scholarly journals Changes of the tidal water levels at the German North Sea coast

1989 ◽  
Vol 43 (3-4) ◽  
pp. 325-332 ◽  
Author(s):  
Alfred Führböter
2021 ◽  
Author(s):  
Elin Andrée ◽  
Jian Su ◽  
Martin Drews ◽  
Morten Andreas Dahl Larsen ◽  
Asger Bendix Hansen ◽  
...  

<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>


2021 ◽  
Author(s):  
Elke M. I. Meyer ◽  
Ralf Weisse ◽  
Iris Grabemann ◽  
Birger Tinz ◽  
Robert Scholz

Abstract. Storm tides represent a major threat to the low-lying German North Sea coast. Knowledge of extremes is essential for the design of reliable and robust coastal defences. A storm tide that occurred on 12–13 March 1906 along the German Bight coastline still represents one of the strongest events on record. For this event, detailed knowledge of atmospheric and hydrodynamic conditions is still lacking. To assess the potential impact of such an event on today’s coastline, century-long atmospheric reanalysis data together with a manual synoptic reconstruction based on archived weather data were used to drive a tide-surge model and to simulate water levels during the event. Sensitivity experiments were performed to estimate potential amplification of water levels that could have been caused by different time lags between the storm and the astronomical tide. Comparison between the model results and the limited available observational data indicated, that the water levels could be reasonably reconstructed using wind fields from the manual synoptic approach and some of the reanalysis ensemble members. The amplification potential was found to be low because the storm occurred during spring tide and shifts in the phase of the astronomic tide yielded only small changes in total water levels. To summarize, if pressure data are available at relevant locations, historical storm surges can be simulated with reanalysis products and also with a manual synoptic reconstruction.


2011 ◽  
Vol 1 (32) ◽  
pp. 26 ◽  
Author(s):  
Gerd Bruss ◽  
Babriele Gönnert ◽  
Roberto Mayerle

A procedure, based on numerical models is proposed to investigate the processes involved during conditions of extreme water levels within the outer Elbe estuary at the German North Sea coast. Nonlinear interactions between the different processes are analyzed and adverse combinations are simulated yielding new scenarios. Various conditions in the astronomical tide, three major storm events over the North Sea, several external surges and an increase in the mean sea level are analyzed. Techniques for the modeling of each of the isolated processes are developed and individually verified. The isolated processes are temporally shifted relative to each other and superimposed in various combinations. The results obtained from the present method, provide new insights into the nonlinear interactions between the involved processes. Generally, the effects of the processes seem to be reduced in superpositions with high absolute water levels. However, due to the large scatter of the results no general relations are found. New extreme scenarios are determined by iterative maximizations of the peak water level of different superpositions around spring high tide.


The following list has been classified, so far as practicable, according to subjects, in order that it may be useful for purposes of reference. The list does not include publications recording the results of observations made on material supplied by the Association to workers in different parts of the country, of which a considerable amount is sent out each year.


2011 ◽  
Vol 1 (6) ◽  
pp. 6
Author(s):  
C. Ringe-Jorgensen

With reference to the use of high-water frequency curves, which have been suggested by Wemelsfelder as an aid to fix the maximum flooding level, an attempt will be made in the following to estimate how far certain special geographical and meteorological conditions may be expected to influence the shape of the frequency curves for different localities. The investigation concerns a particular point on the Danish North Sea coast compared with the Dutch coast, but its principles may possibly be of interest in a wider sense.


1994 ◽  
Vol 52 (2) ◽  
pp. 220-225 ◽  
Author(s):  
E. Denker ◽  
P. H. Becker ◽  
M. Beyerbach ◽  
A. Büthe ◽  
W. A. Heidmann ◽  
...  
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document