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Abstract: The rivers that drain the Eastern Carpathians were studied under the aspect of the contemporary modifications of the bed elevation using a data base on 60 cross sections. The determination method of the bed elevations dynamics is based on the hydrometric measurements in the pre-established sections, calculating the height of the lowest point of the bed in comparison with the reference level represented by “0” graphic of the hydrometric measuring staff. Thus, it was possible the determination of the fluvial important processes: degradation, aggradation and stability of the river beds. The observation period was comprised between 30-50 years. The dominant fluvial process in our study area is that of degradation of the river beds (over 52%), followed by aggradation (29%) and the rest was represented by river beds with a stable elevation. The mobile layer of the river bed was frequently comprised between 50-100 cm, but the degradation of the river bed registered the biggest incisions, up to 3.5 m. The causality of this phenomenon was studied in this article in which concerns the variability of the discharges that are responsible for the phenomena of scour. The long time variations of the changes of bed elevations are in relation with the changes related to the sediment supply deficit or surplus of the rivers.

Keyword: bed elevation, aggradation, degradation, channel mobile bed, Eastern Carpathians