Acta Scientiarum Polonorum

Aim of this study is analysis of impact of the Wióry reservoir on the streamfl ow drought in the Świślina River. Article include characteristic of the phenomenon streamflow drought, which is the period of persistence of low fl ows in rivers. The issue will be reconsidered in Nietulisko Duże gauge profi le, closing Świśliny River basin with an area of 402.83 km2, which in 2005 was put into operation Wióry water storage reservoir. The Świślina river, along with its tributaries, carries waters from the Świętokrzyskie Mountains – the highest part of the Kamienna River catchment area. The variability, causing long-term periods of low water levels, as well as rapid flooding, was the main reason for the reservoir construction. Currently the Wióry reservoir is the largest and most modern water storage reservoir in the Kamienna River catchment area. Daily discharges from the period 1961–2013 were used as the base data for the study. A sequence of discharges of at least 10-day duration with values equal to or less than Q90% = 0,40 m3·s–1 was recognized as constituting a streamfl ow drought. In the multiannual period 1961–2013, the longest streamflow drought was started in April 2006 and ended in February 2007, after the Wióry reservoir was constructed.