Extreme sea levels and floods: the case study of Klaipėda City, Lithuania

Klaipėda City is located in the Southeast Baltic Sea region, where sea level rise has been observed for decades. The Klaipėda Strait, which separates the Baltic Sea and the Curonian Lagoon, where the port is located, is also more prone to sudden extreme changes in water levels, usually caused by windstorms. Extreme sea level changes pose a threat to port operations, technical structures, city residents, buildings, and infrastructure. Fluctuations in sea levels also affect the water level of the Danė River, which enters the Klaipėda Strait and divides the city into two parts. Therefore, this study aims to determine the past extreme sea level events and their influence on floods in the Danė River within Klaipėda City from 1961 to 2022. For this, the impact of meteorological parameters caused dangerous sea level rises in the Klaipėda Strait, and the following rise of the Danė River was studied. The results show that the annual mean, annual mean maximum, and annual mean minimum water levels in the Klaipėda Strait increased from 1961 to 2022. Also, the number of events where the water level in the Klaipėda Strait was ≥ 100 cm in the Baltic Elevation System was increasing. The increasing frequency of extreme water level events in the Klaipėda Strait puts urban areas at greater risk from Danė River compound floods.