Porous asphalt as a method for reducing urban storm water runoff in Lund, Sweden

Abstract: Flooding is a major risk to the ever increasing urban population, posing a threat to human lives but also causing traffic interruptions, economic losses and pollution. Built up areas are prone to flooding due to the changes of previously pervious surfaces being covered by buildings and impervious pavements, such as asphalt. Furthermore, the resulting increased surface runoff does often not get routed away from the flooded areas due to old or poorly managed drainage systems that do not cope with the effects of the growing urban population. A new approach for mitigating flood hazard in the form of Low Impact Development (LID) has emerged to reverse the negative impacts of the built up areas. This study uses PCSWMM (Storm Water Management Model) to analyse porous asphalt as one of numerous LID practices to reduce the flood risk in a neighborhood in Lund, Sweden. ‘No Change’ scenarios without porous asphalt are compared with scenarios simulating porous asphalt effects with reservoir capacity of 0.25 and 0.5 meters during rainfall events representing 100, 50, 10 and 1 year intensities. Modelling results confirm the effectiveness of porous asphalt in reducing flooded water volumes by 65.6%, 77.5% and 99.2% during 100, 50 and 10 year return rainfall evens respectively. Water volumes classified as flooding do not significantly reduce as storage capacity gets increased from 0.25 meters to 0.5 meters. Further research would be beneficial in comparing the PCSWMM results with other modelling techniques. Additionally, permeable pavements are known to work best in combination with other LID practices, such as green roofs or infiltration trenches, which could also be modelled in PCSWMM together with permeable pavements to find the most suitable solution for the specific area.