The morphological characterization of the watershed remains an essential element to understand the mechanisms of flow, specialy in Amazonien rain forest where ground truth is difficult with the inaccessibility and high logistic costs. Since 1991, the radar (ERS1, JERS1) allowed to process mosaics, brooding the whole of these large watersheds. Since 1955, French Guiana, have an hydrological network which made it possible to know the flows, and to make assessments on theses large watersheds. The aim of this work was in first, to know if the radar data could returns an information, and if these information is linked to the relief (ie. radarclinometry), and can be used to classify the basins according to their morphological characteristics. And then to confront these results with the series of flows and their derivates in order to observe possible correlations with the relief. The results show strong correlations (positive or negative) or none, between the hydrological indicators and these morphological class : for example, the famous relief in “orange skin” seems to be involved in certain aspects of hydraulics of the watershed. On the other hand, the increase in surfaces in flooded plains would decrease hydraulicity.