Trends of mean annual and seasonal discharges of rivers in Serbia

Abstract

Subjects of this paper are trends of annual and seasonal water discharges in Serbia. Data of water discharges at the 94 hydrological stations in the period 1961–2010 were analyzed, using the Mann-Kendall test and Sen's method. It was concluded that 27% of analyzed stations have statistically significant changes on annual level and 14–24% on seasonal level. The annual, winter, spring and summer trends are negative, while positive trends occur at only one station for annual values, on many stations in autumn and at a small number of stations in winter. Considering the quality of data, the results of the Beli Drim River basin require additional research, while negative trends at stations downstream of water reservoirs, primarily in basins of Južna Morava and Drina rivers, are consequences of human activities. Results show that the attention of the competent water management authorities should be directed to the Timok and Južna Morava basins in terms of the expected decrease of amounts of water, and to the basins of Toplica, Nišava, Pusta, Ibar and Kolubara rivers when it comes to increase of amounts of water.