From flooding risk to drought: cities tackle water resilience; From flooding risk to drought: cities tackle water resilience;

From flood risk to safe supply: cities tackle water resilience

In a world struggling with population growth, rapid urbanisation, climate change, flooding, extreme heat and countless other issues, that simple looking word – ‘resilience’ – turns out to have a thousand potential meanings.

The United Nations 2023 Water Conference is taking place in New York City. This past October marked the 10-year anniversary of Superstorm Sandy making landfall along much of the eastern United States. In New York City, 44 residents were killed and much of the city was left without power, access to food, drinking water, healthcare and other services. Sandy was a wake-up call and heightened the need for water resilience not only in New York City, but in cities across the world. Since Sandy, Arup has revitalised our waterfronts such as Hunter’s Point South, worked with residents at NYCHA Red Hook Houses to improve community resilience and protected NYC Transit with flood mitigation measures.

Some of the lessons and interactions from our resilience work in New York have been incorporated into the City Water Resilience Approach (CWRA). Globally, over the past five years, we’ve been using our CWRA with clients in cities all over the world, and discovering the many ways cities and communities struggle to manage flood risk (such as Miami) and secure reliable water supplies (such as Cape Town).

The word resilience can sometimes obscure this richly complex, fast changing and utterly vital area of human development. In this article I want to explore some of the real-world meanings of water resilience – based on the experiences of the clients and communities we’ve worked with across the Global South and Global North.

Issues that flow into one another

Our CWRA was designed by the team to help clients explore and identify the local water issues they face before defining workable, scalable solutions. But as long years of experience have shown us, client goals – be they corporates or city authorities – are often more immediate and pressing than ‘resilience’ as an outcome. It’s data centres needing certainty of supply for operations and cooling. It’s manufacturers concerned that increasing urbanisation might restrict availability of supply for their factories and production. It’s an individual city neighbourhood where water supplies for domestic consumption are facing constraints, with all the social upheaval and upset that that entails.

The immediate issue is usually a singular problem, but our work also tells us that if you don’t design a solution that contributes to greater overall resilience in the system – and water is always a cycle and a system – issues will return.

The implications here are that as practitioners we have to do a better job of explaining the connected dimensions that shape successful water development projects. Today, our work is rarely simply engineering of water infrastructure or the provision of replacement elements in a system. Faced with a growing number of real-world constraints, water resilience is only possible when infrastructure engineering, governance, social norms and public accountability are all part of the solution.

Resilience begins with the individual

Back in 2018, we were asked to help Cape Town in South Africa deal with a major water scarcity crisis. A convergence of local factors, some institutional, some climate-related, some purely incidental, had left neighbourhoods in this city of 4.6 million people facing a public countdown: it was 40 days to the water runs out.

At this stage resilience applies widely. With ‘day zero’ approaching and water running out, city authorities were all too aware of the possibility of social unrest and a situation spiralling out of control.

In our role, we could see how resilience here would mean solving an immediate problem from a number of vantage points at once. We needed to get the population to co-own the problem, by using their water allocation responsibly. That meant honest and open communication, with regular updates on the level in reservoirs to advice on how to conserve water day-to-day. Having a culture where politicians can speak openly about these issues, is not a given. Wherever climate change and population growth intersect to create ongoing water scarcity issues, public transparency and engagement are utterly essential.

Cape Town Cape Town

In 2018, we were asked to help Cape Town following a major water crisis. convergence of local factors, some institutional, some climate-related, some purely incidental, had left neighbourhoods in this city of 4.6 million people facing a public countdown: it was 40 days to the water runs out.

Good governance shapes success

In our work with the CWRA, we discovered that cities, although experiencing widely differing water challenges, found that had similar root cause issues. Clients in Miami and Cape Town shared challenges around communications with their populations, leading to a lack of understanding and difficulties establishing valuable behavioural incentives.

More recently, COVID-19 proved that effective, honest and transparent government messaging on a national issue, is pivotal to getting everyone to respond in a beneficial manner. Water related risks and problems are likely to become more and more familiar around the world, highlighting the growing need for good governance.

Resilience as a corporate risk factor

Companies always consider operational risks, and water has been growing in significance for many types of business. We mentioned data centres at the start of this article – few people stop to think that every email they send typically represents the use of 4.5ml of water. For big agri-businesses in areas of growing water scarcity like California, the gallons of water required are beginning to be weighed against the importance of the food that is grown and sold. Just as beef cattle are in the sights of environmentalists for the production of greenhouse gases, so almonds’ use of 12 litres of water per nut (2.6 gallons), is becoming an issue of public debate.

Public concern is growing too. Companies’ social license to operate depends on being recognised as good stewards of water, not being wasteful or polluting. Approaching water resilience within a wider framework of environmental, social and governance (ESG) commitments requires thoughtful investigation and a commitment to change the operational fundamentals where needed.

Natural resilience is preferable (if possible)

Finally, even as water resilience has begun to gain recognition for its undoubted importance, it’s important to see it in the wider context of other climate goals. Given the scale and speed of carbon emission reductions needed, water resilience cannot count as such, unless we prioritise interventions and solutions that are low, no CO2 emitters or even net positive.

This means being innovative and not relying on hard physical "grey" infrastructure when we’re approaching issues such as water pollution and flooding. Alternative infrastructure options that are "blue" and "green" make use of natural processes instead. This approach means making biodiversity and nature part of the foundational, strategic planning of any major water scheme, being responsive to what the surrounding environment offers and needs. For example, New York City has been a pioneer in green infrastructure, and Arup has helped to implement rain gardens, bioswales, permeable pavement, constructed wetlands all across the city.

Funding is never a given

Projects that address water systems and their resilience, tend to be major multi-year investments, often revealing the need for systemic improvements touching many elements of a city or region’s catchments and water infrastructure. As such early conversations/ investigations of funding are critical as costs can be significant and success depends on certainty of investment for a number of years.

Our recent work in Africa has included approaches using ‘Decision Making under Deep Uncertainty’ (DMDU), can help prioritise resilient investments in the water sector, by looking through a wide range of plausible scenarios, whilst providing an understanding into the sequencing of schemes. This enables adaptability and flexibility.

Our partners at the World Resource Institute set up the African Cities Water Adaptation (ACWA) fund to address this issue for cities in Africa with urgent water resilience goals. Similar bodies and sources of funding will be needed in other areas of the world, and we can only hope that some of the commitments made at both COP27 and COP15 on ‘loss and damage’ transfers from wealthier to developing nations are directed at water resilience priorities.


Resilience takes many forms. It requires that we listen to communities, look beyond immediate needs, sometimes addressing outstanding social and political issues, and maintain a focus on nature-first solutions. Resilience will always be a mix of the utterly tangible, the pressing and local, but also the ideal and ongoing. As engineers and planners and water industry specialists, we know that resilience takes collaboration between all relevant parties. Only then can we achieve locally owned, lasting resilience across cities, catchments and rural contexts at once.