Built on sand: Dutch find unlikely ally against water

The Netherlands is deploying an unlikely ally as climate change intensifies the low-lying country's age-old fight against floods: more than 666,000 truckloads of sand to shore up a crucial dike.

While building on sand has traditionally been a byword for wobbly foundations, the Dutch say they have found a new method to turn the substance into a 50-year wall against the water.

The Dutch are also planning to export the idea of using sand to prevent floods elsewhere in the world, as global warming and rising waters threaten more countries.

The project comes as UN climate talks this fortnight in Madrid heard that concentrations of planet-warming CO2 in the atmosphere have reached levels not seen in three to five million years, leading to rising sea levels.

The dike in question, called Houtribdijk, needed urgent reinforcement after nearly half a century serving as one of the Netherlands' most important flood defences.

"We had a dilemma: there are no rocks in the Netherlands. This means having to import them at great cost from countries like Norway," said Stefan Aarninkhof, hydraulics professor at Delft University of Technology.

"Or we had to find another solution and use material that was close at hand. That material was sand."
The agency said in a statement that "sandy reinforcement" of such a dike "is a worldwide first."
"After the reinforcement the levee will be able to withstand a severe storm that, on average occurs every 10,000 years."