A review of models for low impact urban stormwater drainage

Low-impact development urban stormwater drainage systems (LID) are an increasingly popular method to reduce the adverse hydrologic and water quality effects of urbanisation. In this review, ten existing stormwater models are compared in relation to attributes relevant to modelling LID. The models are all based on conventional methods for runoff generation and routing, but half of the models add a groundwater/baseflow component and several include infiltration from LID devices. The models also use conventional methods for contaminant generation and treatment such as buildup-washoff conceptual models and first order decay processes, although some models add treatment mechanisms specific to particular types of LID device. Several models are capable of modelling distributed on-site devices with a fine temporal resolution and continuous simulation, yet the need for such temporal and spatial detail needs to be established. There is a trend towards incorporation of more types of LID into stormwater models, and some recent models incorporate a wide range of LID devices or measures. Despite this progress, there are many areas for further model development, many of which relate to stormwater models in general, including: broadening the range of contaminants; improving the representation of contaminant transport in streams and within treatment devices; treating baseflow components and runoff from pervious surfaces more thoroughly; linkage to habitat and toxicity models; linkage to automated calibration and prediction uncertainty models; investigating up-scaling for representation of on-site devices at a catchment level; and catchment scale testing of model predictions.