Efficiency of blue-green stormwater retrofits for flood mitigation – Conclusions drawn from a case study in Malmö, Sweden

Research output: Contribution to journalArticle


Coupled one-dimensional (1D) sewer and two-dimensional (2D) overland flow hydrodynamic models were constructed to evaluate the flood mitigation efficiency of a renowned blue-green stormwater retrofit, i.e. Augustenborg, in Malmö, Sweden. Simulation results showed that the blue-green stormwater systems were effective in controlling local surface flooding in inner-city catchments, having reduced the total flooded surfaces by about 70%. However, basement flooding could still be a potential problem depending on the magnitude of the inflows through combined sewer from upstream areas. Moreover, interactions between blue-green retrofits and the surrounding pipe-system were studied. It was observed that the blue-green retrofits reduced the peak flows by approximately 80% and levelled out the runoff. This is a substantial advantage for downstream pipe-bound catchments, as they do not receive a cloudburst-equivalent runoff from the retrofitted catchment, but a reduced flow corresponding to a much milder rainfall. Blue-green retrofits are more effective if primarily implemented in the upstream areas of a pipe-bound catchment since the resulting reduced runoff and levelled out discharge would benefit the entire network lying downstream. Implementing blue-green retrofits from upstream towards downstream can be considered as a sustainable approach.


External organisations
  • Ramböll Sverige AB
  • DHI Sverige AB
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Water Engineering


  • Blue-green, Cloudburst, Urban Drainage, flood mitigation, Retrofit, stormwater, Stormwater system, Stormwater runoff, SUDS, LID
Original languageEnglish
Pages (from-to)60-69
Number of pages10
JournalJournal of Environmental Management
Publication statusPublished - 2018 Feb 1
Publication categoryResearch

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