Implications of extreme waves and water levels in the southern Baltic Sea

Several coastal areas in the south of Sweden are subjected to flooding and erosion. Such events depend on the magnitude and frequency of water levels and wave heights as well as their joint occurrence. Long time series of climate data from the south coast of Sweden were employed to investigate the statistical properties of extreme events in terms of the waves and water level changes. Through the combined analyses of waves and water levels the probability of extreme events occurring in the southern Baltic Sea was assessed. The study also established relevant probability distributions to characterize such extreme events as a basis of various risk assessments related to the impact on the coastal areas of large storms. Furthermore, an attempt was made to estimate the conditions after climate change. Based on available forecasts and scenarios of future climate change the corresponding probability distributions were determined. The study suggests that a run-up level, with a 100-year return period from today, in the year 2100 may occur up to thirteen times more frequently.