When it comes to climate change impacts, estuaries are the proverbial canaries in the coal mine. These unique habitats, which are also home to 22 of the world’s 32 largest cities and are essential hubs for global commerce, face not just the threat posed by rising sea levels, but also a complex nexus of increasing storm risks, droughts, water and air pollution, and marine dead zones.
However, these escalating environmental risks have also helped establish estuaries as centres for what Maggie White of the International Secretariat for Water and her colleague Philip Enquist of SOM Architecture describe as a “new generation of civil engineering” – an emerging school of thought that recognises how the natural habitats of the past could be key to delivering the climate resilience we will need in the future.
So-called eco-engineering concepts have never been more popular and delegates gathered at the Global Estuaries Forum in Deauville this week heard of a host of examples from around the world where developers and city-planners are using natural engineering phenomena to reduce flood risks and improve water quality. There is certainly a need for them. As White observed, the 60 per cent of the world’s population that live in coastal areas and estuaries are facing a “slow-moving tsunami” that could see sea levels increase six feet by the 2100s. Citing a recent analysis by the World Bank, Brian Kilkelly, chief executive of the World Cities Network, similarly revealed that while the global economic cost for cities of flooding is expected to increase $1tr a year, only 20 per cent of the world’s 150 largest cities have climate change plans in place.
Moreover, only four per cent of the world’s 500 largest developing world cities, many of which are facing the most severe climate impacts, are deemed investment grade and creditworthy, making raising the capital necessary for climate resilience projects extremely challenging. The financing issue may be less acute in developed nations, but even here government austerity programmes have meant numerous countries have seen flood defence budgets cut. All of which means that the appeal of eco-engineering concepts that use lower cost measures such as mudflats, reed beds, and sand bars, rather than hard engineering levees and sea walls is growing fast, not least because these new approaches are not just cheaper, they are often more effective as well.
Victor Beumer, landscape ecologist with the world-leading Dutch water and flood management agency Deltares, reveals one such project detailing how an initial proposal to raise a levee in one Dutch town was shelved after residents complained it would spoil their view. Instead Deltares planted a willow forest in the lowland beyond the dyke, creating a natural barrier that will dissipate damaging waves in the event of a storm surge. Beumer stressed that the project still had to be comprehensively modelled as it had to deliver on its primary goal of protecting the properties and reducing flood risks. But he insisted that the results have been welcomed on all fronts. “The inhabitants are happy as they still have a view, the government is happy because it costs less, and there are also biodiversity benefits,” he says.
The willow planting is just one of a host of case studies from the Netherlands where new so-called soft engineering options are becoming increasingly prevalent. Similarly, in Toronto (pictured) an equally ambitious project is well underway to redevelop the city’s previously neglected waterfront while also tackling the flood risks that afflict the Canadian city. It may be perched on the shores of Lake Ontario, but natives of Toronto have too often neglected the opportunities presented by their own lake and travelled to enjoy some of the neighbouring Great Lakes instead, according to Brenda Webster, manager of planning and design at the Waterfront Toronto agency. However, the city has embraced a strategy of taking advantage of its most obvious natural asset and in recent years has invested around $1.2bn in developing the waterfront, catalysing a further $9.6bn of private investment in the process.
Waterfront Toronto took a conscious decision to “lead with landscape” and develop some of the parks and leisure areas in the district ahead of the buildings. The strategy is paying off and attracting new investors and developer to the area, but it has also served the dual purpose of drastically reducing flood risks that had been significantly increased by a century-old decision to effectively build over the Don Valley estuary that once fed the lake. The use of landscape and storm water permeable parklands has reduced the risk of flooding and now Waterfront Toronto is turning its attention to restoring the estuary to the lower don lands.
“We will rebuild an estuary that was paved over 100 years ago,” explains Webster. “We built a city and in-filled an estuary, but now we have a huge flooding issue so we now want to rebuild the estuary. Its main job will be flood protection, but we present it as a park, and then development next to it becomes much more practical… If we get water right, everything else falls into place. If you have the space for managing water then you have enough park space.”
