摘要：The article presents the main results of substantiating the materials used when conducting experimental studies of channel processes in a river, the channel of which is composed of easily eroded soils. It is substantiated that the Amudarya sand cannot be modeled on a geometric scale since the model deposits are too small (powder) and lose the property of loose bodies. In such cases, a material with a decrease in specific gravity without a decrease in diameter is used as a substitute for sand. Since the sediment diameter cannot be reduced, the actual scale of the model remains distorted. It is indicated that the sediment diameter cannot be reduced, then in fact, the scale of the model remains distorted. Therefore, when the bottom of a river bank is made of sand that does not lend itself to geometric modeling, regardless of the change in the specific gravity of the natural material, to ensure the mobility of the sand on the model, it is necessary to distort the vertical scale.Distortion of scales is also necessary because when using in laboratory conditions the same sand that formed the bed of the river, at any depth with a low velocity, the model observes bottom resistances to the flow of the flow compared with nature. The vertical and plan scales of modeling were calculated, respectively, equal to 50 and 57. According to the results of the calculations, the value of the coefficient of mobility of bottom sediments was established, which was equal to 1.
