Can nature save our cities from the global water crisis?

Climate change & disaster risk reduction

Cities around the world experience water as being either too little, too much, or too dirty, and often usually a combination of the three. Rapid urbanisation, climate change, biodiversity loss and landscape degradation mean that many cities are facing chronic water insecurity. In 2023 alone, two-thirds of the global population experienced water stress, while cities from Cape Town to São Paulo have faced severe droughts over the past decade. Meanwhile, excessive rainfall and poor infrastructure left cities like Nairobi and Jakarta struggling with catastrophic flooding.

The growing urban water crisis

The economic cost of flooding is staggering. According to the multinational professional services firm Aon, urban flooding globally caused USD 105 billion in damages in 2021, disrupting economies, displacing millions, and overwhelming emergency response systems. In 2021, record-breaking floods in Germany and Belgium caused over €46 billion in damages, highlighting the vulnerability of even well-developed urban areas.

Water pollution further exacerbates urban water challenges. 80% of the world’s wastewater is discharged untreated into rivers, lakes, and oceans, contaminating drinking water and harming ecosystems. The UN estimates that polluted water leads to 1.8 million deaths annually, primarily due to waterborne diseases. Additionally, industrial waste and plastic pollution in urban waterways disrupt aquatic life and reduce the availability of clean water for consumption and irrigation.

A direct result of climate change is that the hydrological cycle has changed with flows between physical states (liquid, gas, ice and back) speeded up, resulting in more infrequent, shorter, and more intense precipitation in many parts of the world. Floods and droughts follow each other in close succession, while higher temperatures provide a fertile breeding ground for algal blooms and water-borne diseases.

The water sector globally is underinvested with the recently released World Bank report “Funding a Water-Secure Future: An Assessment of Public Spending” finding that in 2023 just 1.2% of public funding was invested in water infrastructure globally. More concerningly, the report finds that the annual funding shortfall to achieve SDG 6.1 (achieve universal and equitable access to safe and affordable drinking water for all) and SDG 6.2 (achieve access to adequate and equitable sanitation and hygiene for all) is USD 140.8 billion.

The question is no longer if cities will be affected by water crises, but rather, how can cities adapt for a more water-resilient future?

A nature-based approach to water resilience

Nature-based Solutions (NbS) offer a powerful, cost-effective way for cities to tackle water challenges. Instead of relying solely on expensive grey infrastructure, cities can leverage natural systems to manage water sustainably. NbS investments are also a way of protecting investments in grey infrastructure by reducing the risk of flood damage, siltation, and salinisation. Green roofs, wetlands, urban forests, and permeable surfaces not only reduce flooding and improve water quality but also enhance biodiversity and create healthier urban spaces. For these investments in NbS to be sustainable it is important that they are included in the municipal asset register, listed as an item of grey infrastructure, such as a dam or a wastewater treatment works. Only then will they attract an annual operation and maintenance budget to keep them in the condition whereby they can continue providing service.

However, there is much work to be done at all levels. Investments in urban NbS projects are on the decline and only 37% of the world’s 500 most populous cities have specific strategies in place to sustainably manage and protect nature. A comprehensive study by the World Economic Forum (WEF) Nature Positive: Financing the Transition in Cities released in 2024 shows that from 2018 to 2023 there was a 47% drop in water-related urban nature finance approvals by the major multilateral development banks. Further, the report finds that only 0.3% of global urban infrastructure spending is allocated to NbS and on average less than 10% of total approved project expenditure from MDBs between 2018 and 2023 was directed towards urban nature projects.

For cities looking to take action, the message is clear: Nature is not an obstacle to urban development, it’s the foundation for a sustainable future.

A call to action for cities worldwide

CitiesWithWater webinar series

The CitiesWithWater webinar series, an initiative under the CitiesWithNature platform, will showcase leading examples of how urban areas are integrating NbS into water management strategies and financing their implementation. Examples include Barcelona highlighting its innovative use of urban wetlands and stormwater harvesting to reduce dependence on external water sources. Similarly, Bogotá has restored its high-altitude wetlands, ensuring long-term water security for its residents while preserving critical ecosystems, while Cape Town is developing a large-scale managed aquifer recharge system using a blended finance model developed with support of the World Bank.

A key takeaway from these discussions is that collaboration between city planners, environmentalists, the private sector, and communities is essential.

Inspiring action through visual storytelling

Recognising the power of visual storytelling, the CitiesWithNature International Photography Competition is inviting photographers to capture how nature is shaping urban water resilience. From rain gardens in Melbourne to mangrove restorations in Manila, powerful images are helping to highlight solutions to water being too little, too much or too dirty. The competition not only raises awareness but also inspires decision-makers to invest in sustainable, nature-based water solutions.

The challenges of urban water management are daunting, but cities do not have to tackle them alone. Through global platforms like CitiesWithNature and initiatives like the CitiesWithWater webinar series, cities can learn from one another and implement tested, scalable solutions. Investing in NBS is not just about securing water for today, it’s about ensuring resilience for generations to come.

Click below to learn more about the upcoming photography competition and webinar series.