Three-Dimensional Hydrodynamic and Sediment Transport Modelling of a Shallow Urban Lake in the Brazilian Amazon

Monitoring lakes is essential to understand their metabolism, guide management strategies, and contribute to the understanding of climate change, as these environments act as biomarkers. This study aims to propose an environmental assessment of Água Preta Lake, a shallow Amazonian Lake located in an urban area, through the three-dimensional modeling of hydrodynamics and sediment transport. The simulations, performed with the DELFT3D-FLOW model, used meteorological and physical data from the lake as boundary conditions. The results showed good statistical indicators, providing evidence of the model's reliability. Since it is a shoal lake fed by intense discharge with a high sediment load, this input directly influences the lake's circulation, promoting the resuspension of sediments and the redeployment of nutrients in the water column. This process increases water turbidity, alters the dynamics of biota, favoring the dominance of phytoplankton and floating macrophytes, which contributes to eutrophication and reduced water quality. The study emphasizes the importance of continuous surveillance, managing anthropogenic influences, and implementing restoration efforts to prevent the progressive degradation of urban lake ecosystems.