Impact of North Atlantic Oscillation on water resources in South Western Poland

The paper presents the influence of the North Atlantic Oscillation (NAO) on the water resources, especially considering groundwater discharge (baseflow) in south-western Poland. The impact of long-term changes of meteorological conditions on the water resources of this area in the 1966-2015 was determined on the basis of changes in the baseflow and total stream flow. Statistical analysis of meteorological and hydrological data showed that the runoff from the Sudeten mountain range and its foreground depends on the circulating climate factors (like the NAO). The annual NAO index best describes the variability of the average annual (12-month) total stream flow and groundwater discharge calculated from February to January and March to February, while the winter NAO index best describes the variability of the average annual (12-month) total stream flow and groundwater discharge calculated from March to February and April to March. The winter NAO index also best describes the variability of the average six-month (6-month) stream flow and groundwater discharge calculated from April to September. In the above-mentioned cases, the values of the Pearson correlation coefficient are at a high level and reach the value of -0.65.