It looks like an ordinary flower bed, a strip of greenery in the Bagijnhof in Delft. At least in the eyes of the unsuspecting passerby, but residents know better. This bed, which extends the length of the entire court, was constructed in 2023, after the site experienced major flooding. Petrification in the area and the raising of the railway area a little further away led to problems with water. Suddenly the Bagijnhof had turned into a pit.
The municipality exchanged parking spaces for greenery with an underground water storage system via semi-open and porous concrete blocks. “Excess water can now be temporarily stored and drained in a controlled manner,” points out Marjolijn Haasnoot, professor of climate adaptation and affiliated with Utrecht University, Deltares and the Scientific Climate Council (WKR). “There was no dangerous situation here, there was never any extreme rain,” says Haasnoot. “The nuisance has been resolved.”
But nuisance caused by extreme rain can turn into insecurity. And the Netherlands is insufficiently prepared for this. Not because the risks are unknown, but because other priorities are structurally given priority. The Dutch Safety Board (OVV) draws this conclusion in a report that was recently released. Due to urbanization, much of the natural water storage and drainage has disappeared and the population density has increased. On top of that is climate change, resulting in an increase in extreme weather. The disruption this can lead to is structurally underestimated, according to the council.
The OVV substantiates its point by extensively reconstructing three examples. The short circuit in a power distribution station in Nijverdal in 2023, which caused a power outage for a few hours at more than eleven thousand electricity connections. Extreme rain in Doetinchem that led to the closure of the emergency department in 2024. And extreme rain in Enschede in 2024, which flooded two neighborhoods, resulting in 57 homes being declared permanently uninhabitable.
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Low-lying Delft city center
The report is the reason for a walk with Haasnoot through the city center of Delft. Intended to make visible which places in the Netherlands are extra vulnerable if extreme rain falls. The OVV writes in the report that there are “indicatively 47 comparable neighborhoods” to Pathmos and Stadsveld, the Enschede neighborhoods where things went wrong. There is “a vulnerable location, vulnerable homes and residents in vulnerable positions, so that extreme rain can have major consequences.”
The Pathmos district in Enschede.
Photo Eric Brinkhorst
The OVV does not want to reveal exactly which 47 neighborhoods in the Netherlands are involved. Because the map is intended to be “indicative”. “The map shows that there are more neighborhoods that may be vulnerable,” a spokesperson wrote in response to questions. “More research is needed to assess whether this is actually the case.”
A data analysis by NRC – based on the map printed by the OVV and two criteria that are also mentioned in the report, namely the percentage of pre-war homes and financial prosperity in a neighborhood – shows that this probably includes three neighborhoods in Delft (see box). But there is no certainty about that. In order to see how a low-lying municipality like Delft deals with vulnerable places in practice, we walk from the station via the Westsingelgracht along the Phoenixstraat to the Bagijnhof.
Haasnoot points out the high level of the water in the canals. “That usually goes well, but if a lot of rain falls here, the margins for draining water are small,” she says. This is the case in many places in the Netherlands. “You can compare the Netherlands with a Swiss clockwork. Everything fits together precisely and very ingeniously. But if something goes wrong somewhere in the system, it can quickly come to a standstill.”
Vulnerabilities sometimes due to small things
The fact that the OVV has shifted the emphasis from the nuisance of water to the safety risks that extreme rain can cause is new, says Haasnoot, who was part of the supervisory committee of the OVV investigation and in that role monitored the findings. “To get an idea of these risks, not only do stress tests have to be carried out to know how far the water can reach in extreme situations, but also the vulnerability of functions or a specific area must be looked at,” she says.
That is also an insight that the OVV report really provides: who does what if things go wrong?
Haasnoot mentions an “insight” from the report that vulnerabilities sometimes lie in small things – which can sometimes be remedied relatively easily. “One of the reasons was that the emergency room [in Doetinchem] flooded so quickly that the entrance is very low. At the power distribution station [in Nijverdal] it turned out that the grid operator assessed the risks of extreme rain as low and knew little about the risks of high groundwater levels in the area, which is why he did not take any measures.”
“The problem is not a lack of knowledge about where nuisance can occur, but a lack of choices to prevent it,” says Haasnoot. “The available information does not always reach the right parties.” The examples that the OVV reconstructs also show this. “Take the question: who should inform whom?” says Haasnoot. “For example, is it the responsibility of municipalities to warn network operators if the groundwater level rises, or should network operators actively ask about this?”
According to the OVV, this is also about the nature of the information, knowing that water will come is not enough, people must know what they can and should do. The example in Doetinchem shows how much difference that can make. The emergency room had to close on July 21, 2024 due to extreme rain. When it rained heavily again on September 2, the hospital staff knew what had to be done. Sandbags were ready and the fire brigade immediately knew which well they needed to go to pump out water. That was not immediately clear the first time, on July 21.
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Well-known lessons
At the same time, there are also well-known lessons in the OVV report that were previously not followed. “For example, many streams in the Enschede area have been filled in, which means that water cannot drain properly. We have known that for a long time,” says Haasnoot. “Or that grid distribution stations are located along streams or in low areas, because there is little space in the Netherlands. That is not new knowledge either.”
The tricky part extreme rainsays Marjolijn Haasnoot, is that it rarely occurs, and certainly almost never in the same place. “Yet we must protect ourselves against it, we will have to deal with it more often due to climate change.” Haasnoot sees the fact that a renowned institute such as the OVV has now also spoken out about this as an important step in raising awareness of a subject that she has been involved with all her working life.
And that, say both they and the OVV, is desperately needed. “We know that climate change is happening,” says Haasnoot. “We also know that it is necessary to adapt to this. Our infrastructure, the way we build, the places where we build.” The paradox, according to the professor, is that when push comes to shove, other priorities are often set.
For example, the report describes that the grid operator gives priority to the problems caused by the overcrowded power grid over preventing disruptions due to extreme rain. “Or build in the floodplains,” says Haasnoot. “The government has decided not to allow new construction there, due to the risk of flooding. Yet this still happens. Because agreements had already been made, for example.”
Not just system choices, also human work
According to Haasnoot, it is inevitable that it ultimately comes down to spatial choices. “Almost every report talks about this: where do we build, how do we build, and what do we accept and what do we not accept.” In a country where every square meter is divided and used, this requires management that goes beyond individual projects or local solutions and where water, soil and climate should be the starting point. Who should take that responsibility? “Good question,” says Haasnoot.
At the same time, the OVV report shows that it is not just about major system choices, but also about human work. To know who should act and when, which functions are vulnerable and where small interventions can have major consequences. “That is also an insight that this report really provides,” says Haasnoot. “Who does what if things go wrong?”
Back in the Bagijnhof in Delft, the green bed looks a bit bare – like a lot of greenery in the cold winter months – but with a trained eye it is also functional. The water can be collected here, the nuisance has disappeared. But not every neighborhood in the Netherlands receives this attention, and not every risk is recognized in time. A lot of knowledge is available. The question is what choices the Netherlands is prepared to make before extreme rain really causes major damage.
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