Sediment regime of the Danube River in Serbia

Abstract The total length of the Danube section in Serbia is 587.5 km, and it has three specific sections: (1) Pannonian Plain Danube (or the Middle Danube) has all characteristics of lowland rivers. The stretch downstream of Novi Sad is under the influence of the Iron Gate 1 backwater during low water flows; (2) Iron Gate Danube, where the river is confined in the gorge. Now it is a reservoir, with completely altered natural characteristics. (3) Western Pontic Danube (or the Lower Danube), downstream of the gorge. This paper presents the sediment regime in the Serbian sector of the Danube River, both upstream and within the Iron Gate Reservoir. Extensive field investigation data were used to describe the most important parameters of sediment transport and deposition processes, including riverbed composition and suspended sediment characteristics (grain size and concentration). The influence of large tributaries of the Danube (the Tisza, the Sava, and the Velika Morava) is also addressed. Activities conducted in the Iron Gate 1 reservoir under the Sediment Regime and Morphological Changes Monitoring Program is also described. Data obtained during implementation of the Program form the basis for the description of changes in the Danube sediment regime that occurred following erection of the Iron Gate Dam. It revealed that the most important consequence of the Iron Gate 1 HPNS Dam is permanent deposition of sediment in the Iron Gate Gorge portion of the reservoir, the water and environmental management implications of which are becoming increasingly important. However, upstream stretches of the reservoir are not subject to uniform sedimentation processes; instead, the sediment regime depends on current hydrologic and hydraulic conditions within the watercourse and/or the hydro-power plant operating mode.