bedload transport, headwater stream, Carpathians, flysch

Flysch lithology (i.e. alternation of less resistant claystones and sand-stones) affects bedload transport parameters in view of relatively fine-sized sedi-ment supply resulting in low flow resistance of channels. Flood competence method (Q20 flood) and marked particle displacement method (up to Q1-2 flow) was applied to determine critical conditions for the incipient motion of grains in channel bed. The beginning of bedload transport in flysch headwaters under lower values of critical conditions when compared to other regions was confirmed by application of the criteria of unit stream power and unit discharge. The simulated values of bedload transport intensity (1D transport model TOMSED) during a high-magnitude flood in both supply-limited and transport-limited headwaters are significantly lower than it was observed in torrents of the Alpine environment.