Again, the use of natural streams, wetlands, reeds, and other broadly natural habitats requires a shift in mind set for some engineers – “civil engineers prefer pave and pipe to slow and spread,” quips Webster. But the prospect of an attractive, parks-rich, climate resilient new district has secured widespread business and political support, not least because the project has already delivered $3.2bn in economic output and supported over 16,000 jobs. “It’s the support of the public and business that is critical to moving in the right direction,” adds Webster, acknowledging that without public and corporate buy-in it would have been harder to secure political support for a long term project that will stretch across several electoral cycles.
Public support will also be crucial if a startlingly ambitious proposal for the San Francisco Bay is to get off the ground. White revealed that plans are being developed to tackle the increasing flood risks and sea level rise threatening the region by developing a manmade archipelago that would enable cultivated flooded areas and the creation of salt marshes. The hope is that in addition to curbing the risk presented by storm surges to Bay-front properties the creation of new habitats could spawn new industries as oysters, shellfish and salt water crops could all be harvested from the area.
Of course, eco or soft engineering is not the only means of enhancing climate resilience. There is still a place for hard engineering projects and in Nantes, France it is being backed up by hard policy, with all new buildings required to look for an alternative solution for discharging the storm water that leads to runoff pollution in the Loire River, rather than simply disposing of it into the river and sea. Christian Couturier, vice president of urban community in Nantes, even raises the prospect of a tax on storm water that would charge people who fail to take action to ensure the ground is not watertight. In addition, the city is planning to build a 6,000 cubic metre tank to store storm water before sending it for treatment.
This engineering is necessary to combat the engineering of previous generations, which has had far less benign results. “The Loire River has been frequently modified and channelled,” explains Couturier. “It is three metres below what it used to be, but this generates a lot of dysfunctions as when the sea level rises the water flows in very quickly as the mudflats are located higher than the river in places. Salt water can move a lot of kilometres inland and the water quality in the estuary is pretty poor.”
It is unintended consequences such as this that make eco-engineering so attractive, given there are generations of evidence demonstrating how natural features can limit flood risks. White and Enquist suggest there should be five guiding principles that shape this emerging school of thought: new urban development should be set back from coast to allow for natural features, there should be better co-operation between the agencies managing the up and down stream of river systems, awareness should be raised that healthy estuary leads to healthy cities, the economic opportunity for green industries created by eco-engineering should be stressed, and developers should recognise that soft engineering frequently offers more value than hard engineering solutions that can fail.
Beumer agrees a change in culture among policymakers, planners, engineers and developers is required, but argues that this will only occur if people stop treating eco-engineering projects as highly innovative. “People say this is innovative, but it’s been being done for over 10 years and if you call it innovative people want the government to pay for it and businesses won’t take the risk,” he observes. “There needs to be more of a focus on proving the business case, because you can get business to support it and fund it, as long as you have a clear view of the beneficiaries. People talk about the economics [of eco-engineering], but we need to scale it down to the business case, as these projects are always local.”
And there is growing evidence that the business case can be hugely compelling. Well managed eco-engineering projects not just deliver on their primary function of reducing flood risks at relatively low cost, they can also create valuable new habitats for biodiversity, introduce new leisure space for people, support new fisheries and crops, and even increase house prices.
Experts speaking at the Global Estuaries Forum agreed that the only thing stopping wider adoption of eco-engineering projects was political and business support, although that is increasing fast as the approach matures and public backing for new developments increases. As Brice Lalonde, former French environment minister and special adviser on sustainable development to the UN Global Compact, observed a previous French President once pursued a failed plan to introduce highways to the country’s iconic cities with the words: “cities must adapt to cars”.
“We fought that argument and won, and now people are realising cars need to adapt to cities,” Lalonde added. “Now we are seeing the same problem with estuaries. Ships are getting bigger and bigger and some people are saying we need to dredge estuaries to allow them access. But estuaries are so rich in biodiversity because they are shallow. We need to adapt to estuaries, not the other way around.”
That is the promise eco-engineering holds out, just so long as enough people realise that when it comes to water it is better to slow and spread than pave and pipe.
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