5.4 Estuaries in the Southern North Sea Region
113
Habitat [ha]
End of nineteenth/early
twentieth century*
Mid twentieth century**
Recent***
Difference [ha]
Elbe
Subtidal
Tidal flats
Marsh
Total Elbe
Sea Schelde
Subtidal
Tidal flats
Marsh
Total Sea Schelde
Weser
Subtidal
Tidal flats
Marsh
45,801
34,300
21,843
3,347
929
3,241
56,917
40,764
7,609
45,915
25,771
18,736
3,241
889
1,483
52,995
43,255
4,793
42,293
33,000
8,882
3,329
824
682
54,088
40,322
6,306
Total Weser
-3,508
-1,300
-12,961
-17,769
-18
-105
-2,559
-2,682
-2,829
-442
-1,303
-4,574
Fig. 5.41 Habitat loss at the estuaries Schelde, Weser and Elbe. * Data covers different time spans
from the end of the nineteenth century to the beginning of the twentieth century. Data for the Weser
not available. ** Data covers different time spans for each estuary. *** Data for the Elbe from
1992–1995, for the Schelde 2000 and for the Weser 2005–2008. Source: TIDE Project Consortium
(2013)
The orange area illustrates that the upper ground water body is saline and the blue color
indicates that the lower saline ground water body is penetrating further inland. Therefore,
the installation of wells to extract ground water is impossible. The width of inland intrusion
of the salt water zone is depending on the ground water recharge at the higher areas and, for
example, from the tide regime and soil properties (see Chap. 4). The fine-grained material
of the marshes (former salt marshes) almost prevents ground water recharge in a reasonable
amount.
Ecological Consequences in Brief
The change of tidal range indicates that considerable alterations have taken place in
the estuary. These changes influence the ecological, chemical and physical composition
of the estuary. A lot of habitats were destroyed or are under deterioration because of
increasing current velocity (Fig. 5.41). Shallow water areas are either lost because of reclamation or more frequently inundated because of changes in high and low water regime.
The brackish water zone is penetrating further upstream with consequences for flora and
fauna, and in low-lying marsh lands also for water extraction for feeding cattle with fresh
water.
Exercise
1. According to estuarine development the main driver for change has been identified as
trade and shipping. The consequences of the change have been outlined. The interrelationship with natural dynamics and the disturbance of the natural environment was
113
Habitat [ha]
End of nineteenth/early
twentieth century*
Mid twentieth century**
Recent***
Difference [ha]
Elbe
Subtidal
Tidal flats
Marsh
Total Elbe
Sea Schelde
Subtidal
Tidal flats
Marsh
Total Sea Schelde
Weser
Subtidal
Tidal flats
Marsh
45,801
34,300
21,843
3,347
929
3,241
56,917
40,764
7,609
45,915
25,771
18,736
3,241
889
1,483
52,995
43,255
4,793
42,293
33,000
8,882
3,329
824
682
54,088
40,322
6,306
Total Weser
-3,508
-1,300
-12,961
-17,769
-18
-105
-2,559
-2,682
-2,829
-442
-1,303
-4,574
Fig. 5.41 Habitat loss at the estuaries Schelde, Weser and Elbe. * Data covers different time spans
from the end of the nineteenth century to the beginning of the twentieth century. Data for the Weser
not available. ** Data covers different time spans for each estuary. *** Data for the Elbe from
1992–1995, for the Schelde 2000 and for the Weser 2005–2008. Source: TIDE Project Consortium
(2013)
The orange area illustrates that the upper ground water body is saline and the blue color
indicates that the lower saline ground water body is penetrating further inland. Therefore,
the installation of wells to extract ground water is impossible. The width of inland intrusion
of the salt water zone is depending on the ground water recharge at the higher areas and, for
example, from the tide regime and soil properties (see Chap. 4). The fine-grained material
of the marshes (former salt marshes) almost prevents ground water recharge in a reasonable
amount.
Ecological Consequences in Brief
The change of tidal range indicates that considerable alterations have taken place in
the estuary. These changes influence the ecological, chemical and physical composition
of the estuary. A lot of habitats were destroyed or are under deterioration because of
increasing current velocity (Fig. 5.41). Shallow water areas are either lost because of reclamation or more frequently inundated because of changes in high and low water regime.
The brackish water zone is penetrating further upstream with consequences for flora and
fauna, and in low-lying marsh lands also for water extraction for feeding cattle with fresh
water.
Exercise
1. According to estuarine development the main driver for change has been identified as
trade and shipping. The consequences of the change have been outlined. The interrelationship with natural dynamics and the disturbance of the natural environment was