Expectations and reality of sustainable stormwater management : A review of implementation of Nature-Based Solutions - A case study of Southern Stockholm

Abstract: The shrinking of permeable areas in favour of urban development is a phenomenon described in both scientific literature and policy documents. Changes in rainfall intensity and frequency following climate change are expected, but predicting the exact magnitude of these changes remains unclear. The uncertainty of what we will have to face in the future and when it will happen causes a blur of activities that may successively influence the mitigation of climate change. This study aims to explore and understand sustainable stormwater management within nature-based solutions (NBS) by reviewing both scientific and grey literature, as well as development plans in a specific area in southern Stockholm. Both risks and benefits of NBS implementation in urban stormwater management have been reviewed and described. Moreover, it is found in the literature that conceptual ambiguities and uncertainties of the NBS concept lead to weaker decision-making and planning processes. The goal of this study was to understand stormwater management recommendations for climate change mitigation, how these recommendations relate to detailed planning documents, what types of solutions are considered and proposed in the planning process, whether there is a link between the NBS and the proposed solutions, and finally, whether spatial analysis can help in the planning process in locating the strengths and weaknesses of the planned construction in flood-prone areas. The results of this study indicates whether the selected detailed development plans follow the recommendations of strategic documents. Detailed planning documents followed the recommendations to a limited extent. Moreover, in terms of spatial analysis, the analysed plans rarely referred to Skyfallsmodell, the model used to represent the flood-risk caused by 100-year rain event. In one of the cases of the early-stage detailed development plan, the new construction area were proposed inside an area with significant risk of flooding. The use of spatial analysis could help urban planners to identify both areas unsuitable for development and locate places suitable for NBS implementation.