Cities need to expand what they might now consider ‘their’ water infrastructure to include the entire river basin on which they depend, says the Arup report Cities Alive: Water for People. The report has been endorsed by the International Water Association (IWA) and was launched at the IWA World Water Congress & Exhibition in Tokyo,
The report highlights that the world’s 100 largest cities occupy less than 1% of the planet’s land area, whilst the basins that provide their water resources cover over 12% and serve almost a billion people. Water basins are vital for supplying cities with water, collecting all the surface water and groundwater in the area, says the report. Cities impact stewardship for hundreds of miles and have the potential to influence how their water basins are managed, yet they invest very little in them.
The report calls for more ‘upstream thinking’ in how cities approach water management. This means greater collaboration, working with landowners, businesses and local authorities further upstream to consider the water basin as a whole.
Understanding how a city’s water basin behaves does not only lead to better water management but can protect the local environment and ensure the wellbeing of residents, says Arup. The report outlines recommendations for successfully managing and maintaining water basins, including:
working together - city governments, businesses and water organisations should be working with land owners and land managers further upstream to reduce flood risk, improve water quality and encourage more sustainable water sources;
working with nature - all basins are different; cities need to understand the flows of water, sediments, nutrients and ecology of their basins, to formulate and provide successful designs and solutions. The Leeds Flood Alleviation scheme in the UK, for example, was developed after Leeds experienced widespread flooding for a number of years, most recently in 2015. It took a basin-wide approach in implementing landscaped natural flood defences (NFM), and adjustable weirs to improve water continuity. The scheme now protects 500 businesses and 3,000 homes.
Dr Mark Fletcher, global water leader, Arup, said, “Recognising the importance of the entire water basin is essential as urban water resilience is not possible without rural water resilience. In simple terms, we must be more water-wise. 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."