematic map of published research on the ecosystem effects (including ecosystem services) of marine MMS while in place and following cessation of operations (i.e. including effects of alternative decommissioning options). This map is undertaken as part of the UKRI DREAMS project which aims to develop a system to show the relative effects of implementing different decommissioning strategies in the North Sea. Method For the purpose of this map, we will keep our focus global, in order to subsequently draw comparisons between marine regions. The proposed map will aim to answer the following two primary questions: 1. What published evidence exists for the effects of marine man-made structures while in place on the marine ecosystem? 2. What published evidence exists for the effects of the decommissioning of marine man-made structures on the marine ecosystem? The map will follow the Collaboration for Environmental Evidence Guidelines and Standards for Evidence Synthesis in Environmental Management. Searches will be run primarily in English in at least 13 databases and 4 websites. Returns will be screened at title/abstract level and at full-text against pre-defined criteria. Relevant meta-data will be extracted for each study included. Results will be used to build a database of evidence, which will be made freely available. This map, expected to be large, will improve our knowledge of the available evidence for the ecosystem effects of MMS in the global marine environment. It will subsequently inform the production of multiple systematic-reviews and meta-analyses.

Recently formed methane- derived carbonates from the North Sea floor

1985 ◽  
pp. 263-266 ◽  
Author(s):  
Martin Hovland ◽  
Mike Talbot ◽  
Snorre Olaussen ◽  
Lars Aasberg
Keyword(s):  
North Sea ◽  
Sea Floor ◽  
The North ◽  
The North Sea

XXIV.—Chalk Boulders from Aberdeen and Fragments of Chalk from the Sea Floor off the Scottish Coast

1915 ◽  
Vol 35 ◽  
pp. 263-296 ◽  
Author(s):  
William Hill
Keyword(s):  
North Sea ◽  
Northern Coast ◽  
Sea Floor ◽  
The North ◽  
The North Sea

In December 1908 I received from Mr A. Earland a fragment of a rock, believed to be chalk, which had been dredged from the bottom of the North Sea. Mr Earland also informed me that he believed boulders of a similar rock occurred in some profusion near what is known as the Kinnaird Deep, off the northern coast of Aberdeenshire. As a result of our correspondence a little later, Professor D'Arcy Thompson asked me to investigate such boulders as might presumably be chalk, dredged from the northern parts of the North Sea during the operations of the s.s. Goldseeker, a vessel employed by the North Sea Fisheries Commission, and he has kindly permitted me to include a description of the boulders found by the Goldseeker in the details of this paper.

scholarly journals Coastal archaeologies: settlement on the changing North Sea littoral

Antiquity ◽  
2017 ◽  
Vol 91 (358) ◽  
pp. 1095-1097
Author(s):  
Hans Peeters
Keyword(s):  
Sea Level ◽  
North Sea ◽  
British Isles ◽  
Prehistoric Archaeology ◽  
Sea Floor ◽  
The Past ◽  
The North ◽  
The North Sea ◽  
The Many ◽  
Rising Sea Level

Over the past decade or so, the submerged prehistoric archaeology and landscapes in the area that is known to us today as the North Sea have received increasing attention from both archaeologists and earth scientists. For too long, this body of water was perceived as a socio-cultural obstacle between the prehistoric Continent and the British Isles, the rising sea level a threat to coastal settlers, and the North Sea floor itself an inaccessible submerged landscape. Notwithstanding the many pertinent and pervasive problems that the archaeology of the North Sea still needs to overcome, recent research has made clear that these rather uninspiring beliefs are misplaced.

scholarly journals A decision support system for assessing offshore wind energy potential in the North Sea

Energy Policy ◽  
2012 ◽  
Vol 49 ◽  
pp. 541-551 ◽  
Author(s):  
Christoph Schillings ◽  
Thomas Wanderer ◽  
Lachlan Cameron ◽  
Jan Tjalling van der Wal ◽  
Jerome Jacquemin ◽  
...  
Keyword(s):  
Decision Support ◽  
Decision Support System ◽  
Wind Energy ◽  
North Sea ◽  
Support System ◽  
Offshore Wind ◽  
Energy Potential ◽  
The North ◽  
The North Sea ◽  
Wind Energy Potential

Wind wake effects of large offshore wind farms, an underrated impact on the marine ecosystem?

2020 ◽  
Author(s):  
Corinna Schrum ◽  
Naveed Akhtar ◽  
Nils Christiansen ◽  
Jeff Carpenter ◽  
Ute Daewel ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Sea ◽  
Large Scale ◽  
Spatial Scales ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The North ◽  
The North Sea ◽  
Ocean Hydrodynamics

<p>The North Sea is a world-wide hot-spot in offshore wind energy production and installed capacity is rapidly increasing. Current and potential future developments raise concerns about the implications for the environment and ecosystem. Offshore wind farms change the physical environment across scales in various ways, which have the potential to modify biogeochemical fluxes and ecosystem structure. The foundations of wind farms cause oceanic wakes and sediment fluxes into the water column. Oceanic wakes have spatial scales of about O(1km) and structure local ecosystems within and in the vicinity of wind farms. Spatially larger effects can be expected from wind deficits and atmospheric boundary layer turbulence arising from wind farms. Wind disturbances extend often over muliple tenths of kilometer and are detectable as large scale wind wakes. Moreover, boundary layer disturbances have the potential to change the local weather conditions and foster e.g. local cloud development. The atmospheric changes in turn changes ocean circulation and turbulence on the same large spatial scales and modulate ocean nutrient fluxes. The latter directly influences biological productivity and food web structure. These cascading effects from atmosphere to ocean hydrodynamics, biogeochemistry and foodwebs are likely underrated while assessing potential and risks of offshore wind.</p><p>We present latest evidence for local to regional environmental impacts, with a focus on wind wakes and discuss results from observations, remote sensing and modelling.  Using a suite of coupled atmosphere, ocean hydrodynamic and biogeochemistry models, we quantify the impact of large-scale offshore wind farms in the North Sea. The local and regional meteorological effects are studied using the regional climate model COSMO-CLM and the coupled ocean hydrodynamics-ecosystem model ECOSMO is used to study the consequent effects on ocean hydrodynamics and ocean productivity. Both models operate at a horizontal resolution of 2km.</p>

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