Impacts of future sea level rise and high water on roads, railways and environmental objects: a GIS analysis of the potential effects of increasing sea levels and highest projected high water in Scania, Sweden

Abstract: This study uses GIS analyses to investigate the risk that increasing sea levels and highest projected highwater pose by increasing the risk of inundation on state-owned roads and railways as well as environmental objects in their side areas. This is done through an assessment of sea level rise projections and a risk analysis, which points out where vulnerable features are located and provides timeframes and durations for the risk. Climate change caused by increasing emissions of greenhouse gases since the mid-19th century has amongst other things led to an increase in both melting of the cryosphere and thermal expansion in the oceans, which has caused the sea level to rise at an increasing rate over the last century. An increasing sea level could inundate land, roads and railways as well as environmental objects, and due to this, the Swedish Transport Administration incorporates climate change adaptation for e.g. sea level rise when constructing and maintaining both state-owned roads and railways as well as their side areas. This thesis uses analyses in geographical information systems to investigate and visualize as well as calculate the statistics of the effects of future sea level rise. Several potential sea levels and the highest projected high water are included in the study, with the objective to locate state-owned roads, railways and environmental objects at risk of inundation from an increasing sea level. Sea levels up to 5.0 meters above the current sea level are analyzed and divided into four long-duration and four short-duration risk levels, based on different time horizons, with or without the addition of the highest projected high water in the study area. This study focuses on the southernmost county of Sweden, Scania, where approximately 5 % of the total area is affected by the analyzed sea levels. An increasing sea level is found to mainly affect the coastal region of Scania, but some affected land areas stretch further inland. Environmental objects are at higher risk of inundation compared to road and railway features. The highest risk of inundation is found for species rich side areas to roads and railways as well as for both existing and needed fauna passages for medium sized fauna, while other investigated features are at lower to no risk of inundation. The effect of different sea levels differs between different areas of Scania, and 21 of the 33 municipalities in the county are affected to some extent. The percentage of investigated features within each municipality is presented, as well as a detailed study of the two most affected municipalities. The thesis concludes that several areas and features are subject to different levels of inundation risk and suggests how preventive action could be prioritized.