[en] The radioactive tracers, modern elements which make possible infinity of studies, are nowadays one of the main tools in the human activity. The radioisotopes, are used in medicine, industry, special programs, etc. This project is about the use of radioactive tracers in the study of the movement of solid material in the bottom of the rivers. This study is important, because it allows to make conclusions on the characteristics of material transport in the bottom, and from there, to establish certain deposit areas or the thickness of the layer of transport. The general principle of the method is the immersion or launching, in a previously established place, of a radioactive material whose characteristics are identical to those of the natural silt of the area in study, followed by an accompaniment to know the migration of this silt by means of a radiation detection equipment. Later on the traditional methods based on empiric formulas will be compared, to confront them with this method and to determine the reliability in the process