Green and Blue Infrastructure in Cities
Over 50% of the global population currently lives in urban areas. Cities are particularly exposed to climate change and environmental problems due to the impact of anthropic activities. In urban environments, additionally, the negative effects of climate change are amplified by settlement features (impervious surface, buildings, transport infrastructure, socio economic activities) Flooding, heat and drought, in particular, are hazards which are increasingly characterising the urban areas (see Chapters 2 and 3) More than 40% of urban land is currently covered by impervious surfaces as roads, buildings and parking lots (Benedict and McMahon, 2012) Climate change and anthropogenic pressures, such as land use conversion, have altered the functions of ecological systems and have consequently modified the flow of ecosystem services in terms of their scale, timing and location (Nelson et al. 2013; see Chapter 5) This trend is going to increase as the urban world population is expected to rise to over 67% by 2050 (UN DESA, 2012) Urban resilience can be defined as the ability of an urban system to adapt (maintain or rapidly return to previous functions) when facing a disturbance (Pickett et al. (eds. 2013; Lhomme et al. 2013; Meerow et al. 2016) According to academic and policy interests, it is crucial to improve urban resilience to cope especially with climate imbalances and related issues. Implementing a traditional grey approach, alongside green and blue design strategies, can enhance urban resilience, especially in a long term time frame. Traditional grey infrastructure, as concrete buildings, underground drainpipes, and pumping stations, can be effective but mono functional and non adaptive tools. On the contrary, green infrastructure (GI) integrates natural processes and is more flexible and adaptive (Voskamp and Green and Blue Infrastructure in Cities