In natural rivers, bed forms built of sandy and gravel-sandy fractions may be formed on the river bed at some determined hydraulic conditions. Depending on the type of the flow they can be two- or three-dimensional forms (2D, 3D) and they can have straight or curved crestlines (dunes: barkanous, sinusous, lunate, linguoid or catenary). Any bed form can exist individually (for example isolated dunes), but mostly they occur as accumulated single forms. These forms are placed parallel or transverse to the flow. Moreover, they can be arrangement across the flow. The subject the bed forms arising was involving and still is many scientists from abroad and from Poland and the main topic of investigations. Most of the paper covers the issue of sandy bed forms (in the form of ripples and dunes) which one shaping bottom of the lowland rivers [Młynarczyk (1998), Dąbkowski (1989)] and bed forms which observed on the submarine bottom [Pruszak 1998]. So far, there have been only a few publication in the world concerning existing sandy-gravel and typical gravel dunes [Carling at al. 2000, 2005]. This paper presents results of the hydraulic parameters calculations above gravel curved crestline dunes along the estuary part of the Raba ...
The paper presents very important, both from practical and theoretical reasons, problem of forming the river bed-forms within the gravel-bed mountainous riverbed and the influence of those bed forms on the discharge value. In natural rivers, due to the complicated nature of the discharge and changes in the water level, the bed forms are quite complicated structures. Those forms are changing in length and height and when present they change hydraulics conditions of the discharge. They could be both 2-dimentional and 3-dimentional, situated in all pars of the cross section. Up to now there are only a few notes and papers about the gravel bed forms which can be found in rivers. Most of scientific papers focus on sand riverbed forms. The present paper shows and concentrates on the field measurements of gravel bed forms found in the estuarial part of the mountain river - the Raba River - in Polish Carpathians. Such research was carried out first time in Poland. The research focuses here mostly on geometrical parameters of these bed forms such as height, length, stoss and trough angle as well as granulometric characteristics of gravel built those forms. Basing on in-site measurements many different hydraulics ...
