Economic evaluations of urban green and blue space interventions: a scoping review

While a number of studies have estimated the economic value of existing urban green and blue spaces (UGBS), few studies have attempted to value the impact of new UGBS interventions. We set out to identify primary studies in both peer-reviewed and grey literature that conducted economic evaluations of UGBS interventions, and to critically assess the methods and tools employed. We searched seven bibliographic databases to identify peer-reviewed studies, and grey literature was identified through a series of targeted searches on databases that included EVRI, Google Scholar, Social Value UK, New Economics Foundation, and OpenGrey. Study quality was assessed using adapted versions of the Drummond checklist and Krlev's quality assessment framework. Forty five eligible studies were included in the analysis; most were of medium quality (n = 27), and a large proportion (n = 22) used cost-benefit analysis. We observed inconsistencies in relation to the selection of benefits, use of discount rates, and sensitivity analysis, as well as a general lack of stakeholder input. Further, we identified a range of different instruments and evaluation techniques, but no clearly defined methodological framework that studies adhered to. Greater consensus is needed on the application of methodologies used to value UGBS interventions if evaluations are to remain credible and inform future investments.