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 ...
Results of investigation of structure of purple willow have been presented in the paper. Bushes were created manually and consist set of single branch of purple willow. It allows to represent variability of bushes structure growing on flood planes. Evaluation of bushes concentration were done by direct measurements. Hemispherical photos also were done. Results coming from analysis of concentration of bushes indicate possibility of using this method in field investigations of bushes structure. ...
The results of investigations carried out in the stream Bukowiński are pre-sented in this paper. The aim of investigation was definition of influence of wood jam on change of dimensionless coefficient of resistance and coefficient of rough-ness. The performed measurements included cross-section leveling and longitudinal leveling of the stream channel, bed sediment sampling, and hydrometric meas-urements. Cross-section leveling included five cross-sections in the 47-m long stream sector; these were located upstream and downstream the wood jam and in its region. Differentiation of water flow velocity in the region of wood log was shown. The dimensionless coefficient of resistance was calculated taking into ac-count the equivalent bottom roughness determined by use of Gladki`s formulae [van Rijn 1984]. In the aim of the qualification of the equivalent bottom roughness three samples of bottoms sediment were taken in the cross-section with the log. It was found that the wood log in the Bukowiński stream caused a change of hydraulic conditions of water flow and, in consequence, the dimensionless coefficient of resistance in the wood jam section increased by about 71%. The coefficient of channel roughness was also determined and it was shown that the coefficient of roughness in the section of wood jam, ...
