Beyond the conventional dike-building measures, the management plans should pay due attention to improving the eco-morphological structure of riverbeds and the restoration of natural water retention areas. Here again, the costs are borne by the communes, which may however receive government subsidies amounting to 50% (or 80% for intercommunal works). In particular, new urban development must be prohibited in flood zones unless the retention volume lost can be offset and unless they do not increase risks downstream and upstream.