Extreme water levels and wave run-up in Falsterbo peninsula, Sweden - Future scenarios by extreme value analyses

Located in the Baltic Sea coast, the study area, Falsterbo peninsula is in the south-west corner of Sweden and a very low-lying area, which makes it very vulnerable to a future sea-level rise phenomenon and wave action. High water levels and large waves and run-up heights in connection with the global warming can cause serious damages within the area, which is a very prestigious place regarding its location and all the facilities it holds. This means that the area is in danger of land loss due to flood-based inundation and erosion, flooding of residential areas, and saltwater intrusion to fresh water aquifers. Objectives: The main aim of this study is to analyze water levels, waves and run-up heights with the using existing water level and wind data to determine future water levels in Falsterbo peninsula. The future water levels will be obtained by means of different analyses, taking into account water levels only and water levels and run-ups together so that a ground for assessing the possible consequences can be prepared. Procedure: In the first phase of the study, the water level data was compiled and monthly extremes were extracted out of it. Then, an extreme value analysis on water levels only was conducted and future projections were made. In the second part of the study, available wind data was utilized to obtain corresponding wave characteristics and run-up heights in two different points of the peninsula. Wind and wave climates off the southern and western parts of the area were analyzed prior to extreme value analyses on the combination of water levels and run-up heights. These extreme value analyses led to having the most realistic and probable water level values in the 20 and 100-yr time intervals. Trend analyses were also included within these extreme value analyses to see the temporal variation in the water level and run-ups. Finally, the report was concluded with discussions about results and some critical points and conclusive remarks. Conclusions: The analyses performed indicate that water level rise by itself and water level rise combined with wave action can have drastic effects on Falsterbo peninsula. It was found out that 84 and 160 cm of rise in sea level can be expected for the years 2020 and 2100. On the other hand this rise goes up to 229 and 333 cm for the same time intervals in the southern part of the peninsula if run-up phenomenon is considered together with the water level rise. These future sea level heights are, no wonder, seriously threatening the peninsula, which is below 3-meter water level with 90% of its area. In other words, in 2100, for instance, more than 90% of the southern part may be under water. It was also concluded that southern coasts are much more vulnerable to sea level rise and wave action in this respect, and coastal impact analyses in Falsterbo peninsula should be made in a point-wise manner. The future sea levels obtained can cause flooding on the coast and no wonder these levels will be the cause of diminishing of attractive and important sandy beaches. Nonetheless, the flooding may even proceed to the residential areas and disrupt life routines in this prestigious area. Thus this study together with its analyses and results is a good indicator of the future scenarios in sea water levels. It is thought that in the light of findings of this study, grounds for further research and planning of appropriate protection measures and design of necessary sea defense structures against indicated potential dangers are laid. (Examensarbetet är utfört vid TVRL, Avd teknisk vattenresurslära)