Sediment Regime of the River Danube (1956–1985)

Abstract

During the investigated period (1956–1985), the natural sediment regime of the River Danube has changed significantly due to various human interventions on the Danube itself and on its main tributaries. The total mass of suspended sediment transported to the Black Sea annually varies between 25 and 80 × 10⁶ t. The sediment transport quickly rises where the bigger tributaries (Tisza, Sava, V. Morava) join the Danube within a relatively short reach. Before the construction of barrages and hydropower stations, the share of bedload in the total sediment transport reached about 20% on the German and Austrian Danube reach. On low-land sections this share drops to about 1% or less.

The most important human interventions affecting sediment transport include retaining and collecting the eroded soil and rock materials on the slopes of basins; damming the rivers for navigation and energy production purposes; dredging the bed material from the river channel for industrial use at a rate much higher than the bedload transporting potential of the river, etc. Because of the summarized effects of these anthropogenic factors, the suspended sediment and bedload transport show a decreasing tendency at almost every station investigated.

The presented results also show how the damming effect of the river barrages causes characteristic changes in the grain-size distribution of both the suspended sediment and the riverbed material. As human interventions have continued on the River Danube and in its basin since 1985, it is now high time to collate all available sediment data for the following 20-year period and compile a similar monographic summary (1986–2005) based on this data.