You can edit the properties of the source node by:The mixed Zoning/Surface type values are adapted from the same sources as the Agricultural and Forest source nodes
- Double clicking the left mouse button over the source node icon;
At the bottom of each dialogue box you will find three buttons that allow you to move forward or backwards through the five dialogue boxes. You can edit any of the data presented on the active dialogue box. The buttons and their operation are described below:
|Activates the next dialogue box for editing.|
|Activates the previous dialogue box for editing.|
|Cancels the editing session. Selecting this button on any of the dialogue boxes will terminate the editing session and all changes made to data on any of the dialogue boxes will be discarded.|
|Ends the editing session. All changes made to the parameters displayed on any of the dialogue boxes will be accepted. The Finish button is displayed on the fifth dialogue box.|
When the Auto Run mode is turned on, clicking the Finish button will automatically run the simulation model. A progress bar will be displayed while the simulation is running.
For Urban source nodes, each zoning/surface type has appropriate base flow and storm flow pollutant concentrations for that zoning (eg. rural residential) or surface type (eg, sealed roads, unsealed roads). The Zoning/Surface Type is selected on Page 1 of the Wizard, and changes the default values displayed on pages 3, 4 and 5. Prior to MUSIC version 6.2, MUSIC had three source nodes, Urban, Agricultural and Forest. The 'mixed' Zoning/Surface type values are adapted from contains the same sources as the Agricultural and Forest source nodes, these were the default pollutant concentrations for urban source nodes in MUSIC versions prior to 6.2pollutant concentration parameters as the prior default 'Urban' values. For all other Zoning/Surface types, the pollutant concentration parameters are Sydney Catchment Authority (2012).
Table 1. Default pollutant concentrations for each source node
Source Node Type
|Pollutant Concentration (log mg/L)|
|Total Suspended Solids||Total Phosphorus||Total Nitrogen|
|Base Flow||Storm Flow||Base Flow||Storm Flow||Base||Storm|
|Mean||Std Dev||Mean||Std Dev||Mean||Std Dev||Mean||Std Dev||Mean||Std Dev||Mean||Std Dev|
The default urban parameters were the basis for guidelines such as the Victoria Stormwater Committee (1999) BPEM Guidelines : Stormwater. It is generally recommended that these are adopted when modelling for the purposes of demonstrating compliance with this guideline. This is because using other landuse/surface types will result in larger/smaller treatment systems being required. The percentage reductions set in the guidelines combined with the 'diminishing returns' effect as concentrations decrease mean that if the starting point concentrations are lower, treatment to a percentage reduction will be harder to achieve and the required treatment size will be larger. Conversely, higher concentrations will typically require a smaller treatment system.
The Mean and Standard Deviation values displayed in the text boxes are displayed as the Log of the concentration in mg/L. Concentrations in the normal domain are displayed on the schematic distribution graphs on the dialogue box.
- Mean: A constant value set at the value displayed in the Mean text box; or
- Stochastically Generated: A stochastically generated concentration whose mean and standard deviation will be consistent with those displayed in the Mean and Standard Deviation text boxes.
Changing the Mean and Std Dev of the Log concentrations in the text boxes will change the corresponding concentration values displayed on the accompanying graph.
The default autocorrelation coefficient is set to zero to allow the same model run by different users to produce the same magnitude of loads, however you can specify the auto correlation coefficient if required (say if needing to calibrate against measured concentration data) and should use the values as set out in the table below:
It is important to note that the autocorrelation coefficient will not significantly affect the treatment train effectiveness produced by music, but simply ensures that the variation over time in concentrations during storm events and baseflow conditions is more ‘realistic’. Depending on the time-step and coefficient used, there can be variations in mean annual loads for the same model run on different computers, however the maximum difference is usually within 10% of the previous run.
Serial correlation (also called autocorrelation) is the correlation between pollutant concentration at time t, and the previous time-step, t-1. music does not model autocorrelation for lag periods of more than one time-step.