Note 3 in the Design Notes series covering modelling stormwater treatment and stormwater reuse systems (MUSIC guidelines), issued in August 2012.
The following MUSIC Guidelines have been developed by Parsons Brinckerhoff (PB) for the City of Greater Geelongfor use in modelling stormwater treatment and stormwater reuse systems. MUSIC (Model for Urban Stormwater Improvement Conceptualisation) is a commonly used conceptual design tool for stormwater systems.
This document aims to provide information to developers, consultants and reviewers on the use of the MUSIC software, including appropriate input parameters to adopt for stormwater treatment and reuse systems within the Cityof Greater Geelong.
A meteorological data template was created for the City of Greater Geelong using rainfall and evapotranspiration data for Geelong.
The Geelong Salines (Moolap) rainfall station (station 87023) data was used to determine the reference year for the City of Greater Geelong. This station was chosen given it has a rainfall data record from 1/4/1897 to 31/3/2009. The analysis of the data for this period determined that the year of 1985 most accurately represents the long-term meteorological records for Geelong.
The meteorological data template for Geelong was created from the Geelong North pluviograph data, as no pluviograph data was available for Geelong Salines. Analysis of the data from the two rainfall stations ensured that the data for Geelong North accurately represented the Geelong Salines rainfall data. Table 1 outlines the information from the chosen rainfall station.
Table 1 Adopted rainfall station for the City of Greater Geelong
||Mean Annual Rainfall
Monthly evapotranspiration values have been estimated from average potential evapotranspiration contour maps for Victoria (Hydrological Recipes Estimation Techniques in Australian Hydrology, 2004). Average monthly potential evapotranspiration values for Geelong are shown in Table 2.
Table 2: Average monthly potential evapo-transpiration for
|Average potential evapotranspiration (mm)
(Source: Hydrological Recipes Estimation Techniques in Australian Hydrology, 2004)
Port Phillip Bay, Corio Bay and Bass Strait Targets
The Best Practice Environmental Management Guidelines (BPEMG) outline pollution reduction targets for urban stormwater discharge into Port Phillip Bay (refer to Table3). These targets are also relevant to urban stormwater discharges to Corio Bay and Bass Strait.
Table 3: Stormwater pollutant reduction targets (BPMEG,1999)
||Total Suspended Solids (TSS)
||Total Nitrogen (TN)
||Total Phosphorous (TP)
||Gross Pollutants (GP)
Other receiving waters
The City of Greater Geelong would like to maintain strict regulation of urban stormwater discharge into other wetlands and waterways. Geelong City Council should be contacted for guidance on pollution reduction targets for proposed development that dischargeto other receiving waters.
Default MUSIC Parameters
Rainfall-runoff parameters are outlined in the MUSIC User Manual (CRC for Catchment Hydrology, 2005) (see Table 4).
Table 4: Rainfall-runoff default parameters for Melbourne (MUSIC User Manual, 2005)
Pollution Concentration data
The default parameters for the pollution concentration data (total nitrogen, totalphosphorus and total suspended solids) should be used for identified land uses (MUSIC Input Parameters, 2004).
The timestep for water treatment modelling is defined in the MUSIC Input Parameters guideline (Melbourne Water, 2004) asbeing equal to or less than:
- The Time of Concentration of the smallest sub-catchment, and
- The shortest detention time (under design flows) of the treatment measures being modelled
The MUSIC Input Parameters guidelines also note that if these times are less than 6 minutes, the 6 minute time step should be used.
The MUSIC software can be used to model stormwater reuse systems, and to estimate harvested volumes and security of supply. The systems can be modelled using the pond, wetland or rainwater tank treatment nodes in MUSIC.
The modelling period from 1982 to 2005 should be adopted for stormwater water reuse models using the Geelong North rainfall. The City of Greater Geelong should be contacted for this information.
The timestep adopted for the water reuse model is dependent on the proposed mechanismof stormwater extraction. For proposed stormwater extractions involving the use of pumps or buffer storages, an hourly time step should be adopted as a minimum. This sub-daily time step allows for a more accurate representation of peak flows generated by MUSIC and more accurate harvesting volume estimates.
