Hydrodynamic model of the Lower Biebrza River flow - A tool for assessing the hydrologic vulnerability of a floodplain to management practices

Floodplains are complex and dynamic ecological systems, and two important components of these systems, the hydrology and vegetation are closely linked. The aim of this work was evaluation of influence of the changes in vegetation structure on the flood extent in the floodplain. The study area was the Lower Biebrza Basin, fairly undisturbed river-marginal peatland, located in the north - eastern Poland. The flood extent and average flood depth were determined by GIS analysis in combination the level calculated by hydrodynamic model with the Digital Elevation Model of the floodplain. Different scenarios of land use with actions like grazing or mowing, scrub and trees cutting, and secondary succession were analyzed. Obtained results show that the variation of the flood extent is strongly related to the vegetation structure of the floodplain, and the applied approach enables a quantitative analysis of a flooded area magnitude.