[tech-no-logical]

you do know the deltawerken were only built with a maximum of 40 cm sea level rise in mind, right ? and we're now thinking of about 100 cm by 2100. true, that does not mean the netherlands will disappear right away, but we will see more flooding than before 1953, especially with extreme weather getting more extreme.

so the question is more whether it will be economically viable to keep the land dry. personally, with the more pessimistic IPCC scenarios in mind, we will come to the point where that decision needs to be made. not in my lifetime, most likely not in yours, but still.

as to your last sentence : we have never seen a scenario like the ones now looming over us.

[jacquesm]

They were built with that in mind, yes. But since then they've been raised several times already and there is continuous maintenance on weak points.

The real problem is the rivers, keeping water out from the seaside is actually a simpler problem than preventing the interior from being flooded once the rivers are substantially below sea level themselves.

Sea dikes and fortifications can be raised (at a cost), but river dikes can't really be raised easily and besides that the water needs to go somewhere. And I did write that on larger time scales there is a real risk, and I believe that anything over several meters rise sustained would be a serious problem and would cause some of the land to revert back to the sea.

But long before then you'll see the same in other countries, Italy, the UK, the USA, France, Germany and Spain all have areas that would be much harder and earlier hit than NL because they have no fortifications whatsoever as a starting point and it would take decades to plan and construct them.

[tech-no-logical]

the weak points (like the haringvlietdam and maeslantkering) can't (easily) be raised. and yes, the rivers will be a problem when we need to close the maeslantkering for extended periods of time when the sea level rises. it doesn't matter where the water comes from : the sea or the rivers, it will cause severe floods at some point.

I guess we differ on the 'economically viable' part. but in the really long run (say greenland being free of ice) my guess is no amount of money is going to save the netherlands.

[jacquesm]

In the really long run everything humans have ever made except for the pyramids is unstable. It would be really strange if the current living generation is somehow the exception. Houses are built for a couple of decades, they sometimes stand for a hundred years or more but that's not the rule and should not be taken as guidance for the future. Companies can move if there is enough time.

What will happen is that at some point - still quite a bit into the future - humanity as a whole will have to adjust to a new coastline and as long as it is economically viable they'll try to milk the structures already built. But in the end, on that timescale it is a non-event.

A bigger question will be how we will house and feed a 10 billion plus number of human beings on a reduced landmass with all the 'good bits' already taken. There will be wars and famine in that future and I don't think we will be able to avoid that forever. Again, history is full of upheaval, we certainly won't have seen the last of it.

But to suggest NL will disappear in the next couple of years/decades is not in line with my expectations based on what I know about this stuff. (More than most, less than what I would like to know but there is only so much time.)

As for the rivers, pumping out the water forcibly would allow the surge barriers to remain in place but would severely disrupt the economy (harbors inaccessible) and would require pumping capacity that we currently do not have (those rivers carry an enormous amount of water).

[akie]

What is cheaper: building artificial dams and islands off the North Sea coast (for example), or re-settling 7 million people while simultaneously losing all your economic output?

[SiempreViernes]

The cost for resettling will mostly be shouldered by the people of the Netherlands, that's how migration works: you pay up, you walk out on your own, or you stay behind in whatever misery you are tying to escape.

[dwild]

> But long before then you'll see the same in other countries, Italy, the UK, the USA, France, Germany and Spain all have areas that would be much harder and earlier hit than NL because they have no fortifications whatsoever as a starting point and it would take decades to plan and construct them.

No one here is arguing whether they can do anything about it. We are arguing about whether the Netherlands can do it. I'm pretty sure that anyone that believe that the Netherlands will disappear under water will agree that all theses coasts you mention will disappear too.

[jacquesm]

The point is that they will disappear long before NL and yet here we are discussing the one country that has spent decades preparing for rising sea levels disappearing.

[dwild]

> that has spent decades preparing

And that's a major part to argue about, whether it's a fight that's worth it or not.

[WJW]

We have seen exactly this scenario before, only this time the expected water levels are a few decimeter to a few meter higher (depending on the time scale). It's not like the delta works are the technological limit to what we can do. At the time, they were designed to meet the expected requirements and no further.

If the requirements change, we will rebuild them to the new requirements.

[tech-no-logical]

if the requirements say 7 meters (the sea level rise if greenland is ice free) building higher dikes will not work. and although that is a long-term scenario, it is not unlikely. hence the 'not if, but when' in the article.

[jacquesm]

Why won't dikes not work?

[WJW]

I wonder about this too. We have several dikes already that are much higher than seven metres. From everything I hear, we're not anywhere near the limits of feasible dike height, not in terms of engineerable strength nor in economic feasability (they're mostly just earth walls, after all).

[jacquesm]

That, and dikes need not be made of earth, they can have concrete as well.

The biggest risks with dikes are seepage and shifting, especially a problem with old river dikes before we properly understood how to make them.