Hydromorphodynamics modeling of dredging and dumping activities in Mirim lagoon, RS, Brazil

Abstract

This study aims to employ a combination of numerical models to simulate bed evolution under various operational strategies within two navigation channels in Mirim Lagoon, Brazil. The model simulations accurately represent the water levels within the lagoon. These findings suggest that river discharge plays a pivotal role in shaping the temporal patterns of sediment transport within the system. The morphodynamic model reveals that sediment transport and bed evolution primarily occur in a southwest-to-northeast direction, following the flow of water. The greatest sediment accumulation is observed in the central and southern regions of the lagoon. Our results confirm that channel dredging induces significant variations in lagoon physical parameters, such as current velocity. The bed evolution results indicate that rapid siltation of the channel follows dredging, suggesting a substantial increase in bottom evolution within the navigation channels compared to the unaltered scenario. Our findings highlight that the utilization of hydromorphodynamic modeling, with a particular emphasis on dredge-and-dump strategies, can serve as a precise methodology to enhance natural mechanisms that positively influence channel depth and stability. This approach also enables us to predict unfavorable changes in physical parameters over both the medium and long term.