Green approach receives blue-print
The Blue-Green infrastructure approach includes using streets to convey stormwater and direct runoff to areas like parks and plazas where it can be retained. BGI is effective in improving water quality during everyday rain events and helps control the flooding of carefully selected 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, which revealed the multiple, interrelated benefits that often make BGI cost-efficient.
Climate change is not only resulting in stronger cloudbursts, but also increasingly severe storms and hurricanes throughout the world. As a result, coastal protection is a priority, but it is important to consider all the pros and cons to make climate adaptation more cost-efficient – and to respect the living shoreline as well.
Ramboll has assisted the Danish Coastal Directorate with cost- benefit analyses for a new coastal planning tool which will form part of the Directorate’s new guide to the municipalities. Ramboll is engaged in a number of coastal protection projects in Denmark, and is also helping municipalities in the US. In Washington, DC, for example, 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 reduce future flooding only to a limited extent. We are now conducting a cost-benefit analysis of the protection level currently proposed and the 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.
The riverine protection measures proposed are a mix of grey infrastructure and so-called Blue- Green infrastructure (BGI) that provides the ‘ingredients’ for solving urban and climatic challenges by building with nature. The added value includes an extension of the existing Riverwalk Trail, additional green space, a living shoreline concept and better access for users. According to Phetmano Phannavong, a Flood Risk Manager from Washington, DC, it is this kind of collaboration that is needed to make our cities more resilient.
Miami-Dade County in the US is also looking for cost-effective approaches to stormwater management. 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, states that the county was particularly impressed with the proposal’s emphasis on innovative ways to manage stormwater with BGI – and the emphasis on cost-effectiveness.