Spatiotemporal evolution of mine tailings released in sand-bed rivers

The dispersion and fate of mine tailings in riverine systems are studied through classical morphodynamic evolution analysis. This paper develops a 1D sediment formulation to assess the long-term spatiotemporal evolution and spreading of a single iron-ore tailings pulse deposited in the Paraopeba River (Brazil) in 2019. In this numerical analysis, sediment density is used as a surrogate to track the tailings along the river within the active layer and substrate. Based on observed data, the Sorting Engelund-Hansen Equation (SEH) for sand-bed rivers was recalibrated, since its parameters were based on large flume experiments and were limited to ambient sediment material. The simulation results align with observed tailings spreading, showing bed aggradation in low-velocity zones, such as the pool upstream of the Igarapé spillway, a suitable location for monitoring and control.The rapid bed degradation near the source zone (Ferro Carvão Creek confluence) is explained, as this material easily entrains into suspension.