The knowledge of the discharge - duration - frequency (QdF) curves (linking quantiles of different durations for a given frequency), and flood hydrographs of a certain return period is essential. On the one hand, for several needs of basin integrated hydraulic modelling, the necessary hydrological information can only be considered with synthetic hydrographs, which are the upstream inputs in the hydraulic models. On the other hand, the QdF concepts allow us to express the more and more present social request (for instance, to determine some protection purposes). Moreover, some hydraulic modellings often need a quantification of extreme events. The AGREGEE model is a tool devoted to the midterm and long-term actions, and it enables to estimate flood quantiles, relative to fixed exceedance probability. The regional QdF models, developed from the analysis of the discharge (Q) Continuously exceeded during the duration d, and maXimal in the season (called QCXd), allow us to type the flood behaviour of basins, even if they are not gauged. Also, they allow to build, for a given return period, an instantaneous Mono Frequency Synthetic Hydrograph (MFSH), the volume of which is consistent with the volumes deduced from basins observations or validated Q(P) simulations. Especially because of their great spatial representativity, and their great scale integration they can be used to establish some MFSH on little mountainous basins with rapid run-off.