scholarly journals Characterisation and evolution of the River Rhine system

2008 ◽  
Vol 87 (1) ◽  
pp. 7-19 ◽  
Author(s):  
F. Preusser
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Swiss Alps ◽  
Tectonic Activity ◽  
Rift System ◽  
Main Stream ◽  
River Rhine ◽  
The North ◽  
Late Tertiary ◽  
The North Sea

AbstractThe River Rhine and its tributaries represent one of the largest drainage systems in Europe. Its prominence among other fluvial systems is due to the location of its headwaters within the central Swiss Alps, which were repeatedly glaciated during the Quaternary, and the concurrence of major parts of the River Rhine course with the European Cenozoic Rift System. Sediments of the Rhine have thus recorded both changes in climate and tectonic activity as well as sea level change in the lower part of the river course.The River Rhine is composed of different subdivisions characterised by distinct geographical and geological settings. Vorder-and Hinterrhein in the headwaters are inner-alpine rivers frequently influenced in their course by tectonic lines and the blockage of valley floors by the deposits of mass movements. The Alpenrhein is located in a main Alpine valley that drains into a large foreland basin, the Bodensee (Lake Constance). The Hochrhein flows out of the lake following the Jura Mountains in a western direction. All these areas display a series of geological features such as moraine ridges and outwash plains, which directly reflect Quaternary glaciations of the Alps. The Oberrhein (Upper Rhine) Valley, as a graben structure, is part of the rifting system that started to develop during the middle Tertiary. The northern end of the graben is represented by the triple junction of the Mainz Basin, which is mainly characterised by the remains of marine transgressions that occurred during the initial rifting phase. The Rhine continues following the western branch of the tectonic system by passing through the Rhenish Massif. Uplift in this so-called Mittelrhein (Middle Rhine) area is well documented by a flight of late Tertiary to Quaternary river terraces. This region is also characterised by young volcanic activity as found, for example, in the Eifel volcanic field. The Niederheinische Bucht (Lower Rhine Embayment), especially the Roer Valley Rift System, represents the northern continuation of the rifting system. This area is characterised by differential uplift in the southern and subsidence in the northern part of the basin, which continues into the Netherlands. Here, the main stream of the River Rhine is separated into different branches developing an active delta at the coast of the North Sea. When the North Sea Basin was covered by ice during the Elsterian, Saalian and probably also the Weichselian glaciation and global sea level was low, the Rhine continued its course through the English Channel and flowed into the North Atlantic off Brittany.

scholarly journals Origin of a deep buried valley system in Pleistocene deposits of the eastern central North Sea

1995 ◽  
Vol 12 ◽  
pp. 7-19
Author(s):  
Inger Salomonsen
Keyword(s):  
Sea Level ◽  
North Sea ◽  
River System ◽  
Sea Level Changes ◽  
Upper Pleistocene ◽  
The North ◽  
Late Tertiary ◽  
Deltaic Sedimentation ◽  
The North Sea ◽  
Glacial Periods

In the North Sea, the sedimentary development of the late Tertiary and early Quaternary was dominated by deltaic sedimentation in a fast subsiding basin. During the Pleistocene, pronounced climatic changes affected the sedimentation of the area and progradation of the delta systems ceased. The Middle and Upper Pleistocene sedimentary successions consist of alternations of marine and fluvial deposits, partly reworked during glacial periods. Seismic records from the Danish sector of the North Sea reveal numerous deep incisions cut down from various levels of the Middle and Upper Pleistocene successions. These incisions are concluded to form a pattern of buried valleys. Detailed seismic stratigraphic analysis shows the occurrence of various internal unconformities within these buried valleys. It is concluded that the valleys originate from a river system developed in periods of repeated sea-level changes. Pluvial erosion during glacial sea-level lowstand and glacial meltwater action is proposed to have been responsible for the origin of the valley system. Thus, in Middle and Upper Pleistocene glacial periods drainage and associated sediment transport occurred from Northwest and Central European land areas via a presently buried river system in the southeastern North Sea towards a depositional basin north and northwest of the Danish North Sea sector.

