Disclaimer:
The authors are solely responsible for the content of this report. Material included herein does not represent the opinion of the European Community, and the European Community is not responsible for any use that might be made of it.
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The vegetation on the edge of the marsh near Waarde consists of species of the high marsh such as Sea Couch (Elytrigia atherica) and Red Fescue (Festuca rubra). At some places also Sea Plantain (Plantago maritima), sea milkwort (Glaux maritima) en Greater Sea-spurrey (Spergularia media subsp. angustata) and rarely Common Scurvy-grass (Cochlearia officinalis subsp. officinalis) (van der Pluijm and de Jong 2008). Erosion of the edge of the marsh has an effect on the vegetation: change from the specific basin vegetation into species specific for marsh cliffs. Since the creation of the groynes, erosion of mud flats and marsh cliff decreased, sedimentation was enhanced and more high marsh vegetation started to grow at the cliff edge (Figure 4). At two measure locations (pq 5 and pq 7) the vegetation of Seaside Arrowgrass (Triglochin maritima) has been replaced by Red Fescue (Festuca rubra), Sea Couch (Elytrigia atherica) and locally also Sea Plantain (Plantago maritima) (van der Pluijm and de Jong 2008).
A bird counting project is performed in this area (province Zeeland) in the period January 2010-January 2011. The intertidal flat near Waarde serves a diversity of migratory and wintering birds. This area is an attraction for duck species like Eurasian Wigeon (Anas Penelope), Common Teal (Anas crecca) and Northern Pintail (Anas acuta), and waders like Dunlin (Calidris alpine), Common Oystercatcher (Haematopus ostralegus), Grey Plover (Pluvialis squatarola) and European Curlew (Numenius arquata). The area is also suitable for breeding birds like Common Redshank (Tringa tetanus) and Common Tern (Sterna hirundo).
Some critical notes
The groynes were successful to stop the erosion of the mudflat and the shore of the marsh, but according to some experts some negative aspects have to be considered. In the first place was the height of the groynes too high due to which the sedimentation was too fast. This is a problem in the frame of the Nature development in the Netherlands because the mudflat will evolve much quicker to a marsh which was not the objective of the groynes. The marsh will additionally evolve to a high marsh which was also not the objective. The enhanced sedimentation, induced by the groynes, could not be stopped although the objective is already achieved. In the future, more adaptive management is needed with adaptable and removable constructions.
Secondly, during the building of the groynes no attention was addressed to the local morphology. The building of the groynes caused a partial closing of the Zimmerman channel, a local short-circuit channel through the Valkenisse sandbars (Figure 5). This resulted in less discharge in this short-circuit channel (the flood flow found another direction and the ebb flow is hindered by the ends of the groynes), by which this is threatened to disappear over time.
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Groynes at the marsh near Waarde
Table of content
- 1. Description of measure
- 1a. Measure description
- 1b. Monitoring
- 1c. Monitoring results
- 2. Execution of main effectiveness criteria
- 2a. Effectiveness according to development targets of measure
- 2b. Impact on ecosystem services
- 2c. Degree of synergistic effects and conflicts according to uses
- 3. Additional evaluation criteria in view of EU environmental law
- 3a. Degree of synergistic effects and conflicts according to WFD aims
- 3b. Degree of synergistic effects and conflicts according to Natura 2000 aims
- 4. Crux of the matter
- 5. References
Additional information
for this measure:
No further information available.
for this measure:
No further information available.
Monitoring results
The erosion problem is illustrated in Figure 3. Since the construction of the groynes, the erosion at the intertidal flat habitat had stopped (Schelde nieuwsbrief 2002).The vegetation on the edge of the marsh near Waarde consists of species of the high marsh such as Sea Couch (Elytrigia atherica) and Red Fescue (Festuca rubra). At some places also Sea Plantain (Plantago maritima), sea milkwort (Glaux maritima) en Greater Sea-spurrey (Spergularia media subsp. angustata) and rarely Common Scurvy-grass (Cochlearia officinalis subsp. officinalis) (van der Pluijm and de Jong 2008). Erosion of the edge of the marsh has an effect on the vegetation: change from the specific basin vegetation into species specific for marsh cliffs. Since the creation of the groynes, erosion of mud flats and marsh cliff decreased, sedimentation was enhanced and more high marsh vegetation started to grow at the cliff edge (Figure 4). At two measure locations (pq 5 and pq 7) the vegetation of Seaside Arrowgrass (Triglochin maritima) has been replaced by Red Fescue (Festuca rubra), Sea Couch (Elytrigia atherica) and locally also Sea Plantain (Plantago maritima) (van der Pluijm and de Jong 2008).
A bird counting project is performed in this area (province Zeeland) in the period January 2010-January 2011. The intertidal flat near Waarde serves a diversity of migratory and wintering birds. This area is an attraction for duck species like Eurasian Wigeon (Anas Penelope), Common Teal (Anas crecca) and Northern Pintail (Anas acuta), and waders like Dunlin (Calidris alpine), Common Oystercatcher (Haematopus ostralegus), Grey Plover (Pluvialis squatarola) and European Curlew (Numenius arquata). The area is also suitable for breeding birds like Common Redshank (Tringa tetanus) and Common Tern (Sterna hirundo).
Some critical notes
The groynes were successful to stop the erosion of the mudflat and the shore of the marsh, but according to some experts some negative aspects have to be considered. In the first place was the height of the groynes too high due to which the sedimentation was too fast. This is a problem in the frame of the Nature development in the Netherlands because the mudflat will evolve much quicker to a marsh which was not the objective of the groynes. The marsh will additionally evolve to a high marsh which was also not the objective. The enhanced sedimentation, induced by the groynes, could not be stopped although the objective is already achieved. In the future, more adaptive management is needed with adaptable and removable constructions.
Secondly, during the building of the groynes no attention was addressed to the local morphology. The building of the groynes caused a partial closing of the Zimmerman channel, a local short-circuit channel through the Valkenisse sandbars (Figure 5). This resulted in less discharge in this short-circuit channel (the flood flow found another direction and the ebb flow is hindered by the ends of the groynes), by which this is threatened to disappear over time.
