Developing and testing a cost-effectiveness analysis to prioritize green infrastructure alternatives for climate change adaptation

Green infrastructure has been increasingly identified as an option to help manage climate change impacts in urban areas, although its implementation is still not widely promoted in urban planning. This is because of the lack of detailed analysis for decision-makers regarding construction and maintenance costs for different types and how effective various measures are at managing precipitation at a catchment scale. This paper contributes to fill this gap in knowledge by developing a green infrastructure cost-effectiveness ranking index (GICRI) able to evaluate the stormwater runoff volume reduction of multiple green infrastructure alternatives under different climate change scenarios, over differing spatial configurations and combining this performance data with their construction and maintenance costs. After applying this model over two case study areas, this paper provides three main insights. First, climate change projections have a significant impact on green infrastructure cost-effectiveness. Second, as green infrastructure cost-effectiveness is influenced by the spatial scale, there are different challenges for larger cities and smaller regional towns. Building on this, the paper argues that GICRI can be a simple and fast heuristic to increase the use of green infrastructure by informing decision-makers regarding how and where to prioritize investment or where greater modelling is needed.