| Summary: | The paper presents the variability of the Piwonia River flows in the Parczew profile (catchment area of 391 km2) in hydrological years 2009/10-2015/16. Based on monthly flow and daily water level measurements, flow-level curves and hydrograms of water flows were drawn. The analysis of the weather conditions in the catchment area showed that in the analyzed period there were two very wet years (2010, 2014), three wet years (2011, 2013, 2016), one normal year (2012) and one dry year (2015). The total of annual precipitation in very wet years was 150 mm (130% of the norm) higher than the average for multi-years, and in the dry year it was 60 mm (86% of the norm) lower. The intensity of instantaneous flows ranged from 0.26 m3∙s-1 in 2015 to 5.5 m3∙s-1 in 2010. The average annual flow of the river in multi-years was SSQ = 1.68 m3∙s-1 and ranged from 1.19 m3∙s-1 in 2015 (dry in terms of precipitation) to 2.13 m3∙s-1 in 2010 (very wet). The direct reasons for the variability of river flows are: weather conditions, retention capacity of lakes and fish ponds, and exploitation of hydrotechnical structures. The hydrological year 2014/15 was characterized by the highest variability of flows, while in the hydrological year 2010/11 the lowest variability was recorded.
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