What can idealized storm surge simulations tell us about worst case scenarios?

2021 ◽  
Author(s):  
Elin Andrée ◽  
Jian Su ◽  
Martin Drews ◽  
Morten Andreas Dahl Larsen ◽  
Asger Bendix Hansen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Sea Level ◽  
North Sea ◽  
Wind Direction ◽  
Water Levels ◽  
Sea Levels ◽  
The North ◽  
The North Sea ◽  
Sea Coast ◽  
North Sea Coast

<p>The potential impacts of extreme sea level events are becoming more apparent to the public and policy makers alike. As the magnitude of these events are expected to increase due to climate change, and increased coastal urbanization results in ever increasing stakes in the coastal zones, the need for risk assessments is growing too.</p><p>The physical conditions that generate extreme sea levels are highly dependent on site specific conditions, such as bathymetry, tidal regime, wind fetch and the shape of the coastline. For a low-lying country like Denmark, which consists of a peninsula and islands that partition off the semi-enclosed Baltic Sea from the North Sea, a better understanding of how the local sea level responds to wind forcing is urgently called for.</p><p>We here present a map for Denmark that shows the most efficient wind directions for generating extreme sea levels, for a total of 70 locations distributed all over the country’s coastlines. The maps are produced by conducting simulations with a high resolution, 3D-ocean model, which is used for operational storm surge modelling at the Danish Meteorological Institute. We force the model with idealized wind fields that maintain a fixed wind speed and wind direction over the entire model domain. Simulations are conducted for one wind speed and one wind direction at a time, generating ensembles of a set of wind directions for a fixed wind speed, as well as a set of wind speeds for a fixed wind direction, respectively.</p><p>For each wind direction, we find that the maximum water level at a given location increases linearly with the wind speed, and the slope values show clear spatial patterns, for example distinguishing the Danish southern North Sea coast from the central or northern North Sea Coast. The slope values are highest along the southwestern North Sea coast, where the passage of North Atlantic low pressure systems over the shallow North Sea, as well as the large tidal range, result in a much larger range of variability than in the more sheltered Inner Danish Waters. However, in our simulations the large fetch of the Baltic Sea, in combination with the funneling effect of the Danish Straits, result in almost as high water levels as along the North Sea coast.</p><p>Although the wind forcing is completely synthetic with no spatial and temporal structure of a real storm, this idealized approach allows us to systematically investigate the sea level response at the boundaries of what is physically plausible. We evaluate the results from these simulations by comparison to peak water levels from a 58 year long, high resolution ocean hindcast, with promising agreement.</p>

scholarly journals Mean sea level variability in the North Sea: Processes and implications

2014 ◽  
Vol 119 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Sönke Dangendorf ◽  
Francisco M. Calafat ◽  
Arne Arns ◽  
Thomas Wahl ◽  
Ivan D. Haigh ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Sea Level Variability ◽  
Mean Sea Level ◽  
The North ◽  
The North Sea ◽  
Mean Sea Level Variability

Storm surges in the North Sea during the winter 1953-4

1956 ◽  
Vol 235 (1201) ◽  
pp. 260-274 ◽  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Storm Surges ◽  
Rate Of Change ◽  
The North ◽  
Order Of Magnitude ◽  
The North Sea ◽  
Sea Ports ◽  
Phase Angles

Records of sea level for several North Sea ports for the winter of 1953-4 have been in vestigated. They were split into 14-day intervals, and each 14-day record was Fourieranalyzed to determine if any non-astronomical periods were present. There was evidence of some activity between 40 and 50 h period, and a determination of the phase angles at different ports showed that the activity could be due to a disturbance travelling southwards from the north of the North Sea. The disturbance was partly reflected somewhere near the line from Lowestoft to Flushing, so that one part returned past Flushing and Esbjerg towards Bergen while the other part travelled towards Dover, and there was evidence of its existence on the sea-current records taken near St Margaret's Bay. These results were confirmed by subtracting the predicted astronomical tidal levels from the observed values of sea level and cross-correlating the residuals so obtained for each port with those found at Lowestoft. The residuals at Lowestoft and Aberdeen were compared with the meteorological conditions, and it was found that, although they could be attributed to a large extent to conditions within the North Sea, there was an additional effect due to a travelling surge which was of the same order of magnitude at both Lowestoft and Aberdeen and which was closely related to the rate of change with time of the atmospheric pressure difference between Wick and Bergen.

