Experimental study of the structure of the bottom relief in the conditions of a dredging cut

This study analyzes the structure of bedforms that develop within dredged navigation cuts. Numerous observations of channel bed transformation indicate that immediately following sediment excavation, bedforms begin to emerge on the cut bottom, with crest elevations exceeding the designed cut depth. It is concluded that the formation of bedform relief leads to a reduction in navigable channel depth. Observations of channel relief structure in lowland navigable rivers, documented in the authors' previous studies, reveal that the bottom relief consists of dunes and underlying waves, the heights of which are comparable to those of the dunes. Consequently, their formation further contributes to a decrease in the guaranteed depth within the cut. These losses are most significant in areas of extensive dredging where the cuts are long. The aim of this research is to investigate the structure of bottom relief formed under various conditions in a 50-meter hydraulic flume. A comparative analysis of dune parameters showed that the relative height of dunes within the cut is half that of dunes observed in the same areas prior to dredging. Simultaneously, second-order waves were located beneath the dunes, with third-order waves below them. The heights of these waves were similar to those of the dunes. Based on these findings, it is concluded that the design of dredging operations should account for the impact of dunes and waves in the channel relief, which can lead to a reduction in navigable depth. However, it should also be noted that the size of dunes and waves within the dredged cut will be smaller compared to those formed under natural conditions.