Can blue-green infrastructure aid climate change adaptation by preventing flooding?

Abstract: The risk of pluvial flooding is going to increase as climate change causes an increase in intense precipitation along with urbanisation leading to an increase in impermeable surfaces. In the last decade, cities such as Malmö and Copenhagen have already experienced severe pluvial flooding that has caused extensive damage. Adapting to climate change by creating flood resilient urban areas is therefore important and blue-green infrastructure (BGI) may be one measure to accomplish this. This thesis has used a hydrological model called TFM-DYN to investigate whether BGI can aid the mitigation of pluvial flooding. A GIS-based urban flood model (e.g. TFM-DYN) can also assist in selecting the best locations to construct BGI. The investigation was performed in the town of Häljarp located in south-eastern Sweden. The model was set-up with two different hyetographs simulating two different scenarios, both scenarios are based on rain events that have occurred only a few kilometres from the study area in Malmö respectively Copenhagen. The first scenario modelled represented a current scenario of a 100-year rain occurring in the year 2020, the second scenario represented future 100-year rain, calculated with a climate factor so that it is representable for the year 2100. Analysing the result from the two rainfall scenarios, one can conclude that Häljarp is at risk for flooding, especially for the future scenario. After BGI was retrofitted to the area, the simulation showed that BGI significantly lowered the water depth after both rain scenarios as well as reducing the areal extent for several water depth-classes. The decrease in water depth was greater for the 100-year rain in the year 2020 where the average reduction in water depth was 7,1 centimetres. Based on this result, as well as a literature study performed, the conclusion is that BGI can be an effective way for municipalities to adapt to climate change by increasing their flood resilience.