Development of a GIS-based hydrologic model and Decision Support Tool for Sydney estuary catchment, Australia

Abstract

The quality and sustainability of estuarine environments in large port-cities like Sydney are strongly impacted by increasing human activities. Investigations of water and sediment quality have identified urban stormwater as the most important contemporary source of chemical pollution in the estuary. A sound understanding of the transport of pollutants in an urbanised environment is a prerequisite to responsible management. An integrated hydrological model allowing estimation of pollutant distribution and loading from an urbanised catchment to the estuary should thus be a key tool to assist decision makers in testing and validating urban development impact. A GIS-based quantitative hydrological model coupled to a Decision Support System (DSS) for water quality management was developed to quantify stormwater runoff, and pollutant loading for diverse precipitation scenarios. The Urban PARC (Pollutant Area & Runoff Computation) Model consists in a series of workflows allowing assimilation of physiographic and environmental data, including topography, land use, pedology and precipitation at various temporal and spatial resolutions. The model was developed in ArcGIS and applied to simulate water and pollutant loading in stormwater for precipitation scenarios ranging from single events to average annual rainfall within the Sydney catchment. The Urban PARC Model was used to simulate the impact of remediation scenarios on pollutant loading. Tests presented here show that it can be successfully used as a DSS to predict the potential impact of remediation strategies on the urban environment and water quality management. The modelling applications and results for water and pollutants discharge produced by the current research are comparable with published data at various scales. Although additional work will be necessary to validate the model parameters for the entire Sydney catchment, the model provides a substantial platform for urban environment research and management.