Long-term observations of Upper Vistula tributaries, made by the author, showed that the narrowing and straightening of rivers and their floodplains resulted in accelerated riverbed erosion and the increase of flood risks. River floodplains are widely acknowledged as being very important for biodiversity, therefore by their narrowing they lose their natural patterns and, as a consequence, decline in habitat and species diversity.
In the last years a new approach in river management and engineering appeared: the EU Water Framework Directive constitutes an important step for more ecological river training. In consequence an increasing number of restoration projects have been initiated in the last years.
In the present paper the author tried to study and check the possibilities of flood plain widening upstream of the town of Nowy Sącz situated along the Duna-jec River (km: 111.900 - 107.500), where devastated lands occurred. In the urban area of Nowy Sącz the levees distance was left unchanged. For the new conditions the numerical simulation by 1D mathematical model Rubarbe was carried out. The obtained results showed a significant decrease in the flood peaks upstream of Nowy Sącz and lesser decrease in the town.