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Bio-Optical Characteristics in Relation to Phytoplankton Composition and Productivity in a Twin Arctic Fjord Ecosystem during Summer
Published in Neloy Khare, Climate Change in the Arctic, 2022
Irrespective of proximity to the glacial end, where high discharge of freshwater occurs, stratification was observed throughout the fjord with occasional shoaling of thermohaline contours (phase 2) in the mid-fjord indicating upward movement of the water masses probably caused by wind flow or bottom topography in Kongsfjorden. Difference in the intrusion of AW into the fjords and/or strength of glacial melting could be clearly discerned between the sampling phases indicating the dynamic oceanographic features of both the fjords. Both the fjords were observed to be influenced by Atlantic-origin warm and saline water (AW) masses superimposed by a slim layer of fresh and cool surface water (SW) run-off from the glaciers (SW: T = 1–5°C, S < 34.7 psu, 0–15 m) and AW (T = 5.5–7°C, S > 34.9 psu, 15–60 m). The observed stratification in this twin-fjord ecosystem signified a shift from Arctic to Atlantic predominance in summer (Svendsen et al. 2002; Piwosz et al. 2009; David and Krishnan 2017).
Risk from cyberattacks on autonomous ships
Published in Stein Haugen, Anne Barros, Coen van Gulijk, Trond Kongsvik, Jan Erik Vinnem, Safety and Reliability – Safe Societies in a Changing World, 2018
Jan Erik Vinnem, Ingrid Bouwer Utne
There are considerable differences with respect to impact resistance to external impact in the various types of infrastructure systems. In Norway for example, there has been a study project ongoing to establish possible concepts for fjord crossing of some of the largest fjords on the West coast of Southern Norway. For a possible fjord crossing of the Sognefjord, a floating bridge concept has been specified to have 1563 MJ kinetic energy resistance, corresponding to a ship of about 31,500 tdw, travelling at a full speed of 17.7 knots (Statens Vegvesen, 2013). Smaller bridges along the coast are believed to have resistance at least one order of magnitude lower, but the consequences of a collision against a smaller bridge may be less extensive. When it comes to offshore structures, the traditional resistance has been designed to take the impact from a drifting service vessel. Typically, this was a value of 14 MJ for many years (Vinnem, 2013), but is in recent years increased to around 50 MJ (Yu & Amdahl, 2018), due to increasing size of service vessels used for these installations. The largest offshore structures, the concrete gravity based structures (so-called Condeep structures), which we commonly installed in the North Sea some 20 years ago, have a push-over resistance about 200 MJ (Vinnem, 2013). This is almost an order of magnitude lower than the specified resistance of the bridge for the fjord crossing of the Sognefjord. Most of the offshore structures have capacity in the order of 50 MJ or less.
Introduction to Estuaries
Published in James L. Martin, Steven C. McCutcheon, Robert W. Schottman, Hydrodynamics and Transport for Water Quality Modeling, 2018
James L. Martin, Steven C. McCutcheon, Robert W. Schottman
Fjords are generally long and narrow with steep sides and relatively deep waters. Width- to-depth ratios are commonly less than 10:1. Typically, fjords are strongly stratified and have shallow sills at the estuarine mouth that often limit mixing of deep waters (Figure 10). Usually, fjords are formed by glaciation and are found in Alaska, British Columbia, and Norway as well as other locations. Puget Sound, in Washington State, is an example of a fjord. The freshwater streams that feed a fjord generally pass through rocky terrain. Little sediment is carried to the estuary and the bottom is likely to be a rocky surface. The longitudinal salinity gradients and depths in Knight Inlet fjord, British Columbia, are illustrated in Figure 10.
Numerical investigations of the dynamic response of a floating bridge under environmental loadings
Published in Ships and Offshore Structures, 2018
Yanyan Sha, Jørgen Amdahl, Aleksander Aalberg, Zhaolong Yu
The Norwegian Public Roads Administration is running a project ‘Coastal Highway Route E39’ which aims to replace the existing ferries by bridges or tunnels along the west coast of Norway. These installations will be constructed to cross the large and deep fjords, which may have a length and depth up to 5000 and 600 m, respectively. This critical site condition makes it almost impossible to build bridges with fixed foundations. Therefore, floating bridges become a better choice as the conventional piers or pile foundations are not required. The superstructure of the floating bridge is alternatively supported by floating pontoons or floaters. Many very large floating structures (VLFS) have been designed and constructed in the past several decades. They are primarily used as floating airports, ports and storage facilities. The experience from these VLFS can deliver useful information for floating bridges. However, the design and construction experience is still quite limited for large-scale floating bridges. Hence, further research is required to extend the knowledge from the fixed-foundation bridges to the bridges with floating foundations.
The Future of the Tunnel Crossing: The Submerged Floating Tube Bridge
Published in Structural Engineering International, 2020
Arianna Minoretti, Xu Xiang, Inger Lise Johansen, Mathias Eidem
The SFTB could be realized as a single-span bridge for short crossings, or as a bridge lying on pylons for shallow areas. The fjords on the west coast of Norway are areas of long crossings where the sea depth can reach up to 1.3 km. Under these conditions, a possible solution could be an SFTB vertically stabilized with floating pontoons or with tethers (Fig. 2), connecting the structure with the seabed. The tethers are the same structures used in Norway for TLP elements.