The impact of the dam in the Bistrica River on the aquatic ecosystem

Authors: Nataša SMOLAR - ŽVANUT, Matjaž MIKOŠ, Barbara BREZNIK
Citation: Acta hydrotechnica, vol. 23, no. 39, pp. 99-115, 2005.
Abstract: On the Bistrica River we tried to find out the effects of damming and abstracted water for the small hydropower plant Mojstrana, as reflected in the hydrological, morphological and biological parameters of the aquatic ecosystem. Water flow and flow velocity were measured and the basic hydrologic parameters were determined. Sediment analysis was carried out with Wolman sampling. A grading (particle-size) curve of the surface and subsurface layer were prepared based on combining of the Wolman samples of the surface layer and rigid or adaptable composition with the Fuller grading curve providing grain-size assessment of the subsurface. Further, we performed an inventory of mesohabitats and phytobenthos sampling. The results have indicated hydrological, biological and morphological changes in the water ecosystem below the dam. There also occurred fragmentation of mesohabitats, and reduction in diversity, size and hydrological characteristics. Lower discharge and flow velocities were measured and a high level of downstream fining was identified. Due to the damming and water abstraction there occurred changes in species composition and abundance of phytobenthos.
Keywords: damming, water flow, mesohabitats, river sediments, phytobenthos
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