Sensitivity analysis of a parameterization of coagulation in an aqueous transport model

A three-dimensional aqueous transport model, ALGE, was developed at the Savannah River National Laboratory (SRNL) as a tool for emergency response. Recently, coagulation and break-up of suspended sediment and particulate (contaminant adhered to sediment) matter has been added as a new model capability via bilinear interpolation of salinity and turbulence. A sensitivity analysis was performed by comparing time series of suspended sediment and particulate concentrations at various locations when the model's parameters (particle size and density) are altered. Concentrations produced by the model match well with the literature, producing concentrations between 0.05 and 0.25 kg/m³. Simulations of suspended sediment also show similar trends to the literature, where concentrations reach equilibrium faster in a salinity driven environment (>0.5 days) when compared to a freshwater environment (∼1 day). Sensitivity results show significant differences (P-values <0.05) between suspended sediment experiments in both freshwater and saltwater systems when all parameters (particle diameter, density, fraction of mass) vary, whereas significant differences (P-value <0.05) between particulate tracer experiments occur primarily at the source of the release.