Shifting sands? Coastal protection by sand banks, beaches and dunes

Hanley, M. E., et al., 2014. Coastal Engineering

Original research (primary data)
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In a closely integrated system, (sub-) littoral sandy sediments, sandy beaches, and sand dunes offer natural coastal protection for a host of environmentally and economically important areas and activities inland. Flooding and coastal erosion pose a serious threat to these environments, a situation likely to be exacerbated by factors associated with climate change. Despite their importance, these sandy ‘soft’ defences have been lost from many European coasts through the proliferation of coastal development and associated hard-engineering and face further losses due to sea-level rise, subsidence, storm surge events, and coastal squeeze. As part of the EU-funded THESEUS project we investigated the critical drivers that determine the persistence and maintenance of sandy coastal habitats around Europe’s coastline, taking particular interest in their close link with the biological communities that inhabit them. The successful management of sandy beaches to restore and sustain sand budgets (e.g. via nourishment), depends on the kind of mitigation undertaken, local beach characteristics, and on the source of ‘borrowed’ sediment. We found that inter-tidal invertebrates were good indicators of changes linked to different mitigation options. For sand dunes, field observations and manipulative experiments investigated different approaches to create new dune systems, in addition to measures employed to improve dune stabilisation. THESEUS provides a ‘toolbox’ of management strategies to aid the management, restoration, and creation of sandy habitats along our coastlines, but we note that future management must consider the connectivity of sub-littoral and supra-littoral sandy habitats in order to use this natural shoreline defence more effectively.

Case studies

Basic information

  • Case ID: INT-056-1
  • Intervention type: Restoration
  • Intervention description:

    objective – dune stabilization by vegetation for coastal defence specific intervention here (part of THESEUS project; (Innovative technologies for safer European coasts in a changing climate) –'planting dominant native grasses such as Ammophila species that function as dune builders due to their extensive root systems and ability to grow under constant sand burial'

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Coastal erosion  Positive daily sand accumulation was estimated from the foot and the top of the sand dunes by positioning astro-turf mats near to the fixed quadrats (following Steiger et al., 2003). this is coded as coastal erosion (climatic impact) because the objective here is to assess suitability of intervention to stabilize dunes for coastal defence
  • Approach implemented in the field: Yes
  • Specific location:

    South Milton in Devon

  • Country: United Kingdom
  • Habitat/Biome type: Coastal |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: Note that this study is only briefly summarized as a case study in a broader review of the literature and other case studies (which are not relevant to code for us however, this is the only NBS intervention with relevant outcome measures) We found a significant increase in Ammophila cover (ANOVA, F (2,99) = 4.37 P = 0.015) through time (October 2011 to June 2013 — Fig. 4) indicating that establishment of the Ammophila plugs was successful. Establishment and growth varied with position on the dune however; there was significant increase in Ammophila cover only at mid-level (F(2,30) = 3.57 P = 0.041) and particularly at the dune base (F(2,30) = 10.67 P b 0.001). This corresponds with variation in sand deposition; an average 14.5 g m2 d−1 of sand was deposited at the dune base compared to only 2.3 g m2 d−1 at the top. At first glance this may seem counter-intuitive, but in fact there is much evidence that several sand dune species, Ammophila included, demonstrate enhanced growth where sand deposition is relatively high (see Maun, 2009 for a detailed synthesis).
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: Yes
  • Impacts for the ecosystem: Unclear
  • Ecosystem measures: we surveyed changes in Ammophila cover and associated plant biodiversity in fixed quadrats on each of the three dunes. unclear because - Thirty further species were recorded within our dune quadrats, but all species were observed at only very low abundances and there was no significant variation in species number through time (ANOVA, F (2,99) = 1. 71 P = 0.186). More interestingly perhaps, of the thirty species observed, only 7 are typically associated with sand dune habitats. The remainder were generalist ruderals (weeds). Consequently while Ammophila establishment has been successful at South Milton, plant community biodiversity is limited, possibly due to limited movement of propagules from nearby natural sand dunes.

  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: