River Dune Behavior in Dredged Areas

Abstract

Safe navigation in rivers often requires repeated dredging operations. River dunes are causing shallow areas, so a better understanding of dune behavior can aid decision-making on dredging strategies. A new dune-tracking method was developed to analyze dunes after dredging. This knowledge was combined with information on dredging methods and intensity. This enables the analysis of dune development after dredging and the assessment of the impact of dredging methods such as topping (removing sediment from the crest) and swiping (transferring sediment from the crest to the trough). The results show that dredging increases the growth rate of dunes, especially when the discharge increases after dredging. For the studied dredging intensities, topping has a more pronounced effect than swiping on the immediate reduction of dune height. The changes in dune heights due to dredging are within the natural dune height variability. In the long term, topped dunes exhibit larger growth rates than those undergoing swiping. So dredging does have an effect on dune dynamics, in particular on the dune height growth rates.