Draft Melbourne Water MUSIC Guidelines

Melbourne Water are establishing new MUSIC Guidelines and a draft has been released for comment by industry.

The new guidelines introduce updated soil parameters for use within the Melbourne Region based on calibrated models. These are most suitable for areas with clay soils of at least 0.5 to 1.0 m depth and are derived from calibrations ranging from the northwest, north and southeastern parts of Melbourne. The change from the existing guidelines will result in a reduction in runoff volumes from pervious areas consistent with observations of field data. Users should apply judgement as to whether these are suitable for their particular application and adjustment may be needed for sites with sandy soils, unusual groundwater and baseflow conditions or different climate and slope conditions.

There are also a new set of 10 year rainfall periods for the six rainfall regions across Melbourne based on revised analysis of the latest data available. Both mean annual rainfalls and data quality were analysed to select the periods. These allow more reliable modelling of rainwater and stormwater reuse systems with a range of rainfall and drying periods and support wetland water level and spell analysis. The new rainfall periods also provide consistency with the Constructed Stormwater Wetlands Manual which requires a minimum of 10 years of rainfall data.

Support for representation of varying surface types with different pollutant concentrations is now provided and there is improved guidance throughout to help users set up models with confidence.

Guidance is provided for preparing a flux file for use with the Wetland Analysis Tool to assess wetland water level patterns and increase confidence that these will support the plants selected.

These changes represent a significant improvement upon the existing guidance to support the development of more robust models

Please contact us or Micah Pendergast at Melbourne Water if you're interested in learning more.