The history and future of the North Sea benthos

1978 ◽  
Vol 76 (1-3) ◽  
pp. 193-200
Author(s):  
P. E. P. Norton
Keyword(s):  
North Sea ◽  
Bottom Type ◽  
The North ◽  
Late Tertiary ◽  
Long Term Changes ◽  
History Of ◽  
The North Sea ◽  
Temperature Depth

SynopsisThis is a brief review intended to supply bases for prediction of future changes in the North Sea Benthos. It surveys long-term changes which are affecting the benthos. Any prediction must take into account change in temperature, depth, bottom type, tidal patterns, current patterns and zoogeography of the sea and the history of these is briefly touched on from late Tertiary times up to the present. From a prediction of changes in the benthos, certain information concerning the pelagic and planktonic biota could also be derived.

scholarly journals Large-scale forcing of the European Slope Current and associated inflows to the North Sea

Ocean Science ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 315-335 ◽  
Author(s):  
Robert Marsh ◽  
Ivan D. Haigh ◽  
Stuart A. Cunningham ◽  
Mark E. Inall ◽  
Marie Porter ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Tide Gauge ◽  
Density Gradients ◽  
Current Transport ◽  
Tide Gauge Records ◽  
The North ◽  
Wide Range ◽  
The North Sea ◽  
Northern North Sea

Abstract. The European Slope Current provides a shelf-edge conduit for Atlantic Water, a substantial fraction of which is destined for the northern North Sea, with implications for regional hydrography and ecosystems. Drifters drogued at 50 m in the European Slope Current at the Hebridean shelf break follow a wide range of pathways, indicating highly variable Atlantic inflow to the North Sea. Slope Current pathways, timescales and transports over 1988–2007 are further quantified in an eddy-resolving ocean model hindcast. Particle trajectories calculated with model currents indicate that Slope Current water is largely recruited from the eastern subpolar North Atlantic. Observations of absolute dynamic topography and climatological density support theoretical expectations that Slope Current transport is to first order associated with meridional density gradients in the eastern subpolar gyre, which support a geostrophic inflow towards the slope. In the model hindcast, Slope Current transport variability is dominated by abrupt 25–50 % reductions of these density gradients over 1996–1998. Concurrent changes in wind forcing, expressed in terms of density gradients, act in the same sense to reduce Slope Current transport. This indicates that coordinated regional changes of buoyancy and wind forcing acted together to reduce Slope Current transport during the 1990s. Particle trajectories further show that 10–40 % of Slope Current water is destined for the northern North Sea within 6 months of passing to the west of Scotland, with a general decline in this percentage over 1988–2007. Salinities in the Slope Current correspondingly decreased, evidenced in ocean analysis data. Further to the north, in the Atlantic Water conveyed by the Slope Current through the Faroe–Shetland Channel (FSC), salinity is observed to increase over this period while declining in the hindcast. The observed trend may have broadly compensated for a decline in the Atlantic inflow, limiting salinity changes in the northern North Sea during this period. Proxies for both Slope Current transport and Atlantic inflow to the North Sea are sought in sea level height differences across the FSC and between Shetland and the Scottish mainland (Wick). Variability of Slope Current transport on a wide range of timescales, from seasonal to multi-decadal, is implicit in sea level differences between Lerwick (Shetland) and Tórshavn (Faroes), in both tide gauge records from 1957 and a longer model hindcast spanning 1958–2012. Wick–Lerwick sea level differences in tide gauge records from 1965 indicate considerable decadal variability in the Fair Isle Current transport that dominates Atlantic inflow to the northwest North Sea, while sea level differences in the hindcast are dominated by strong seasonal variability. Uncertainties in the Wick tide gauge record limit confidence in this proxy.

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