On chosen problems with sand-gravel subaquatic dunes formation along the outlet highland river

In the paper the research results of forming observations of sand-gravel dunes developing on the riverbed along the outlet reach of the highland type of river. The subject of subaquatic river forms one can fi nd in many scientifi c works, however most of the existing papers cover sand dunes and ripples found in the lowland rivers. Moreover, the majority of research was conducted in laboratory fl umes, since all fi eldworks need very complex research, complicated logistic as well as is extremely money consuming (hiring ships, diving bell, long time echosounding etc.). Thus there is a nowadays need to present fi eld data covering a subject of the river bed forms which still could be considered as dunes but are built up with material coarser then 2 mm (which is fi ne gravel) and coarser. The research reach described along the present paper is lying in the region of confl uence of the Raba and the Vistula Rivers, within the outlet of the Raba River, close to Uscie Solne, just below the Polish Carpathians mountains line. The research results show such parameters as: length, height and granulometric composition of the dunes found along that reach as well as the hydrodynamics parameters such as: shear velocity, shear stresses and resistant coeffi - cients. Having gathered in one place the fi eld measurements results many relationships between mentioned parameters are presented. The work could be useful for river engineers, fl uvial geomorphologists, geologists and ecologists working with river channels