Abstract
Through the study of the various units which constitute the alluvial plain, the delimiting flood risk zone of the river can be easily defined. However, it is sometimes more difficult to precisely determine its external limit. A first outline of typology of the various contacts between the flood hazard zone and the embankment is proposed here. Moreover, for each new form or new contact highlighted, a translation from a cartographic point of view is proposed in agreement with graphic semiology and constraints necessary to the elaboration of the official documents like French risk prevention plans of floods (PPRI) and atlases of flood hazard zones.