Studies of bed forms in the Wisloka river and water reservoir at Krempna

Attempt was undertaken at determination of the kind of river bed forms occurring on the bottom of the Wisłoka River and in the water reservoir at Krempna. The paper aims at examination of the conditions of bed forms and determination of their kinds according to classification criteria. Conditions of formation of bottom forms were defined according to the criteria given by Simons and Richardson [after Dabkowski et al. 1982], Robert [after Radecki-Pawlik 2006], Zanke [1982], Hjulsröm [after Sundborg 1967], Ashley [1990] and van Rijn [1984]. In the course of studies three measurements of velocity in appointed cross-sections were performed during the period July-September 2005. During measurements samples of bottom sediments were collected and their granulometric compositions determined. Great differentiation in the granulometric composition was found in particular parts of the point bars giving evidence of the process of process of washing out small fractions from the interstitial spaces in the proximal part of the point bars. The examined bars were qualified according to the criteria by Ashley to the type of lateral and point bars of lens-like shapes in longitudinal profile. Bed deposit samples from the reservoir at Krempna were collected. The bed deposits of the reservoir are constituted of fine mineral material. Variability of granulation in deposits layers was stated. According to the Zanke’s nomogram in two examined reservoir cross-sections no movement of bed material exist and according to the Simons and Richardson’s diagram in the examined cross-sections the bed should be flat. However, in the inflow cross-sections II at the higher flow and bed-shear stress over 1 N·m-2 ripples may occur. This is confirmed by underwater photos taken in the Krempna reservoir. They permitted to define the morphological structure of the bed. In the reservoir, the occurrence of bed forms was not found.