A key goal of the directive 2007/60/EC on the assessment and management of flood risks by the European Union is the preservation and restoration of floodplains in order to reduce the risk of adverse consequences associated with flood events. The realization and implementation of these goals requires a quantified description of floodplains and an evaluation of the impacts on the damage potential. Within the Era-Net-CRUE project PRO_FLOODPLAIN a methodology named Flood-plain Evaluation Matrix (FEM) was developed in 2008 taking into consideration these requirements. The FEM-method for the integrated assessment and evaluation of floodplains has been successfully used for the evaluation of floodplains of the Austrian Danube River. In order to enhance and develop the FEM method, it was subsequently applied to other rivers of various hydromorphological types. This work deals with the Lavant River in Carinthia in southern Austria and the Ill River in Vorarlberg in western Austria. The required hydrologic (flood peak reduction and flood wave translation) and hydraulic parameters (water level) to describe effects of flood retention are obtained by unsteady 2D simulations. With these data, all potential floodplains in the river basins are assessed. The results are analyzed and compared to each other. For a final assessment of floodplains for future flood risk management, an integrated evaluation in hydrological (peak reduction, wave translation) and hydraulic (water level) terms is presented. With the results of this work, the effects and value of floodplains within the river basins of Lavant and Ill can be quantified and serve as a basis for future spatial planning implementing flood risk management plans, as it is required by European and Austrian law.