This research was focused on the relationship between river discharge and organism drift. It was carried out for three years in a small heavily modified river in Saxony (Germany). The amount and species composition of drifting invertebrates were observed, depending on discharge and flow velocity. A station was installed where the flow velocity was continually measured and drifting organisms were caught with nets. An inventory of the aquatic community (benthic invertebrates) was taken to determine the species living in the river at the research station. The highest drift density measured was 578 organisms per m3 at a flow velocity of 0.90 m s-1 , the mainly drifting organisms were Chironomidae. Different organisms groups started drifting at different flow velocities. Heavy impacts, such as dredging the river and flood waves, affected the aquatic ecosystems and severely changed the aquatic community regarding the number and the diversity. Some of the aquatic invertebrates such as the Anthothecata completely disappeared after dredging. It was found that many different terrestrial organisms were part of the drift. The typical family of soil biota Collembola represented the largest share.
Calculation methods are presented in the form as obtained by as concerns bank deformations of water reservoirs and down-stream levels of hydropower weirs as influenced by water waves initiated by wind, vessel transport as well as by reservoir emptying and publicated in this article. Effect of long-wave destruction takes place during the processes. and Příspěvek předkládá metody výpočtu deformací břehů vodních nádrží i dolních úrovní hydroenergetických stupňů vlivem proudění, větrných vln i vln způsobených plavbou lodí, jakož i vln při vypouštění vody z nádrže. Projevuje se při tom působení dlouhovlnného rozrušování.