A system for monitoring level variations of at least one bottom region (20) of a soil subjected to erosive and sedimentary agents, which comprises at least one monitoring element (15) fastened to the bottom, the at least one monitoring element (15) comprises a sensor apparatus (120) for detecting a response (|u x|) of the at least one monitoring element (15) with respect to a stress (fs). The stress (fs) is a stress able to determine vibrations originating displacements (|ux|) of at least part of the at least one monitoring element, the response is a function of the displacements (|ux|) of at least part of the at least one monitoring element (15) and apparatus (150) are provided for analyzing the response with respect to a stress (fs), identifying characteristic frequencies (λi*) and correlate the characteristic frequencies (λi*) with a lowering (Δlp) of the bottom region (20).