1 / 28

RESTORING ECOSYSTEM FUNCTIONS IN A HEAVILY DISTURBED ESTUARY

RESTORING ECOSYSTEM FUNCTIONS IN A HEAVILY DISTURBED ESTUARY. Tom Maris, Stijn Temmerman & Patrick Meire. Schelde: disturbed estuary. Function. Structure. Driving forces: - Dredging & embankments Pollution Climate change. loss of ecosystem functions Impact on: safety economy

merrill-evans
Download Presentation

RESTORING ECOSYSTEM FUNCTIONS IN A HEAVILY DISTURBED ESTUARY

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RESTORING ECOSYSTEM FUNCTIONS IN A HEAVILY DISTURBED ESTUARY Tom Maris, Stijn Temmerman & Patrick Meire

  2. Schelde: disturbed estuary Function Structure • Driving forces: • - Dredging & embankments • Pollution • Climate change • loss of • ecosystem functions • Impact on: • safety • economy • ecology

  3. Schelde: disturbed estuary 44000 30 28,4 42000 25 42341 20,3 40000 20 38000 15 Surface (ha) % intertidal area 36000 10 35853 34000 5 32000 0 1900 1990 total surface % intertidal Loss of intertidal habitat loss of goods and services

  4. Schelde: disturbed estuary Increasing tides: risk for floodings

  5. Schelde: disturbed estuary slope , current speed   marsh erosion  Increasing tides: habitat loss

  6. Schelde: solutions? Function Structure Sustainable solutions: Restoring functions Managed realignment? - Elevation often not suitable - Not always compatible with safetyplan Return to pristine situation is impossible. Flood control area: restoring safety Controlled reduced tide: restoring ecology

  7. Pilot studyLippenbroek How to restore estuarine nature in an area far below MHW?

  8. estuary FCA polder Outlet estuary CRT Ring Dike Lowered FCA dike polder Inlet Outlet Ring Dike Lowered FCA dike Concept FCA – CRT safety, ecology and a new ecosystem • Safety: FCA • - Lowered dike stretch • Critical tides: whole storage capacity • Only few times/year! • Ecology: CRT • - Introducing estuarine ecosystem • Tidal regime in area • Two times a day!

  9. Pilot project Lippenbroek Management scenario Lippenbroek Lippenbroek 1: Ring Dike 2: FCA dike 3: Inlet sluice 4: Outlet sluice 4 3 2 1 1 1 1 10 ha of tidal nature developping since March 2006

  10. Pilot project Lippenbroek 10 ha of tidal nature developping: May 2008

  11. Introducing macrotidal regime • Reduction of high water level by 3 meter • No reduction of spring – neap variation

  12. Introducing macrotidal regime Intertidal habitat development

  13. Tide - Sedimentation

  14. Tide - Sedimentation Tidal marsh ? ? ? Tidal flat

  15. Tide - Sedimentation

  16. Spring 2006 Winter 2008 Spring 2006 Winter 2008 High Mean Low spring 2006 Winter 2008 Zoobenthos Low Terrestric species + Insects+ others Mean Max density in fine sediments 200000 / m² Aquatic species + insects High Aquatic species + insects Sediment (cm)

  17. Phragmites australis Ranunculus repens Salix sp. Typha latifolia Lythrum salicaria Iris pseudacorus Callitriche sp. Veronica beccabunga Alisma plantago-aquatica Vegetation: colonisation of bare sites • Colonising species (40) • Low inundation frequency: • 30 species • Wetland + ruderal species • Salix and Phragmites potentially dominant • Averaged inundation frequency: • 27 species • Ruderal + wetland species • Salix, Phragmites, Typha: pot. dominant • High inundation frequency: • 10 species • typical wetland species • Typha potentially dominant

  18. Water quality

  19. Water quality: oxygen

  20. Water quality: Silica DSi delivery on 3/7/2006

  21. Delivery when DSi is limiting Water quality: Silica

  22. Water quality: Nitrogen On average 1 kg N retention per ha per tide

  23. FCA-CRT: sustainable? Ring dike Overflow dike ??? CRT

  24. ??? future Sedimentation Elevation (m TAW) date Flattening of the area Changing inundation frequencies: decrease of accretion?

  25. Erosion

  26. Lippenbroek conclusion • Tidal marsh restoration in area below MHW is possible • Tidal regime and sedimentation can be tuned • Sedimentation rate can be reduced to preserve storage capacity • Sedimentation rate can be maximased to prepare a low site for succesful managed realignment • Tidal marsh restoration in area below MHW is possible • Tidal regime and sedimentation can be tuned • Tidal marsh restoration in area below MHW is possible • Tidal regime and sedimentation can be tuned • Sedimentation rate can be reduced to preserve storage capacity • Tidal marsh restoration in area below MHW is possible • Tidal regime and sedimentation can be tuned • Sedimentation rate can be reduced to preserve storage capacity

  27. Ready for the big work? Thanks

  28. Introducing macrotidal regime HW Maximum inflow Start inflow Stop inflow Start outflow stagnant 6.0 Estuary 5.0 sluice 4.7 4.0 Water level (m TAW) 3.0 2.0 Polder 1.0 0.0 0 2 4 6 8 10 12 Time (hour)

More Related