Management of freshwater resources as well as coping with increasing natural disasters like flooding are issues currently plaguing cities across the globe. The higher frequency in extreme events like storms with a higher density of rainfall causing rapid flooding and violent landslides are just some of the many consequences associated with climate change (Momm-Schult et al., 2013). Cities have long changed the landscape and therefore the relationship between biological and physical aspects of the environment, e.g. from natural soils to impervious roadways, walkways and buildings, having created a large impact on the urban water cycle and perpetuating flood risk due to a lack of permeable surfaces (Botkin & Beveridge, 1997).
It has been suggested in the literature that cities have the potential to adapt to such risks through increasing the amount of green space or ‘green infrastructure’ within urban landscapes. In Japan, for example, it has been recognized for some decades now that non-structural interventions and catchment management options must be employed to combat the risk of flooding in cities (Takeuchi, 2002 in UNEP-CBD, 2012). It will be important to consider how cities have altered the natural landscapes and ecosystems on which they were built and what this means for sustainable urban water management now and into the future.
In order to achieve sustainable water management in cities, it will be important to consider them as complex ecosystems (Tjallingii, 1993; McDonnell, et al., 1997 in UNEP-CBD, 2012), including the consideration of urban evapotranspiration (ET) rates, interception and infiltration, water quality, urban ecosystem services, groundwater recharge, etc. (UNEP-CBD, 2012). One example where urban planning has taken these factors into consideration comes from New York City, where Schewenius, McPhearson & Elmqvist (2014) noted that this city is faced with significant challenges, including pollution, climate change, sea level rise, storm-water management, and human population growth. As such, urban planning and policy-making have begun to invest in green infrastructure as a cost-effective tool for achieving sustainability and resilience goals in the city (Schewenius, McPhearson & Elmqvist, 2014). Blue roofs, larger street tree pits, green streets, porous concrete and vacant lots are used to control storm-water and provide additional ecosystem services (Schewenius, McPhearson & Elmqvist, 2014). This plan, known as the NYC Green Infrastructure Plan, commits to a total of US$24 billion over 20 years to control 10% of storm-water runoff using green infrastructure. This plan showcases the importance and effectiveness of urban green space for local ecosystem services in the city such as flood adaptation through the consideration of a more natural urban water management scheme (Schewenius, McPhearson & Elmqvist, 2014).
The search for new innovative flood protection concepts is essential for urban adaptation to flood risk (Van Loon-Steensma, Schelfhout & Vellinga, 2014). Urban green spaces that are based on criteria to withstand extreme conditions in the current climate, which may in addition be more robust to extreme conditions in a future climate, may enhance the nature of landscape values, may offer new opportunities for combining functions, may be cheaper than traditional reinforcements, and/or may provide new socioeconomic opportunities for urban regions across the globe, are consequently valuable options for cities in the face of climate change (Van Loon-Steensma, Schelfhout & Vellinga, 2014).
Green spaces will inevitably provide an approach to improve resilience to climate change in cities, thus enabling the city to self-organize, to buffer disturbance, and to learn and adapt to pressures (Momm-Schult et al., 2013). In strengthening resilience to climate change, the principal potential benefits of green spaces are derived from the enhancement of infiltration into more permeable surfaces, thus reducing flood risks and increasing evapotranspiration in vegetated areas (Momm-Schult et al., 2013). Green spaces also have an economic value through raising property values as surrounding areas become more attractive (Momm-Schult et al., 2013).
Therefore, in order to successfully integrate green spaces in urban areas, policies and management must reach farther and wider than has been traditionally experienced. As mentioned previously, it will be important to consider cities as ecosystems with modified biophysical features. As such, planners, politicians, scientists and other key stakeholders must work together to successfully implement green spaces on a context basis in order to adapt to flood risk and benefit the city as a whole. Schewenius, McPhearson & Elmqvist (2014) suggest that urban futures can become more resilient and sustainable through an integrated social-ecological system approach to urban policymaking, planning, management and governance. There needs to be more pressure on planners to direct urban growth and development towards increased protection of ecosystems both within and outside cities that produce vital ecosystem services necessary for adapting to flood risks (Schewenius, McPhearson & Elmqvist, 2014). It is imperative that we consider new and innovative ways to mitigate and adapt to the consequences of climate change. Urban green spaces are one small step towards understanding the true complexity of urban ecosystems and thus fostering urban resilience.
“Scientists have been warning about global warming for decades. It’s too late to stop it now, but we can lessen its severity and impacts” – David Suzuki
*This article was written for the final project of my Masters Degree in Integrated Water Resources Management (IWRM) from McGill University. This is a summary of the article.