Dutch-engineered Sand Engine controls floods naturally

Erosion happens. So how do you harness these natural processes to re-nourish beaches and fortify the coastline?

The Netherlands is augmenting its world class system of dikes and sea gates with technology that mimics natural systems and their ability to hold back the sea.

If all goes according to plan, a crescent-shaped mound of sand along their south-central coast will eventually disappear -- rearranged by ocean currents into a buffer that will protect the coastline for the next two decades. Yale Environment 360 reports.

Until now, this coastline needed sand replenishment every five years, which required expensive dredging that damaged marine ecosystems.

With the Sand Engine -- a big reservoir of sediment currently 21 million cubic meters in volume -- the goal is to fortify and re-nourish eroding beaches as ocean currents gradually redistribute the dredged material.

When the sand is fully spread out, it will protect 12.4 miles of shoreline from the current rate of sea-level rise. And if the amount of water increases, “we’ll just add more,” says the technology’s creator, Marcel Stive at Delft University of Technology.

It’s the signature project of Building with Nature, a consortium of industries, researchers, and public agencies looking to harness natural systems for hydraulic engineering. It was completed in 2011 with $67 million.

Dutch researchers are also working on new dike material: flexible cement to attach energy-absorbing stones, geotextiles that prevent internal erosion, super-strong grass to dampen wave action, and even "bio grout" (calcium excreted by bacteria when fed a particular diet).

Managing water is a big business in The Netherlands, bringing in $10 billion in a year. The country is considering a $1.34 billion package of flood-protection upgrades, including sand dunes and "hybrid dikes" with vegetation on the seaward side.

Meanwhile, on the other side of the Atlantic, Philadelphia is leading the way with "natural infrastructure" investments of more than $1.67 billion over the next 25 years to retrofit its stormwater management system, according to the Natural Resources Defense Council.

[Via Yale Environment 360, Fast Company]

Images: Rijkswaterstaat / Joop van Houdt, Zandmotor via Flickr

This post was originally published on Smartplanet.com

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