A continental-scale predictive simulation tool for accidental spills in major South American water courses

ABSTRACT Water quality modeling tools are valuable for decision-making in response to water contamination events, which often impact public water supplies. However, in South America, there is a lack of tools designed to mitigate the effects of such disasters. This study presents SPLACH-AS, a novel predictive tool for accidental pollutant releases. The tool integrates water quality modeling methodologies with a continental-scale hydrologic -hydrodynamic simulations, making it uniquely suited for data-scarce environments. To evaluate its performance, validation tests were conducted for three major accidental spills in Brazil, including dam failures that released large volumes of mining waste and sediments into extensive watersheds. The simulation results were compared with observational data, an alternative water quality model, and a simplified assessment method to evaluate the tool's accuracy and efficiency Overall, the calibrated SPLACH-AS tool performed relatively well in modeling contaminant plume dispersion, closely aligning with observed data. These findings highlight SPLACH-AS tool as a valuable resource for large-scale pollutant transport simulations. Additionally, the tool also has the potential to serve as a foundation for developing an Early Warning System (EWS) addressing the gap in South America where no such systems are currently available.