Thef goal of this research has been to provide a decision support system for locating authorizing gravel harvesting in floodplains in accordance with the 1992 water act and the 1994 gravel harvesting act. Hydrodynamical models are used to simulate an aquifer response to hydraulic Works such as swelling-up or gravel harvesting by generating different scenarios. The validity of the models and inputs data as well as the boundary conditions can be verified and optimized depending on the morphodynamical context of the river. Other parameters pertaining to geomorphological anthropogenic and resource use are being taken into account for environmental decision making. A Geographical Information System (G.I.S.) is used to analyze and manage these spatial 'data. The hydrodynamical models are validated and linked to the G.I.S. allowing simulation and visualization of results through development of specific applications. The proposed comprehensive model is comprised of an anthropical, historical and updated environmental data bank, linked with two hydrodynamical models. It is applied to the Loire and is floodplain in the Forez plain (42 - France).
