Storm surges in the North Sea

1958 ◽  
Vol 11 (3) ◽  
pp. 124-129 ◽  
Author(s):  
J. Darbyshire ◽  
Mollie Darbyshire

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.


Ocean Science ◽  
2009 ◽  
Vol 5 (3) ◽  
pp. 369-378 ◽  
Author(s):  
A. Sterl ◽  
H. van den Brink ◽  
H. de Vries ◽  
R. Haarsma ◽  
E. van Meijgaard

Abstract. The height of storm surges is extremely important for a low-lying country like The Netherlands. By law, part of the coastal defence system has to withstand a water level that on average occurs only once every 10 000 years. The question then arises whether and how climate change affects the heights of extreme storm surges. Published research points to only small changes. However, due to the limited amount of data available results are usually limited to relatively frequent extremes like the annual 99%-ile. We here report on results from a 17-member ensemble of North Sea water levels spaning the period 1950–2100. It was created by forcing a surge model of the North Sea with meteorological output from a state-of-the-art global climate model which has been driven by greenhouse gas emissions following the SRES A1b scenario. The large ensemble size enables us to calculate 10 000 year return water levels with a low statistical uncertainty. In the one model used in this study, we find no statistically significant change in the 10 000 year return values of surge heights along the Dutch during the 21st century. Also a higher sea level resulting from global warming does not impact the height of the storm surges. As a side effect of our simulations we also obtain results on the interplay between surge and tide.


2011 ◽  
Vol 1 (5) ◽  
pp. 34
Author(s):  
J. B. Schijf

The North Sea is a shallow sea and therefore it is very sensitive to wind effects. As a result the water levels along the coasts are, in addition to the tidal oscillations subject to a considerable wind setup and exceptionally severe gales throughout history have been accompanied by inundations of the low-lying regions bordering the North Sea, in particular its southern part. No stretch of coast has suffered more than that belonging to the Netherlands and the adjacent parts of Belgium and North Western Germany. Several factors combine to bestow on us this doubtful privilege.


Author(s):  
Robert Muir Wood ◽  
William Bateman

Around the coasts of the southern North Sea, flood risk is mediated everywhere by the performance of natural and man-made flood defences. Under the conditions of extreme surge with tide water levels, the performance of the defences determines the extent of inland flooding. Sensitivity tests reveal the enormous increase in the volume of water that can pass through a defence once breaching is initiated, with a 1 m reduction in sill elevation doubling the loss. Empirical observations of defence performance in major storm surges around the North Sea reveal some of the principal controls on breaching. For the same defence type, the maximum size and depth of a breach is a function of the integral of the hydraulic gradient across the defence, which is in turn determined by the elevation of the floodplain and the degree to which water can continue to flow inland away from the breach. The most extensive and lowest floodplains thereby ‘generate’ the largest breaches. For surges that approach the crest height, the weaker the protection of the defence, the greater the number of breaches. Defence reinforcement reduces both the number and size of the breaches.


2013 ◽  
Vol 13 (8) ◽  
pp. 2017-2029 ◽  
Author(s):  
S. F. Kew ◽  
F. M. Selten ◽  
G. Lenderink ◽  
W. Hazeleger

Abstract. The low-lying Netherlands is at risk from multiple threats of sea level rise, storm surges and extreme river discharges. Should these occur simultaneously, a catastrophe will be at hand. Knowledge about the likelihood of simultaneous occurrence or the so-called "compound effect" of such threats is essential to provide guidance on legislation for dike heights, flood barrier design and water management in general. In this study, we explore the simultaneous threats of North Sea storm surges and extreme Rhine river discharge for the current and future climate in a large 17-member global climate model ensemble. We use a simple approach, taking proxies of north-northwesterly winds over the North Sea and multiple~day precipitation averaged over the Rhine basin for storm surge and discharge respectively, so that a sensitivity analysis is straightforward to apply. By investigating soft extremes, we circumvent the need to extrapolate the data and thereby permit the model's synoptic development of the extreme events to be inspected. Our principle finding based on the climate model data is that, for the current climate, the probability of extreme surge conditions following extreme 20-day precipitation sums is around 3 times higher than that estimated from treating extreme surge and discharge probabilities as independent, as previously assumed. For the future climate (2070–2100), the assumption of independence cannot be rejected, at least not for precipitation sums exceeding 7 days.


1978 ◽  
Vol 1 (16) ◽  
pp. 61
Author(s):  
A. Langerak ◽  
M.A.M. De Ras ◽  
J.J. Leendertse

In the mid-1950s the Netherlands government embarked on a massive construction program, called the Delta Plan. Its purpose was to enhance protection from floods caused by the North Sea in the estuaries of the Rhine, Meuse and Scheldt. According to the plan, all connections to the sea were to be closed by dams, except the New Waterway to Rotterdam and the Western Scheldt. In 1974 all dams and dikes were complete except the dam closing off the Eastern Scheldt from the sea. In view of growing opposition to a complete closure, plans were revised in 1976, and instead of the dam, a storm surge barrier will be constructed. This barrier will reduce the tidal range in the Eastern Scheldt and will be closed during storm surges. In support of engineering and environmental studies related to the construction and operation of this barrier, a large numerical model has been developed, which covers the Eastern and Western Scheldt and the adjacent offshore area. The section of the North Sea which is included in the model is about 120 km long and 30 km wide, running from Blankenberghe in Belgium to Scheveningen in the Netherlands (Fig. 1). The bathymetry of the model area varies widely. In general it slopes from the shore to about 25 m at 30 km from the coast. In certain sections of the offshore area, the bottom is relatively flat; in other areas it has offshore bars and the bottom contains underwater sand dunes with a height of several meters. In the estuaries the tidal flow has scoured deep channels. The tidal flats near the North Sea are generally sandy, but the ecologically important tidal marshes located more inland contain much finer material. The flow and the water levels in the region which is modeled are generally tide-induced. However, the influence of meteorological effects is always present and sometimes dominates water movements and water levels (storm surges). The influence of the fresh water discharges is of much less importance; generally their effects can only be noticed in the immediate vicinity of the discharge. The tides in the offshore area of the model are part of the complicated tide system in the North Sea. The semidiurnal tidal wave propagates along the coast in a northeasterly direction. During this propagation the amplitude reduces from about 1.90 m near Blankenberghe to about .85 m near Scheveningen.


1978 ◽  
Vol 31 (3) ◽  
pp. 378-383
Author(s):  
D. Prandle

A number of numerical models of various sections of the North Sea have been developed, primarily for flood prediction; these simulate both the propagation of the astronomical tide and the generation and propagation of storm surges. The tides effectively originate in the deep ocean and their propagation into shallow seas can be simulated for an almost infinite period ahead. Surges are generated by the action of wind and pressure gradients, particularly over the shallow sea regions in the northern and central North Sea.


1982 ◽  
Vol 1 (18) ◽  
pp. 47 ◽  
Author(s):  
Jacques C.J. Nihoul ◽  
Francois C. Ronday

A three-dimensional non-linear hydrodynamic model is developed for the determination of the mesoscale (tides, storm surges, ...) and macroscale (residuals, gyre, ...) circulations in the North Sea. The model consists of a hierarchy of submodels of different grid sizes, with interactive coupling at boundaries. The model is used to study the impact of coastal engineering projects along the Belgian coast and in the Scheldt estuary.


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