ReviewA systematic review of the human health and social well-being outcomes of green infrastructure for stormwater and flood management
Introduction
Urban flooding is a growing challenge due to increasing urbanization, population growth and pressures on land use (CRED, 2015; Hallegatte and Corfee-Morlot, 2011). This challenge is exacerbated by climate change, which is predicted to increase both rainfall frequency and intensity (IPCC, 2012; Schreider et al., 2000). Indeed, the consequences of catastrophic flooding have been well documented globally, including economic losses (Hallegatte et al., 2013; NOAA, 2018), adverse physical and mental health outcomes (Ahern et al., 2005; CRED, 2015; Du et al., 2010; Saulnier et al., 2017), and intensification of social inequalities (Ajibade et al., 2013; Chatterjee, 2010; Nur and Shrestha, 2017; Walker and Burningham, 2011).
While the effects of catastrophic flooding events are more conspicuous, the consequences of chronic, localized stormwater-related flooding are also of major concern (Center for Neighborhood Technology, 2014; Jha et al., 2012; Winters et al., 2015). High-intensity rain events can trigger low-grade flooding of streets, homes and basements, particularly in cities with aging combined sewer systems, poor drainage, and extensive impervious surfaces (Chang et al., 2018; Douglas et al., 2010; Ranger et al., 2011). This type of urban flooding can result in economic losses, degrade natural systems, and affect human productivity, health, and psychosocial well-being (Kennedy et al., 2008).
One increasingly popular set of stormwater and flood management strategies aims to mimic natural hydrological systems to manage runoff and flooding in built environments. Such “green infrastructure” is described as part of several umbrella terms, such as blue-green infrastructure (BGI), Sustainable Drainage Systems (SuDS), Low Impact Development (LID), water sensitive urban design (WSUD), Best Management Practices (BMPs) for stormwater runoff, natural or nature-based infrastructure, and ecosystem-based adaptation (EbA) (Bartesaghi Koc et al., 2017; Fletcher et al., 2015; Liao et al., 2017; McKissock et al., 1999; Mell, 2013; Wright, 2011; Young et al., 2014). Here, we collectively refer to all of these concepts as green infrastructure (GI).
GI for stormwater and flood management has been studied extensively by engineers, urban planners, ecologists, and economists, but with relatively limited integration between the fields, or attention to the consequences beyond physical infrastructure or environmental impacts. There is indeed a large body of evidence on the ability of GI to capture stormwater and reduce runoff, improve water quality, and achieve environmental benefits (Eckart et al., 2017; Gill et al., 2007; Moore et al., 2016). However, there is far less systematic documentation of outcomes directly related to human health and social well-being. Reviews on the broader relationships between nature or greenspace and human health have highlighted the importance of this connection, but also the preponderance of observational and cross-sectional studies that lack the ability to establish causality (Demuzere et al., 2014; Hartig and Kahn, 2016; Houghton and Castillo-Salgado, 2017; Houlden et al., 2018; Jackson, 2003; Jackson et al., 2013; Lachowycz and Jones, 2011; Sandifer et al., 2015; Tzoulas et al., 2007; Wolf and Robbins, 2015). These reviews summarize studies on green building design or general green space, but do not describe studies specifically on stormwater and flood management. There is also a wide body of literature on the importance of human perceptions, knowledge, and behavior on flood risk management (Aerts et al., 2018; Terpstra et al., 2009; Vávra et al., 2017), but the ability of GI projects to improve these human dimensions is unclear.
The study of human health and social well-being is complex, with interconnected explanatory factors and outcomes. To disentangle the different ways in which health and well-being can be affected by GI designed for stormwater and flood management, we explored four pathways (Fig. 1):
- a.
Physical health (e.g., waterborne or respiratory illness, accidents, injuries, deaths)
- b.
Mental health (e.g., stress, anxiety, depression)
- c.
Economic well-being (e.g., property damage/value, human displacement and lost productivity)
- d.
Flood resilience and social acceptance of GI (e.g., knowledge and perceptions of flood risk and GI, desire to install or use GI)
To identify empirical support for the hypothesized causal links between GI designed for stormwater and flood management and human health and social well-being outcomes, we conducted a multidisciplinary systematic literature review. We hypothesized that GI designed for stormwater and flood management has a positive effect on these four pathways for individuals, households, and communities.
With this review, we aim to inform the design of multidisciplinary, comprehensive evaluations of GI projects, thereby enabling decisionmakers to identify an effective suite of solutions to mitigate urban flooding.
Section snippets
Operationalization of concepts
In defining GI for stormwater and flood management, we referred to the larger-scale concept of GI as natural areas that provide flood protection and water quality benefits to cities (Chenoweth et al., 2018; Mell, 2013; U.S. EPA, 2017; Young et al., 2014). We also included neighborhood- and site-scale GI within cities as infrastructure that “uses vegetation, soils, and other elements and practices to restore some of the natural processes required to manage water and create healthier urban
Search results
In total, the search process resulted in 19,145 initial results from journal databases and 2062 results from the gray literature (Fig. 2). After removing duplicates, 14,955 titles were screened for inclusion. Of these, 4607 full-text documents were reviewed. During the full-text screen, studies were excluded for various reasons, such as only reporting on the technical performance of GI (n = 3044), and being purely descriptive or not reporting data on changes in at least one outcome of interest
The state of the evidence
Out of more than 20,000 publications we identified about GI designed for stormwater and flood management, only 18 studies directly analyzed outcomes relating to human health or social well-being. Of the 4607 papers reviewed, most (n = 3044) evaluated the technical efficacy of GI, and another 578 provided descriptive case studies of GI construction and performance. We analyze these types of studies in forthcoming review papers. Although most of the 18 studies we included were of high quality,
Conclusions
Green infrastructure is more than just the sum of its technological and hydrological performance; indeed, Young et al. (2014) argue that “GI is only infrastructure through its ability to deliver goods and services.” For effective application in real-world settings, GI will require widespread acceptance and maintenance of facilities to reduce flooding and improve ecological and human well-being. The limited social research and evaluation demonstrated by this review reflects an opportunity to
Declarations of interest
None.
Acknowledgements
We greatly appreciate Joshua Miller and Marianne "Vicky" Santoso from The Young Research Group for their suggestions on the structure of our figures. We are also grateful to Dawn Walker and Linda Young from the Center for Neighborhood Technology for their conceptual feedback. Funding: This material is based upon work supported by the National Science Foundation under Grant No. 1848683. This work was also supported by Leslie and Mac McQuown and by the Resnick Family Social Impact Fund, Institute
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