dcsimg Enhancing blue-green infrastructure in grey urban areas - Ramboll Group

Enhancing blue-green infrastructure in grey urban areas


The traditional grey approach to urban infrastructure is neither a solution to water-related problems induced by urbanisation, density and surface sealing, nor a way to mobilise all the potential benefits connected with water as a feature of people’s living environment. Obviously, blue-green infrastructure (BGI) offers urban regions a feasible, more valuable solution to the challenges of climate change in the future. This column focuses on the benefits and added values stemming from BGI, especially its impact on improving social life and human-environmental relations. From an overall perspective beyond individual projects and their specific local conditions, we have identified a range of significant benefits of (well-designed) BGI solutions and compared them with traditional grey ones. BGI solutions follow the idea of creating multiple utilities.

Herbert Dreiseitl

BGI is a very important water-related eco-system service provider as it: 1) helps to recharge the urban groundwater aquifer, 2) balances the water regime, by reducing peak discharge of stormwater runoff and sustaining base flow rates, 3) reduces soil erosion and nutrient destruction, 4) reduces instream disturbances and 5) provides stormwater runoff cleansing to improve water quality.

BGI is a driver for biodiversity as it improves rich biotopes and landscape connectivity, protects aquatic ecosystems and creates biodiversity-rich zones to improve flora and fauna.

BGI works as a moderator for urban climate as it reduces urban heat island effects, balances the day-night temperature regime and supports air ventilation. Furthermore, it reduces the biophysical impacts of land cover changes as well as the risks of urban soil dry-out and air pollution like dust.

BGI increases the adaptability and resilience of urban infrastructure by improving water management functions and the capacity of mitigation to handle the growing risks of climate change, including weather extremes. The provision of BGI often improves human physical and mental health because it upgrades space for recreation, exercise and social activities. BGI thus saves health costs (two to five times lower costs than with grey solutions).

BGI supports biophilia – people’s affiliation with nature – as it connects people with natural forms, elements or processes, with recursive effects on people’s health and willingness to protect nature.

BGI supports social interaction and integration as it increases the tendency to use open spaces for group activities and the commitment to spend time with families and friends.

BGI enhances a city’s reputation as it signals a city’s overall attractiveness and liveability and enhances the reputation of a city’s governmental institutions for focusing on residents’ living conditions. BGI increases property values by improving the social and aesthetic attractiveness of the surrounding land and buildings and therefore its real-estate value.

BGI reduces stormwater management costs dramatically in a holistic and long-term perspective compared to merely mono-functional grey infrastructure.

Despite these impressive benefits compared to traditional grey solutions, blue-green infrastructure is still far from the standard for urban water management.

In late 2015 or early 2016 the Ramboll Foundation will release a more detailed report on the overall societal impact of BGI, the constraints of and conditions supportive to BGI implementation and practical recommendations.

Based on a research project at the Zeppelin University in Germany, the National University of Singapore, and MIT and Harvard University in the USA, funded by the Ramboll Foundation and headed by the Ramboll Liveable Cities Lab (LCL). Edited by Herbert Dreiseitl (LCL), Bettina Wanschura (LCL), Matthias Wörlen (ZU), Manfred Moldaschl (ZU) and James Wescoat (MIT).


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