[en] Radionuclides realeased by nuclear plants in surface waters are not simply transported by the water. Other complex phenomena occur : adsorbtion/desorbtion to sediments, sedimentation and accumulation on river's bed, interaction with interstitial water, and eventually resuspension in the water column. The aim of this work is the description and modelling of the majors processes which govern the contamination of surface waters and sediments by radionuclides to food chain and to man. The model is applied to the river Meuse. The results shows a good aggreement with available field measurements realized during routine surveys.