In July 2021, heavy rainfall in Limburg, Belgium and Germany caused major disruptions and damage. What happens if such an exceptional downpour occurs in Zeeland? To gain insight, the Province of Zeeland and the Scheldestromen water board commissioned a water impact study on possible flooding in Zeeland during an extreme rainfall event. The next step is to make agreements with regional partners about preparations and measures based on this water impact study. The ultimate goal is to ensure that roads, hospitals, energy companies and other so-called vital functions remain available during such extreme situations.
Regional Stress Test
The rainfall in Limburg in 2021 was exceptional and rare: 200 millimeters of rain fell within 48 hours. This extreme situation exceeds every standard that the water system in the Netherlands must meet. It is not the intention, and nearly impossible, to design the environment so that there is no longer any nuisance. But due to climate change, the chance of extreme showers is increasing. That is why it is important to be prepared for such extreme showers. Like other provinces, Zeeland has mapped out the possible effects through a water impact study. On behalf of the national government, a Regional Stress Test has been conducted throughout the Netherlands to show the impact such a shower has on vital functions and infrastructure.
What does the Zeeland water impact study show?
The water impact study is based on computer models and shows where flooding can occur in Zeeland during an extreme rainfall scenario. The models show that a large part of Zeeland may experience flooding. The water depth on the surface can vary from a few centimeters on the street to locally more than two meters, especially along waterways and in natural low areas.
Rural area
A large part of the Zeeland water system consists of polders with pumping stations and other water management installations that can pump excess water to external waters. Because the distance is short, water flows away quickly. But during extreme rainfall, it can take longer for excess water to be discharged from the land.
Urban area
Many urban areas can experience flooding. In older residential cores, it is often a few centimeters of water on the street, with locally lower areas having about one meter of water depth. In newer neighborhoods, larger water depths can occur (up to decimeters), which in many cases are discharged within about two days. In some neighborhoods, spikes are seen where flooding can last up to about five days.
Next step: discussing risks
The water impact study clearly shows which areas in Zeeland are vulnerable to flooding during exceptionally extreme rainfall. The Scheldestromen water board, Province of Zeeland, Rijkswaterstaat and the Zeeland Safety Region will work together on the results. The water impact studies are shared with managers of vital infrastructure, such as energy companies, hospitals and road managers, and with other managers such as municipalities and nature managers.
In 2026, the Province, the water board and the Safety Region will engage in discussions with these parties. Today, on January 20, there is a first meeting. The risks, possible consequences and actions to be taken are mapped out. The ultimate goal is to ensure that important facilities remain available during extreme rainfall. This way, Zeeland is better prepared for the future.