By Michael Rothenborg and Martin Zoffmann, November 2017
Climate change is bringing stronger cloudbursts, storms and hurricanes throughout the world, and effective adaptation is rarely cheap. But climate projects can be more cost-efficient – especially if they combine technical excellence with so-called blue-green infrastructure (BGI), a network that provides the ‘ingredients’ for solving urban and climatic challenges by building with nature.
Ramboll has used this formula on many projects around the world – from Copenhagen and other Nordic capitals to megacities like Singapore and New York.
And projects are also well underway in two other American cities. In Washington, DC, the Department of Energy and Environment is assessing the potential effect of flooding from the Potomac River in the face of
rising sea levels and storm surges, as well as the impact of extreme rainfall.
Ramboll used advanced hydraulic modelling to illustrate how the level of resiliency planned for storm surges and a rise in sea level will only reduce future flooding to a limited extent.
“We are now conducting a cost-benefit analysis of the protection level currently proposed and the higher protection level recommended, to show the value of increasing the present resilience, not only in terms of lower risks but also in terms of added value,” says Ramboll Project Manager Trine Munk.
The riverine protection measures proposed are a mix of grey infrastructure and BGI. The added value includes an extension of the existing Riverwalk Trail, additional green space, a living shoreline concept and better access (pictured).
Approval from external experts
The BGI approach includes using streets to convey stormwater and thus direct runoff to areas like parks and plazas, where the water can be detained or retained. BGI is effective in improving water quality during everyday rain events and helps control the flooding of carefully selected detention areas during extreme rain events, including potential flooding caused by hurricanes.
In 2016 BGI received approval from independent experts at the National University of Singapore, Zeppelin University in Germany, Harvard University’s Graduate School of Design and the Massachusetts Institute of Technology (MIT). The experts delivered input to a study spearheaded by Ramboll’s Liveable Cities Lab, which revealed the multiple, interrelated benefits that often make BGI cost-efficient.
Phetmano Phannavong, a flood risk manager from Washington, DC, values the input that Ramboll and the City of Copenhagen have given on the Potomac River project:
“It is this kind of collaboration that is needed to make our cities more resilient,” says Phetmano Phannavong.
Stormwater in Miami Miami-Dade County is also looking for cost-effective approaches to stormwater management.
In a challenge for ideas Ramboll’s Liveable Cities Lab successfully proposed combining BGI with partner FocalPoint’s biofiltration technology, which utilises physical, chemical and biological mechanisms of soil, plant and microbe complex to remove pollutants typically found in urban stormwater runoff.
Jim Murley, Chief Resilience Officer at Miami-Dade’s Regulatory and Economic Resources Department, says:
“We were particularly impressed with the proposal’s emphasis on innovative ways to manage stormwater with blue-green infrastructure.”
“Similarly, we appreciate the emphasis on costeffectiveness, as this is an essential component of any approach.”
In the wake of the hurricanes that struck the USA this autumn, it became apparent that many Americans are inadequately insured against extreme weather – not least because the incentives are insufficient. Insurance and damage prevention in the EU are also far from optimal, shows a new study that Ramboll and the Institute for Environmental Studies at Vrije Universiteit, Amsterdam, have developed for the European Commission.
Some of the main problems are that EU countries perform poorly when it comes to providing incentives for signalling or reducing risk, and households either fail to fully acknowledge the benefits of extreme weather insurance or are unwilling to pay the current premium rates.
Source: Insurance of weather and climate-related disaster risk. Ramboll et al. July 2017.