Summary:

The aim of this paper was assessment of flood risk in the catchment of the Mała Wełna River on the reach from Gorzuchowskie lake to Kiszkowo weir No 1 (Brudzewko). The annual maximum discharges with given probability of exceedance 10%, 1% i 0,2% were calculated on the basis of data obtain from the Polish hydrological year-books: 1965-1975 and 1978-1983, and own data for the period 2000-2009. The maximum annual discharges were calculated on Institute accord-ing to the Meteorology and Water Management (IMGW) method, where the distri-bution of probability of exceedance of the annual maximum floods is calculated as the probability of alternative of two non-eliminated independent events. The max-imum annual discharges with given probability were inputted to RUBiKoN hy-draulic model, which allow to calculated localization of points of the highest water level on the cross-section of Mała Wełna river channel. Digital elevation model of the river valley were performed on the basis of topographic maps in the scale 1:10 000 with use of ArcGIS program with Spatial and 3D extension. Water levels in cross-sections and digital elevation model allow to establish the area where the flood risk probability is low (one on 500 years), medium (one on 100 years) and high (one on 10 years).