Results of investigation on suspended sediment delivery from small lowland, agriculturally used catchment of Zagożdżonka River, located in central Poland, during snowmelt periods of 2001– –2007 are presented. The study catchment‘s area, upstream of the well equipped gauging station at Czarna, is 23.4 km2. Suspended sediment concentration and sediment yield has been calculated and analysed for 15 snowmelt flood events. The relationship between suspended sediment concentration and the discharge has been analyzed. It has been found that the relation, in majority of the cases, has the form of clockwise hysteresis, however the existance of other types of hysteresis i.e. anticlockwise and “8” shape, have been also confi rmed. Signifi cant relation between suspended sediment yield and runoff volume of snowmelt flood events has been also found.
This paper present information on particle size variation during rainfall and snowmelt flood from the small agricultural catchment. The grain size distribution during two rainfall, three snowmelt and one rainfall-snowmelt flood was compared. The average percentage of clays size material (<4 µm) for all samples was 2.7%, silt size material (> 4 µm and <62 µm) was 42.8% and sand (>62 µm) was 54.5%. The average median (d50) for floods ranged between 49.8 microns and 98.3 microns depend on the flood.