Sand Dune Construction and Rehabilitation

Needs Address

Measures against erosion, storm surges, flooding, inundation

Adaptation effects

Reduced coastal erosion and flooding

Overview and Features

Artificial dunes are engineered to mimic the functioning of natural dunes to provide a barrier between the sea and land, responding to changes in wind and/ or sea level. Construction involves the placement and shaping of sediment from dredged sources into dunes. Rehabilitation involves building fences or planting vegetation on the sea-facing side of dunes to stabilise sand surfaces.

Figure: Simplified illustration of dune erosion caused by storm surge (Source: Adapted from Charlier & De Meyer (1998) Ref: Charlier, R.H. and De Meyer, C.P. (1998) Coastal Erosion: Response and Management, Volume 70. Berlin: Springer Verlag)

Cost

• Since the most basic sand dune construction projects consist simply of the deposit of dredged material onshore, followed by shaping using bulldozers, simple dune construction costs are not expected to be significantly different from beach nourishment costs in terms of cost per cubic metre of sediment used. 
• Additional costs may however, be introduced through the requirement for dune grass planting and fencing.
• Factors which are likely to influence the unit costs of dune construction are:
• Costs for deposit of dredged material
• Cost for equipment i.e. bulldozers
• Costs for human resources
• Potential additional costs for dune grass planting and fencing
• Costs very depending on site size, distance from dredge site, material required(e.g. dredged material versus fences and vegetation), construction versus rehabilitation, frequency of replenishment required
• The restoration of existing dunes can cost considerably less than the construction of dunes if new sediment is not needed 

Energy source

• Fuel etc. for construction equipment
• Human resources for maintenance

Ease of maintenance

Maintenance of naturally occurring and artificially created dunes is accomplishable at a community level

Technology performance

Dune protection meets multiple management objectives, such as habitat protection, public access to environmental and recreational resources and hazard mitigation

Considerations

• Can be carried out concurrently with beach nourishment
• Need to convince the public and government of the need for dune

Co-benefit, suitability for developing countries

• Dunes can provide habitats for plants and animals
• Protection of wildlife habitat
• Groundwater recharge
• Protection of coastal fisheries
• Dunes have often been deconstructed by local communities, who may therefore oppose the creation of such a barrier to beach access
• Dunes can challenge financial gain through decreasing the development tourism potential of a site
• Success of this approach varies dependent on local commitment – awareness raising campaigns could help local communities better understand the coastal protection role of dunes and promote local efforts to preserve dunes

Information Resources

ADB, 2014. Technologies to Support Climate Change Adaptation. Asian Development Bank. Available at: http://www.adb.org/sites/default/files/publication/149400/technologies-climate-change-adaptation.pdf [25 November 2014]

Charlier, R.H. and De Meyer, C.P. ,1998. Coastal Erosion: Response and Management, Volume 70. Berlin: Springer Verlag

ClimateTechWiki. N.d. Artificial Sand Dunes and Dune Rehabilitation. Available at: http://www.climatetechwiki.org/content/artificial-sand-dunes-and-dune-rehabilitation [26 November 2014]

Wetland International, n.d. Green Coast – the Tsunami Response. Available at: http://www.wetlands.org/OurWork/OurCases/tabid/2661/mod/601/articleType/ArticleView/articleId/10/Green-Coast–the-Tsunami-Response.aspx [19 March 2015]