In determining the security of supply and harvested volume of a scheme, the MUSIC flux files should be used, adopting the water release and water demand figures over the simulation period.
Non potable water demands for stormwater reuse schemes include open space irrigation and toilet flushing. Typical values for total annual water demands and monthly use are outlined below.
Open Space Irrigation
Annual Volume Requirements
Typical annual application rates for grass irrigation are outlined below:
- Drought tolerant grasses – 350 mm/m²
- Non drought tolerant grasses – 500 mm/m²
Site specific application rates for grass irrigation should be adopted where available.
Application rates applied for tree irrigation should be considered on a species specific basis.
Monthly Proportion requirements
Demand profile for open space irrigation needs tobe estimated from similar facilities and usage patterns. Where these usagepatterns are not available, Table 5 can be used to allocate annual demand overeach month of the year.
Table 5: Monthly Proportion of Annual Rainfall Volumes
Other nonpotable uses
In estimating the total annual demand for non potable uses, recorded data should be applied where available. Melbourne Water WSUD Engineering Procedures (2005) should be adopted where practical to calculate these demands in the absence of recorded data. In distributing this total demand for each month of the year, consideration should be given to potential use of nonpotable water. Considerations include sports seasons for sports club rooms, typical school days for school use etc.
Typical fraction impervious values for the various land use types are outlined in the MUSIC Guidelines (Melbourne Water, 2010). These values are shown in Appendix A. In residential areas, the'Typical Value' to be adopted shall be as per the allotment size. Aerial photographsand the Victorian Planning Scheme maps for Geelong can be useful tools for determining the fraction impervious of a particular property or catchment. The recommended values are consistent with the Geelong Housing Diversity Strategy (2007).
Submission of MUSIC modelling reports
The submission of MUSIC models to the City of Greater Geelong should be supplemented by brief report that outlines assumptions adopted. The submitted information should include the following:
- Description of the function and intent of the treatment system
- Description of how fraction impervious was calculated (what figures were used for different zonings)
- Description of and documentation for any departure from these guidelines.
Summary of Performance
- Mean annual load reduction for TSS, TP, TN and GP
- Percentage of pollutant reduction achieved for each device within the treatment train
- Percentage pollutant reduction achieved for the total treatment train
- Average annual volume of stormwater diverted from source for reuse (if applicable)
- Reliability of the preferred stormwater harvesting option based on an annual and summer security of supply (if applicable).
MUSIC Model Data
- Sqr orSqz model of catchment with treatment devices
- Sqr orSqz model of catchment without treatment devices
- Use of reference rainfall year (1985) for stormwater quality modelling
- Use of reference rainfall years (1982 – 2005) for stormwater reuse modelling
- Use of recommended evapotranspiration data in Table 2-2
- Fluxfile for any stormwater harvesting options from ponds, wetlands or closed storages (rainwater tank).
- If available, an electronic copy of the catchment and subcatchments used in ArcView or other approved format. If an electronic copy is not available, a hard copy is acceptable.
- Bureau of Meteorology
- CRC for Catchment Hydrology, 2005, MUSIC User Manual
- CSIRO, 1999, Urban Stormwater: Best Practice Environmental Management Guidelines
- Grayson R.B., Argent R.M., Nathan R.J., McMahon T.A., Mein R.G., 2004, Hydrological Recipes – Estimation Techniques in Australian Hydrology
- Greater Geelong City Council, 2007, Geelong Housing Diversity Strategy
- Melbourne Water, 2005 WSUD Engineering Procedures: Stormwater
- Melbourne Water, 2004, MUSIC Input Parameters
- MUSIC GUIDELINES – Recommended input parameters and modelling approaches for MUSICusers – Melbourne Water 2010
Other reference documents
Fraction Impervious for residential areas shall be the “Typical Value” for the appropriate lot size
Source – 'MUSIC GUIDELINES – Recommended input parameters and modelling approaches for MUSIC users' – Melbourne Water - 2010