Delft, The Netherlands, 23 Jul 2021

Rector Eddy Moors discusses the severe rainfall and floods

Rector Eddy Moors discusses the severe rainfall and floods in Germany, Belgium and the south of the Netherlands in national newspaper Algemeen Dagblad (AD). ''If we accept that there will be occasional floods, we should be well prepared, so that the damage is limited. If we do not accept this, we should take action to have better drainage of water.''

Severe showers and floods more likely

Limburg may experience extreme flooding more often as a result of prolonged, heavy rainfall. The question is how residents can arm themselves against this. “We have to accept that this happens every now and then or look elsewhere for better water drainage.”

Eddy Moors, professor of Water and Climate at VU University Amsterdam and Rector of IHE Delft, had to pack his bags in the 1990s when the Rhine threatened to flood. He lived a hundred meters from the river and was one of the many who had to evacuate. He finds the images from Germany that he now sees particularly intense. “It reminds me of all those people who put their stuff in the car to evacuate. People sometimes underestimate the power of water.”

All the more reason to better prepare the affected residents in Limburg for flooding. Because severe flooding of the Meuse and smaller rivers is to be expected more often, says Moors. "Due to higher temperatures and a larger supply of moisture, including through warmer seawater, the humidity is higher and there are more extreme showers," explains Moors. And also showers that linger longer over an area, such as now happened in Limburg, Germany and Belgium. A low-pressure area was blocked and remained in the same place for a longer period of time. "That mainly happens in the interior. We also see it above Austria and France. We expect such showers more often, the only question is whether they will fall in the same place.”

Are these floods related to climate change?
"It's too early to say that, but they fit the picture. This is a very extreme case, but unfortunately, it is expected to happen more often.”

Can we arm ourselves against such storms?
“We have to do something about CO2 emissions, but it takes a long time to reduce them. Places that lie low along rivers must be more alert to flooding, the population must know better what to expect. They must know which escape routes there are, roads must remain accessible. Perhaps people should consider when designing their home that does not immediately become uninhabitable in case of flooding.”

But if water comes in meters high, it quickly becomes uninhabitable, right?
“Of course there are limits. But if you look at old houses along the IJssel, you will see that there are slots in the doorposts so that people can place planks there. That will not always stop everything, but it can be a solution for some people. It is also good to not build in areas that are not suitable.”

In recent decades, a lot of effort has been put into widening and deepening the Meuse. Does that have to happen again?
“You can see that there are now problems with the smaller rivers, such as the Geul in Valkenburg. The question is always how much it costs to broaden or deepen these, and what the benefits will be. Not only financially, but also in terms of the experience of living in that environment. Do we accept that there are occasional floods, then we are well prepared, there are no fatalities and the damage is limited or insurable. Or do we not accept that? Then we have to look at better drainage of water.”

How is it possible that there were so many victims in Germany and Belgium and not in the Netherlands?
“We are the drain for the water coming from those countries. In a short time, it started to flow very fast, because it comes down steeply. Especially in the outer bends, there is a risk that the river undermines the bank. In other places in the world, it is quite normal for rivers to move. We are not used to that in Europe, but we will also have to keep that in mind.”

How?
"By no longer building in those outside bends. For a village like the German Schuld, the question is whether you should rebuild it in that spot. The water flows very fast into the valley, and then it's difficult to get away.”

We do not see that in Limburg.

“That's because the rivers are flatter here. We are more in an outlet, in the valley, so the water flows less quickly. And the further it goes, the wider the rivers, so I expect the problems will disappear as the water gets further.

Can't Germany do more to prevent these problems from happening again?
“There seems to be too little space to absorb so much water. But the Netherlands and Germany will certainly make agreements. If Germany doesn't do anything, we will have to see for ourselves what is needed.”

Now Limburg is ravaged by floods. You indicate that such showers will return. Are other parts of our country also exposed to similar risks?
“I don't expect so. In the Achterhoek you have the Leerinkbeek that comes from Germany, which can cause problems. But that river already comes from a flatter part of Germany, so the speed is lower. What I do expect is that problems can arise in cities if there are prolonged, extreme showers. Then there is insufficient water storage.”

What can we learn?
“You can see that it is difficult to predict when high water will happen. We have never experienced this and our models are not good enough. The predictions will be improved in the future because of these floods. And we can look at how we can better alert people. In Costa Rica, for example, we are investigating how to incorporate social media. It is also good to look at countries such as Bangladesh, where this happens much more often. We can learn how to deal with it. In such countries you often see health problems arise. We have to be careful that sewage water does not enter our homes during floods, by keeping them separate.”

The current water level is many times higher than usual. What should we expect?
“I'm afraid there can always be more rain. Suppose it continues to rain heavily for longer, it could last even longer. You will have to accept that.”

This interview with our Rector Eddy Moors was originally published in Algemeen Dagblad in Dutch.

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