Assessing flooding and possible adaptation measures using remote sensing data and hydrological modeling in Sweden

Abstract

Recently, Europe is experiencing more frequent and greater floods compared to the last 500 years due to climate change among other factors. This has increased the associated risks, especially in urban areas, which poses a great challenge to all stakeholders. To protect traffic networks from possible floods, this paper uses QGIS, remote sensing data, and HEC-HMS model to assess flooding events and possible adaptation measures. Two case studies have been taken; 1) a 60-mm rainstorm that occurred in 2012 on a main road in the Northern part of Sweden (NB)); and 2) a 35-mm rainstorm that occurred in 2019 in the Southern part of Gothenburg (GO). The resulting flood hydrographs show that the peak reached are 0.5 m3/s and 3.8 m3/s in GO and NB, respectively. To adapt to these flood events, four adaptation measures were assessed namely afforestation, permeable pavements & green roofs, multi-use detention basins and culvert installation considering food production, biodiversity, prosperity, and the environment. The study has shown that afforestation is an effective flood risk mitigation measure to handle both moderate and extreme rain events. Well-maintained permeable surfaces and green roofs are effective in reducing flooding due to moderate rainfall, but not in reducing the impacts of extreme rainfall events. Well-designed multi-functional detention basins are good flood protection measures, however, if they are not well-maintained, their efficiency may be reduced by up to 90 %. Culverts are effective for frequent and limited rain events, but extreme rain events may even increase flood risk and thereby contribute to damaging the infrastructure.

Keywords

• Flood inundation
• Remote sensing
• Hydrological modeling
• QGIS
• HEC-HMS