Model hydrodynamiczny przepływu wielkich wód rzecznych w Basenie Dolnym Biebrzy

The aim of this work is calibration of a 1D numerical model of river flow within the Lower Biebrza Basin. To simulate the flow in the Biebrza valley, a one-dimensional unsteady open – channel flow model UNET, which is a component of computer software HEC-RAS, was applied. The geometry of the river channel and floodplain are described by cross sections in the number of 47. The river cross sections were measured by manual sounding for the main channel part and topography of the floodplain was calculated from the Digital Elevation Model. Plant’s map was used to defi ne spatial hydraulic roughness, which was described by Manning’s coefficient (n value) using Chow’s tables, in the floodplain, and n values for the river channel were selected during calibration process of model. The hydrodynamic model was calibrated for measured and historical date for flood in 1992 and 1999.