A new calibration of the continental sediment model MGB-SED AS

Sediment modeling is an essential tool for understanding and managing sediment transport in river basins. With increasing impacts caused by changes in land use and occupation, models such as MGB-SED AS have played a crucial role in analyzing these processes, particularly in environmentally diverse regions like South America. This study aimed to enhance the performance of the MGB-SED AS model through recalibration and revalidation, improving the accuracy of suspended sediment discharge (SSD) simulations in the region's river basins. This process involved updating two fundamental parameters: the K Factor, measuring soil erodibility, and the C Factor, representing land management and cover. Both factors are critical for accurately modeling sediment dynamics and assessing the impacts of land use changes. The recalibration replaced the previous values of the K and C Factors with updated values derived from recent studies and databases reflecting South America's specific soil and land use conditions. Subsequently, the model's calibration parameters were adjusted to align simulated results with observed conditions in the river basins. Following this step, rigorous revalidation evaluated the recalibrated model's performance in terms of SSD simulations. Recalibration results revealed substantial improvements in simulation quality. Although the MGB-SED AS had already reliably simulated sediment fluxes and concentrations, updating the K and C Factors further enhanced estimate accuracy. The analyses demonstrated improved performance metrics, strengthening the model's applicability in complex and diverse scenarios. To validate the improvements, the model's performance was tested in five major South American river basins: the Amazon, Madeira, Doce, Araguaia, and São Francisco. These basins, including some of Brazil's largest rivers, were chosen for their representativeness in terms of climatic, geological, and land use diversity. Results consistently showed improved SSD simulations, demonstrating the model's capability to simulate varying sediment transport regimes and environmental conditions. This update enables more robust integration with studies on environmental impact and large-scale water sustainability. The recalibrated MGB-SED AS offers a scalable and adaptable tool, empowering researchers and managers to use it for integrated watershed management. Combining high spatial resolution and precise estimates, the enhanced model is established as a reference for studies on water planning, soil conservation, and environmental impact mitigation. Thus, the recalibration of the MGB-SED AS represents a significant advancement in sediment modeling for South America. By incorporating updated parameters and validating its performance in major river basins, the model reaffirms its role as an essential tool for managing water and sediment resources.