Trends in Monthly Natural Streamflow in Romania and Linkages to Atmospheric Circulation in the North Atlantic

• Main Author: Marius-Victor Birsan
• Format: Article in Journal/Newspaper
• Language: unknown
• Subjects: Kendall; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10.1007/s11269-015-0999-6

Natural and reconstructed monthly streamflow records from 172 river basins in Romania (143 with full records and 29 with less than 10 % missing values) have been analyzed for trends with the nonparametric Mann-Kendall test for the period 1956–2005. The statistical significance of trends was tested for each station on a monthly basis. Changes in the streamflow regime in Romania are demonstrated. The monthly flow presents upward trends from August to January, and predominantly downward trends from February to June. The most important changes are the increasing streamflow trends from September till November, which are well explained by the increase in autumn precipitation. The annual streamflow shows a dependence on latitude, with increasing trends in the northern part, and decreasing in the south. Strong negative correlations between the North Atlantic Oscillation and the mean annual streamflow have been found in western and southern Romania, highlighting the influence of the large-scale atmospheric circulation on Romanian annual streamflow in these areas, as well as the important orographic role of the Carpathian Mountains. Copyright Springer Science+Business Media Dordrecht 2015 Natural flow regime, Reconstructed streamflow, Romania, Mann-Kendall, Monthly trends, North Atlantic Oscillation