From data gathered during an airborne scanning campaign of the intertidal zones of the Loire estuary in august 2002 from the sea (Saint-Nazaire) to the immediate upstream of Nantes, a methodology of aggregation of topographic data of different planimetric and altimetric resolutions was developed. The exploitation of this Unified DTM made it possible to extend the approach of estuarians dynamics to the cartography of the mudholes, to the calculation of side submersibilities of the river and to the evaluation of oscillating volumes.