Author(s): T. Cochrane; K. Chakravarthy; H. Kumar; S Shipton; F. Charters; P. Christensen
Linked Author(s):
Keywords: Cloud-based modelling; MEDUSA; Multi-scale simulations; Urban stormwater quality; Water quality management
Abstract: Urban stormwater runoff is a major source of diffuse pollution impacting the ecological health of receiving waterways. Traditional contaminant load models often rely on aggregated land-use assumptions, limiting their ability to identify pollutant hotspots or predict instream concentrations and with few attempts to implement city-wide modelling. To address these gaps, we developed the Instream Contaminant Concentration Model for Christchurch, New Zealand - a cloud-based decision-support system that integrates surface-level pollutant generation with instream water quality outcomes at multiple scales. ICCM combines the MEDUSA 2.0 contaminant load model with treatment simulation and scenario management modules, enabling source-to-discharge modelling for a city of over 400,000 people. Over 225,000 impervious surfaces are simulated for TSS, zinc, and copper loads for individual events in multiple years. Results are aggregated at treatment system, sub-catchment, and waterway reporting nodes, supporting compliance with regulatory thresholds. ICCM simulations demonstrate pollutant reductions under progressive implementation of ~500 treatment systems, achieving up to 77% TSS and 71% zinc reductions in some catchments by 2043. The platform’s scenario manager enables rapid evaluation of “what-if” options for treatment strategies and urban intensification. This work illustrates how multi-scale and cloud-based modelling can transform stormwater management, providing robust evidence for planning and investment decisions.
Year: 2026