Cities must improve resilience of entire water basin to avoid Day Zero

After Cape Town’s water supply crisis earlier this year, cities around the world are being urged to rethink their water management strategies.

According to the Cities Alive: Water for People report by consultancy firm Arup, one in four large cities already face water stress, and water demand is projected to increase 55% by 2050.

“Growing urban populations the world over are inexorably driving this rising demand for water. Concurrently, changing climate is driving extreme events in cities, from drought to floods, resulting in severe economic outcomes,” Arup Fellow Dr Mark Fletcher wrote in the report.

To address these challenges, cities must expand what they consider ‘their’ water infrastructure to include the entire river basin, the report found.

This is important as the world’s 100 largest cities occupy less than 1% of the planet’s land area, while the basins that provide their water cover more than 12% and serve close to one billion people.

As such, city governments and water utilities must work with landowners and water managers further upstream to safeguard water supplies.

“Recognising the importance of the entire water basin is essential as urban water resilience is not possible without rural water resilience,” Fletcher said.

“With up to 4.3 billion people expected to live in cities by 2050, this is something city leaders and water managers need to be looking at now. Whilst this is a challenge, it also provides a significant opportunity to revolutionise how urban water systems are designed and retrofitted, and how they can deliver greater benefits for all.”

The report, which launched at the International Water Association (IWA) World Water Congress in Tokyo recently, set out five key principles to help cities rethink their water strategies.

These include: putting people at the heart of sustainable city planning; creating basin sensitive cities; designing integrated infrastructure; using water for city regeneration; and breaking down barriers across governments, education, industry and communities.

It said creating ‘blue’ cities – those that bring water to the fore, rather than hiding it in the ‘grey’ infrastructure of pumps and pipes – is the only sustainable option.

“By applying five core principles when planning and designing blue cities, we can shape a better world,” the report said.

“We can achieve a positive water management state that is considerate of the whole water cycle. This will boost cities’ resilience to the inevitable challenges of climate change, increasing global population and urbanisation. People-focused blue cities will be maximising their chance of long-term prosperity and economic health.”

The IWA endorsed the report, and IWA Cities of the Future program manager Corinne Trommsdorff said the key message was about the importance of building water-wise cities.

“Cities that are connected to their basins, designed in a water-sensitive way, and delivering services that are sustainable, flexible and robust,” she said.