Dutch learn to live with rising seas

The watermark column inside Amsterdam's city hall is more than just a tourist attraction, it's a reminder that the Dutch capital like much of the rest of the Netherlands is well below sea level.

Some 70 per cent of the country's economic output is generated below sea level, protected by a complex-system of ancient dikes and modern cement barriers that hold back water from the sea and the multitude of rivers that weave through the country.

Now, with scientists' predicting that sea levels will rise by about one metre this century, the Dutch are reversing centuries of tradition to create natural flood plains for rivers as well as rebuild mangrove swamps as buffers against the sea.

"We've been adapting for 1,000 years. That's nothing new. It's just that climate change is going faster than it was before," said Lennart Silvis, the operational manager of the public-private Netherlands Water Partnership.

Instead of raising dikes, the Dutch want to reclaim land and build public recreation areas that can absorb storm surges.

Rather than dredging sand to maintain beaches, they are looking at dumping piles of sand offshore to create "sand engines" shifted by the tides. Marshes may be renewed to break the power of incoming waves.

There is even a campaign called Room for the River which would weaken levees to recreate natural flood plains along rivers, including the Rhine and its tributaries which flooded in 1995 following heavy rainfall that almost led to a calamity.

While the dikes can be shored up, as happened in 1995 preventing the country from being submerged in six metres of water, the dikes could collapse if the sand and clay that form the barriers absorb too much water over time.

Hence the need for a longer-term solution given the possibility the Netherlands may face sustained pressure from its rivers throughout this century as glaciers in Switzerland melt, raising the water level of the Rhine.

River discharge in the country is expected to rise 12.5 per cent in the coming years. This is on top of rising levels already seen in the past 10 to 12 years.

Those who work to promote such ideas say natural water buffers are a smarter move than building higher flood walls that may not stand the test of time as sea and river levels rise.

"€100 billion spent on safety alone under uncertain conditions is maybe not the wisest investment," said Raimond Hafkenscheid, director of the Co-operative Programme on Water and Climate in The Hague.