Trend analysis of annual water discharge and sediment load in the Juzna Morava River (Serbia) during 1958-2007

Abstract

Global climate change and changes caused by human activity have had a considerable impact on river systems. Recent studies have observed different trends of water discharge and sediment transport for the largest rivers in the world. This paper deals with the trend analysis of suspended sediment load (Qs) at the most downstream hydrological station of the Juzna Morava (Mojsinje). The data, which were obtained from the Republic Hydrometeorological Service of Serbia (RHSS), included daily values of water discharge (Q) and suspended sediment concentration (SSC) for the time period 1958-2007. The trend of sediment load was determined using the non-parametric Mann-Kendall test, while the Pettitt test was used to establish the transition year. The results show that the average perennial suspended sediment load for the given time period was 2.47x10(6) t (160.5 t/km(2)/yr), ranging from 0.04x10(6) t (2.6 t/km(2)/yr) to 9.85x10(6) t (640.3 t/km(2)/yr). The average decrease in sediment yield was 5.15 t/km(2)/yr with high statistical significance of 0.001. Using the Pettitt test, the year of 1985 was determined as a transition year in suspended sediment load. Suspended sediment load declined by 71% in the period after 1985.