International audienceCoastal seas, marine part of the coastal zone, are particulary attractive for human society. Human activities involve interactions that can lead to conflicts and to ressources degradation. In order to analyse the coastal system, the Geomer laboratory has developed a modelling platform of Human Activities Dynamic (DAHU) which contains a specific module adapted to the human marine activities (DAHU-MAM). This paper presents applications developed on the Iroise Sea (France). Three scenarios are proposed in an operational coastal management objective: (1) highlighting potential conflicts of use, (2) impact of a shipwrek (3) or impact of a substructure installation.Les mers côtières, franges marines des zones côtières, sont ...