Dynerosion vid kraftiga stormar i Skanör-Falsterbo

Sammanfattning: Abstract Title: Dune erosion during storms in Skanör-Falsterbo - simulations with the help of XBeach Authors: Mikael Dunér and Axel Flodin Vacher Supervisors: Professor Magnus Larson and Doctoral Student Björn Almström, Division of Water Resources Engineering at Lund Institute of Technology, Lund University. Presentation of problem: With a rising sea-level, because of the climate change, the risk of flooding in coastal regions is increasing. Specially effected is areas like Skanör-Falsterbo that is located at a low level above the sea-level and along a long coastline. To be able to handle the problems with a rising sea-level it is a demand for an understanding of how the climate will change and how this will affect the coast. To create an understanding of how the coast might change, different models are used to simulate predicted climate scenarios. Objectives: In this report, the focus has been to study how the model XBeach works and how well it can be used to simulate a storm in the Skanör-Falsterbo area. Simultaneously the result from the simulations are analysed to help the Municipality of Vellinge to understand how well the sand dunes will work as flood protection during different storm scenarios. Procedure: By connecting data collected by the Municipality of Vellinge, the Swedish Meteorological and Hydrological Institute SMHI, and SWECO a Swedish consultant company, with measured profiles of the coast made by the authors, simulations are created with the help of the program Matlab and a toolbox named Open Earth Toolbox. ArcGIS has also been used for the creation of bathymetry from topography data and naval charts. The simulations have been done with XBeach and the result has then been processed with the program Quickplot. Conclusions: During the work with XBeach, both strengths and weaknesses in the model has been found. The code for the model is open so the possibility to specify it for a specific use is good. This freedom also means that the user will need a better understanding of the model and programming in general, to be able to get the most out of the model. There is no user interface that helps the user so the need of external programs like Matlab is a good help to avoid writing text files yourself. In the results from the simulations you can see that the sand dunes are sensitive to big storms and that a change in the profile of the coast is to be expected during this century. There are different methods to limit the erosion but they will lead to recurrent costs. The results also point out the need of a good city planning so that the municipality can avoid the high-risk areas.