Nauka Przyroda Technologie

Abstract. The article gives an up-to-date evaluation of the Vistula river bed in the sector close below the Włocławek barrage. In the recent 38 years a new type of channel bottom has been shaped as the result of bed erosion in regulated river sector below the Włocławek dam and reservoir. The new channel bottom is characterized by forced bed erosion and a new flood plain rising in a non-typical way. The process of forming of a new flood plain has been slowed down by limited amplitude of water level fluctuations, a change in running the hydroplant and lack of fine- grained material in channel bottom at the distance of 18 km. The “hungry water” activates load accumulated on the flood plain in the period of 1968-2002. The constant threat of dam catastrophe, the endangered road bridge in Włocławek and degradation of other utility values of the river make it necessary to heighten the minimal water level in the lower stand of the dam.