Anthropogenic impact and morphology channel response of Beskydian gravel-bed rivers: a case study of the Ostravice River, Czechia

This paper presents an analysis of both the contemporary and historic development of the geomorphic regime of the Ostravice River channel in the Czech part of the Outer Western Carpathians. The assessment concentrates on the conditions and causes of the channel development in the last 200 years compared with the state of European channels. The original anabranching river pattern has gradually been replaced by a single narrowed channel. At some sections, the original riverbed has lowered by as much as 2.5 m in the second half of the 20th century. These changes were due to strong anthropogenic impacts in the form of river-channel control and construction of dams. A large influence on the contemporary processes was also exerted by changed hydrological conditions and a predisposition of flysch lithology in a channel bedrock to erosion. Currently, the deficit of transportable sedimentary material along with the changed morphology of channels with concentrated water flows are intensifying erosion processes.