Climate and monuments

The heavy rainfall, the increasingly violent storms and the fluctuating temperatures. All these climate changes have a major impact on our living environment. Monuments are increasingly at risk of being damaged by, for example, extreme hailstorms or falling trees. What are the consequences of the climate for heritage?

Monumentenbezit is also facing new challenges around climate change. How do you deal with that? We share a number of scenarios that we have experience with.

Nuisance due to rain

None of our monuments are located in a flood-prone area. However, we have already suffered from extreme rainfall on a number of occasions. “In some cases, the water can naturally subside, as recently happened at the Ruins of Brederode when the bridge there was under water due to heavy rainfall. But in other cases, you really have to take action yourself,” says project leader Robin Koot.

This was the case at Radboud Castle last year. When a number of locks in the Afsluitdijk did not work and there was flooding due to heavy rainfall at the same time, water entered certain areas. Together with the fire brigade, the water was then drained to the IJsselmeer. Fortunately, there was hardly any damage to the interior.

Adapting buildings

Our colleagues who are involved in the maintenance of the monuments on a daily basis are always looking at water. How is it drained? What does the roof surface look like? With a small surface area, there is often less water nuisance. Where necessary, we adapt the monument without affecting the appearance. This is increasingly necessary due to the changing circumstances. “For example, at the Grote Kerk Veere we have expanded the drainage capacity of the rainwater drainage by installing an extra drain due to the increase in rainfall. In addition, we have increased the diameters of the clean water sewer, so that there is more capacity to drain water quickly.”

What we have started doing differently due to the increase in rainfall is that we have gutters and rainwater drainage checked and cleaned more often. We include this as standard in the annual maintenance for the monument, but it now has to be done more often than before. Where that used to be once a year, for example, it is now twice or more.

Green management

Not only during the maintenance of the building, you are more often busy repairing damage caused by weather conditions, more time is also spent on restoring the greenery. “In the past, storms have sometimes damaged the greenery around our monuments,” says director-manager Mark van den Bos. “We are increasingly receiving reports of a fallen tree after a storm has raged, such as last year at the Ruïne van Teylingen. You are now encountering this more and more often. So we are freeing up more budget for replanting the greenery around the monuments. In management and maintenance, you may now also have to intervene earlier or more often than before, such as pruning the trees at more times. So it is about adjusting the strategy of green management and being more alert.” Planting trees, plants or other crops is not something that happens just like that. We do this on the basis of a green plan. Mark: “We always continue to look at the historical layout and on that basis you make a plan for the greenery.”

Green also plays an important role in the restoration of Buitenplaats Trompenburgh. The existing green structure is being adapted, based on a design by landscape architects Karres+Brands , and reconstructed to a 17th ^century design. Robin: “We are going to plant 345 new trees for this. For planting the new garden, we are choosing plants that are resistant to heat and require little water during certain periods. For example, we are not planting oak trees but lime trees, because they are stronger and can withstand a more difficult climate better.”

Heat problems

The amount of rain is increasingly offset by longer periods of drought. This also causes more and more problems, says Robin. “About 2 or 3 years ago, the entire moat at Slangenburg Castle was dry. Then I had to rush there in the evening to save as many of the carp as possible together with the animal ambulance.”

A challenge we face around heat is also related to water. If it has been dry for a long period and then a lot of rain falls in a short period of time. Then the water cannot infiltrate into the ground. The soil remains marshy and is damaged by recreation. In dry periods, erosion due to treading is also a danger to the greenery. Nature does not get the chance to recover if many people walk over it. "That is why we have made a plan at the Naarden Vesting for where we allow people in and where not. In this way, we give nature more space to recover," says director-manager Mark.

By alternating dry and wet periods there is also a greater chance of grass growing between the stones, as happened at the Burcht van Oostvoorne. These plants cause damage to the monument, so they have to be removed.

Direct and indirect consequences

“In previous winter periods, the cellar of Slangenburg Castle was also flooded. We had to pump it out then too,” adds director-manager Mark van den Bos. “These are direct consequences of climate change that we are already noticing and that we have to anticipate. But there are also indirect consequences…”

It may sound strange, but a high groundwater level is actually good for monuments. Mark explains this further. “If the wooden pile foundation under the building is under water, you will not have any problems with rotten piles. As soon as your pile heads come above water, oxygen comes in and they start to rot. We hear more and more that this happens in the heritage sector. Fortunately, we have not had any problems with this yet!”