A6: The Ohře River: under anthropogenic pressure

2 days, Czech Republic; Trip leaders: Faměra M.1, Hošek M.1, Elznicová J.2, Kiss T.3, Matys Grygar T.1
1The Czech Academy of Sciences, Czech Republic, 2J. E. Purkyně University, Czech Republic, 3University of Szeged, Hungary
Contact: famera@iic.cas.cz
Price: 190 EUR
Transportation: bus; Participants: Minimum 15, Maximum 20
Departure: Prague, Hotel Diplomat (8:00); Return: Prague, Hotel Diplomat
Includes: field trip guidebook, transportation, accommodation, breakfast, lunch packets, snacks and dinner.
Degree of physical difficulty: Intermediate level of physical fitness is required. The trip will include short walks (within 1km distance), frequently on unpaved quarry floors (trekking shoes are recommended).

The sedimentary record of the Ohře River valley was influenced by natural and anthropogenic forcings. The Ohře catchment has long been impacted by agriculture, ore and coal mining, and energy production. During recent millennia, the meandering channel in the lower reach was affected by direct human impacts. In the 1960s two dams were constructed on the river. The trip will start in the upper river reach, thus downstream sedimentological changes will be introduced and human imprints identified. On the floodplain of meandering Röslau R. (tributary of the Ohře River, Skalka Reservoir) a hotspot of Hg pollution will be visited. Further downstream the laterally unstable Ohře built a wide floodplain in the Cheb and Sokolov basins. Further downstream the channel is incised in a montane area, with several tributaries polluted by As, Pb, and Zn from historical mining. Here the river mostly deposits and reworks channel bars, some of them with severe historical pollution.
In the lower river reach, incising paleomeanders will be shown along with the modern narrow channel belt (downstream the Nechranice Reservoir, in Žatec), which highly influenced the deposition pattern of polluted sediments. Finally, a flat floodplain with early Holocene terraces levelled by the Anthropocene sediments will be presented near Budyně nad Ohří.
Left: 3D image of the beginning of the formerly meandering Ohře R. downstream the Nechranice Reservoir (Google Earth); Right: Typical appearance of sediment strata from the Ohře floodplain retrieved by manual grove corer.
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