Flood Lessons

Introduction:
After a 1953 storm killed 1800 people in the Netherlands, the Dutch built an elaborate system of dikes and dams to prevent another flooding disaster. Host Bruce Gellerman talks with a flood risk analyst in the Netherlands about the reasons and the resources it took to put the protection in place.






Transcript:

GELLERMAN: One third of the Netherlands is below sea level, and while the picture of the little boy in wooden shoes holding back the sea with his finger in the dike is an enduring, perhaps endearing, image of Holland, it's far from accurate.

Following what's called "the Misery of 1953," the worst flood in modern Dutch history, the Netherlands built an elaborate and formidable sea defense system. On the line from Delft is J.K Vrjiling, a flood risk analyst at the Technical University Campus in the 17th century city. Thank you for joining me.

VRJILING: Thank you.

GELLERMAN: Describe this, what's called, I guess, the Delta Works. The system of dikes and gates.

VRJILING: Yeah, the Delta Works are, in principle, based on the shortening of the coastline. From the old days on there have been always estuaries going into country, and that meant along these estuaries long dikes had to be maintained. And the main principle was to shorten the coastline and close off these estuaries by new and formidably strong dikes.

GELLERMAN: As I understand it, these Delta Works were designed to be tough enough to stand up against a storm so strong it would occur only once in 10,000 years?

VRJILING: That's correct.

GELLERMAN: How could that possibly be? How could you design something and know that it's going to last for 10,000 years?

VRJILING: It doesn't last for 10,000 years without maintenance. But it's based on an extrapolated storm search. We have 100 years of statistics about storm surge levels on the Dutch coast, and this is extrapolated to a level of once in 10,000 years, and that's our five meter storm surge level.

GELLERMAN: Five meters is as high as it would get, you predict, in 10,000 years?

VRJILING: Once in 10,000 years, yes.

GELLERMAN: And this system of dams and dikes could actually withstand that?

VRJILING: Yep, it should be able to withstand that.

GELLERMAN: Professor, I was reading about another expert in Rotterdam at Erasmus University, Anton Smitz , and he's a biologist. And he says that there are reasons for concern caused by these dikes and dams.

VRJILING: Yeah, he's not an engineer so he has doubts if it's possible to increase the height of the dikes and the strength of the dikes. So his idea is that we, as Dutchmen, were not wise to inhabit this low laying lands and that we do better in leaving them over to the sea again and let nature have free reign in our areas. But we say that's not so practical. We started to live here, we have a comfortable life here, and our technical means are sufficient to protect us against floods as long as we keep our own promises.

GELLERMAN: So Professor, you don't sound very concerned. You sound like this system...

VRJILING: No, the only concern that we really have is that the politicians are able to take decisions, eh? That may be also the case in New Orleans – that if you find out that you have to do something, that you're then able to do it.

GELLERMAN: I don't understand.

VRJILING: Suppose we measure sea level rise, and how many years does it then take to get a political decision to increase the strength of the dikes?

GELLERMAN: I see. So you're expecting that the sea will rise, perhaps at a greater rate than had been anticipated, and that the political decision-making process will be slower than that?

VRJILING: Exactly. That could be the case. And that's the main danger in my eyes.

GELLERMAN: Well, Professor, thank you very much. I appreciate it.

VRJILING: Okay, thank you very much.