Nourished beaches replace armoured coasts

Thursday, 15 April 2010 15:58

Areas vulnerable to sea level rise introduce ecological engineering to curb threats from the sea. But it could all be academic if we lose Greenland, warn researchers.

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Ever since the 1400s, the Netherlands has built dykes to protect the flood-prone country against storms and tides. Concrete dykes and metal barriers have been set up to harden the coastline and fight the forces of nature.

After Hurricane Katrina hit New Orleans in 2005, many favoured protecting Louisiana and other regions with defences similar to that of the Netherlands.

A change of philosophy
However, faced with enormous costs and the risk of an ecosystem breakdown, both the Netherlands and the state of Louisiana are now considering softer approaches to self-defence, where natural coastal processes will be used to protect urban areas rather than concrete dykes and metal barriers.

The concept – called ‘ecological engineering’ – is based on the idea of working with nature rather than confronting nature’s forces head on.

In a recently published feature article in Nature, SEI researcher Richard Klein, along with experts from the Netherlands and the US, discusses this new concept and present pros and cons of working with nature rather than against it.

It could all be academic
The concept of ecological engineering stems from the idea that restored wetlands, beaches and natural floodplains can help deltas and coastal areas adapt to rising seas and recurring storms. For instance, the Dutch Delta Committee, a panel set up to develop guidelines on how to keep the country dry as sea levels rise, estimates that beach nourishment will render the coast more resilient to storms and sea level rise.

The plan also includes pulling sand from the sea floor and spreading it along the Dutch coast, a process that will gradually build an extra kilometre or two of coastline as an added buffer.

- If the Netherlands goes ahead with this strategy, the plan would be the first of its kind on this scale, says Richard Klein.

But uncertainties surrounding ecological engineering mean that developers risk building castles out of sand: there is still little data on the costs and benefits of ecological engineering under different scenarios of sea level rise.

- You can work with nature all you want, but it’s all academic if we lose Greenland, says Klein.

Read the entire article here