By Oliver Guglielminetti, Global Product Manager – Pumps Water & Wastewater, and Ove Fjordmand, Denmark Country Manager, Sulzer.
Flooding is now considered the costliest natural hazard in Europe with river and sea flooding costing billions of euros a year. Widespread flooding in the Ahr Valley and along the Erft River in Germany in July 2021, for example, was calculated to have caused at least €40.5 billion in damage to infrastructure and trade.
For every 1-degree Celsius temperature rise, the air can hold up to 7 percent more water vapour according to the laws of thermodynamics. This phenomenon was identified as a key contributor to the deadly flash floods experienced in Spain last autumn, and led climate scientists to conclude that rainfall was 12% heavier and twice as likely compared to the cooler pre-industrial climate.
Sea levels are also forecast to rise. A recent study concluded that flooding could increase between 9% and 49% compared to 2020 levels, exacerbated by development on flood plains and the seafront.
All factors considered, the cost of flooding will increase exponentially without mitigation. While limiting global warming to below 2°C would halve these impacts, flood prevention and adaptation strategies are also needed.
Are legal requirements enough?
Under the Flood Risk Management Directive, EU member states are required to assess the risk of flooding and establish flood risk management and action plans for larger rivers.
Vienna is an excellent example of a proactive approach; following catastrophic floods in 2002 which cost Austria €3 billion in damage, Vienna’s flood defence system was significantly upgraded. Last September, Storm Boris put those defences to the test. While picturesque towns across Austria and Eastern Europe were inundated Vienna’s flood defences stood strong.
Industry experts called the investment in flood defences a success, claiming the damage avoided was far higher than the original investment in flood protection. Meanwhile, the European Union has set aside over €10 billion in aid to deal with flood damages elsewhere.
However, this level of proactivity is not commonplace. Even though many municipalities and local governments have definitive data from predictive modelling tools on the likelihood and impact of flooding in their jurisdictions, a large proportion are taking a ‘watch and wait’ approach.
Yet this approach could eventually cost more. In Denmark, a 2024 study found that a 20-year torrential rain event would cost around DKK 112 billion (€15 billion) in damage, but protection measures would only cost DKK 69 billion (€9.25 billion).
Part of the barrier to action revolves around who should pay. Should finance come from a national or local government pot? And should those that benefit the most including insurers, local businesses and householders also contribute?
Any investment in flood defences must also be more urgent than other priorities – whether that’s growth for businesses, or high-impact community investments for government actors. It can be difficult to secure an investment to defend against a flood that may happen, when investments in hospitals and schools for example will have an immediate impact. In Denmark, a new bill is under consultation requiring wastewater management companies to implement solutions to protect larger areas from groundwater flooding jointly with the landowner.
The time to protect the future is now
Given the multifaceted nature of flood protection schemes, most measures are complex to design and take several years to build. Continuing to wait until the situation worsens will almost certainly incur billions more euros in damage. Instead, the time is now to invest in flood defence.
The Ringkøbing Fjord flood defence in west Denmark is another remarkable example of a proactive approach. Having been reclaimed from the sea, the land surrounding Ringkøbing is protected by a series of dykes and a sea lock, which have successfully kept the water at bay. However, projections for the average water level in the area expect it to rise by 600 mm by 2060, which has led the local water utility, Ringkøbing-Skjern Forsyning A/S, to implement a large-scale development of the drainage and flood defence systems.
Reliable, robust, futureproofed
Part of this flood defence system rolled out by the water utility was the installation of two new pumping stations that will be critical to maintaining the water levels in the area. While the initial arrangement accommodates the forecasted sea level rises to 2060, its sophisticated design means that the station is futureproofed to 2100. In fact, most pump stations are now designed with a 75-year lifespan and sufficient space to install larger pumps every 20-25 years that can handle increasing volumes of floodwater. In addition, 3D modelling and virtual reality simulations are increasingly used to improve project outcomes.
To maximise performance, the station consists of a mix of XFP submersible pumps and VUPX vertical pumps. The reliability and robustness of such pumps is a critical success factor.
While most pump stations only operate for a few hours to a few hundred hours every year, unexpected downtime at the wrong moment could be catastrophic. As well as encountering highly variable flow rates, storm pumps must also withstand the debris that is often swept up by floodwater. That makes it vital that the pumps deployed for flood defences are designed and manufactured to industry-leading standards with the latest innovations to ensure a long lifetime of high reliability, blockage-free operation even under tough conditions.
Growing evidence points to a significant opportunity for cities to reduce the impact and cost of flood damage. In many cases new infrastructure will be needed, and in others old infrastructure will require upgrades. Either way, with billions of euros in potential savings on the line, now is the time to ensure flood defences will efficiently meet current and future demands.
