57 
Fig. 7.4.6: Water level distribution (input signal: 3 positive single signals, wave height 5 m, 
from the north, North Sea 2 km) 
Left: after 14 hours with realistic depth distribution (T 1800 s) 
Flight: after 5 hours with constant water depth (h 500 m, T 600 s) 
7.4.2 Local water level evolution 
Fig. 7.4.7 shows the water level evolution at stations on the western coast (Wick, Aberdeen, 
North Shield, Immingham, Lowestoft) and on the eastern and southern coast (Stavanger, 
Hirtshals, Esbjerg, Borkum, Ijmuiden) of the North Sea. The times indicated relate to the start 
of the input signal at the northern model boundary. 
Besides the initial signal, a secondary signal resulting from diffraction and interference 
patterns or from reflection is visible at all locations. The stations were chosen in such a way 
that the primary signal arrived about simultaneously in the west and east, i.e. the stations 
have about the same geographical latitude. For example, both the primary and secondary 
wave signals reach Borkum earlier than Ijmuiden. As in the spatial representations in section 
7.4.1, also Fig. 7.4.7 shows a higher primary signal in the west and north, while the 
secondary signal is more pronounced in Ijmuiden, Borkum, Esbjerg (Fig 7.4.7) and 
Cuxhaven (Fig. 7.4.9), i.e. in the south-eastern North Sea. 
The primary signal east of about 5° E is low because it reaches the wave shadow of Norway 
only by diffraction. By contrast, the western coasts are exposed to the full initial signal which 
is, however, weakened by dissipation (see Fig. 5.4.4). 
Figs. 7.4.8 and 7.4.9 (as well as Figs. 7.1.2 and 7.1.3) also show the influence of a higher 
input signal on the local evolution of water levels. In contrast to Aberdeen (Fig. 7.4.8), that 
influence is low at the German coast. At Cuxhaven (Fig. 7.4.9), the secondary component 
increases more strongly than the primary component.