God may have made the world,

but the Dutch made the Netherlands.

This is the Maeslant Barrier

and it's one part of the Delta Works,

a set of megastructures that hold back the ocean

when high seas threaten to flood this country.

This is one of the world's largest movable structures,

a pair of 210-meter-long gates designed to seal off

the main shipping route to Rotterdam port and hold back storm surges.

Depending on whose measurements you believe,

somewhere between a fifth and a third of the Netherlands sits below sea level,

a lot of that reclaimed from the ocean over years

through managing marshlands and moving earth and pumping water.

There are areas of the Netherlands described as "former islands",

and these gates are part of the enormous system

that Dutch engineers built to keep this country dry.

And a couple of hours northeast of here is where they learned to do it.

This is just one part

of the 10 square kilometres of Waterloopbos

and it was built when the only way to simulate water

was to use water.

It's now a national monument

and nature is taking back these structures,

these experiments.

- Waterloop means how the flow runs through a system,

that is Waterloop in Dutch.

Over here, we mostly did what we call model studies,

so basically simulating nature at a certain, smaller scale.

The whole area started more or less

after the second World War, so around 1950,

when there was a big demand for model studies related

to the Delta Works in the southwest part of the Netherlands.

It was for the Delta Works

but we also did many studies all over the world,

studies of the harbour of Libya, harbours in Tunisia,

harbours in the Far East, Hong Kong.

The main reason for building the Waterloopbos here is

that we needed a lot of space for the models

because, around 1950, all the models were outdoor.

And another thing is you need water.

Where we are standing here is basically the bottom of the former Zuiderzee.

So we are here standing at the level,

let's say, minus two or minus three metres below mean sea level.

Here we have a natural water drop of about five metres

so we just have to open the gate at that part of the wood

and the water will flow freely through this area.

We are standing in what we call the Delta flume,

an enormous rectanglar box, so to say,

and now you see more an artist's impression of this flume

with certain sections cut out and placed perpendicular to the original flume wall.

In this flume, the studies are related to the design of breakwaters.

These breakwaters are enormously costly,

in the order of, let's say, 100 million euros.

If you take a section out of your breakwater

and then scale it down to about one to five,

and test it here.

I've been in meetings where they fight for every centimetre of the block.

Well, if we propose, let's say, that the blocks will be one metre,

they ask, could not be the block 95 centimetres

or 96 centimetre or 97 centimetres because that is money.

Each centimetre you could use on a block is money

and therefore this was one of the cash cows of Delta Hydraulics,

doing these studies, which are expensive,

but still cheap in the design of a big breakwater.

At the moment, the Waterloopbos is a kind of tourist attraction.

The upcoming of the computer, that was one of the main reasons

that this area was left around 2000.

We do excursions for tourists

to see how we operated the old, outdoor models

and this flume is handed over

to the natural monument organisation about two years ago.

So although we left the territory in 2000,

this flume was still operational for about 15 years

because you cannot easily replace this flume to another place.

- The Water Act, part of Dutch law, requires the government

to maintain flood defences.

And it establishes a maximum risk that's allowed.

So there are parts of the Netherlands that, in law, it must take

a one-in-10,000-year weather event to flood.

The trouble is that the predictions for what "one in 10,000 years" involves

keep getting worse.

Since they were completed in 1997, the gates of the Maeslant Barrier

have only been closed in defence twice,

but that's going to become more common in future.

Flood defences that were researched here were designed

to protect the cities and towns that people already lived in

but with those defences in place, people kept building

and the consequences of failure keep growing.

The Dutch are going to have to keep making the Netherlands

for a long time yet.