The Benefits of Continuous Simulation Stormwater Quality Modelling in Christchurch

Stormwater Conference

Continuous simulation water quality modelling uses long term continuous rainfall records and evapotranspiration input data to model runoff from urban catchments. Utilising long term rainfall records allows continuous models to better represent runoff by considering factors such as antecedent days between storm events, system storage and infiltration. Pollution runoff concentrations can be attributed to various land uses and surface types within the catchment which allows for estimated mean annual loads to be determined for urban stormwater runoff. A range of stormwater treatment devices can then be modelled to size stormwater treatment devices accordingly and undertake contaminant load modelling.

A water quality model of the Avon River catchment in Christchurch has been developed using eWater’s existing Model for Urban Stormwater Improvement Conceptualisation (MUSIC) continuous simulation water quality model. The rainfall-runoff model has been calibrated to local climatic and catchment land use parameters for both directly connected impervious area (DCIA) and total impervious area (TIA). As the contaminant load rates are directly correlated with runoff, a good calibration is crucial to provide accurate outcomes for both contaminant load modelling and designing stormwater treatment devices.

This paper presents a summary of the rainfall-runoff model calibration results against both DCIA and TIA parameters and summarises the suitability of this model for use in Christchurch and other regions within New Zealand.

MUSIC has currently been used to size street-scale rain gardens in central Christchurch for the Ōtākaro An Accessible City project, to quantify the estimated reduction in Total Suspended Solid (TSS) load entering the Avon River from the Knights Drain catchment, assess the suitability of rainwater harvesting tanks for the King Edward Barracks development in Christchurch, and to undertake a comparative assessment of various stormwater facility configurations for the Curletts Stream catchment that were not sized to Council guidelines due to size constraints.

Conference Papers

1105 - Gareth Bailey - Benefits of Continous Simulation Stormwater Quality Modelling.pdf

pdf
2 MB
26 Jun 2018

2. The Benefits of Continuous Simulation Stormwater Quality Modelling in Christchurch.pdf

pdf
930 KB
26 Jun 2018