24
cially for the comparison in this report, the introduction positions
in the IfMH model are not exactly identical with those of the DHI
model, by which the sources were always placed exactly at the mouths
öf the rivers.
Case studies:
A
Pollutant source, river Elbe (Figs. 3, 4)
The results of both models clearly show that a substance introduced
in the region of the mouth of the Elbe arrives in the Skagerrak via
a narrow strip along the West coast of Jutland. In the Inner German
Bight, the concentrations remain high for a long time. In the IfMH
83tudy, the material appears to reach the Skagerrak somewhat more
quickly. The reason apparently lies in the differing position of in-
troduction, which - in the case of the IfMH simulation - lies circa
50 km northwestwards of the mouth of the Elbe.
B Pollutant source, river Rhine/Meuse (Figs. 5.6)
Here, the position of introduction of the IfMH model computation
lies circa 30 km westwards of the Rhine/Meuse estuary. The quantity
of substance introduced, spreads out along the Netherlands and Ger-
man coasts., In the DEI study the material reached the Skagerrak
gomewhat more quickly northeastwards; in the IfMH study the concen-
trations near the West and East Frisian Islands are comparatively
larger. In the IfMH model computation a fraction of the substance
reached the Inner German Bight.
C Pollutant source, river Humber (Figs. 7, 8)
The introduction position in the IfMH model lay circa 40 km east-
wards of the Humber estuary. The temporal development of the spread-
ing clearly shows that the material from the English East coast did
not enter the Inner German Bight. Parts of the quantity of substance
Introduced advance somewhat further eastwards, as in the case of the
DEI model. Furthermore, it is noteworthy that from this source also
the material introduced entered the Skagerrak,
With the models presented, simulations for other rivers have also
been carried out. The results are not described here in detail. How-
ever, their cumulative effect has a bearing upon the potential bur-
dening of the North Sea.
D "Burdening" (Fig. 9, 10)
The 8simulations for individual river inputs shown here, can be car-
ried out 8simultaneously, in a model computation, for all river 1n-
puts. The distribution of substances which result therefrom can be
interpreted not only as an estimation for the load placed upon indi-
vidual North Sea regions but also for the North Sea as a whole. In
