Аннотация:When modeling channel deformations on the mountain and sub-mountain rivers, it is necessary to take into account the fractional composition of the sediments, since diameters of separate fractions can differ by several orders. In this case, modeling based only on mean diameter can lead to qualitatively and quantitatively incorrect results, which do not correspond to the physics of the phenomenon under consideration. The mathematical and numerical model of transport of sediment and bottom deformations in “shallow water” approximation taking into account sediment heterogeneity is proposed and tested in laboratory experiments and on a real object.