The problem of studying the peculiarities of sound propagation in shallow seas is an urgent task of hydroacoustics, since it is associated with human production activities in coastal zones and waters of shallow seas. A shallow sea for a sound field is a waveguide in which certain modes propagate. Features such as "extinction" modes and dispersion distort the picture of the sound field. There is also a complex interference situation due to reverberation interference and multiple re-reflections. To avoid information loss, it is proposed to use narrowly directed parametric radiation without side lobes. The issues of equipment selection are considered, the law of temporary automatic gain control (TAGC) for the study of bottom layers is calculated. The results of the analysis of echograms for depths of 1-2 m are presented. The possibility of identifying layers and anomalies is shown.

Keywords: shallow sea, sound propagation, modality, waveguide, TAGC's law, structure data, layers, profilograph, anomalies