Evaluating stormwater micropollutant control strategies by the application of an integrated model

The estimation of micropollutant (MP) fluxes in stormwater systems is a fundamental task to enable the elaboration of strategies to reduce stormwater MP discharge to natural waters. Dynamic models can represent important tools which can integrate the limited data provided by monitoring campaigns. This study presents an application of an integrated dynamic model to estimate MP fluxes in stormwater systems in combination with stormwater quality measurements. MP sources were identified by using GIS land usage data. Runoff quality was simulated by using a conceptual accumulation/washoff model. A stormwater retention pond was simulated by using a dynamic treatment model based on MP inherent properties. Model results uncertainty was estimated with a pseudo-Bayesian method. The model was applied in an industrial/residential catchment to evaluate two different control strategies (based on source control and enhancement of existing treatment) for reducing heavy metals (copper, zinc) and organic MP (fluoranthene). The runoff quality model showed high uncertainty, with prediction bounds strongly affected by the exceptionally high measured concentrations. The model quantified the greater benefits of the source-control strategy in terms of MP loads discharged in the environment and sediment accumulated in the pond, highlighting the potential of integrated models as support for stormwater pollution management.