134
A.C. Smaal . A. van der Hoek
The Delta project, particularly the storm-surge barrier, represents state-of-the-art
storm-surge protection. The revolutionary designs and techniques, particularly with
regard to foundation preparations and the use of foundation mattresses, reflected both
innovative thinking and effective communication between scientists specializing in
hydrodynamics and geomorphology and civil engineers (van Westen and Colijn 1984;
Watson and Finkle 1990). The use of prefabricated components and the methods developed to install heavy constructions in open water influenced by waves and currents
represent an important breakthrough in marine civil engineering. Moreover, this design represented a watershed in Dutch political decision making about the natural environment (Nienhuis and SmaalI99~).
12.2
Responses of Ecology and Economy
12.2.1
Ecology
The Delta project has fundamentally changed the hydraulic, morphological and ecological characteristics of the region (Table 12.1). The overall change can be summarized
as the loss of dynamic gradients (de Vries et al. 1996). The open and interconnected
estuaries interfacing rivers and the sea have been replaced by isolated lakes and lagoons. Gradients have been replaced by discrete boundaries. New ecosystems with different characteristics developed within these new physical boundaries (Table 12.2). The
factors controlling the newly created water systems are now biological and chemical
(nutrients) rather than physical. A comparison of the Delta region before and after the
Delta project reveals the following main change. (see Sects. 12.2.1.1-12.2.1.4)
12.2.1.1
Biodiversity
The total loss of 216 km 2 (59%) of tidal flats and 63.5 km 2 (68%) of salt marsh has significantly decreased characteristic estuarine habitats (Table 12.2) and has truncated
salinity gradients. Part of the intertidal area has become a terrestrial habitat; another
part is now under shallow freshwater. Increased transparency and the lack of fast curTable 12.1. Present-day characteristics of former estuaries Haringvliet, Grevelingen, Oosterschelde
which originally included Krammer-Volkerak, Veere and Westerschelde
Haringvliet Lake
OosterLake
LakeVeere WesterGrevelingen scheJde
Volkerak
schelde
TIdes
Stagnant
Stagnant
Tidal
Stagnant
Stagnant
TIdal
Salinity
Fresh
Saline
Saline
Fresh
Brackish
Saline
Trophic status
Eutrophic
Oligotrophic Mesotrophic Eutrophic Eutrophic
Eutrophic
Polluted
Yes
No
No
Minor
Minor
Yes
A.C. Smaal . A. van der Hoek
The Delta project, particularly the storm-surge barrier, represents state-of-the-art
storm-surge protection. The revolutionary designs and techniques, particularly with
regard to foundation preparations and the use of foundation mattresses, reflected both
innovative thinking and effective communication between scientists specializing in
hydrodynamics and geomorphology and civil engineers (van Westen and Colijn 1984;
Watson and Finkle 1990). The use of prefabricated components and the methods developed to install heavy constructions in open water influenced by waves and currents
represent an important breakthrough in marine civil engineering. Moreover, this design represented a watershed in Dutch political decision making about the natural environment (Nienhuis and SmaalI99~).
12.2
Responses of Ecology and Economy
12.2.1
Ecology
The Delta project has fundamentally changed the hydraulic, morphological and ecological characteristics of the region (Table 12.1). The overall change can be summarized
as the loss of dynamic gradients (de Vries et al. 1996). The open and interconnected
estuaries interfacing rivers and the sea have been replaced by isolated lakes and lagoons. Gradients have been replaced by discrete boundaries. New ecosystems with different characteristics developed within these new physical boundaries (Table 12.2). The
factors controlling the newly created water systems are now biological and chemical
(nutrients) rather than physical. A comparison of the Delta region before and after the
Delta project reveals the following main change. (see Sects. 12.2.1.1-12.2.1.4)
12.2.1.1
Biodiversity
The total loss of 216 km 2 (59%) of tidal flats and 63.5 km 2 (68%) of salt marsh has significantly decreased characteristic estuarine habitats (Table 12.2) and has truncated
salinity gradients. Part of the intertidal area has become a terrestrial habitat; another
part is now under shallow freshwater. Increased transparency and the lack of fast curTable 12.1. Present-day characteristics of former estuaries Haringvliet, Grevelingen, Oosterschelde
which originally included Krammer-Volkerak, Veere and Westerschelde
Haringvliet Lake
OosterLake
LakeVeere WesterGrevelingen scheJde
Volkerak
schelde
TIdes
Stagnant
Stagnant
Tidal
Stagnant
Stagnant
TIdal
Salinity
Fresh
Saline
Saline
Fresh
Brackish
Saline
Trophic status
Eutrophic
Oligotrophic Mesotrophic Eutrophic Eutrophic
Eutrophic
Polluted
Yes
No
No
Minor
Minor
Yes