Building more resilient cities: Managing our water infrastructure

One thing is clear from the recently published Resilience from the Ground Up report: City dwellers are worried about water. When researchers asked people across ten global cities to rank which infrastructure is most vulnerable to climate-related risks, 41 percent of respondents cited water infrastructure. This was higher than for any other kind of infrastructure, including food, transport, energy or housing.

As pointed out by the European Environment Agency’s inaugural European Climate Risk Assessment, however, risks to all these kinds of urban infrastructure are interlinked. Floods affect housing and transport, for example, while droughts threaten food security and human health. The Economist Impact survey found levels of concern were similar for droughts (38 percent) and floods (37 percent).

From global awareness to local action

Awareness is growing of environmental risks in general, and water risks in particular. In the latest edition of the World Economic Forum’s Global Risks Report, four of the top five risks over a ten-year timeframe are related to the environment or climate change. Meanwhile, water infrastructure has been rising up the agenda at annual climate COP events.

“Without action from cities and governments to make their water infrastructure more resilient, high-risk areas will see investors increasingly divest or exit, as climate risks are coming into the picture”, says Tabea Müller, Zurich Insurance’s Climate Resilience Lead for Benelux. “This will shift risks in these areas onto the public sector, disadvantaging vulnerable groups by widening the gap between those with and without the ability to protect themselves against worsening climate impacts.”

In improving the resilience of their water infrastructure, it is critical for cities to look at worst-case climate scenarios. “As insurers,” says Müller, “we are used to focusing on tail risks – those that are low probability, but high impact. However, many cities tend instead to measure their resilience against middle-of-the-road climate scenarios, because these are less costly to guard against.”

Cities in China are often noteworthy exceptions: many are planning improvements to infrastructure, such as wastewater systems, around worst-case climate scenarios to 2100 rather than middle-of-the-road scenarios to 2050. “They understand the business case for investing more now to save costs in the long term,” Müller adds.

Cities are at increased risk from flooding

The 2024 European Climate Risk Assessment cites pluvial and fluvial flooding – from rainfall and rivers, respectively – as the most urgent threats to infrastructure in Europe, the fastest-warming continent in the world. It notes that European countries have a generally good record in guarding against coastal floods, but rising sea levels will increasingly also put coastal defenses to the test.

Flood events can impose significant costs over wide areas. Floods in Slovenia in 2023, for example, caused damage that will cost one sixth of the country’s GDP to repair. Meanwhile, research by Zurich UK found that 42 percent of London’s commercial buildings are at risk of flooding from torrential rain, with the cost to a business averaging £82,000.

Investment in flood resilience

Some countries in Europe have a stronger track record than others in building resilient water infrastructure. In the floods of 2021, for example, which caused over 200 deaths and an estimated 44 billion euros worth of damage, the Netherlands was significantly less affected than neighboring Belgium or Germany.

In part this reflects luck, as rainfall was worse in Germany than the Netherlands – and also cross-border cooperation, as Germany did not release water from dams that would have worsened the effects in the Netherlands. However, it also reflects the initiatives the Netherlands has taken over the previous decades, at both municipal and national level, to minimize the impact of flooding.

Many of these initiatives are “nature-based solutions”, which involve working with nature rather than constructing infrastructure such as barriers. The Dutch government’s “Room for the River” program, for example, involves a conscious decision not to develop land at most risk of flooding – a challenge in a country with an intense housing crisis. Instead, these buffer zones along rivers are used for nature reserves, recreation and agriculture, with a scheme that compensates farmers when floods ruin crops.

Cities around Europe are beginning to take action to increase water resilience. Belgium, for example, recently introduced a law obliging sellers of properties to disclose flood risk on a standardized scale. However, the recent floods in Valencia were a stark illustration of the urgency of implementing lessons learned, as the changing climate continues to make once-rare events more common.

From water stress to sustainability

With climate change causing more extremes of weather, many cities are not only at heightened risk of floods but also prolonged droughts. They can learn lessons from other localities that have built infrastructure to improve management of water when it is scarce – such as Cyprus, which captures 90 percent of its waste water for re-use; or Bermuda, where the lack of a natural water supply has led to households installing reservoirs to collect rainfall from the roof.

Reducing consumption of water is a key part of the equation. Price signals will play a key role – as water becomes more expensive, people will be more incentivized to use it carefully. Another option is caps on water usage, though drought-prone areas often face a challenge in balancing their need to manage water with their reliance on tourism: Barcelona is among the first cities to be considering water usage caps that also apply to hotels.

Education is also critical, along with improving access to water-saving technologies such as flow-control taps and shower heads, or butts for capturing rainwater. The Belgian region of Flanders provides an inspiring success story, with residents using about ten liters per day less than a decade ago.

An integrated approach to floods and droughts

At infrastructure level, an integrated approach is key. Cities need to maximize their potential to act as a sponge – soaking up and storing water in periods of excess rainfall, to be drawn from in periods of shortfall. Here again, nature-based solutions can play an important role. For example, Zurich has worked with Madrid’s city government on planting more trees and replacing hard surfaces with water-permeable green areas, including by moving a major highway underground.

Some European countries are already committing to targets on reducing “land take” to maximize their sponge potential. Other solutions such as green rooftops can bring multiple benefits, buffering water in heavy rain, while also providing insulation and a habitat for biodiversity. To bring benefits at scale, solutions such as these need to be incentivized by public policy.

Turning the tide

“Advocating for nature-based solutions can be challenging,” says Tabea Müller, “because benefits are harder to quantify than for more technical solutions. This is because they can include intangibles such as improved livability as well as financial implications for operation and maintenance costs and asset lifespans. Zurich is at the forefront of efforts to quantify benefits, solidifying the business case for working with nature as a way to improve the resilience of water infrastructure.”

As noted in the London Climate Resilience Review, an independent report commissioned by the Mayor of London, cities have multiple tools at their disposal – from raising awareness to building skills, improving the sustainability of drainage systems and reforming building regulations.

The key is to bring all these tools together under a clear strategic vision that recognizes the critical importance of water infrastructure in climate adaptation.