Nemuno ties Smalininkais nuotėkis kitų Europos upių kontekste: panašumai ir skirtumai ; Annual runoff of the Nemunas river and some selected European rivers: similarities and differences

The mean monthly and annual discharges of 6 European privers (Va- nem-Gota, Vuoksi, Dauguva, Nemunas, Vistula and Oder) for the period of 1807-2009 have been analyzed conceming to the variations throughout the year and long-term fluctuations. The both standardized unfiltered as weIl as the 5-year moving averages have been used to evaluate the long-term trends and the major hydroc1imatic phases (dry and humid) over long time periods. The synchronicity of runoff fluctuations in selected rivers was investigated by the method of c1aster anglysis too. The results indicate that according to the main features of the hydrograph, the Nemunas River is very similar to the Dauguva River, but according to the ratio between monthly extremes 11, the Nemunas River (11 =3,6) shows more likeness to the Vistula. (11 = 2,6) as to the Daugava (11 = 6,8). Maximum positive correlation of annual runoff was found between the Nemunas and Daugava (the correlation coefficient r = 0,76, statistically significant at 990/0 level) and the largest negative correlati- on - between the Oder and Vuoksi ( r = - 0,57 at 99% level). Cluster analysis shows that has been combined three inflexibile pairs of the rivers, totally: 1) the Daugava-Nemunas, 2) the Vistula-Oder and 3) the Vanem-Gotha- Vuoksi. The Daugava-Nemunas pair was combined in to one group with the 3-d pair (Vanern-Gotha- Vuoksi). On the other hand, despite of the synchronism between the annual runoff fluctuations of the four above mentioned rivers (Nemunas, Daugava, Vuoksi, Vanem-Gotha), some differences between the duration of dry and wet periods exist.