Adaptation Strategy: Dune Building / Restoration

Barrier IslandsBeach NourishmentBreakwatersCoastal WetlandsDikesDune Building / RestorationFloodwallsGroynesReef SystemsScour ProtectionSeawallStorm Surge Barriers
Amphibious BuildingsDry FloodproofingEmergency Planning PreparednessEvacuation RoutesSecondary DikesWarning SystemWet Floodproofing
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Easement and CovenantsLand AcquisitionLand TrustProtected Area Zoning

Dunes develop from sand deposits that represent a store of sediment in the zone just landward of normal high tides. Dune building or restoration is the process of stabilizing existing coastal dunes through coastal management practices such as planting dune vegetation and using sand fences. During storm surges, coastal sand dunes act as a resilient barrier against the disruptive forces of wind and wave action and help reduce the amount of erosion by supplying sand to eroded beaches during storms.1 They also provide habitat for rare and endangered species.2

How it works

Types of dune building / restoration

  • Blowouts usually exist within older vegetated dunes in the foredunes. They are landforms of erosional dunes that are usually depressions shaped like a trough, bowl, or saucer. Blowouts may also occur as hollows from wind erosion from an existing sandy substrate or dune.
  • Parabolic dunes develop from the continuous transport of sand through a blowout. They are composed of two trailing arms that enclose a deflation basin, an actively advancing nose, and depositional lobe. This process leads to the development of a U-shape (i.e., parabolic) or V-shaped dune.
  • Transgressive sand sheets and dune fields are relatively large aeolian deposits of sand that are formed as a result of downwind movement of sand across a vegetated to semi-vegetated terrain. Transgressive sheets are primarily flat to undulating duneless sheets, whereas transgressive dune fields comprise various types of dunes on the surface
  • Foredunes develop on the landward side of an active beach at the rear part of the backshore. Generally, foredunes consist of convex, symmetrical to asymmetrical dune ridges parallel to the sore. Although the morphology of foredunes vary they may be placed into three main categories, namely: incipient foredunes, established foredunes, and relict foredunes 7 8

Benefits

  • Provides effective defense against coastal erosion and flooding
  • Ability to adjust in response to wind, wave, and sea conditions
  • Acts as sand reservoirs that contribute to maintaining beach equilibrium.
  • Preserves the structural integrity of beaches to respond to events such as storm surges. 9

Challenges

  • Requires careful long-term management due to constant change
  • Can be overwhelmed by invasive plant species, e.g., grass which can prevent the natural migration of sand
  • Invasive plant species on dunes displace native plants that help to stabilize dunes against rapid erosion. This could lead to the encroachment of forest species.

Example projects

Hondsbossche Dunes

Noord Holland, The Netherlands

In 2015, the Hondsbossche and Pettemer sea dike was reinforced with 30 million cubic meters of sand in a foreshore and beach nourishment. The project was intended to improve flood safety and spatial quality.3 Beach grass and sand fences were used to build an artificial dune landscape. The idea was that the dunes will bolster the protection of the beach from storm surges but also evolve overtime from wind and wave action.

British Columbia’s Pacific Rim National Park Reserve

Located along the beaches of British Columbia’s Pacific Rim National Park Reserve are some of Canada’s rarest sand dune ecosystems.4 However, the Wickaninish Beach dune ecosystem are being affected by invasive species (European and American Beachgrass), which prevents dynamic sand movement and allows forest land to expand upon the dunes.5 The native plant species have roots that are critical to the structural integrity of the dunes and prevents wave erosion. In 2008, Parks Canada started an ambitious five-year restoration project to restore the Pacific Rim sand dune ecosystem with the primary goal of removing invasive plant species. Monitoring programs show that in 2010 alone over 1 hectare of invasive species was removed and currently over 60% of the dune ecosystem is restored.6

Citations

  1. 1. ↑

    “Shoreline & Waterway Management.” Dune Protection and Improvement, http://www.dnrec.delaware.gov/swc/shoreline/pages/duneprotection.aspx.



  2. 2. ↑

    “Coastal Sand Dunes.” CRD, 14 Nov. 2013, https://www.crd.bc.ca/education/our-environment/ecosystems/coastal-marine/coastal-sand-dunes.



  3. 3. ↑

    “Sand Nourishment - Hondsbossche Dunes, NL - Building with Nature Guideline.” Deltares Public Wiki, https://publicwiki.deltares.nl/display/BTG/Sand nourishment - Hondsbossche Dunes, NL.



  4. 4. ↑

    Parks Canada Agency, and Government of Canada. “Sand Dune Restoration.” Sand Dune Restoration - Pacific Rim National Park Reserve, 28 Mar. 2018, https://www.pc.gc.ca/en/pn-np/bc/pacificrim/nature/restauration-restoration/dunes.



  5. 5. ↑

    Ibid.



  6. 6. ↑

    Ibid.



  7. 7. ↑

    Sloss, C. R., Shepherd, M. & Hesp, P. (2012) Coastal Dunes: Geomorphology. Nature Education Knowledge 3(10):2https://www.nature.com/scitable/knowledge/library/coastal-dunes-geomorphology-25822000/



  8. 8. ↑

    Pacific Rim National Park Dune Restoration (BC, Canada): https://www.youtube.com/watch?v=0UQ7-0QtYMQ



  9. 9. ↑

    Protection Benefits of Coastal Sand Dunes. http://njseagrant.org/wp-content/uploads/2015/04/draft-DUNE-MANUAL-chapter-3.pdfhttps://www.pc.gc.ca/en/pn-np/bc/pacificrim/nature/restauration-restoration/dunes



  10. i1. ↑

    Damme, Bart Van. The New Hondsbossche Dunes at Camperduin by Adriaan Geuze/West-8, Petten, NL. http://www.studiovandamme.com/wp-content/uploads/2015/08/The-New-Hondsbossche-Dunes-at-Petten-by-West-8-Camperduin-NL.jpg.



  11. i2. ↑

    Restoration Work at Pacific Rim National Park. https://www.pc.gc.ca/en/pn-np/bc/pacificrim/nature/~/media/C7243409B0154EB38EF6318A051C9843.ashx?w=500&h=235&as=1.



  12. i3. ↑

    Figure 1. Sloss, C. R., Shepherd, M. & Hesp, P. (2012) Coastal Dunes: Geomorphology. Nature Education Knowledge 3(10):2. https://www.nature.com/scitable/knowledge/library/coastal-dunes-geomorphology-25822000/



  13. i4. ↑

    Figure 2. Sustainable Earth Actions. (nd). Hondsbossche and Pettemer Sea defence. https://www.vanoord.com/sustainability/climate/hondsbossche-and-pettemer-sea-defence



  14. i5. ↑

    Figure 3. Insert link

Changing Coastlines
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