Wpływ jazu w Konstancinie-Jeziornej na kształtowanie się jakości i ilości zasobów wodnych oraz roślinności wodnej rzeki Jeziorki

The article presents impact of weir on diversifi cation of quality and quantity of water resources and phytocoenosis. The study area was at Konstancin-Jeziorna weir on Jeziorka River. Jeziorka River is the Landscape Protected Area. In that case the weirs can not contribute to unfavourable environmental change and to deteriorate water quality. Water quality and hydrometric measurements was investigated in three cross-sections: tailwater, headwater and end of backwater. Depth, average velocity and flows was measured. Physico-chemical analysis include: temperature, pH, conductivity, colour, turbidity, BOD5, CODMn, dissolved oxygen, N-NO3, N-NH4, P, Fe, Na i K. The phytocoenosis was investigate in cross-section at 20-100 m intervals. The result of the research was that the weir has influence on diversification of flows in Jeziorka River. The weir cause decrease of velocity and increase of depth in headwater. Diversification of flows cause changes in some water quality indexes (colour, turbidity, dissolved oxygen, BOD5). Moreover there is the diversification of aquatic phytocoenosis exist in the neighbourhood of the weir.