A framework for integrated assessment of blue-green infrastructure: A decision support tool for evaluating climate adaptation and social benefits in relation to construction and maintenance costs

In an era of changing climate, rapid urbanization, and densification there is a need for spaces that can manage extreme weather events, such as heat waves and heavy precipitation, whilst simultaneously be attractive for the urban citizens, i.e., multifunctional spaces. In this paper a framework for integrated assessment of the potential of multiple urban blue-green infrastructure (BGI) elements to provide climate regulating and social functions, i.e. multifunctionality potential, based on best research available, in relation to cost for construction and maintenance to be used in planning is presented. The assessment of functions and costs is done on a nominal scale from 1 to 5 using a mixed-method approach (systematic literature review, model simulations and workshops). The integrated assessment is presented in a multifunctionality potential and cost matrix and allows for weighting of each function and cost, as their relative importance is context dependent. It is shown that the majority of BGI elements have a relatively low potential to provide multifunctionality in terms of urban stormwater management, heat stress reduction and recreation. Some of them to a low cost (e.g., road verges, ditches, permeable pavements) others to a high cost (e.g., green roofs and walls). The highest multifunctionality potential is found in large parks, but to a high cost. The most favourable element, i.e., high potential in relation to costs is urban forests. The matrix presented here is considered usable for making general well informed integrated decisions in planning and to enhance the awareness of single and multiple functions of BGI elements.