Increasing extreme rainfall calls for greater awareness and action
Governments, businesses and citizens need to become more aware of the safety risks posed by extreme rainfall, and take more action to reduce them. That is the main conclusion of the report ‘Onveiligheid door extreme regen’ (‘Safety risks from extreme rainfall’), published today by the Dutch Safety Board. Professor Marjolijn Haasnoot of Deltares was a member of the supervisory committee.
Vulnerability and cascading effects
In recent years, extreme rainfall has occurred more frequently as a result of climate change, reflected in intense downpours, larger rainfall areas and prolonged wet periods. Extreme rainfall not only causes damage and disruption, but can also lead to unsafe situations. The potential cascading effects that may arise from power outages or failure of other vital infrastructure pose a serious safety concern, the Safety Board notes.
Margreet van Marle, expert in vital infrastructure at Deltares, explains: “Vital functions are closely interconnected. Problems with electricity, telecommunications or accessibility can quickly affect other functions. These chain dependencies receive too little attention in climate adaptation plans, while accessibility is crucial for crisis response and recovery.”
Karin de Bruijn, flooding expert at Deltares, adds: “Water-related disruptions were long considered ‘a nuisance’, but this new report recognises them more as a genuine safety risk. Flooding can lead to hospital closures, power outages, failure of vital infrastructure and health impacts. This shift — from nuisance to safety concern — is a significant change from previous policy. It makes the need for better preparation even more urgent.”
Stress tests and warnings
Stress tests help municipalities, water authorities and provinces to identify the risks associated with extreme rainfall. The Safety Board recommends sharing results more widely and taking into account multiple simultaneous risk factors. It also calls for accelerated implementation of large-scale climate adaptation measures, and improved, earlier local weather warnings for citizens and businesses.
Marjolijn Haasnoot emphasises: “If you identify and understand vulnerabilities in advance, you can prevent much of the damage and take more targeted action. Stress tests provide increasing insight, and by expanding weather warnings to include potential impacts, governments, businesses, and citizens can prepare and act in time when a situation arises.”
Not preventable, but manageable
The impacts of extreme rainfall cannot be fully prevented, but they can be reduced. However, awareness of the risks and possible measures among citizens and companies remains limited. Large-scale interventions — such as sewer upgrades and the creation of water retention areas — continue to lag behind, even though they require long lead times.
Early warnings can be an effective and efficient measure. Hydrometeorologist Jan Verkade of Deltares explains: “Citizens and organisations must be aware of their risks and know what to do when warned about an imminent extreme rainfall event. This requires close cooperation between various parties: meteorologists, hydrologists, water managers, authorities responsible for public order and safety, operators of vital infrastructure, and the communities affected.”
Deltares Managing Director Annemieke Nijhof already stressed the importance of climate preparedness in an interview with Dutch newspaper 'Het Financieele Dagblad' last November. She noted: “We will increasingly face incidents that make people wonder: how is this possible? We need to start preparing now, together. And I also want to emphasise the importance of self-reliance.”
