Changes in water discharges of the Baltic states rivers in the 20th century and its relation to climate change

The river discharge changes in three Baltic States and its relation to changes in the main climatic variables such as precipitation and air temperature were analyzed using observed data and methods of empirical statistical analysis. The study is important for the development of efficient water resource management systems and validation of climate change impact models. The application of the Mann-Kendall test reveals that a significant increasing trend in winter air temperature and precipitation was determined for all 3 investigated periods (1923–2003, 1941–2003 and 1961–2003). The same trend was found for the winter and annual discharge time series. No trend was observed for the spring, summer and autumn seasonal streamflow and summer low flow series for most of the Baltic region. In general the relation between the main meteorological and hydrological parameters and the tendency in river discharge trends is common for all of the Baltic States, and might be associated with the regional impacts of global climate change.