Gewässerökologische Wirkungen von Kleinwasserkraftwerken

In order to analyse current and future potential ecological effects of single and multiple hydroelectric plant on a small river in the Black Forest area of Germany, the biocommunities of benthic macroinvertebrates and beetles living at the river banks were used to estimate ecological quality of the river, which is in some parts among the highest in the area. Those sections of the watercourse which have only residual discharges almost always show lower flow velocities than sections with complete discharge. When several river sections with residual discharges follow in succession, transport of coarse-grained bedload is interrupted, and only fine-grained substratum is available for colonisation by macro-invertebrates and beetles. The reduced flow velocity and the limited transport of bedload alters the available habitats, shifting lower hydro-ecological zones upstream. The extent of long-term detrimental effects should therefore be assessed for suitable reference sections of a river covering all potentially affected hydro-ecological zones.